, Alberto J. Espay2, Alfonso Fasano3 and Francesca Morgante4
(1)
Neurology Department, King’s College Hospital NHS Foundation Trust, London, UK
(2)
James J. and Joan A. Gardner Center for Parkinson’s Disease and Movement Disorders, University of Cincinnati, Cincinnati, Ohio, USA
(3)
Division of Neurology, University of Toronto Morton and Gloria Shulman Movement Disorders Clinic and the Edmond J. Safra Program in Parkinson’s Disease Toronto Western Hospital, UHN, Toronto, Ontario, Canada
(4)
Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
8.1 Disorders of Speech
8.1.1 An Introductory Note
Communication disorders can have a great impact on quality of life, as they cause changes in self-identity, relationships, social and emotional disruptions as well as feelings of stigmatization; thus, these changes cause individuals to be vulnerable to social isolation [1]. In children, these can also lead to emotional and behavioural problems, which affect access to education and socialization.
Communication disorders are classified as non-neurologic (e.g. structural defects such as cleft palate or glossectomy) and neurologic, which are further divided into disorders of language and disorders of speech. The complexity of communication can be affected at several levels, thus explaining why speech disorders are common but highly non-specific.
Speech disorders are disorders of movement among which dysarthria is the most common, followed by dysphonia, mutism, stuttering and aprosodia. After dysarthria, aphasia, a disorder of language, is the most common disorder of communication and will only be briefly mentioned in the differential diagnosis.
8.1.1.1 Anatomy of Speech
The anatomy of language and its syntactic aspects (which largely depend on circuits involved in working memory) will not be discussed as it falls outside the scope of this chapter (for a review, see [2]).
Words are composed by sound elements called phonemes, whose representations are thought to be stored in parts of the left inferior frontal cortex and are independent from their semantic meanings. Phonemes are activated and transformed into a speech motor programme consisting of consonant and vowel sounds. This process passes through two steps: planning, i.e. the formulation or recall of a general representation (‘engram’) of speech units, and programming, i.e. the correct and coordinated activation of different learned motor sequences (subprogrammes) which provide specific parameters for muscular groups. Premotor area and supplementary motor area (SMA) of the language-dominant hemisphere are involved in planning function. Premotor cortex is mainly involved in choosing between competing programmes. SMA is considered to play a crucial role in the preparation of internally driven movements and in initiation of spontaneous speech, control of rhythm, phonation and articulation. Moreover, since in speech production emotionally driven output reaches its highest expression, it is conceivable that limbic structures, together with the right hemisphere, might play a key role.
Speech is a very complex human task requiring the synchronous and timely contraction of many muscle groups associated with respiration (responsible for the correct coordination of voluntary air emission), phonation (depending upon the glottal flow produced by vocal folds’ vibration), resonance and articulation [3]. Resonance is the process through which sounds are amplified and modified by the vocal tract resonators (mouth cavity, velopharyngeal structures, nasal cavities), and the different vowel sounds are determined by the varying shape and width of the resonance cavity, which depend upon lip and tongue position. Articulation denotes the modification of sounds that lead to the production of recognizable words, through the complex coordination of the vocal tract articulators (the tongue, soft palate, and lips); at this level, primary sounds produced by phonation are transformed into consonants.
Speech production requires the proper function of cranial nerves V, VII, IX, XI and XII as well as of spinal nerves supplying muscles of respiration, i.e. the phrenic and intercostal nerves. Speech muscles, apart from those of respiration, are innervated by the cranial nerves arising from the bulbar region (the pons and medulla oblongata) of the brainstem. These neurons are under fine control of the upper motor neurons primarily located within the precentral gyrus and premotor cortex of both hemispheres. The control exerted by the upper motor neurons over the brainstem effectors is modulated by the basal ganglia and the cerebellum. The basal ganglia (especially the left putamen) control scaling and automaticity of the muscles involved in voice production. The cerebellum ensures that voice production is smoothly and accurately executed. Like any other movement, speech physiology also relies on the sensory system, especially the auditory, as clearly shown by speech motor disorders associated with congenital deafness.
8.1.2 How to Recognize
Voice assessment relies on physician experience in appreciating the perceptual qualities of patients’ speech output. Clinical tool and clinician-based voice assessment questionnaires are also available (Table 8.1).
Table 8.1
Clinical tool and questionnaires for the evaluation of dysarthria
Scale | Description |
|---|---|
GRBAS | Assessing: Grade (i.e. overall severity of dysphonia), roughness, breathiness, asthenia and strain |
Frenchay Dysarthria Assessment | Based on the examination of a series of tasks performed by the patient on command, covering areas such as reflexes, respiration, lips, jaw, palate, vocal cords, tongue and intelligibility |
Robertson Dysarthria Profile | Surveying performance on respiration, phonation, facial musculature for articulation, articulation, intelligibility |
Intelligibility of Dysarthric Speech | Involving the procedure of audiotaping randomly selecting words or sentences and also assessing speaking rate, rate of intelligible speech and communication efficiency ratio |
Voice Handicap Index | Assessing the impact of dysarthria on patient’s functioning |
Voice-Related Quality of Life Index | Assessing the impact of dysarthria on patient’s quality of life |
8.1.2.1 Dysarthria
Dysarthria (defined as anarthria in its most severe form) is a motor speech disorder, historically used to describe a group of conditions causing disturbances in muscular control of the speech mechanism due to the impairment of motor processes involved in speech execution [4]. The modern definition of dysarthria is ‘a speech disorder characterized by dysfunction in the initiation, control and coordination of the articulatory structures involved in speech output’.
Few studies have addressed the incidence and prevalence of dysarthria. Overall, 90 % of adults with motor neuron disease [5], up to 90 % of adults with advanced Parkinson’s disease (PD) [6] and 40 % of children with cerebral palsy [7] may have an associated speech disorder, generally dysarthria. Twenty percent of all stroke patients may present with dysarthria [8], but this percentage rises to 30 % in strokes of the internal capsule [9].
Many other conditions that have an impact on respiration, phonation, resonance, articulation or prosody might cause dysarthria. Regardless of the underlying aetiology, speech will have lower quality and reduced intelligibility. Several classification systems have been proposed.
Dysarthria can be classified according to the timing of onset as:
1.
Congenital, associated with developmental disorders due to brain damage before or during birth (Table 8.2 describes the milestones of speech and language development).
Table 8.2
Principal developmental milestones of axial functions
Time | Speech and language | Stance and balance | Locomotion |
|---|---|---|---|
1 m | When held upright, holds head erect and steady | ||
2 m | Vocalizes sounds—gurgling and cooing | Holds head up for short periods | |
3 m | Laughs | Holds head steady | |
4 m | Holds head up steadily Can bear weight on legs | ||
5 m | Can roll over | ||
6 m | Rolls in both directions | ||
7 m | Imitates speech sounds | Sits without support Reaches for things | |
8 m | Says ‘dada’ and ‘mama’ to both parents (is not specific) | Begins to crawl | |
9 m | Combines syllables into word-like sounds | Stands while holding onto something | |
10 m | Crawls Cruises | ||
11 m | Says ‘dada’ and ‘mama’ to the right parent | Stands alone for a couple of seconds | |
12 m | Jabbers word-like sounds | Walks holding on to furniture | |
13 m | Uses two words skilfully (e.g. ‘hello’ and ‘bye’) | Bends over and picks up an object Stands alone | |
15 m | Walks backwards | ||
17 m | Uses a handful of words regularly | Likes riding toys | |
18 m | Can walk alone Walks up a few stairs holding hand | ||
19 m | Runs | ||
21 m | Can walk up steps alone | ||
23 m | Can use 50 single words | ||
24 m | Half of speech is understandable Can make short sentences | Walks up and down stairs 2 feet per step | |
27 m | Speaks clearly most of the time | Jumps up off the ground | |
33 m | Carries on a conversation of two to three sentences | ||
3y | Uses four to five words in a sentence Constantly asks questions. Speaks in sentences | Goes up stairs 1 foot per step and downstairs 2 feet per step | |
4y | Many infantile substitutions in speech | Hops and stand on 1 foot for up to 4 s | Goes down stairs 1 foot per step, skips on 1 foot |
5y | Fluent speech with few infantile substitutions in speech | Skips on both feet and hops | |
6y | Fluent speech |
2.
Acquired later in life, e.g. after a stroke or a head injury (static) or in the context of a degenerative neurological disease (progressive); the majority of patients with progressive neurological diseases will experience dysarthria during the course of the disease.
Since dysarthria can result from damage at different levels of the central and peripheral nervous system, in the 1950s, Peacher [10] and Grewel [11] classified dysarthria on the basis of lesion topography. However, the most commonly used classification was developed by the Mayo Clinic in 1969, which recognizes six major types of dysarthria (Table 8.3) [4]. This was based on short speech samples taken from 30 patients in each of seven discrete neurological groups, each patient having been unequivocally diagnosed as being representative of that diagnostic group. Three experts independently rated each of these samples on each of 38 dimensions of speech and voice using a 7-point scale of severity and classified dysarthria according to the area of the nervous system implicated.
Table 8.3
Etiological classification of dysarthria
Type | Voice quality | Part of nervous system implicated | Associated findings | Note | Diseases |
|---|---|---|---|---|---|
Flaccid | Weak and breathy, hypernasality, consonant imprecision, reduced phonation time, liquid-sounding (phonation is accompanied by a gurgle) | Lower motor neuron (nuclei, roots or axons) of cranial nerves V, VII, IX, XI and XII and phrenic and intercostal nerves | Lips: poor seal, abnormality at rest, abnormality of spread, dribbling of saliva Palate: asymmetry at rest and during activation Tongue: weakness abnormality at rest, fasciculation, poor alternating movements Pharynx: dysphagia Vocal cords: dysphonia | Speech characteristics vary according to the nerves and muscles affected and the associated weakness and reduced muscle tone. Some aspects of speech may be normal | Bulbar palsy (brainstem stroke, trauma, poliomyelitis, basilar meningitis); neuropathies (Guillain–Barré syndrome); myasthenia gravis |
Spastic | Strained, strangled, harsh, poor control of the volume, hypernasal, slow, consonant imprecision, poor intonation | Upper motor neurons (precentral gyrus and premotor cortex) and their descending axons (running into the internal capsule and the cerebral peduncles) | Slowing and weakness of bulbar musculature (e.g. reduced palatal elevation or alternating movements of the tongue, dysphagia, bilateral facial paralysis, dysphonia). Little muscle atrophy apart from that associated with disuse Presence of pathological reflexes (sucking reflex, hyperactive jaw reflex). Emotional liability | Unilateral lesion (usually dominant hemisphere): mild and transient impairment of speech Bilateral lesion: severe and permanent dysarthria | Unilateral stroke. Bilateral stroke (pseudobulbar palsy) Primary lateral sclerosis |
Ataxic | Harshness of vocal tone with monopitch, excess and equal loudness and prosodic stress with breakdowns (‘scanning speech’); tremor; irregular articulator with imprecise consonant production and distorted vowels; prolonged phonemes and intervals; slow rate | Cerebellum (especially the vermis) | Clinical signs of cerebellar dysfunction (especially gait, balance and eye problems) | Stroke, multiple sclerosis, spinocerebellar ataxias (SCA) | |
Hypokinetic | Breathy, monotone voice (monopitch and monoloudness) with reduced loudness. Articulation tends to be imprecise | Basal ganglia | Parkinsonism (particularly associated with hypomimia and axial motor problems, e.g. freezing of gait) | Often associated with speech festination or palilalia | Degenerative or vascular parkinsonisms |
Hyperkinetic | Strained hoarseness and inappropriate voice arrests; prolonged phonemes; variable rate (too fast and/or too slow); tremulous | Basal ganglia | Dystonia, chorea, myoclonus, tremor and other dyskinesias | Heterogeneous range of speech characteristics resulting from involuntary movements that disturb the rhythm and rate of motor activities | Huntington’s disease and other choreas; oromandibular dystonia; laryngeal dystonia; essential tremor |
Mixed | Highly variable, in general similar to spastic dysarthria accompanied by a wet sounding voice with rapid tremor Another type is hypokinetic dysarthria accompanied by rapid speaking rate | Damage in more than one area and resulting in speech characteristics of at least two groups | Variable depending on the underlying pathology | Different subtype Spastic–flaccid Ataxic–spastic Ataxic–spastic–flaccid | Amyotrophic lateral sclerosis, multiple strokes, multiple sclerosis, Wilson’s disease, multiple system atrophy |
Stroke is the most common cause of dysarthria, which may be the first and only clinical manifestation of ischemia, as in case of lacunar syndromes (‘pure motor hemiparesis’, ‘ataxic hemiparesis’, ‘dysarthria-clumsy hand syndrome’). A ‘pure dysarthria’ syndrome has been also described. Almost 90 % of non-cerebellar strokes causing dysarthria are left-sided, and severity of dysarthria is generally worse with left-sided lesions [13]. A prospective study of patients with ischemic stroke and dysarthria without aphasia found that 82 % of patients reported no ongoing difficulties at 6 months post-stroke [13].
Pseudobulbar palsy (also known as supranuclear bulbar palsy) is a syndrome associated with bilateral upper motor neuron damage, and it is associated with many different neurological disorders—stroke in most cases—bilaterally disrupting neural signals to the cranial nerves (Table 8.3 for symptoms).
Dysarthria can emerge at any stage of PD and tends to worsen in later stages. PD-associated speech may include any or a combination of the following: hypophonia (low voice volume and vocal decay), dysphonia (a breathy, hoarse or harsh voice quality), hypokinetic articulation (imprecise consonants and vowels due to reduced range of articulatory movements), dysprosodia (reduced voice pitch inflections or monotone speech) and dysrhythmia (palilalia with festination, dysfluency, hesitancy or stuttering) [14]. A close correlation between temporal features of parkinsonian speech and gait (e.g. speech and gait festination) has been reported by different studies; these features appear not influenced by deep brain stimulation (DBS) or levodopa [15, 16].
Speech is particularly affected in atypical parkinsonisms. Patients with multiple system atrophy (MSA) frequently present with a mixed dysarthria with ataxic–spastic features, frequently accompanied by dysphonia due to motor involvement of the vocal cords. Patients with progressive supranuclear palsy (PSP) frequently have festination and palilalia, abnormalities believed to be localizable to the pallidum. Parkinsonian voice might be indirectly impaired by associated problems such as drooling and tremor or dystonic postures of head, jaw, lips and tongue.
Childhood apraxia of speech (or developmental verbal dyspraxia) is a rare developmental disorder involving the acquisition of coordinated movements needed for speech; it is typically accompanied by additional deficits in both oral and written language function. Heterozygous mutations of the transcription factor FOXP2 have been confirmed by multiple additional reports [17]. Other communication impairments may co-occur, with dysarthria also commonly noted.
Speech sound disorder is another rare condition characterized by difficulties with the production and proper use of specific speech sounds (most commonly omission or substitution of a small number of specific sounds). It is common in young children and persists in 4 % of 6-year-olds. This condition has diagnostic overlaps with other developmental speech disorders and has been associated with a specific candidate gene (FOXP1), which is also implicated in various conditions, including dyslexia, intellectual disability and autism spectrum disorder.
Functional dysarthria is frequently presented by patients with other functional disorders and sometimes helps the diagnosis of accompanying symptoms of unclear nature; in most cases it is characterized by a mixture of stuttering and aphonia. A striking feature is represented by the occurrence of episodic mutism and/or the high variability and distractibility of the vocal production.
8.1.2.2 Dysphonia
Dysphonia (aphonia in its most severe form) is defined as a disturbance of phonation; therefore, it indicates the involvement of the vocal cords due to different (either local or neurological) causes. Spasmodic dysphonia is sometimes incorporated within the classification of dysarthric disorders; however, it is generally considered to be more closely related to the pathology of focal dystonia (see Chap. 6). Dystonia of vocal cords might complicate recovery from spastic dysarthria and, as such, can be a form of secondary dystonia.
8.1.2.3 Dysprosody
Dysprosody (aprosodia in its most severe form) is defined as a disturbance of prosody, which is the term applied to the inflectional melodic quality of speech, also carrying information that is not explicitly linguistic (e.g. the intonation used for questions or sarcasm). It is non-specific but frequently seen after unilateral lesions in the motor cortex or basal ganglia (especially putamen). Historically, it was considered a function of the right hemisphere, but most cases are actually associated with left hemispheric lesions.
Foreign accent syndrome is a form of dysprosody characterized by normal speech and language with a disturbed inflection in such a manner that speech is reminiscent of a non-native speaker; it can be caused by lesion in the left putamen, motor cortex, frontal white matter or frontal motor convexity.
8.1.2.4 Mutism
Mutism is the term used to defined a complete loss of speech in a conscious subject with no clear organic lesions (functional mutism) or, more rarely, with lesions of the neuraxis (organic mutism).
Functional mutism is commonly seen in psychosocial conditions (e.g. ‘selective mutism’, which is the refusal or withholding of speech in situations in which speech is expected, e.g. school, despite speaking in other situations), psychosis (e.g. as a negative sign in schizophrenia), catatonia or autism.
Organic mutism might be subdivided into three types, according to the area of the nervous system affected:
1.
Cortical: lesion of Broca’s area (often at the onset of a motor aphasia or in the context of a global aphasia), diffuse bilateral lesions (pseudobulbar palsy), SMA or anterior cingulate gyrus (ACG).
2.
Subcortical structures: lesions of any part of the dentato-thalamo-cortical pathway (e.g. post-thalamotomy in PD patients or cerebellar mutism); bilateral lesions of the mesencephalic reticular formation in the ventral tegmental area (akinetic mutism) or of its projections to the SMA/ACG, through the lateral hypothalamus or through frontal white matter. Mutism has been described in young patients with rapid-onset dystonia–parkinsonism due to ATP1A3 mutations, along with motor delay and ataxia [18]. Cerebellar mutism is mainly seen in children but there are also reports in adults; it usually appears 1–6 days after posterior fossa surgery in children with cerebellar or fourth ventricle tumours. Other causes of mutism (even in the absence of lesions in the above-mentioned areas) are autoimmune or infective/postinfective encephalopathies [anti-NMDA (N-methyl D-aspartate) receptor antibody encephalitis, lupus, HIV or subacute sclerosing panencephalitis]. Other causes that have been reported are hematomas, arteriovenous malformations, tumour and traumas of the posterior fossa, especially when the right cerebellar hemisphere is involved.
3.
Peripheral nervous system: bilateral pharyngeal or vocal cord paralysis.
In most cases mutism is reversible. Exceptions include patients with autism or with severe involvement of peripheral nervous system (e.g. neurotmesis of laryngeal nerves). Patients recovering from organic mutism have normal speech production and normal language, although they may talk very slowly, with short sentences (e.g. just yes or no). Cerebellar mutism usually lasts from a few weeks until 6 months, but can be followed by severe dysarthria.
Dysrhythmic disorders of speech are disorders of speech automaticity and rhythm and comprise different phenomena (stuttering, festination, palilalia, echolalia).
Stuttering is ‘a disturbance in the normal fluency and time patterning of speech that is inappropriate for the individual’s age’, as defined by the Diagnostic and Statistical Manual of Mental Disorders.
Three forms are recognized:
1.
Developmental stuttering (DS) is the most common form, affecting at least 5 % of children with a gradual onset generally between the ages of 3 and 8 years (male-to-female ratio is about 2 to 1). It generally resolves before adulthood (up to 80 % of those who stutter will recover spontaneously by puberty without the intervention of professional treatment) [19]. In adults with persistent DS, men are five times more affected than women. Anxiety worsens DS while singing, reading aloud and speaking alone lessen dysfluency. Secondary behaviours (such as eye blinking, jaw or nose jerking and head movements) are typical features of DS, possibly developed as strategies to minimize the severity of stuttering.
An early study on monozygotic twins found that 70 % of DS was linked to genetics [20]. The first genes to be associated with DS are those involved in the lysosomal enzyme-targeting pathway: N-acetylglucosamine-1-phosphate transferase (GNPTAB), GNPTG and NAGPA [21]. Mutations in these genes have been found in less than 10 % of unrelated stutterers with familial history; different chromosomal regions have been identified in other cases. How these deficits result in the presumed speech-specific neuropathology associated with stuttering is not yet known. Researchers have hypothesized that stuttering mechanisms may include a lysosomal malfunction, where there is reduced efficiency of lysosomal targeting catalytic enzymes. Notably, mutations in GNPTAB and GNPTG are known to also cause mucolipidosis types II and III.
Studies looking into pathophysiology have shown that patients with stuttering show a right hemisphere dominant profile of activation during speech, possibly due to a compensatory mechanism for a deficit located in the speech-dominant left hemisphere. Accordingly, pathology and neuroimaging studies (diffusion MRI) found abnormalities in gyrification patterns in Broca’s and Wernicke’s areas as well as white matter tract anomalies below the somatotopic representations of the larynx and the tongue. Another hypothesis is that DS results from a neuromotor dysfunction involving dopamine receptors, as shown by higher fluorodopa uptake in the ventral limbic cortical and subcortical regions of patients with moderate to severe DS, compared to non-stuttering control subjects.
2.
Neurogenic stuttering typically results from acquired disorders of the brain, such as stroke, basal ganglia diseases (as in PSP; see below), or other developmental disorders, such as Down syndrome (which can present with rates between 10 and 45 %). Lesions of left motor thalamus (ventrolateral nuclei), which receives direct cerebellar and pallidal efferent projections, may lead to perseveration on the first syllable of words or stuttering speech. Stuttering has been documented after thalamic DBS (either Vim or CM), globus pallidus pars interna (GPi) or subthalamic nucleus (STN), especially for those patients who had DS in their childhood [22]. In other cases, DBS has been found beneficial.
3.
Functional (psychogenic) stuttering begins suddenly after emotional trauma or stress; also occurs in patients with history of psychiatric illness [23].
Festination is characterized by a rapid and accelerating rate of speech. It is typically seen in basal ganglia lesions or disorders (PSP in particular), and it often coexists with gait problems (festination of gait) and other speech disorders, particularly hypophonia and palilalia.
Palilalia is rapid speech with uninhibited repetition of syllables, words or phrases; it sometimes referred to as autoecholalia, i.e. the compulsive repetition of utterances. Lesions restricted to the external portion of the globus pallidus can lead to palilalia.
Echolalia is defined as the automatic repetition of sounds, words (also known as echologia) or phrases (or echophrasia); along with echopraxia, it belongs to the category of echophenomena, automatic imitative actions without explicit awareness.
Imitation and emulation are healthy phenomena in child development, as they promote learning. However, echolalia persisting beyond the age of 3 years is considered pathological, and it is typically seen in Gilles de la Tourette syndrome or within the autism spectrum disorders (see Chap. 3). Other less commonly associated conditions are transcortical aphasias (Table 8.4), psychosis, catatonia, abnormal startle reactions, epilepsy and dementias.
Table 8.4
Major characteristics of different types of aphasia
Type of aphasia | Repetition | Naming | Auditory comprehension | Fluency |
|---|---|---|---|---|
Non-fluent (or expressive) | Mod–severe | Mod–severe | Mild difficulty | Non-fluent, effortful, slow |
Fluent (or receptive) | Mild–severe | Mild–severe | Defective | Fluent paraphasic |
Conduction | Poor | Poor | Relatively good | Fluent |
Mixed transcortical | Moderatea | Poor | Poor | Non-fluent |
Transcortical motor | Gooda | Mild–severe | Mild | Non-fluent |
Transcortical sensory | Gooda | Mod–severe | Poor | Fluent |
Global | Poor | Poor | Poor | Non-fluent |
Anomic | Milda | Mod–severe | Mild | Fluent |
Echolalia can be further classified as follow: ‘Mitigated echolalia’ is used when the original stimulus is repeated with modifications. The term ‘ambient echolalia’ describes the inclination to automatically repeat words from the surrounding environment, which are usually neutral to the patient. ‘Speech prompt catatonia’, also referred to as echoing approval, describes a form of echoing speech readiness or impulsivity in a brief, reflex-like manner; another classification includes immediate or delayed, semi-communicative or communicative echolalia (for a review, see [24]).
8.1.3 How to Distinguish from Related Disorders
The nature of the speech disturbance usually reflects the underlying pathology and if correctly identified can be of great assistance in the differential diagnosis. For instance, the speech characteristics of flaccid dysarthria reflect the effects of weakness of the bulbar musculature. Therefore, the clinician’s hearing is an excellent diagnostic instrumental and can easily diagnose most of the aforementioned conditions. Visual inspection is also important when it comes to observation of body posture and movement (e.g. in case of DS). Table 8.5 lists the clinical approach to patients with speech motor problems. Accompanying signs are also important for the etiological diagnosis, e.g. resting tremor in the case of parkinsonian dysarthria or acute hemiparesis in the case of stroke.
Table 8.5
Clinical approach to patients with speech motor problemsa
Tasks | Aim | |
|---|---|---|
Assessment of orofacial muscles involved in speech during non-speech activity | Strength, symmetry, range, tone, speed, coordination and accuracy; during rest, sustained posture and movement | Oral motor examination to rule out involvement of bulbar muscles, nerves or nuclei |
Isolated oral movements | Stick out your tongue Bite your lower lip Pucker your lips Lick your lips Clear your throat Cough | Determine the presence or absence of an oral, nonverbal or buccal–facial apraxia |
Oral motor sequencing | For example, ‘Show me your teeth, then pucker your lips, then bite your lower lip, then open your mouth, then puff out your cheeks’ | |
Vowel prolongation | /a/ /i/ /u/ as long/loud/high/low as possible; with high and low pitches | Respiratory support (depending on the length of vowel prolongation and loudness) Voice quality (normal, hoarse, harsh, breathy) Integrity of the larynx (modulating the pitch) Tremor occurrence |
Repeating monosyllables | /p/ /t/ /k/ as fast, clearly, steady as possible; self-paced or paced at different frequencies | Articulation: precision with the lips (p), tongue to alveolar ridge (t), tongue to palate (k) |
Repeating combined monosyllables | /p – t – k/ as fast, clearly, steady as possible; self-paced or paced at different frequencies | Articulation: precision with the lips (p), tongue to alveolar ridge (t), tongue to palate (k) Rate and regularity |
Repeating multisyllabic words or sentences | For example, artillery, impossibility (the same word n times) | Voice quality (hoarse, harsh, breathy) Articulation (e.g. sound spr-, pl-) Regularity (rhythm) and prosody Consistency of productionb |
Normal speaking | Read aloud or describe a picture (e.g. cookie theft or picnic picture) or converse | Size and modulation of pitch and loudness Intelligibility Speech ratec Language: phonological/phonetic/semantic paraphasias, syntactic errors, intelligibility |
The differential diagnosis includes other neurological disorders of communication.
Apraxia of speech (AOS) is defined as an articulatory disorder resulting from impairment of the capacity to programme the positioning of speech musculature and the sequencing of muscle movements for the volitional production of phonemes. The speech musculature does not show significant weakness, slowness or incoordination in reflex and automatic acts to account for the speech impairment. Apraxia of speech is a controversial entity because it is, for many speech experts, an integral part of aphasia, representing a phonological selection disorder; others believe that it is a phonetic—i.e. motor—disorder [25]. Nevertheless, AOS may be the used to define patients with communicative disorders in the overt absence of language (i.e. aphasia) and articulatory (i.e. dysarthria) problems, even when many cases also have (or will soon develop) aphasia and dysarthria.
Salient signs for identifying AOS are:
1.
Effortful trial and error, grouping articulatory movements and attempts at self-correction (the patient recognizes the error)
2.
Dysprosody unrelieved by extended periods of normal rhythm, stress and intonation (not clear if part of primary disorder)
3.
Articulatory inconsistency (different types of errors and even normal trials) on repeated productions of the same utterance (‘phonetic variability’)
4.
Difficulty initiating speech
Common causes are lesions in the dominant hemisphere (Broca’s area extending into the anterior insula). In recent years, it has been recognized that AOS can be caused by the same neurodegenerative processes causing slowly progressive conditions, such as primary progressive (non-fluent/agrammatic) aphasia. Recent studies have confirmed that AOS can evolve independently of any other neurological deficits (primary progressive AOS), with pathologic changes in the superior premotor and supplementary motor areas [26]. Interestingly, some of the reported patients later developed signs of PSP, frontotemporal lobar dementias or corticobasal syndrome (CBS) and also displayed other forms of nonverbal orofacial apraxias [27]. Most patients have been found with tau or ubiquitin/TDP43 pathology.
Aphasia is a disorder of language defined as the loss or impairment of the power to use words as symbols or ideas that results from a brain lesion. Aphasia is the second most common disorder of communication after dysarthria. Depending on the underlying lesion, different types have been described (Table 8.4). For the purpose of this chapter, non-fluent (also known as agrammatic or Broca’s aphasia; previously known as motor or expressive) aphasia needs to be distinguished from speech disorders. In non-fluent aphasia, the word form production (output or phonological lexicon) is affected due to lesions within Broca’s area in the dominant hemisphere (Brodmann areas 44 and 45). Therefore, patients may have an impairment of ordering phonemes in each word (e.g. ‘mobiketor’ instead of ‘motorbike’, phonemic paraphasias) or in the selection of sounds required to produce phonemes (e.g. ‘tar’ instead of ‘car’, phonetic paraphasias). Sometimes, patients have difficulties in accessing the right word and pick one belonging to the same semantic concept (e.g. ‘motorbike’ instead of ‘car’, semantic paraphasias). The combination of these paraphasias might lead to the production of totally unrecognizable words (neologistic paraphasias).
By far, the most common causes of non-fluent aphasia are strokes, whereby an acute onset is the key historical clue, followed by the same focal neurodegenerative diseases described for AOS, in which the onset is rather insidious.
8.1.4 How to Reach a Diagnosis
Additional biometric information on voice may be gathered using aerodynamic measures (e.g. peak flow), neurolinguistic and acoustic analysis with dedicated voice analysis software. Surface electromyography has been also proposed for speech and respiration analysis.
Virtually all patients with dysphonia should undergo an inspection of their larynx and vocal cords via laryngoscopy with assessment also during phonation (e.g. stroboscopy). Neuroimaging may identify patients with acute ischemic stroke (particularly by means of diffusion-weighted MRI) or other structural lesions. When a vocal cord paralysis is seen, the radiologist’s attention should be directed towards the neck and thorax, looking for conditions (neoplasms or aneurysms) affecting the laryngeal nerves.
8.1.5 How to Treat
There is a paucity of evidence-based treatments for dysarthria. While there has been a considerable amount of research done related to the treatment of dysarthria associated with various conditions, most studies have included few subjects with variable baseline features.
Whenever possible, the first step is to treat the medical condition underlying the speech disorder (e.g. cholinesterase inhibitors for myasthenia gravis, plasma exchange or IV immunoglobulin for autoimmune neuropathies). As for PD, it is known that levodopa has a modest effect on hypophonia and almost no effect on speech rate and syllable repetition capacity [14]. Botulinum neurotoxin is effective for the treatment of spasmodic dysphonia and for voice tremor. Functional neurosurgery is generally ineffective in movement disorders, and it often worsens (or induces) hypophonia or stuttering. Regardless of the target, bilateral DBS causes more frequently dysarthria than unilateral procedures.
When the aforementioned treatments do not help, a number of specific surgical treatments directed at specific symptoms of dysarthria might be considered, e.g. pharyngeal flap or sphincter pharyngoplasty procedure to reduce hypernasality or thyroplasty to improve voice quality in vocal cord paralysis or weakness. Prosthetics might also have a role, such as palatal lift prosthesis providing velopharyngeal closure that reduces hypernasality associated with some flaccid dysarthrias or augmentative and alternative communication (AAC). AAC refers to any system of communication that is used to supplement or replace speech. This could range from ‘low-tech’ aids such as signing systems, drawing and writing or communication books to ‘high-tech’ aids such as computerized voice output communication aids, e.g. voice amplified to increase loudness in parkinsonian patients.
Most patients with dysarthria might benefit from behavioural and—especially—rehabilitative methods. However, there have been no published randomized controlled trials to support or refute the effectiveness of speech and language therapy for dysarthria following nonprogressive brain damage [28]. A more recent Cochrane review concluded that there is insufficient evidence to conclusively support or refute the efficacy of the Lee Silverman Voice Treatment (LSVT) for the dysarthria of PD [29]. LSVT mainly relies on biofeedback and respiratory support methods and has been found to be particularly beneficial for PD-related dysarthria in small randomized controlled trials [30, 31].
Behavioural communication interventions based on techniques for management of respiratory/phonatory, biofeedback or orofacial and articulation exercises have been found beneficial in stroke patients.
Speech supplementation strategies can improve intelligibility regardless of the underlying aetiology of dysarthria; these might include alphabet supplementation (where the speaker points to the first letter of each word as it is spoken), semantic or topic supplementation (where the listener is provided with information on the topic area prior to the communication) or a combination of different supplementations.
Computer-based interventions could be effective in patients with dysarthria because they provide feedback and allow individual practice.
In general, speech and language therapy can be used to encourage patients to use their existing speech more effectively, to increase the range and consistency of sound production, to teach strategies for improving intelligibility and communicative effectiveness, to guide the individual to use methods that are less tiring and more successful and to introduce the appropriate AAC approaches if and when required. The aims and objectives of speech and language therapy will depend on the type, nature and severity of the dysarthria; the underlying cause; whether it is acute or progressive; and the communication needs of the individual.
Therapy techniques include strategies to improve respiratory support, phonation and resonance. These involve exercises to reduce muscle weakness and to improve range, consistency and strength of movements of the oral and vocal musculature. Approaches to improve intelligibility may include exercise for pausing, pacing and exaggerating articulation. Advice regarding behavioural and environmental modification can improve communicative effectiveness, which includes techniques that support speech by adding facial expression and gesture, along with being aware of reducing competing noise.
Treatment of stuttering deserves a separate discussion. A systematic review found strong evidence only for clonidine. In light of the presumed overactivity of dopaminergic receptors, a number of neuroleptics (risperidone, olanzapine, tiapride, haloperidol and chlorpromazine) have been tried with some positive results. Pagoclone, a nonbenzodiazepine γ-aminobutyric acid modulator, has shown a reduction in percentage of syllables stuttered when compared to placebo. Selective serotonin reuptake inhibitors (and particularly paroxetine and sertraline) have been found useful in small studies.
Speech therapy remains the first-line treatment method of choice. A meta-analysis found habit reversal training to be an efficacious intervention for a wide variety of maladaptive repetitive behaviours, including stuttering. Other treatments include the fluency-shaping method, which relies on a delayed auditory device, the Lidcombe approach, where parents use a form of operant environmental conditioning to enhance their child’s fluency.
8.2 Disorders of Stance
8.2.1 An Introductory Note
Posture, balance and gait are closely interconnected. Control of axial tone is necessary for maintaining upright stance (Fig. 8.1), and lateral weight shifts are needed to free up the swing leg and initiate a step [32].
Fig. 8.1
The physiology of upright stance. (a) Body orientation can be classified according to the three-dimensional axes: X is the frontal axis (coronal, medio-lateral, lateral) perpendicular to the sagittal plane (anteroposterior); Y is the vertical axis (longitudinal, long) perpendicular to the transverse plane (axial, horizontal); Z is the sagittal axis (anteroposterior), perpendicular to the frontal plane (coronal, lateral). (b, c) The centre of mass (COM) of a distribution of mass in space is the unique point where the weighted relative position of the distributed mass sums to zero. In analogy to statistics, the COM is the mean location of a distribution of mass in space. The centre of pressure (COP) is the term given to the point of application of the ground reaction force (GRF) vector. The ground reaction force vector represents the sum of all forces acting between a physical object and its supporting surface. During quiet stance COM projection on the ground falls on the COP. Base of support (BOS) is the area beneath an object or person that includes every point of contact that the object or person makes with the supporting surface. These points of contact may be body parts, such as feet or hands, or they may include things like crutches or the chair a person is sitting in. (d) Sway can be measured by a force plate, which detects fluctuations of the COP, or by accelerometers, which detect fluctuations of the body COM (not shown). The variation in sway can be characterized by a number of variables such as sway area, velocity, frequency and maximum direction of sway (Courtesy of Eng. Martina Mancini, Portland, Oregon, USA)
The physiology of postural control, especially in the upright position, is complex and takes several years to develop (Table 8.2). Postural control comprises different components (Table 8.6) and relies on the delicate balance between various interacting systems: three major afferent sensory systems (visual, vestibular and proprioceptive senses), an efferent system (including nerves, muscles, bones, joints and tendons) and the strict surveillance by several structures of the central nervous system (CNS). In a healthy subject, sensory weighting largely depends on the somatosensory system (70 %), followed by the vestibular (20 %) and the visual systems (10 %). Each of these afferents has weaknesses (e.g. the optic flow cannot tell us if our own body or the environment is moving; the vestibular system only relies on head position), and therefore their contributions have to be integrated by the CNS. Sensory reweighting is the adaptive process that changes depending upon different sources of sensory input (e.g. in darkness stability mainly relies on proprioception). Such complexity is also displayed in Fig. 8.2, which describes the rapid sequence of events triggered by a perturbation.
Table 8.6
Principal components of postural control
Quiet stance | Postural alignment | The body is oriented with respect to gravity and the environment (e.g. the support surface) (Fig. 8.1). The projection of the COM on the supporting surface falls within the BOS |
Postural sway | Body is not entirely still, as there is continuous movement of the COM (Fig. 8.1). Closing the eyes or cognitive dual task while standing increase sway. COM sway is tolerated as long as its projection stays within the borders of BOS | |
Limits of stability | The maximal displacement of COM in various directions without falling or having to take a step | |
Dynamic postural control | It is required to compensate for COM changes. During gait COM shifts from side to side to successively unweight alternate legs and also moves forward beyond the anterior limits of stability (dynamic limits of stability). Thus, projection of COM is within the BOS only during the double-support time, when both feet are on the ground. Since forward instability is arrested by a step that is placed in front of the COM, gait velocity and step length are integrated in the dynamic balance process Dynamic balance relies on the following strategies Enlargement of the step width increases the BOS in the ML plane, thus increasing the chance that the projection of the COM falls within its borders (in case of ML instability, e.g. ataxia) Increment of the double-support time increases the chance that the projection of the COM falls within BOS in case of AP instability (e.g. parkinsonism) Keeping the arms outstretched and stiffening the leg muscles are unspecific mechanisms mainly seen in ataxic or cautions gait Increasing gait velocity increases the chance that the projection of the COM falls within BOS reducing the single limb support time, typically seen in vestibular diseases | |
Automatic postural adjustments (Figure 8.2) | Anticipatory postural adjustments | These are postural movements that precede voluntary actions to preserve balance in anticipation of internally generated perturbations (feedforward control) |
Reactive postural adjustments | These are movements aimed at recovering balance in response to an external perturbation (feedback control) Recognized postural strategies are Ankle strategy (fixing the joint by activation of gastrocnemius or tibialis anterior) Hip strategy (often accompanied by use of the arms) Stepping strategy (consists of taking a quick step to increase the BOS) Reaching strategy, in which the arms make contact with a support surface to increase the BOS | |
Protective reactions | These are a series of automatic responses to limit body injuries when balance is lost. A typical example is the use of outstretched arms when falling forwards; accordingly, the occurrence of wrist fractures in fallers is rather common, and it has been considered a positive sign, proving the existence of still intact and rapid protective responses | |
Fig. 8.2
Automatic postural adjustments triggered by a perturbation. The figure schematically shows the rapid succession of strategies aimed at preserving body stability after a single perturbation. When one or more stability strategies are impaired, perturbation leads to a near-fall, and when also rescue reactions are not properly working, falling is an inevitable event (see Table 8.6 for details) (From Fasano et al. [33], modified from Marsden et al. [34] and Albanese [35])
The cardiovascular system also participates to the physiology of stance, providing the ability to stand erect without collapsing by avoiding hemodynamic deprivation (see Chap. 2).
8.2.1.1 Disorders of Posture
Besides orthopaedic conditions, abnormal postures of the trunk are a typical feature of many basal ganglia disorders, particularly parkinsonism. Other neurodegenerative disorders (e.g. dementia) might present with postural abnormalities (Table 8.7). Most of these patients have a relative overactivity of flexors over extensor muscles, and hence they may present a classic stooped simian appearance, with flexion of the hips and knees, sometimes the head, and rounding of the shoulders (Fig. 8.3a). Some patients develop specific postures, namely, camptocormia (forward flexion of the trunk), anterocollis (forward flexion of the neck) and Pisa syndrome (lateral flexion of the trunk) [38]. There are no consensus criteria for the diagnosis of these conditions, but most clinicians rely on the severity of flexion (degrees) along the sagittal or coronal plane (Fig. 8.1). This also explains the great variability in studies assessing the prevalence of their associated diseases. Notably, these disorders sometimes coexist in the same individual.
Table 8.7
Proposed classification of disorders of posture based on associated featuresa
Associated features | Causes |
|---|---|
None | Functional Idiopathic (dystonia/focal myopathy?) Senile forms (with or without sarcopenia)b |
Other CNS signs | Dementias (AD, LBD, PDD)c Epilepsy (e.g. Dravet’s syndrome) Dystonia (especially generalized forms) Intracranial hypotension Normal-pressure hydrocephalus Parkinsonism (especially PD and MSA)c Tetanus Tourette syndrome |
Drug induced | Acetylcholinesterase inhibitors Amantadine Dopaminergic blockers (e.g. neuroleptics) Dopamine-enhancing drugs (including dopamine agonists, MAO-B or COMT inhibitors) Valproic acid |
Weakness | Amyloid myopathy Dermatomyositis Facioscapulohumeral dystrophy Focal myositis Inclusion body myositis Inflammatory demyelinating polyneuropathies Limb girdle muscular dystrophy Mitochondrial myopathies Motor neuron disease Myasthenia gravis Myofibrillar myopathies Myopathy with nemaline rods Myotonic myopathies (especially the proximal form) Other myositis/myopathies (e.g. paraneoplastic, hypothyroidism related, postirradiation) Polio/post-polio syndrome Polymyositis |
Fixed deformity, limited range of motiond | Atlantoaxial subluxation Ankylosing spondylitis Disc herniation Severe osteoarthritis Spinal cord pathology (e.g. syrinx, intradural hematomas) Spinal stenosis Spine fracture/malignancies/infections Scoliosis Spine malformation |
Others | Abdominal conditions (e.g. oesophageal hiatal hernia) |
Fig. 8.3
Pathological postures. (a) Typical stooped posture of a PD patient. (b) Camptocormia in PD. (c) Functional camptocormia in World War I veteran (from ‘The psychoneuroses of war’ by G. Roussy and J. Lhermitte, University of London Press, LTD & Paris: Masson Et Cie; 1918). (d) PD patient with anterocollis, which improves after a geste antagoniste, is performed. (e) PD patient with Pisa syndrome, which improves after a geste antagoniste is performed. (f) The impaired perception of the vertical position is seen in patients who do not tilt the head to obtain a horizontal visual field. (g) ‘Pillow sign’ in a patient with PD and dementia. (h) PD patient with long-standing history of Pisa syndrome and scoliosis; the latter is still visible when he lies down
The pathophysiological underpinnings of these postural abnormalities are still not fully elucidated, and different mechanisms, central and peripheral, have been taken into account (Table 8.8).
Table 8.8
Clinical, instrumental and experimental evidence supporting the central and peripheral mechanisms underlying postural abnormalities
Evidence | Note | |
|---|---|---|
Central | Response to levodopa [39] | Rarely observed (camptocormia) |
Response to deep brain stimulation | Inconsistently seen after GPi or STN surgery, it might be related to the condition’s duration (camptocormia) | |
Response to BoNT [40] | Inconsistently seen (camptocormia and Pisa syndrome) | |
Response to anticholinergics | Seen in 40 % of the patients in a retrospective series [41] | |
Occurrence of geste antagoniste | Rarely seen (Fig. 8.3d, e) | |
Rapid onset after stroke [42] | Only described for camptocormia | |
Delayed onset after unilateral pallidotomy (4–9 years after surgery) [43] | Only described for Pisa syndrome | |
Trunk deviation after unilateral lesion in the animal model (spontaneous turning ipsilateral to the lesion, contralateral to the lesion after apomorphine administration) | Observation valid for Pisa syndrome only, consistent with clinical finding that the concavity of trunk inclination is usually directed away from the most affected side. A great R/L asymmetry of motor impairment might be associated with the development of Pisa syndrome [44] | |
Onset after drugs with effects on CNS | Mainly related to Pisa syndrome, with the exception of dopamine agonists and amantadine (anterocollis), valproate (camptocormia) and neuroleptics (retrocollis) | |
EMG evidence of co-contraction | Inconsistently seen; present also in patients with evidence of muscle involvement (might represent a compensatory mechanism, physiologically activated to limit the range of trunk movement) | |
Association with oculomotor abnormalities | Only one study in PD patients with camptocormia [45] | |
Association with sleep disorders | Only one study in PD patients with camptocormia [46] | |
Normalized axial surface of the midbrain statistically smaller than normal controls and negative correlation between severity and sagittal pons area | Only one study in PD patients with camptocormia [47] | |
Impaired perception of the vertical position [48] | Generally seen in patients with Pisa syndrome (Fig. 8.3h) | |
High association with diseases affecting the CNS | Not consistently seen | |
Peripheral | Association with a previous history of back problems or surgery | Never seen for anterocollis; it might be also effect rather than cause |
High prevalence of musculoskeletal pain | It might be also effect rather than cause | |
Evidence for myopathy on EMG (fibrillation potentials, small polyphasic motor unit potentials) | EMG of paraspinal muscles is not standardized and lacks of normative data | |
Evidence for myopathy on MRI (fatty infiltration, muscle atrophy) | Abnormality might be unspecific and/or effect rather than cause | |
Evidence for myopathy on muscle biopsy (abnormal histology) | Abnormality might be unspecific and/or effect rather than cause | |
Unilateral vestibulopathy ipsilateral to the bending side | Only found in one study enrolling PD patients with Pisa syndrome [49]; it might represent a secondary effect of the prolonged tilted position of the head | |
Association with diseases affecting the PNS | Not consistently seen |
Central Mechanisms. There have been conflicting results regarding the pattern of muscular activation on electromyography (EMG). Most studies have reported hyperactivity of either agonist or antagonist muscles. For instance, two main patterns of muscular activation have been described in patients with Pisa syndrome: a dystonic hyperactivity of the ipsilateral paraspinal muscles (pattern I) [40, 50] or hyperactivity of contralateral paraspinal muscles associated with ipsilateral hyperactivity of non-paraspinal lateral trunk muscles (abdominal oblique, iliopsoas and rectus femoris muscles) [44, 50]. This contralateral contraction is in line with other reports of contralateral hypertrophy [51] and might represent a compensatory mechanism, physiologically activated to limit the range of trunk movement. MRI studies have shown mild muscular atrophy with fatty degeneration in patients with pattern I, whereas this was greater and prevalent on paraspinal lumbar muscles ipsilateral to leaning side in pattern II patients (Fig. 8.4) [50], as also found in a CT study [44].
Fig. 8.4
Paraspinal muscle MRI in Pisa syndrome and camptocormia. Axial TSE T2-weighted MRI images at lumbar level might show evidence of atrophy with fatty involution of the paravertebral muscles. The extent of atrophy might vary being mild in patients with pattern I (left and central panels) or greater and prevalent in muscles ipsilateral to leaning side in pattern II patients (right panel). See text for details
Peripheral Mechanisms. Most of the available studies have focused on camptocormia. The observed muscular changes have been considered to be secondary to the abnormal posture caused by the central mechanisms. For example, the atrophy contralateral to the bending side might be due to the stretching stress in some of the patients with Pisa syndrome and EMG pattern I, whereas the ipsilateral muscle atrophy found in patients with pattern II might be caused by muscle disuse [50]. Nevertheless, the primary role of myopathy in the pathophysiology of postural deformities cannot be ruled, as pointed out by different studies addressing PD-related camptocormia as well as ‘idiopathic’ cases of camptocormia. Indeed, biopsies of the paravertebral muscles disclosed different findings: mononuclear cell infiltrates, type 1 fibre predominance with atrophy of type 2 fibres, loss of oxidative enzyme activity, acid phosphatase reactivity of lesions, ragged-red fibres with abnormal mitochondria, extensive diffuse or lobulated fibrosis in camptocormia and indirect signs of paraspinal muscle denervation (also detectable on EMG) [52–57]. Some authors argued that some of these morphological changes are similar to the ones found in experimental tenotomy, where a dysregulation of the proprioception might play a causal role [57].
Integrative Model. Postural disorders most likely result from the interplay of multiple factors. Basal ganglia pathology is necessary but not sufficient, whereas proprioceptive disintegration [57], vestibular imbalance [49], loss of postural reflexes, rigidity and particularly dystonia are important contributory factors [38]. Development of overt postural deformity might lead to a vicious circle, further worsened by age-related acquired soft tissue changes [58]. Likewise, in the setting of chronic pain, muscle spasm develops as a protective mechanism to prevent movement about the damaged joint, thereby promoting abnormal posture. Although it has been argued that aberrant protein aggregation may link PD and camptocormia [55], the reasons why patients with neurodegenerative diseases would develop a localized myopathy of paraspinal muscle are still unclear. Most studies have suggested that myopathic changes, when present, are non-specific and are related to disuse or denervation secondary to the severe primary postural abnormality [38]. It is likely that the different EMG patterns recognized so far are part of a unique dynamic process [55]. For instance, the finding that the development of Pisa syndrome took longer in patients with pattern II than pattern I has argued in favour of a subtle dystonia (i.e. pattern I) at onset, followed by a second compensatory phase (pattern II) [50].
8.2.1.2 Disorders of Balance
Annually, falls are directly or indirectly related to 1,800,000 admissions to emergency departments and 16,000 deaths [59] in the United States alone. Falls are the leading cause of injury-related admissions to hospitals in people of 65 years and over [60], leading to poor quality of life, immobilization and lifespan reduction [61, 62] (Fig. 8.5). Even a single non-traumatic fall may have a severe impact on the global health perception of a person. In addition, due to the psychological burden related to the fear of falling that can develop after falling, ‘active’ avoidance from mobility and loss of independence are also frequently observed [61].
Fig. 8.5
The causes and consequences of falls. A multifactorial process plays a complex role into the pathophysiology of falling. The figure shows the contribution of ageing processes, the few modifiable factors as well as the consequence of falling (From Fasano et al. [33], modified from Leipzig et al. [63] and Voermans et al. [64])
Several conditions impair balance; a ‘disease-oriented’ approach spans across different pathophysiological processes causing falls. Figure 8.6 depicts a proposed model that combines the different pathophysiological mechanisms described for balance disorders [33]. Gait and balance are tightly connected from a pathophysiological standpoint. Indeed, gait disorders are an established risk factor for falls because (1) these disorders can impair CNS regions involved in controlling both gait and postural stability, (2) impaired stepping can destabilize the body’s centre of mass (COM) during walking, (3) an impaired ability to step interferes with the ability to rapidly correct for external postural perturbations (i.e. stepping strategy) and (4) gait impairment can be a secondary epiphenomenon of disorders primarily affecting postural stability (e.g. ataxia).
Fig. 8.6
Neurobiology of falls. The neurobiology of falls relies on specific features, shared by many fallers regardless of their clinical conditions (From Fasano et al. [33]). Abbreviations: FOG freezing of gait, HLGD higher-level gait disorder, PIGD postural instability gait disturbance
8.2.2 How to Recognize
8.2.2.1 Disorders of Posture
Camptocormia (also known as ‘bent-spine syndrome’) is defined as the marked (minimum 45°) flexion in the sagittal plane originating in the thoracolumbar spine, with almost complete resolution in the supine position [38] (Fig. 8.3b). Camptocormia was first recognized in 1818, and it was extensively described as a functional disorder affecting veterans of the World Wars I and II, who developed a persistently bent spine as a manifestation of a possible post-traumatic stress disorder (Fig. 8.3c). The first organic counterpart was described as a consequence of valproate treatment and in 16 elderly patients (mean age of 76) with ‘camptocormism’ [65]. These senile cases were found to have a variety of conditions, i.e. parkinsonism, articular chondrocalcinosis, giant cell arteritis and rheumatoid arthritis. Indeed, many other conditions (especially orthopaedic) might cause camptocormia (Table 8.7). Afterwards, the term camptocormia was extensively used in PD since 1999 [66]; the prevalence rates in this population vary between 3 and 17.6 %. Other neurodegenerative disorders (e.g. MSA or dementia) might also present with camptocormia [67].
Anterocollis (also known as antecollis/anterocaput) is defined as a marked (minimum 45°) neck flexion, partially overcome by voluntary movement with almost complete resolution in the supine position and by passive movement; the patient is unable to fully extend the neck against gravity but is able to exert force against the resistance of the examiner’s hand (Fig. 8.3d). The terms ‘dropped head syndrome’ and ‘chin on chest’ are more often applied to patients with neuromuscular disorders, in whom weakness of neck extension causes the head to drop forwards (Table 8.7). Anterocollis was initially considered a typical feature of MSA, found in 42.1 % of these patients in a retrospective series [68]. It is now acknowledged that up to 6 % of PD patients might also develop anterocollis, with a prevalence reported to be higher in women and in Japanese. Drug-induced forms are also described (following administration of dopamine agonists, donepezil or neuroleptics).
Retrocollis is another—less common—abnormal neck posture, with the head held in extension. It is associated with axial rigidity and is most typically seen in patients with PSP (especially Richardson’s variant), in patients exposed to neuroleptics (tardive dystonia) or in patients with idiopathic cervical dystonia. In rare cases, it can be a feature of PD patients with severe off states.
Pisa syndrome (also termed ‘pleurothotonus’ or lateral flexion of the trunk) is defined as marked (minimum 10°) lateral flexion of the trunk that can be almost completely alleviated by passive mobilization or supine positioning (Fig. 8.3e) [38]. Pisa syndrome was originally described by Ekbom and colleagues as the consequence of acute axial dystonia related to antipsychotic administration [69]. Over the years, it has also been related to non-antipsychotic neuroleptics (e.g. dopamine receptor blockers, such as antiemetics), cholinesterase inhibitors [36] and—more rarely—other psychotropic drugs such antidepressants. In rare instances, idiopathic cases have been described in otherwise normal subjects not receiving any therapy [70]. It has subsequently been described in patients affected by neurodegenerative disorders such as Alzheimer’s disease [71], MSA [72] and PD [73]. The exact prevalence in PD is not known because it was originally reported as ‘scoliosis’ in PD [74, 75] or following post-encephalitic parkinsonism [76]. One study found a prevalence of 2 % in a series of PD patients [40] but it might be higher. Patients tend to lean away from the most affected side, but this is not consistently reported by the published series. An interesting entity is the so-called ‘metronome’ syndrome (or alternating Pisa syndrome), which is rarely seen in patients with neuroleptic-induced Pisa syndrome, who exhibit a deviation contralateral to the presenting one after they are treated with anticholinergics and/or upon neuroleptic withdrawal [77].
Clinically, these postural disorders share some common features, as they:
1.
Are worsened by a prolonged sitting or standing position or by walking but resolve when lying down.
2.
Can develop in a subacute fashion, seldom triggered by a peripheral trauma or medication adjustment (introduction or suspension of drugs either enhancing or reducing dopaminergic or cholinergic transmission within the central nervous system), or in a more insidious, chronic, fashion [51].
3.
Are often associated with severe parkinsonian phenotype (akinetic variant).
4.
Can be associated with a previous or recent history of back problems (e.g. degenerative spinal disease) or surgery.
5.
Are often accompanied by pain, sometimes acute at onset.
6.
Most patients have no awareness of the condition (Fig. 8.3f), especially when onset is gradual and associated with pain.
7.
Are more common in Japanese patients.
8.2.2.2 Disorders of Balance
The American Academy of Neurology concluded that specific conditions are level A (stroke, dementia and gait/postural instability impairment) or level B (PD, neuropathies, lower limb weakness and poor visual acuity) risk factors for falling [78]. In general, disorders affecting the three principal components of postural control might impair balance: afferent systems (vision/hearing loss [79], proprioceptive [80] and vestibular [81] function), efferent systems (orthopaedic conditions or muscular weakness [82]) or the integrative networks within the CNS (frontal or cerebellar ataxia [83]).
Posture abnormalities might also impair balance by shifting the COM away from the centre of the base of support (BOS). It is not surprising that patients with camptocormia tend to have festination (see below) and fall forward, while patients with retrocollis tend to fall backwards (e.g. PSP or patients with stooped posture undergoing overcorrection). Other paroxysmal conditions might destabilize the body (e.g. myoclonus) or impair the background muscular tone required to stand (e.g. cataplexy). An important cause of falls is gait disorders. Accordingly, the most notorious, devastating consequences of gait disorders are falls and reduced mobility, with subsequent impaired quality of life and a reduced lifespan (Fig. 8.5).
In most of these conditions, the diagnosis is easy; however, clinicians might be challenged by specific balance disorders.
Progressive supranuclear palsy is a common cause of insidious balance impairment, presenting with unexplained backward falls; this is typically seen in the ‘Richardson’s syndrome’ but also in vascular parkinsonism (the so-called vascular PSP).
Parkinson’s disease more often causes forward falls after a number of years after disease onset; the well-known stooped posture seems to confer a mechanical protection against backward falls. Indeed, retropulsion seems to be a specific and primary feature of parkinsonian instability, thus explaining why PD patients may also have backward falls several years after disease onset. Some PD patients might have sudden and unexplained falls; in these cases, freezing of gait (FOG) should be considered, especially if falls are sidewise. Balance impairment and FOG need to be distinguished from orthostatic hypotension as the aetiology of falls (see Chap. 2 on ‘Disorders of Tone’).
Cerebellar ataxias, most atypical parkinsonian syndromes, degenerative choreas and severe essential tremor typically present with medio-lateral instability, so a sign of these conditions is that they lose the ability to ride a bicycle. This feature is not lost in PD [84].
Frontal ataxia can be difficult to diagnose, but it is commonly seen in patients with higher-level gait disorders (see below); these patients lack the typical limb, speech and eye abnormalities seen in cerebellar ataxias and commonly exhibit overt signs of frontal lobe impairment.
Sensory ataxias have features similar to cerebellar ataxias with two important differences: eye closure dramatically worsens balance (Romberg sign), and patients have no impairment of oculomotion and speech.
Vestibular disorders (either central or peripheral) are associated with vertigo, which is a subjective or objective sensation of spinning; nystagmus as well as lateropulsion might be present.
Functional (psychogenic) imbalance is rather common, and although it is commonly argued that these patients never fall, there are cases of functional falls as well [85].
‘Idiopathic fallers’ are those subjects who fall in the absence of any overt cause or underlying disease [86]; these are usually elderly subjects with increased gait variability caused by a variety of degenerative or vascular brain disorders.
Tables 8.9 and 8.10 list the elements of history taking and physical and instrumental examination in patients with gait disorders and/or falls. Note that subjects should be asked not only about falls but also about the presence of ‘near-falls’ as these may precede onset of actual falls and also because near-falls can contribute to a fear of falling and thereby to secondary immobility.
Table 8.9
Elements of history taking in persons with gait disorders and/or falls
History taking | |
|---|---|
Temporal nature | Continuous Episodic, which can be subdivided in Random (e.g. paroxysmal dyskinesias) Pseudoperiodic (after a given amount of steps, e.g. FOG, claudication) |
Type of onset and progression | Sudden (e.g. stroke) Insidious (e.g. neurodegenerative disorders) Stepwise (e.g. vascular parkinsonism) |
Walking worse in the dark? | Yes (consider sensory ataxia or vestibulopathy) No |
Use of walking aids | Yes (consider latency to using aids: months vs. years) No (if not, should they? Consider HLGD) |
Medical history | Prior/current diseases Psychoactive medications Intoxication (alcohol) |
Protective factors | Exercise/fitness level Amount of daily walking Adaptation of behaviour/activities |
Fall history | Frequency of prior (near-)falls Single (in absence of extrinsic cause search for risk factors) Recurrent Specific fall pattern? Apparent cause of the falls
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