David A. Isaacs, MD

OVERVIEW

Abnormal movements are a common reason for hospital neurology consultation. Tremor and myoclonus are the most common abnormal movements seen in the inpatient setting. Medications and metabolic disturbances are the most common identified etiologies. Abnormal movements may occur in association with encephalopathy or as an isolated entity. As with encephalopathy, it is more common to identify multiple contributing factors rather than a single cause. Occasionally, a single medication can precipitate tremor or myoclonus, either directly or via a drug–drug interaction. Equally important, drug withdrawal can result in abnormal movements. When abnormal movements occur concurrently with encephalopathy, seizures should be considered and an electroencephalogram (EEG) may be needed for diagnosis. Some abnormal movements commonly seen in the hospital setting include:

•Tremor: Rhythmic involuntary movement, described by the frequency and by its presence at rest, in posture, or with action.

•Myoclonus: Abrupt, lightning-like muscle contractions, which may also occur in trains and be confused with tremor, described by its distribution (generalized, segmental or focal). Negative myoclonus (or asterixis) is abrupt muscle relaxation.

•Asterixis: Abrupt loss of muscle tone resulting in a negative twitch, such as in the arm if the arm is being held up against gravity; it is also known as negative myoclonus.

•Chorea: Dancelike, irregular involuntary movements described as generalized, hemi-, segmental or focal.

•Dystonia: Irregular movements with abnormal posture of the affected body part, often twisting the neck, limbs, or trunk; it may also be seen with tremor and other types of movements.

•Athetosis: Slow, writhing involuntary movements, generally in the upper extremities.

•Hemiballismus: Unilateral, high-amplitude movements resembling more severe chorea.

•Dyskinesia: Term generally used to describe drug-induced chorea, though literally any abnormal movement; specific syndromes involving chorea or dystonia are also often grouped under dyskinesia.

•Tics: Sudden, stereotyped, purposeless movements that are suppressible; they are described as simple if brief and limited to one muscle group (such as a grimace) or complex if of longer duration and affecting multiple muscle groups (such as touching or grabbing, or grunting after grimacing).

•Rigidity: Increased muscle tone that is independent of velocity or position, primarily seen in parkinsonism. Parkinsonian rigidity increases when the contralateral limb is activated, and stiffness is increased resistance to passive movement that is not necessarily from muscle.

•Spasticity: Increased muscle tone that changes with velocity on passive movement, primarily seen with lesions in the motor tracks in the brain and spinal cord.

•Seizure: Episodic motor or sensory disturbance due to synchronous cortical discharges; seizures are not considered a movement disorder, although they can sometimes appear stereotyped like a tic, tremorlike, or even dystonic. Seizures are generally distinguished from movement disorders by a discrete start and stop and a consistent pattern from episode to episode. Consciousness is also often affected, and the impairment may persist after termination of the movements (the postictal period). Focal status epilepticus or epilepsia partialis continua can mimic tremor.

Movement disorders may overlap; a firm distinction is not always possible. Writhing movements may have features of both athetosis and chorea. Twisting movements can be seen in both chorea and dystonia. Tremor and rhythmic myoclonus appear similar.

SYNDROMES

Tremor

Tremor has a broad differential diagnosis, and physical examination cannot always make a clear etiologic diagnosis. Tremors exacerbated by medications and metabolic disturbance can all have similar appearance. Tremor is broadly classified by its occurrence in action versus rest or kinetic versus postural. Features include:

•Resting: Present when at rest, with the body part relaxed; attenuated by posture or voluntary movement; most commonly seen with parkinsonism

•Postural: Tremor seen while holding a sustained posture, such as hands outstretched; essential tremor and enhanced physiologic tremor are postural.

•Kinetic (or action): Present with voluntary movement and attenuated by rest or posture

Differential diagnosis of tremor in hospitalized patients includes:

•Essential tremor: Predominantly postural tremor involving hands or arms, onset in youth to young adult age, often hereditary. Head and voice, or lower extremities, can sometimes be affected as well. Usually no other neurologic deficit, occasional ataxia may appear later in course.

•Renal failure: Tremor and multifocal myoclonus can develop from renal insufficiency, especially with acute exacerbation of renal insufficiency. In metabolic disturbances, abnormal movements are usually multifocal.

•Hepatic failure: Tremor, myoclonus, and asterixis are common.

•Parkinsonian tremor: Resting tremor may be due to Parkinson disease, although drug-induced and other secondary parkinsonisms are also common. Very symmetric tremor is supportive of secondary parkinsonism.

•Medication-induced tremor: Multiple drugs can cause tremor, but some of the most important are corticosteroids, neuroleptics, valproate, lithium, amiodarone, theophylline/adenosine analogs, amphetamines. Withdrawal from medications can also cause tremor. Serotonin syndrome is another important consideration in hospitalized patients with unexplained tremor.

•Psychogenic tremor: Almost any type of tremor. Clues to etiology are abrupt onset, changing direction, marked variability/inconsistency on examination.

Myoclonus

A variety of conditions can appear as phasic motor activities or jerking of a body part. Other conditions that can resemble myoclonus include tics, tremor, and occasionally seizure. Common causes of myoclonus are:

•Hepatic failure: Myoclonus and asterixis are common and are often accompanied by other stigmata of hepatic encephalopathy.

•Renal insufficiency: Myoclonus can occur with renal insufficiency, usually when fairly advanced. Note that medication-induced myoclonus is also more common with renal insufficiency.

•Medications: Multiple medications can cause myoclonus, and it is more prominent with coexistent renal or hepatic impairment (e.g., gabapentin toxicity developing in a patient with chronic, but stable, renal insufficiency).

•Epilepsy: Epileptic myoclonus is most commonly seen with juvenile myoclonic epilepsy but also with severe epilepsies such as progressive myoclonus epilepsy and Lennox-Gastaut syndrome.

•Essential myoclonus: Myoclonus without seizures or other neurologic conditions; it is nonprogressive; it may be sporadic or familial.

•Post-hypoxic myoclonus: Can develop after hypoxic cardiopulmonary arrest, both early while still encephalopathic, and delayed, after intellectual recovery.

•Palatal myoclonus: Fast, rhythmic oscillation of the soft palate and sometimes surrounding muscles, often associated with a clicking sound in the ear. Also known as palatal tremor.

•Juvenile myoclonic epilepsy: Common idiopathic generalized epilepsy with myoclonus (often in the morning), frequently co-existing with generalized tonic-clonic seizures and absence seizures

•Progressive myoclonus epilepsy (PME): Family of disorders with myoclonus, epilepsy, and degenerative changes in neurons

•Cortical reflex myoclonus: Myoclonic movements with cortical discharge; often evoked by an intention to move or a stimulus

Rigidity and Stiffness

Rigidity and stiffness are features of many disorders. The list shows some of the conditions that produce sustained stiffness or rigidity. These two terms have subtly different meanings but are considered together for our discussion.

•Spasticity: Rigidity with increased tendon reflexes, velocity- and direction-dependent resistance to passive movement, and corticospinal tract signs

•Dystonia: Increased tone without corticospinal tract signs. Associated with abnormal posture, often with some slow superimposed tremor or chorea

•Stiff-person syndrome: Increased tone of mainly proximal and paraspinal muscles. Slow and stiff movements and gait

•Tetanus: Rigidity and spasms starting in facial muscles, extending to body and limb muscles

•Parkinsonism: Rigidity and bradykinesia as components of the syndrome; resting tremor may also be present.

•Neuromyotonia: A neuromuscular condition with excessive muscle contraction that may occur with fasciculations, myokymia, muscle rigidity, or muscle cramps

•Myokymia: A neuromuscular condition with involuntary spontaneous firing of muscle fibers that is visible but insufficient to move a joint, often described as rippling, quivering, or “bag of worms” appearance

•Neuroleptic malignant syndrome: Rigidity with fever and mental status changes, usually after initiation or change in dose of neuroleptics. Sometimes called Parkinsonism-hyperpyrexia syndrome, such as when it occurs in patient with preexisting parkinsonism.

•Malignant hyperthermia: Rigidity and hyperthermia, usually precipitated by medications, especially inhaled anesthetics along with succinylcholine or other paralytic drugs

Athetosis, Chorea, Dystonia, Dyskinesia, Hemiballismus, and Tics

Athetosis and chorea classically have distinct features, but clinical discrimination can be blurred.

•Athetosis is characterized by slow, involuntary, writhing movements, often associated with an abnormal posture, which can have a dystonic appearance. Important causes are Huntington disease (HD), neuroleptics, and metabolic disorders, especially hepatic insufficiency.

•Chorea is characterized by more rapid involuntary movements. Some movements can have features of athetosis and chorea. Athetosis can blur the distinction from dystonia, since the slow movement of some dystonias can resemble athetosis. Causes of chorea are numerous but include HD, other hereditary choreas, Fahr disease, Wilson disease, and some paraneoplastic disorders.¹

•Dystonia is abnormal posture that often has superimposed movement that can have the appearance of athetosis. The spontaneous movement is slow and can be temporarily suppressed. Important causes include dystonia musculorum deformans, metabolic disorders such as kernicterus, and degenerative disease including HD. However, the most common cause is medication, often neuroleptics or dopamine-blocking antiemetics.

•Dyskinesia is repetitive movements that have features of chorea with dystonia and have a fairly stereotyped appearance. Common causes are medications, especially dopaminergic agents for Parkinson disease.

•Hemiballismus is a special form of unilateral choreiform movements with often violent involvement of proximal muscles that risk injury. This is among the most violent disorders seen in neurology and often requires hospitalization. The most common cause is infarction of the subthalamic nucleus.

•Tics are brief movements that are stereotyped but differentiated from chorea by their brief character, suppressibility, and the frequent presence of an urge preceding the movement. Tourette syndrome is characterized by a mixture of different tics developing in the first or second decade. (However, the history may be unreliable in some cases so there may be an apparent older age of onset.)

•Hemifacial spasm consists of episodes of clonic movements of the face, typically unilateral, although occasional movements on the opposite side can occur. Symptoms are initially brief clonic movements but evolve to more sustained hemifacial contractions. Cause is typically vascular impingement on the facial nerve.

•Spasmodic dysphonia is a focal dystonia affecting the laryngeal muscles and it comes with a varied presentation. More than 90% of patients have adductor spasm, causing a strained voice, sometimes to the point of making speech almost incomprehensible. The remainder of patients have abductor spasm, which presents with a breathy, whispering voice.² Both conditions are worse with stress.

Ataxia

Ataxia can have several origins. Localization of the ataxia is the first step to diagnosis:

•Cerebellar ataxia: Ataxia of the limbs and/or gait. Repetitive movements are unequal, irregular, and off-target. Often associated with decreased tone, nystagmus. Abnormal saccades may be present.

•Sensory ataxia: Deficits in balance with proprioceptive difficulty and without vertigo. Worse with eyes closed. Associated with other signs of peripheral neuropathy: sensory deficit, reduced reflexes

•Vestibular ataxia: Prominent vertigo. No other cranial nerve deficits such as diplopia or speech change

With localization of the ataxia, a differential diagnosis can be established:

•Cerebellar infarction: Acute onset of cerebellar ataxia, usually unilateral

•Miller Fisher syndrome: Variant of acute inflammatory demyelinating neuropathy with subacute onset of ataxia, areflexia, and ocular motor deficits

•Multiple sclerosis: Stepwise progression of ataxia with cerebellar and corticospinal features

•Wernicke encephalopathy: Associated with ethanol toxicity or malnutrition, prominent nystagmus, plus ataxia

•Ethanol toxicity: Predominately gait ataxia, often without other deficits

•Paraneoplastic cerebellar degeneration: Subacute development of vertigo and nystagmus, often with nausea, progressing to cerebellar ataxia, dysarthria; usually precedes diagnosis of cancer, often ovarian or small-cell lung cancer

•Spinocerebellar ataxias: Family of hereditary cerebellar ataxias usually with corticospinal, brainstem, motor neuron, or cognitive deficits

•Wilson disease: Familial disorder with mainly hepatic presentation but can have cerebellar and/or corticospinal deficits

•Friedreich ataxia: Hereditary cerebellar ataxia with corticospinal deficits, peripheral neuropathy, and cardiac disease; cardiomyopathy is commonly associated.

•Multiple system atrophy: Neurodegenerative condition with a combination of ataxia, dysautonomia, and parkinsonism, although not all findings are present at onset

•Peripheral vestibulopathy: Vertigo, sometimes with gait ataxia. No speech or other findings to suggest brainstem involvement

Specific entities are discussed in the following sections or in respective chapters on vascular, demyelinating, genetic, developmental, toxic, and nutritional disorders.

MOVEMENT DISORDERS

Clinical features and differential diagnoses of individual abnormal movements were discussed earlier. Here, we will discuss specific disorders, with a focus on hospital neurology implications. Comprehensive discussion of movement disorders is not provided here, and the reader is referred to excellent comprehensive sources.³

Parkinsonism

Parkinson Disease

Parkinson disease (PD) is usually idiopathic, although genetic forms have been identified. Drug-induced parkinsonism is discussed later. PD onset is usually between 50 and 70 years, although older and younger cases do occur. Most cases are sporadic, although up to 25% of cases may be familial.

PRESENTATION is usually with resting tremor of one hand. Occasionally decreased arm swing or leg-dragging occur without tremor. At early stages, other motor deficits might not be noticed. However, eventually, patients or clinicians notice slowed and stiff gait with decreased arm swing, stooped posture, and shortened stride. Exam classically shows resting tremor, bradykinesia, rigidity, and postural instability. Cognitive difficulties, particular word-finding trouble, occur late in the disease.

DIAGNOSIS is suspected on the basis of tremor with other motor signs representing a parkinsonian appearance. Diagnosis of PD is clinical; there are no specific diagnostic tests. However, a robust response to levodopa is typical. Due to individual variation in absorption and metabolism, levodopa doses must be pushed above 1,000 mg per day in order to determine responsiveness. Differential diagnosis includes other parkinsonian syndromes, parkinson-plus syndrome, dementia with Lewy bodies, normal pressure hydrocephalus (NPH), essential tremor (in combination with other conditions), multiple system atrophy (MSA), progressive supranuclear palsy (PSP), corticobasal syndrome (CBS), and vascular parkinsonism, among others. Magnetic resonance imaging (MRI) and computed tomography (CT) show no specific findings in patients with PD, and imaging is mainly to rule out structural lesions such as NPH or vascular disease. Routine labs are also negative. Lumbar puncture (LP) is rarely helpful and should only be done if NPH or chronic CNS infection is considered.

MANAGEMENT is generally symptomatic. There are no proven agents that slow the progression of the disease. The approaches to treatment fall into the following categories:

Related posts:

Overview of Hospital Neurology Dizziness, Vertigo, and Imbalance Infectious Diseases Demyelinating Diseases Nutritional Deficiencies and Toxicities Developmental and Genetic Disorders

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