Involuntary Movements



Involuntary Movements


Elan D. Louis



INTRODUCTION

Abnormal involuntary movements, often called dyskinesias, are uncontrollable movements that are usually evident when a patient is at rest and, with rare exceptions (e.g., palatal myoclonus), these movements disappear during sleep. These movements are continual or easily evoked, although some are intermittent or paroxysmal, such as the tics, paroxysmal dyskinesias, or episodic ataxias. Although convulsions, fasciculations, and reflex clonus are involuntary movements, they are not classified with the types of abnormal involuntary movements that are described in this chapter.

The various dyskinesias are distinguished from one another based primarily on the visual inspection of the patient. Hence, the neurologic examination is of central importance when assigning a diagnosis.

The visual opposite of the hyperkinesias are the hypokinesias. Hypokinesia refers to reduced amplitude of movement or a paucity of movement that is not due to weakness or paralysis, but the term is commonly used synonymously with bradykinesia (slow movement), and the two features typically occur together in the parkinsonian states. Furthermore, hesitation and freezing phenomena (i.e., delays and interruptions of movement) are frequent features of parkinsonian states.


TYPES OF DYSKINESIAS

There are a large number of dyskinesias (Table 12.1), and each of these will be described further in the following text.


CHOREA

Chorea refers to brief, irregular contractions that, although rapid, are not as lightning-like as myoclonic jerks. In classic choreic disorders, such as Huntington disease (see Chapter 82) and Sydenham chorea (see Chapter 81), the movements affect individual muscles as random events that seem to flow from one muscle or muscle group to another (Video 12.1). The movements are neither repetitive nor rhythmic. Ballism is a form of chorea in which the movements are more jerk-like and are of large amplitude, producing flinging movements of the affected limbs.


DYSTONIA

Dystonia (see Chapter 76) is a syndrome of sustained muscle contraction that frequently causes twisting and repetitive movements or abnormal postures. The spasms may affect the neck muscles (torticollis) (Video 12.2), periocular muscles (blepharospasm), facial muscles (Meige syndrome), or limb muscles (e.g., writer’s cramp). Dystonia is represented by the following phenomena: (1) sustained contractions of both agonist and antagonist muscles simultaneously (cocontraction) and persisting in the same muscle groups repeatedly (“patterning”), in contrast to the flowing of choreic movements; (2) an increase of these involuntary contractions when voluntary movement in other body parts is attempted (“overflow”); (3) rhythmic interruptions of these involuntary, sustained contractions (dystonic tremor); (4) inappropriate or opposing contractions during specific voluntary motor actions (action dystonia); and (5) torsion spasms that may be as rapid as chorea but differ because the movements are continual, patterned, and of a twisting nature, in contrast to the random and seemingly flowing movements of chorea. The speed of dystonic movements varies considerably from slow (athetotic dystonia) to shock-like (myoclonic dystonia). One of the characteristic features of dystonic movements is that they can often be diminished by tactile or proprioceptive “sensory tricks” (geste antagoniste). Thus, touching the involved body part or an adjacent body part can often reduce the muscle contractions (e.g., patients with torticollis may touch their chin to lessen the spasms).
Inexperienced clinicians might assume that this sign indicates that the abnormal movements are psychogenic; however, the presence of sensory tricks strongly suggests an organic etiology.








TABLE 12.1 List of Involuntary Movements List of Involuntary Movements



















































Hyperkinesias


Akathitic movements


Asynergia


Athetosis


Ballism


Chorea


Dysmetria


Dystonia


Episodic ataxia


Hemifacial spasm


Hyperekplexia and jumping disorders


Hypnogenic dyskinesias


Jumpy stumps


Myoclonus


Myorhythmia


Painful legs-moving toes


Paroxysmal movement disorders (paroxysmal dyskinesias, episodic ataxias, paroxysmal hypnogenic dyskinesias, transient dyskinesias of infants)


Restless legs syndrome


Stereotypy


Tics


Tremor


Hypokinesias


Akinesia/bradykinesia (parkinsonism)


Hesitation and freezing phenomenon



MYOCLONUS

Myoclonus (see Chapter 78) refers to an ultrabrief, shock-like movement that may arise from sudden muscle contractions (Video 12.3) or sudden interruption of ongoing muscle contractions with resultant postural lapses (i.e., negative myoclonus). The most common form of negative myoclonus is asterixis, which frequently accompanies various metabolic encephalopathies. In asterixis, the brief flapping of the outstretched limbs is due to transient inhibition of the muscles that maintain posture of those extremities.

Myoclonus can appear when the affected body part is at rest but it may also occur when it is performing a voluntary motor act (i.e., “action myoclonus”). Myoclonic jerks are usually irregular (arrhythmic) but can also be rhythmical (such as in palatal myoclonus, ocular myoclonus, or limb myorhythmia, with a rate of approximately 2 Hz).


TICS

Tics may be simple jerks or complex sequences of coordinated movements that appear suddenly and intermittently (Video 12.4). When simple, the movements may resemble a myoclonic jerk. Complex tics often include head shaking, eye blinking, sniffing, shoulder shrugging, facial distortions, arm waving, touching parts of the body, jumping movements, or making obscene gestures (copropraxia). Tics are usually rapid and brief, but occasionally, they may involve sustained muscle contractions (i.e., dystonic). In addition to motor tics, phonic tics involve sounds through the nose (e.g., sniffing) or throat (throat clearing) as well as other vocalizations. These range from sounds, such as barking or squealing, to verbalizations, including the utterance of obscenities (coprolalia) and the repetitions of sounds, words, or phrases (palilalia and echolalia). Motor and phonic tics are the essential features of the Tourette syndrome (see Chapter 74). One feature of tics is the compelling urge felt by the patient to make the motor or phonic tic, with the result that the tic movement brings relief from unpleasant sensations that develop in the involved body part. Tics may be voluntarily controlled for brief intervals, but such a conscious effort at suppression is usually followed by more intense and frequent contractions. The spectrum of severity and persistence of tics is wide; the milder the tic disorder is, the more control the patient may exert over the tics.


STEREOTYPIES

Stereotypic movements (stereotypies) occur as repetitive, sometimes rhythmic movements (e.g., hand flapping, head nodding, body rocking), and they may resemble tics; these are encountered in persons with mental retardation, autism, or schizophrenia, although they also occur in normal developing children. Stereotypic movements are also encountered in the syndrome of drug-induced tardive dyskinesia (see Chapter 80) and refer to repetitive movements that most often affect the mouth; in orobuccolingual dyskinesia, there are constant chewing movements of the jaw, writhing and protrusion movements of the tongue, and puckering movements of the lips.


TREMOR

Tremors are rhythmic oscillatory movements. They result either from alternating contractions of opposing muscle groups or from simultaneous contractions of agonist and antagonist muscles. A useful way to differentiate various tremors clinically is to determine whether the tremor is present during different conditions: when the affected body part is at rest, as in parkinsonian disorders; when posture is maintained (e.g., with arms outstretched in front of the body or with elbows flexed with arms in a winged position), as in Wilson disease and essential tremor (see Chapter 73); when action is undertaken (e.g., writing or pouring water from a cup) (Video 12.5), as in essential tremor; or when intention is present (e.g., during finger-to-nose maneuver), as in diseases involving the cerebellum such as ataxias and essential tremor (see Chapters 73 and 79).


ATHETOSIS

Athetosis is a slow, continuous, writhing movement of the limbs, trunk, head, face, or tongue. When these movements are brief, they merge with chorea (choreoathetosis). When the movements are sustained at the peak of the contractions, they merge with dystonia, and the term athetotic dystonia may be applied.


AKATHISIA

Akathitic movements commonly accompany the subjective symptom of akathisia, an inner feeling of motor restlessness or the need to move (Video 12.6). Today, akathisia is most commonly seen as a side effect of antipsychotic drug therapy, either as acute akathisia or tardive akathisia, which often accompanies tardive dyskinesia. In addition to that induced by antipsychotic drugs, pathologic akathisia may be seen in the encephalopathies of confusional states, in some dementias, and in Parkinson disease. Picking at the bedclothes (i.e., carphology) is a manifestation of akathitic movements in patients who are bedridden. Akathitic movements (e.g., crossing and uncrossing the legs, squirming and/or attempting to rise from a chair, pacing the floor) may also be a reaction to stress, anxiety, boredom, or impatience; these may then be termed physiologic akathisia.


RESTLESS LEGS SYNDROME

One other neurologic condition in which there are subjective feelings of the need to move is restless legs syndrome. This is characterized by formication in the legs, particularly in the evening when the patient is relaxing and sitting or lying down and attempting to fall asleep. These sensations of ants crawling under the skin disappear when the patient gets up and walks around.

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Jul 27, 2016 | Posted by in NEUROLOGY | Comments Off on Involuntary Movements

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