Dyskinesia (literally, bad or difficult movement) is a general term covering various forms of abnormal movement, including tremor, tics, ballismus, chorea, habit-spasm, torcollis, torsion-spasm, athetosis, dystonia, and myoclonus.

Such conditions typically involve uncontrollable movements of the trunk or limbs which cannot be suppressed and impair the execution of voluntary movements. The whole body may be involved or the problem restricted to a particular group of muscles.

  1. Athetosis (exaggerated, sinuous, writhing movement of muscles)

The term denotes the slow, irregular, and continuous twisting of muscles in the distal (far) portions of the arms and legs.

These sinuous movements are bilateral (evident on both sides of the body) and symmetric (both sides are similarly affected).

Characteristically, there are exaggerated writhing motions of the fingers, which are spread in a manner reminiscent of a snake-charmer, with alternate flexion and extension of the wrists, and twisting of the muscles in the hands, fingers, feet and toes.

The hands and fingers appear to be in continuous motion and the inability to maintain them in a fixed position causes difficulty with writing and tasks such as fastening buttons. When the feet are involved, the ankles and toes intermittently turn inwards, producing an irregular, unabalanced gait.

In severe cases, there is grimacing, protrusion of the tongue and abnormal articulation of speech. The patient may be able to regain some control over these movements by way of concentration and they are absent during sleep.

  1. Chorea and choreic movements (irregular, spasmodic, jerky)

Chorea is a Greek word meaning dance (as in choreography).

Chorea is characterized by quick, irregular, spasmodic and jerky involuntary movement of muscles, usually affecting the face, limbs and trunk.

The movements resemble voluntary movements but are continuously interrupted prior to being completed. They also disappear or are less prominent during sleep.

There is a general air of restlessness in chronic patients and an excess of motor activity with impaired ability to maintain a posture. Those parts of the limbs closest to the trunk (the proximal portions) are more affected than those further away (the distal portions) and the trunk itself may be affected.

The movements are more rapid and involve more muscle groups than athetotic movements. Unlike tics (see below), they are not predictable and occur at random.

Although bilateral, the muscular movements are asynchronous rather than symmetric, that is the chorea frequently affects one side of the body more than the other. Hemichorea is chorea affecting one side of the body only.

  1. Choreo-athetoid movements

Choreic and athetotic movements may exist in conjunction, when their combined effect is referred to as choreo-athetosis.

The movements may be caused by various pathological processes initiated as a side-effect of certain drugs.

  1. Tardive dyskinesia (involuntary muscle movements late in treatment)

Tardive means tardy, late. The term tardive dyskinesia refers to a type of movement disorder which appears late in treatment, characteristically after long-term treatment with antipsychotic drugs.

The whole body may be involved or the problem restricted to a particular group of muscles. Involuntary, slow, irregular movements of the tongue, lips, mouth, and trunk, and choreo-athetoid movements of the extremities are common. In particular, there may be twisting and protruding movements of the tongue, chewing movements of the jaw, and puckering of the lips. These uncontrollable movements cannot be suppressed.

The term (oro-) facial dyskinesia is sometimes used to describe repetitive smacking, grimacing, champing, chewing, and swallowing movements involving the lips, tongue, and jaw.

  1. Tremor

A tremor may be described as a rhythmic, repetitive movement of some part of the body which results from the alternating contractions of opposing muscle groups. There is, however, no single description (6–10 muscle movements per second) or coarse (4–5 muscle movements per second). They may be caused by antipsychotics or antidepressants, withdrawal from drugs or alcohol.

Types of Tremor
At-rest tremorAt-rest tremors are worse when the affected part of the body is relaxed, supported and at rest, usually improving when the affected limb is used.
Postural tremorPostural tremor is a fine tremor activated during attempts to sustain a posture (e.g., extending an arm, supporting a leg, holding up the head, turning back the wrists) but absent when the limb is supported and at rest.
Action (intention) tremorAction tremors occur mainly, or are most marked, when a movement is attempted, with the result that the patient’s purpose is frustrated. Hence, they are commonly tested for by asking the patient to touch the tip of his nose with the tip of his finger; as the finger approaches the nose the intention tremor increases.
Essential tremorA persistent, fine-moderate tremor (6–10 movements per second) not associated with disease. The tremors are fine, mainly affecting the hand and head. They are common in adults, tend to increase with age and to be aggravated by emotional tension, may be temporarily relieved by alcohol, and may affect particular occupations. They may increase when the affected part of the body is moved.
  1. Tics (habit-spasms)

A tic is a repeated, uncontrolled, purposeless contraction of a muscle or group of muscles. For example, superficially purposeless blinking, mouth twitching, shrugging, or the involuntary contraction of the diaphragm (which results in grunting noises).

These habitual, spasmodic, muscular contractions tend to be experienced as irresistible, but they can usually be suppressed for varying periods of time and they disappear during sleep.

Tics release emotional tension and are generally a sign of minor psychological disturbance, being made worse at times of stress. Occasionally, they are severe, as in Gilles de la Tourette’s syndrome.

  1. J.D. and J.A. Spillane, An Atlas of Clinical Neurology (Oxford Medical Publications, 3rd ed., 1982), p.263.
  2. Lexicon of Psychiatric and Mental Health Terms (World Health Organisation, 1989), Vol. 1, p.7.
  3. J. D. and J. A. Spillane, An Atlas of Clinical Neurology (Oxford Medical Publications, 1982), p.263.