Movement disorder has largely replaced the older term ‘Extrapyramidal disease’. A few movement disorders do arise outside the basal ganglia eg. myoclonus from the brain stem, cortex, or spinal cord, and painful legs/moving toes arise from the peripheral nervous system.

This large group of complex, sometimes bewildering, neurological disorders, is often highly treatable. However, an accurate diagnosis is mandatory before one can think of effective therapy. In this era of neurodiagnostic high–technology, there remains no way to diagnose an involuntary movement other than visual inspection. Words fail to express the subtle nuances which distinguish between various types of movements, and one can learn this art well only by examination of affected patients or videotapes. This article is an attempt to outline a clinical approach to the diagnosis of the common movement disorders.

Types of movement disorders
Movement disorders essentially have either less movement (hypokinesia) or excessive movement (hyperkinesia). Sometimes, there is a combination of both.

The Akinetic–Rigid syndromes
Hypokinesia bradykinesia or akinesia: Poverty of movement in speed or amplitude without any weakness or paralysis.

• Pure parkinsonism: Akinesia or rest tremor associated with rigidity and/or deficits in postural reflexes.
• Parkinsonism plus: Parkinsonism along with other signs eg.
• Vertical gaze paresis: Progressive supranuclear palsy.
• Apraxia due to Corticobasal ganglionic degeneration.
• Autonomic failure, Ataxia: OPCA.

The Hyperkinetic Dyskinetic syndromes
Hyperkinesias or Dyskinesias
A wide variety of abnormal, excessive involuntary movements further characterized according to their regularity, velocity and duration, as well as anatomical distribution, tremors, tics and stereotypies are regular and predictable movements while chorea flows irregularly from one body part to another without a predictable pattern. Myoclonus, clonictics and some tremors are rapid while dystonias and athetosis are slow and sustained, often with a twisting component.

Finally, several hyperkinesias have a tendency to involve certain body regions for example akathisia almost always affects the legs. Tics tend to be most prominent in the face, eyes and neck and dystonic movements occur in all body regions, but are particularly common in the neck muscles.

• Akathisia: Stereotypic movements (usually legs) that occur in response to inner restless feelings.
• Athetosis: Twisting contorsion, either like a dystonia or chorea.
• Hemiballismus: Violent, flinging chorea, involving large, proximal muscles.
• Chorea: Involuntary, rapid irregular flowing movements.
• Dystonia: Twisting sustained postures.
• Hemifacial spasm: Unilateral facial contractions.
• Hyperekplexia: Enhanced and pathological startle response.
• Myoclonus: Shock like jerks, focal or generalized.
• Stereotype: Repetitive movement, simple or complex.
• Tics: Stereotype mainly affecting face, neck and vocal apparatus.
• Tremor: To and fro oscillation around a joint.

Causes

• The paroxysmal dyskinesias are intermittent dyskinesias precipitated by sudden movement, prolonged exercise or by fatigue, stress, or ingestion of caffeine and alcohol. Paroxysmal dyskinesias occurring only in sleep may be a type of seizure disorder.
• Non kinesigenic paroxysmal dyskinesias, however, especially those without a family history are often psychogenic in etiology. One must be very careful before diagnosing a psychogenic movement disorder though. Points in favor are continual rather than of an intermittent nature, frequent distractibility, suggestibility, inconsistency of signs and abrupt stroke–like onset.
• Various drugs can cause movement disorders, apart from the dopamine receptor antagonists the most celebrated ones being the dopamine receptor blocking agents, which can cause acute dystonic reactions, acute akathisia, drug–induced Parkinsonism, neuroleptic malignant syndrome. Certain drugs and thyroxine can exaggerate physiological tremors. Anticonvulsants can induce chorea.
• Although movement disorders are primary motor conditions a number of sensory phenomena can occur. Painful muscle cramps can occur with severe rigidity, dystonia or dystonic spasms of the foot in early Parkinsonism. Those suffering from Parkinsonism may have oral and genital burning pain or numbness and itching. In patients with akathisia, a movement disorder associated with a primary subjective restlessness, patients frequently describe a vague but intense discomfort in their bodies that is relieved by movement.
• In addition to these historical elements a careful medical and family history is important in evaluating hypokinesia and hyperkinesia. Apart from the general systemic examination, psychiatric history is important.