EVALUATION AND MANAGEMENT OF DRUG-INDUCED MOVEMENT DISORDERS
Table 11-1 A Lexicon of Drug-Related Movement Disorders
A variety of abnormal movements may occur during the course of psychotropic drug treatment or following the discontinuation of such treatment. These abnormal movements, which are more prominently associated with neuroleptic drugs than with other psychotropic agents, appear to result from the ability of these agents to affect neurotransmission at dopamine- and acetylcholine-mediated synapses. In the basal ganglia. movement abnormalities may result from blockade of receptor sites, supersensitivity of these receptor sites, or the actions of other modifying neurotransmitters such as Y-aminobutyric acid (GABA) and various neuropeptides. Abnormal movements are offen responsive to a variety of treatment approaches, including dosage adjustment, discontinuation of the offending agent, or the addition of a suitable antiparkinsonian, muscle relaxant, B blocker, or alpha 2-agonist compound.
Akathisia: Motor restlessness accompanied by the subjective sense of inner restlessness, impatience, nervousness. and a vague feeling of discomfort that is worsened by physical inactivity. These patients often fidget, pace. rock forward and backward when sitting, or continuously shift their weight from side to side when standing.
Akinesia: Decreased motor movements often associated with weakness, decreased spontaneous movements, and paresthesias. Akinetic patients tend to have a rigid posture and walk with a shorter stride and diminished spontaneous swings of the arms. These patients appear apathetic, have difficulty initiating usual activities including speech, and may have their movement disorder interpreted as indicative of depression or a withdrawn schizophrenic illness.
Athetosis: Slow, writhing, purposeless movements.
Catatonia: Patient is withdrawn, isolated, and mute, and may show bizarre posture rigidity or immobility, and waxy flexibility. NMS, a complication of neuroleptic drugs must be differentiated from catatonia – a symptom of schizophrenic illness – and may often benefit from discontinuation of medication rather than increased dosage.
Chorea: Rapid, jerky, quasipurposeful nonrhythmic movements.
Dyskinesia: Arrhythmic involuntary spasms of groups of muscles giving rise to a variety of abnormal movements.
Myoclonus: Abrupt, sudden, jerky movements.
Tardive dyskinesia (TD): May occur following prolonged administration of any neuroleptic drug. TD consists of slow, sometimes stereotyped, involuntary movements of the nose, tongue. mouth, face, and, at times, extremities or other parts of the body. The movements are writhing, purposeless, and may or may not be continuous. Mouth movements including sucking, licking, lip pursing, tongue movements, and chewing are the most frequently recognized manifestations of TD. Antiparkinsonian drugs should not be used to treat this disorder.
Withdrawal dyskinesia: Withdrawal dyskinesia, which is generally associated with the same type of involuntary movements as those seen in TD, may occur following the abrupt discontinuation of any neuroleptic drug, after either brief or long-term treatment. Not infrequently, withdrawal dyskinesia is observed and incorrectly diagnosed as tardive dyskinesia.
Respiratory dyskinesia: May be manifested as an irregular respiratory rate, shortness of breath, and chest discomfort. This is a rare syndrome that may occur in association with drug-induced TD.
Dystonia:An abnormality in muscle tone associated with persistent abnormal position of one or more extremities or of the face, neck, or trunk. Dystonia may take the form of an overextended or overflexed posture of the hand, inversion of the foot, pulling of the head to one side, or retraction of the head with or without associated twisting of the back. Acute dystonic reactions to neuroleptic drugs most often manifest themselves by rapid and sustained retroflexion of the neck, which may occur in association with abnormal movements of the tongue, difficulty speaking or swallowing, and occulogyric movements. Rarely, dystonic reactions may affect laryngeal or pharyngeal muscles and be associated with gagging or respiratory distress.
Parkinsonism: Muscular rigidity, poverty and slowness of voluntary movement, tremor at rest (pill-rolling, 4/s), stooped posture, festinating gait, and lack of facial expression often associated with drooling and excessive saliva production. This syndrome may occur spontaneously, due to lesions of the CNS, or may occur during treatment with neuroleptic drugs.
Rabbit syndrome: Fine, rapid tremor of lips (neuroleptic-induced).
Rigidity:Increased muscle tone with continuous passive resistance to movement, lack of facial expression, and micrography are manifestations of muscular rigidity associated with parkinsonism.
Tremor: Rhythmic alternating movements of opposing muscle groups, most often manifested in the fingers. Anxiety produces fine tremors associated with rapid rhythmic movements. Essential tremor is smooth in character, shows a wide range of movements, is usually long-standing, and has a tendency to run in families. Parkinsonian tremor is slow, rhythmic, and often associated with rotational and flexing movements affecting the fingers, hands, and wrists, which tend to move as a unit. Lithium-induced tremor is irregular in rhythm and amplitude. There are jerky movements with flexion and extension of fingers, but usually the hand and wrist are not involved until the condition is far advanced. Lithium-induced tremors are present at rest and tend to become more prominent with intentional movements; they usually fluctuate in intensity and frequency from day to day and there is generally no associated rigidity on passive flexion.