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Extrapyramidal symptoms (EPS) are a variety of symptoms that occur as a result of malfunctioning of the extrapyramidal system due to neurological disorder or the side effects of drugs. As this part of the brain functions in the control of movement the symptoms occur either because of too much movement or too little and are associated with movement disorders. The symptoms include:-

The extrapyramidal system can be affected in a number of ways, which are revealed in a range of extrapyramidal symptoms such as akinesia(inability to initiate movement) and akathisia(inability to remain motionless).

Neurological disorders

The best known EPS is tardive dyskinesia (involuntary, irregular muscle movements, usually in the face). Other common EPS include akathisia (restlessness), dystonia (muscular spasms of neck - torticollis, eyes - oculogyric crisis, tongue, or jaw; more frequent in children), drug-induced parkinsonism (muscle stiffness, shuffling gait, drooling, tremor; more frequent in adults and the elderly),

Although Parkinson's Disease is primarily a disease of the nigrostriatal pathway and not the extrapyramidal system, loss of dopaminergic neurons in the substantia nigra leads to dysregulation of the extrapyramidal system. Since this system regulates posture and skeletal muscle tone, a result is the characteristic dyskinesia of Parkinson's.

Extrapyramidal symptoms can also be caused by brain damage, as in athetotic cerebral palsy, which is involuntary writhing movements caused by prenatal or perinatal brain damage.

Treatment for extrapyramidal symptoms

Anticholinergic drugs are used to control neuroleptic-induced EPS, although akathisia may require beta blockers or even benzodiazepines. If the EPS are induced by a typical antipsychotic, EPS may be reduced by dose titration or by switching to an atypical antipsychotic, such as aripiprazole, ziprasidone, quetiapine, olanzapine, risperidone or clozapine. These medications have a different mode of action which means they are associated with fewer extrapyramidal side effects than "conventional" antipsychotics (chlorpromazine, haloperidol, etc.).

Commonly used medications for EPS are benztropine (Cogentin), diphenhydramine (Benadryl), and trihexyphenidyl (Artane).

Other antidopaminergic drugs like the antiemetic metoclopramide or the tricyclic antidepressant amoxapine can also cause extrapyramidal side effects.


See also