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

Extrapyramidal symptoms (EPS) are various movement disorders such as acute dystonic reactions, pseudoparkinsonism, or akathisia suffered as a result of taking dopamine antagonists, usually antipsychotic (neuroleptic) drugs, which are often used to control psychosis.

The Simpson-Angus Scale (SAS) and the Barnes Akathisia Rating Scale (BARS) are used to measure extrapyramidal symptoms.^[1]

Contents [hide] 1 Causes 2 Conditions 3 Treatment 4 See also 5 References

[edit] Causes

The most common antipsychotic associated with EPS is haloperidol used especially in schizophrenia.^{[citation needed]} Other antidopaminergic drugs like the antiemetic metoclopramide or the tricyclic antidepressant amoxapine can also cause extrapyramidal side-effects.

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.

[edit] Conditions

• Acute dystonic reactions: muscular spasms of neck – torticollis, eyes – oculogyric crisis, tongue, or jaw; more frequent in children
• Akathisia: A feeling of motor restlessness
• Pseudoparkinsonism: drug-induced parkinsonism (muscular lead-pipe rigidity, bradykinesia/akinesia, resting tremor, and postural instability; 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 bradykinesia of Parkinson's.

[edit] Treatment

Anticholinergic drugs are used to control neuroleptic-induced EPS, although akathisia may require beta blockers or even benzodiazepines. If the EPS are induced by an 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 possess an additional mode of action that is believed to negate their effect on the nigrostriatal pathway, 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).

[edit] See also

• Extrapyramidal system
• Yokukansan

[edit] References