ANTIPSYCHOTIC-INDUCED EXTRAPYRAMIDAL SYMPTOMS - ROLE OF ANTICHOLINERGIC DRUGS IN TREATMENT

Acute extrapyramidal symptoms (EPS), specifically the motor syndromes of parkinsonism, acute akathisia and acute dystonia, are among the mos t common adverse effects of antipsychotic medication. They produce phy sical disability and subjective distress, interfere with psychosocial and occupational adjustment, confound the clinical assessment of psych iatric symptoms, and lead to poor compliance with medication. Parkinso nism, akathisia and dystonia can also be chronic conditions in patient s receiving long term antipsychotic treatment. However, the most commo n movement disorder seen in such patients is tardive dyskinesia. The p resence of the obvious movements of this condition can stigmatise pati ents. In the more seven cases, disability may be directly related to t he particular movements, with interference with mobility, respiration, speech, eating, difficulty swallowing and possibly an increased risk of choking. To tackle acute EPS, the clinician will need to consider m odifying the dosage of conventional antipsychotics or switching to a n ew antipsychotic that has a lower liability for these problems. If adj unctive drug therapy is considered necessary, the choice will depend p artly on the particular extrapyramidal syndrome exhibited by the patie nt and partly on the adverse effect profiles of the possible treatment s. Anticholinergic (i.e. antimuscarinic) agents are widely used in psy chiatric practice to treat and prevent EPS. However, there are hazards with these drugs, including a risk of abuse and toxic confusional sta tes, anticholinergic adverse effects (such as dry mouth, blurred visio n, tachycardia, constipation, and urinary hesitation and retention) an d cholinergic rebound phenomena on withdrawal. In the light of these p roblems, it has been recommended that anticholinergic agents are not r outinely administered for the prophylaxis of EPS, unless there is a hi story of acute dystonia or known susceptibility to these antipsychotic -induced motor phenomena. Indeed, the evidence from published studies supports the value of anticholinergic drugs as treatment for EPS rathe r than for prophylaxis. Despite the efficacy of anticholinergic drugs, not all EPS are equally responsive to this treatment. The tremor and rigidity of parkinsonism are reliably relieved by these agents. Howeve r, this syndrome is known to abate spontaneously over time. After 3 mo nths, the majority of patients initially requiring treatment with anti cholinergics can have this therapy withdrawn without a relapse of park insonian symptoms. Therefore, anticholinergics should be periodically withdrawn to test the need for their continued prescription. Acute dys tonic reactions are also effectively treated with anticholinergic drug s. In severe cases, intravenous or intramuscular administration can pr ovide relief in minutes. The place of anticholinegics in the treatment of tardive dystonia is less clear, as only a proportion of patients w ill show any benefit. Anticholinergics also have an uncertain reputati on in both acute and chronic akathisia, being of limited efficacy. Acu te akathisia may respond best to anticholinergics if it is accompanied by parkinsonism, in which case both syndromes may improve. Anticholin ergic drugs are not effective in alleviating tardive dyskinesia. The e vidence suggests that these agents can sometimes worsen the movements, and when discontinued, a modest improvement may be seen in a proporti on of patients exhibiting this condition. However, it has not been est ablished that patients receiving antiparkinsonian medication in additi on to antipsychotic medication are at a greater risk of developing tar dive dyskinesia.