Extrapyramidal syndromes: Epidemiology, pathophysiology and the diagnostic dilemma

Antipsychotics are the mainstay of treatment for acute and chronic psychosis, but these drugs have many troublesome neurological adverse effects. Extrapyramidal syndromes (EPS) of akathisia, dystonia and parkinsonism occur in a majority of patients receiving short and long term antipsychotic therapy. Tardive dyskinesia occurs in 15 to 20% of patients, but may have a much higher prevalence in the elderly. Patient and drug factors strongly influence the risk of the motor and mental aspects of movement disorders. Dopamine, acetylcholine and serotonin (5-hydroxytryptamine; 5-HT) receptor antagonism play important roles in the pathophysiology of EPS. Each EPS has its own unique characteristics that must be considered in a differential diagnosis. Assessment approaches include a careful clinical assessment, systematic use of rating scales, and possibly the use of specialised equipment. Recognition and management of EPS with anti-EPS medicines or antipsychotic dose adjustments early in treatment will substantially reduce treatment-related adverse effects and improve therapeutic efficacy.