Patterns of manual dominance in patients with neuroleptic-induced movement disorders

To explore the association between patterns of manual dominance and extrapyramidal symptoms we examined 32 chronic schizophrenic inpatients at Camarillo State Hospital for signs of tardive dyskinesia (TD) and neuroleptic-induced parkinsonism (NIP) using clinical rating scales (Abnormal Involuntary Movement Scale and Columbia Unified Parkinsons Disease Rating Scale) and specialized electromechanical instruments. Manual dominance was assessed using an eight-item hand preference demonstration test. Patients were divided into dextral (consistent use of right hand) and nondextral (any use of the left hand) groups. Dextrals showed a higher prevalence of TD than nondextrals on clinical rating measures (p < 0.01). Orofacial ultrasound measures of TD revealed a similar association between TD and handedness. The two handedness groups did not differ on either the clinical or electromechanical measures of NIP. Interestingly, 28 of the 32 patients showed greater left than right facial movement. It is hypothesized that patients with more standard patterns of manual dominance may be at higher risk for TD than those with atypical patterns.