POSTURAL REFLEXES IN PATIENTS ON LONG-TERM NEUROLEPTIC MEDICATION

It is not conclusively known whether the amplitude of medium latency postural reflexes is controlled by dopamine. To further assess the influence of supraspinal dopaminergic pathways on postural reflexes, we studied short (SL), medium (ML) and long latency (LL) reflexes in the lower extremity of 10 patients on long term (> 6 months) neuroleptic medication, 5 with and 5 without mild drug induced parkinsonism. A control group consisted of 10 age and sex matched healthy volunteers. In both patient groups, latencies and amplitudes of all 3 responses were identical to normal controls. These findings suggest that a moderate postsynaptic inhibition of central dopaminergic pathways is insufficient to cause enhanced amplitudes of ML responses.