Parkinsonism following bilateral lesions of the globus pallidus: performance on a variety of motor tasks shows similarities with Parkinson's disease.

OBJECTIVES The authors report the results of detailed investigations into the motor function of a patient who, after a heavy drinking binge and subsequent unconsciousness, respiratory acidosis, and initial recovery, developed parkinsonism characterised by hypophonic speech and palilalia, "fast micrographia", impaired postural reflexes, and brady/akinesia in proximal (but not distal) alternating upper limb movements. METHODS In addition to brain magnetic resonance imaging (MRI), different aspects of motor function were investigated using reaction time (RT) tasks, pegboard and finger tapping tasks, flex and squeeze tasks, movement related cortical potentials (MRCPs), and contingent negative variation (CNV). Cognitive function was also assessed. The results were compared to those previously reported in patients with Parkinson's disease (PD). RESULTS Brain MRI showed isolated and bilateral globus pallidus (GP) lesions covering mainly the external parts (GPe). These lesions were most probably secondary to respiratory acidosis, as other investigations failed to reveal an alternative cause. The results of the RT tasks showed that the patient had difficulties in preparing and maintaining preparation for a forthcoming movement. MRCP and CNV studies were in line with this, as the early component of the MRCP and CNV were absent prior to movement. The patient's performance on pegboard and finger tapping, and flex and squeeze tasks was normal when performed with one hand, but clearly deteriorated when using both hands simultaneously or sequentially. CONCLUSIONS In general, the present results were similar to those reported previously in patients with PD. This provides further indirect evidence that the output of globus pallidus is of major importance in abnormal motor function in PD. The possible similarities of the functional status of GP in PD and our case are discussed.