SIGNIFICANCE OF PARKINSONIAN MANIFESTATIONS IN ESSENTIAL TREMOR

Parkinsonian features, notably resting tremor may be seen in some esse ntial tremor patients but the significance of those is unknown. The re ported risk of parkinsonism in essential tremor patients varies from b eing unchanged to 35 times higher than expected. We studied 9 patients with essential tremor who had autopsies. In 6 of the 9 (66%) resting tremor was noted and in 3 (33%) cases fully developed parkinsonism was noted. The parkinsonism was consequent to neuroleptic usage in 2 and to basal ganglia status lacunaris and cribrosus in one case but no con sistent abnormalities were noted in 3 essential tremor only and 3 esse ntial tremor plus resting tremor cases. We conclude that resting tremo r is an age-related natural evolution in some essential tremor patient s. We recommend that the additional diagnosis of parkinsonism in the e ssential tremor be made only when resting tremor, bradykinesia and rig idity are all evident. The risk of ideopathic Parkinson's disease in e ssential tremor cases is similar to the general population.