Essential tremor course and disability

Abstract

Objective: To correlate autopsy findings with the clinical course and disability profile in clinically diagnosed longitudinally followed autopsied essential tremor (ET) patients. Methods: All ET patients followed by one neurologist between 1970 and 2001 who came to autopsy were included. Clinical features and disability were recorded prospectively. Autopsy studies were performed by a qualified neuropathologist. Results: Twenty cases (10 men and 10 women) had ET onset between childhood and age 68 (median 46.5 years). Six cases had additional features of Parkinson syndrome (PS), with presence of bradykinesia, rigidity, and rest tremor (RT). These included progressive supranuclear palsy (PSP; n = 2), drug-induced parkinsonism (n = 2), idiopathic Parkinson disease (PD; n = 1), and basal ganglia status cribrosus (n = 1). Of the remaining 14 ET cases, 6 had additional RT but no bradykinesia or rigidity. Ten of these 14 (71%) reported physical disability. Eleven of the 14 (79%) had only upper limb (UL) tremor at onset, and 8 of these 11 (73%) had subsequent cranial extension of tremor. Two patients clinically had mild cerebellar ataxia but no cerebellar histologic abnormality. There was no consistent brain pathology in the ET or ET + RT cases. Conclusions: UL tremor was the most common onset, which often progressed to the cranial musculature. Functional disability and psychological distress were common in these patients. Functional disability was related to the UL tremor. Six of 20 (30%) had additional features of PS. Six of the remaining 14 (43%) had ET and RT; there was no identifiable pathology in these cases. The risk of PD in ET cases was comparable with that in the general population. PSP in two cases was incidental comorbidity.