Electrophysiological evaluation of tremors secondary to space occupying lesions and trauma: Correlation with nature and sites of lesions

Abstract

Background Electrophysiological evaluation of tremor secondary to intracranial space occupying lesions (SOL) and cranial trauma may provide information regarding pathophysiology of tremors. Objectives To compare the electrophysiological characteristics of tremor secondary to SOL and trauma and to correlate tremor characteristics with sites of lesion, and types of SOL. Methods Multi-channel tremor recording and MRI were performed in 18 patients with predominantly tremor secondary to SOL (F: M = 5:6; age ± SD: 26.6 ± 15.0 years) and following trauma (7 men; age: 27.3 ± 11.0 years). Results In both groups, there was a wide range in the frequency of tremor (2.5–7.5 Hz in the SOL group and 2–7.5 Hz in the post-trauma group) and a strong inverse correlation of the frequency with the duration of EMG bursts (SOL group: r = 0.8, p = 0.004; post-trauma group: r = 0.9, p = 0.02). While all the patients with SOL had regular EMG bursts (synchronous – 54.6%, alternating – 27.3%, mixed – 18.2%), 85.7% of post-trauma patients had irregular EMG bursts (synchronous – 42.9%, alternating – 14.3%, mixed – 42.9%). In SOL group, those with predominantly intrinsic destructive lesions of brainstem, thalamus, or basal ganglia ( n = 7) had a statistically significant lower mean frequency of tremor than those ( n = 4) with either extrinsic or intrinsic compressive lesions (3.5 ± 0.9 Hz vs 6.7 ± 0.6 Hz; p = 0.0001). In the post-trauma group, the patients with additional lesions in thalamus or striatum, apart from white and grey matter lesions had lower mean tremor frequency (3.7 ± 1.0 Hz vs 6.1 ± 1.5 Hz; p = 0.05). Conclusions The electrophysiological characteristics of tremor secondary to SOL and trauma differ and correlate with the nature and sites of lesions. This information, which need to be validated in larger cohort of patients, may be useful in understanding the pathogenesis of tremor.