Neuroanatomical characteristics of late-onset essential tremors: Implications for stereotactic targeting of the ventral intermediate nucleus of the thalamus

Abstract

Background

Essential tremor is the most prevalent movement disorder in older adults, yet its association with aging-related anatomical changes has not been well explored. This study aimed to identify the clinical and neuroanatomical characteristics of medically refractory essential tremor in individuals who are potential candidates for surgical intervention.

Methods

We conducted a cross-sectional descriptive analysis of a population with essential tremors at a single tertiary-level center. Morphometric analysis of structural MRI was performed for 96 samples, and volumetric measurements were compared across four age/sex-matched groups (beta-blocker monotherapy, combination therapy, surgical intervention, and healthy controls).

Results

Individuals with essential tremors had greater ventricular volume than healthy controls. The lateral ventricle volume was 1.57-fold (95% confidence interval, 1.39 to 1.77) larger in the essential tremor subjects, while no significant differences between treatment groups were observed. In terms of stereotactic target coordinate of the ventral intermediate nucleus (Vim) of the thalamus, the width of the third ventricle at the intercommissural plane level was 8.0 ± 2.2 mm in the surgical intervention group, compared with 5.7 ± 2.3 mm in healthy controls. The Vim target coordinates averaged 13.8 ± 1.6 mm laterally from the midline in this cohort; however, one-quarter of candidates had coordinates exceeding 16 mm, substantially differing from previously established atlas-based coordinates of the Vim.

Conclusions

Our findings suggest the potential association between late-onset essential tremor and hydrocephalus, which necessitates careful consideration in stereotactic procedures with regard to the anatomical variability of the third ventricle.