Essential tremor (ET) is a common movement disorder. Resting-state functional magnetic resonance imaging is a noninvasive neuroimaging method acquired in absence of task.
Our study aimed to correlate pretherapeutic ventrolateral thalamus functional connectivity (FC) with clinical results 1 year after stereotactic radiosurgical thalamotomy (SRS-T) for drug-resistant ET. Data from 12 healthy control individuals were additionally included.
Resting state was acquired for 17 consecutive (right-handed) patients, before and 1 year after left unilateral SRS-T. Standard tremor scores were evaluated pretherapeutically and 1 year after SRS-T. Tremor network was investigated using region of interest, left ventrolateral ventral (VLV) cluster, obtained from pretherapeutic diffusion magnetic resonance imaging. Seed-based FC was obtained as correlations between the time courses of the VLV and that of every other voxel. The seed-connectivity maps were obtained pretherapeutically and correlated across all patients with clinical outcome 1 year after SRS-T. One-year magnetic resonance signature volume was always located inside VLV and did not correlate with reported seed-FC measures (P > 0.05).
We report statistically significant correlations between pretherapeutic VLV FC with clinical outcome for 1) right visual association area (Brodmann area, BA19) predicting 1 year activities of daily living decrease (P _unc  = 0.02); 2) left fusiform gyrus (BA37) predicting 1 year head tremor score improvement (P _unc  = 0.04); and 3) posterior cingulate (left BA23, P _uncor  = 0.009), lateral temporal cortex (right BA21, P _unc  = 0.02) predicting time to tremor arrest.
Our results suggest that pretherapeutic resting-state seed-FC of left VLV predicts tremor arrest after SRS-T for ET. Visual areas are identified as the main regions in this correlation.