Differences in intrinsic functional networks in patients with essential tremor who had good and poor long-term responses after thalamotomy performed using MR-guided ultrasound.

OBJECTIVE: Thalamotomy at the nucleus ventralis intermedius using MR-guided focused ultrasound has been an effective treatment method for essential tremor (ET). However, this is not true for all cases, even for successful ablation. How the brain differs in patients with ET between those with long-term good and poor outcomes is not clear. To analyze the functional connectivity difference between patients in whom thalamotomy was effective and those in whom thalamotomy was ineffective and its prognostic role in ET treatment, the authors evaluated preoperative resting-state functional MRI in thalamotomy-treated patients. METHODS: Preoperative resting-state functional MRI data in 85 patients with ET, who were experiencing tremor relief at the time of treatment and were followed up for a minimum of 6 months after the procedure, were collected for the study. The authors conducted a graph independent component analysis of the functional connectivity matrices of tremor-related networks. The patients were divided into thalamotomy-effective and thalamotomy-ineffective groups (thalamotomy-effective group, ≥ 50% motor symptom reduction; thalamotomy-ineffective group, < 50% motor symptom reduction at 6 months after treatment) and the authors compared network components between groups. RESULTS: Seventy-two (84.7%) of the 85 patients showed ≥ 50% tremor reduction from baseline at 6 months after thalamotomy. The network analysis shows significant suppression of functional network components with connections between the areas of the cerebellum and the basal ganglia and thalamus, but enhancement of those between the premotor cortex and supplementary motor area in the noneffective group compared to the effective group. CONCLUSIONS: The present study demonstrates that patients in the noneffective group have suppressed functional subnetworks in the cerebellum and subcortex regions and have enhanced functional subnetworks among motor-sensory cortical networks compared to the thalamotomy-effective group. Therefore, the authors suggest that the functional connectivity pattern might be a possible predictive factor for outcomes of MR-guided focused ultrasound thalamotomy.

Comparative evaluation of the white matter fiber integrity in patients with prelingual and postlingual deafness.

The aim of this study was to perform a comparative investigation of white matter integrity in patients with prelingual and postlingual deafness; we carried out a tract-based statistical analysis of diffusion tensor anisotropy in eight and ten adults with prelingual and postlingual deafness, respectively. Patients with deafness showed significant decreases in diffusion anisotropy at the right internal capsule, the right thalamus, and the splenium of the corpus callosum as well as within the bilateral superior temporal gyrus (including Heschl gyrus) and right temporal white matter. Furthermore, relative to patients with postlingual deafness, those with prelingual deafness showed lower anisotropy in the right superior temporal gyrus, bilateral temporal white matter, and the genu and anterior body of the corpus callosum. We believe that, in patients with deafness, reception of early auditory stimuli before language acquisition might be more critical to white matter maturation and brain reorganization than the nature of auditory stimuli itself or the duration of disuse. These findings provide the theoretical background for early auditory rehabilitation.