Acute stimulation with symmetric biphasic pulses induces less ataxia compared to cathodic pulses in DBS for essential tremor.

BACKGROUND: Symmetric biphasic pulses have been shown to acutely increase the therapeutic window of ventralis intermedius deep brain stimulation (Vim-DBS) for essential tremor (ET) compared to cathodic pulses. Acute supratherapeutic stimulation can induce ataxic side effects in Vim-DBS. OBJECTIVE: To investigate the effect on tremor, ataxia and dysarthria of 3 h of biphasic stimulation in patients with DBS for ET. METHODS: A randomized, doubled-blind, cross-over design was used to compare standard cathodic pulses with symmetric biphasic pulses (anode-first) during a 3-h period per pulse shape. During each 3-h period, all stimulation parameters were identical, except for the pulse shape. Tremor (Fahn-Tolosa-Marin Tremor Rating Scale), ataxia (International Cooperative Ataxia Rating Scale) and speech (acoustic and perceptual measures) were assessed hourly during the 3-h periods. RESULTS: Twelve ET patients were included. During the 3-h stimulation period, tremor control was equivalent between the two pulse shapes. Biphasic pulses elicited significantly less ataxia than cathodic pulses (p = 0.006). Diadochokinesis rate of speech was better for the biphasic pulse (p = 0.048), but other measures for dysarthria were not significantly different between the pulses. CONCLUSION: Symmetric biphasic pulses induce less ataxia than conventional pulses after 3 h of stimulation DBS in ET patients.

Lifestyle factors in multiple sclerosis disability progression and silent brain damage: A cross-sectional study.

OBJECTIVE: To determine the association between lifestyle risk factors with 1/ the Multiple Sclerosis Severity Score (MSSS) and 2/ ongoing subclinical brain damage in non-active MS patients on high-efficacy treatment. METHODS: Cross-sectional study in persons with Multiple Sclerosis (PwMS) investigating lifestyle factors including cognitive reserve (CR), physical activity (PA), smoking status, alcohol use, dietary habits, body mass index (BMI), blood pressure (BP) and cholesterol ratio. Data were collected through validated questionnaires, clinical and laboratory examination. Serum Neurofilament light chain (sNfL) levels were used as a proxy for ongoing brain damage in a subgroup of persons with non-active MS on high-efficacy treatment. Multiple regression analysis (MRA) models explored the relationship between lifestyle factors with the MSSS score and sNfL. RESULTS: 351 PwMS were included (43.04 ± 11.77 years, 69.8% female). Higher CR and PA were associated with a lower MSSS; overweight or obesity and higher systolic BP with a higher MSSS. The MRA model explained 22.2% of the variance for MSSS (R².255, adjusted R².222). Higher BMI and BP were related to lower sNfL. Twenty-3% (R².279, adjusted R².230) of the variance was explained in the MRA model for sNfL. CONCLUSION: Our study suggests an association between a 'brain healthy lifestyle' with disability progression in MS. A cognitive and physical active lifestyle alongside a normal body weight and blood pressure may help to prevent future disability in MS. Longitudinal and interventional research is necessary to gain insight in the causal pathway of these risk factors in preventing disability progression in MS.