Tremor and Disability Outcomes After Deep Brain Stimulation for Multiple Sclerosis-associated Tremor
Samantha Banks1, Matthew Baker1, Eoin Flanagan1, Fiona Permezel1, Lauren Jackson1, W. Tobin1, Orhun Kantarci1, Mark Keegan1, Sean Pittock2, Kai Miller1, Bryan Klassen1
1Mayo Clinic, 2Mayo Clinic Dept of Neurology
Objective:

Describe outcomes of deep brain stimulation (DBS) for MS-associated tremor in a single center and identify baseline features associated with optimal outcomes.

Background:
Tremor is common in MS and may be refractory to medications. DBS is a potential treatment, but concern for side effects and disease exacerbation limit its use. Ideal patient candidates need to be identified.
Design/Methods:
Mayo Clinic patients with MS who underwent DBS for treatment of medication-refractory tremor were retrospectively identified. Demographic, clinical, electrophysiologic, and DBS data were abstracted. Expanded Disability Status Scale (EDSS) and Fahn-Tolosa-Marin (FTM) tremor rating scale were assessed. 
Results:

We identified 18 patients who underwent DBS for MS-associated tremor including: relapsing MS, 2; secondary progressive, 8; primary progressive, 8. Median age of MS onset was 32 years (range, 21 – 65). DBS surgery was performed at median age of 49.5 years (range, 28 – 75) with a median follow-up of 2.5 years (range, 0 – 22) after. Seven patients were on MS disease modifying therapy. After surgery, no clinical relapses (0/18) or new MRI lesions (0/8) occurred. One patient had an early surgical complication (1/18). There was no change in EDSS following DBS surgery (median preoperative 6 [3 – 6.5]; postoperative 6.25 [1 – 8]; p=0.2). There was a reduction in FTM score with stimulation (preoperative median 13 [4 – 22], postoperative last follow-up 11 [2 – 16], p=0.03). There was an interaction (p<0.001) between preoperative EDSS score and tremor outcome, such that all patients with preoperative EDSS ≤3 or ≥6.5 had sustained improvement in FTM, while those with preoperative EDSS 3.5 to 6 had variability in tremor outcomes (5/8 sustained improvement).

Conclusions:

DBS represents a potential avenue for treatment of severe tremor in MS and did not provoke inflammatory MS activity in our cohort. Baseline EDSS may be a helpful tool to identify ideal DBS candidates.

10.1212/WNL.0000000000210835
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