Post-deep brain stimulation — gradual non-stimulation dependent decrease in strength with attenuation of multiple sclerosis tremor

Abstract

Tremor in multiple sclerosis is considered to be a persistent and progressive sign. We describe five patients with multiple sclerosis in whom upper limb tremor severity gradually decreased over a period of several years after deep brain stimulation. In every case this attenuation of tremor was accompanied by increasing pyramidal weakness in the relevant upper limb. In two patients this attenuation of tremor remained after stimulation was permanently switched off. In one other patient, where upper limb strength remained normal, tremor severity gradually worsened in spite of continuing stimulation. There was a highly significant difference (p = 0.0007) between the changes in intention tremor severities when the arms with increasing pyramidal weakness (n = 9) were compared to those in which normal strength was retained throughout follow-up period (n = 3); intention tremor decreased in the former and increased in the latter by means of -3.66 and +4.0 points of a 0-10 tremor scale respectively. There was also a significant correlation (0.699; p = 0.0359) between decreasing upper limb strength and decreasing intention tremor severity for the upper limbs of patients that had undergone contralateral DBS.

Tremor in inflammatory neuropathies

“…This suggests that the presence of tremor accounts for part of the disability measured by the ONLS, similarly suggested by Ahlskog et al 26. Interestingly, in multiple sclerosis tremor, as limb weakness progresses, tremor may improve, suggesting a necessary role for limb strength in generating tremor 27. This may similarly be true for patients with inflammatory neuropathy and tremor but we observed that none of our patients reported worsening of tremor associated with improvement in their neuropathy (and strength) after treatment with intravenous immunoglobulins or other immunomodulators.…”

Deep brain stimulation for movement disorders: update on recent discoveries and outlook on future developments

“…High-frequency stimulation is required. Tremor occurring in multiple sclerosis can also respond [51], although these patients often have coexisting disabling ataxia which may be less predictably responsive to the surgery. The extent of functional disability due to tremor, rather than coexisting ataxia should be clarified during preoperative assessment.…”

Understanding Tremor in Multiple Sclerosis: Prevalence, Pathological Anatomy, and Pharmacological and Surgical Approaches to Treatment

“…102 This permanent tremor reduction has been attributed to limb weakness (occurring with MS progression) preventing the expression of tremor. 102 …”