Tremor is among the most physically disabling symptoms associated with multiple sclerosis (MS). Symptomatic therapies provide at best a modest benefit to affected patients. The effect of MS disease modifying therapies (DMTs) on the severity of MS tremor is unclear.
- To compare the change over time in scores of tremor-related activities of daily living (TRADL) between subjects treated with natalizumab (NTZ) and other MS DMTs
- To compare changes over time in visual analog scale (VAS) of tremor severity and tremor related handicap (TRH) by DMT
Questionnaires were sent to North American Research Committee on MS (NARCOMS) participants reporting mild or greater tremor on the Tremor and Coordination Scale during semiannual updates between Fall 2010 and Spring 2012. Three groups of subjects were invited to participate: Current NTZ recipients, previous NTZ recipients, and a random sample of patients on other MS DMTs. Respondents answered questions regarding their experience of tremor, including history, location, and symptomatic treatment, as well as tremor-specific scales (TRADL, TRH, VAS) to indicate both current tremor severity and tremor severity when the current DMT was initiated. For both TRADL (range 25-100) and VAS (range 1-10) higher scores reflect worse tremor. Changes between the treatment groups were compared using ANOVA.
Respondents were 96.0% white, 78.1% female, and the mean age was 55.5 + 9.3 years. Of 567 subjects, 202 were taking NTZ, 136 were previously on NTZ, and 229 had never taken NTZ and were on other DMTs. Subjects on NTZ were more likely to report tremor improvement on their DMT (28.7% on NTZ vs. 14.0% previously on NTZ vs. 14.4% on other DMT, p=0.0007). Mean baseline TRADL score was 43.5 + 15.8, and did not differ between treatment groups (p=0.475). Over a mean recall period of 6.2 + 4.6 years, the TRADL score increased by 1.8 points among NTZ subjects, 3.3 points in those previously on NTZ, and 5.4 points in those never on NTZ (p=0.009). The VAS score improved among NTZ-treated subjects and worsened in prior NTZ and other DMT groups (-0.1 vs. 0.1 vs. 0.3, p=0.027). TRH responses did not yield associations between change in tremor-related embarrassment or physical handicap with current DMT.
NTZ is associated with less worsening in MS-associated tremor compared to other MS DMTs. Longitudinal studies will be needed to confirm these results in prospective fashion.