Background: To collect preliminary data on the effects of mexiletine on cortical and axonal hyperexcitability in sporadic amyotrophic lateral sclerosis (ALS) in a phase 2 double-blind randomized controlled trial. Methods: Twenty ALS subjects were randomized to placebo and mexiletine 300 or 600 mg daily for 4 wk and assessed by transcranial magnetic stimulation and axonal excitability studies. The primary endpoint was change in resting motor threshold (RMT). Results: RMT was unchanged with 4 wk of mexiletine (combined active therapies) as compared to placebo, which showed a significant increase (P =.039). Reductions of motor evoked potential (MEP) amplitude (P =.013) and accommodation half-time (P =.002), secondary outcome measures of cortical and axonal excitability, respectively, were also evident at 4 wk on mexiletine. Conclusions: The relative stabilization of RMT in the treated subjects was unexpected and could be attributed to unaccounted sources of error or chance. However, a possible alternative cause is neuromodulation preventing an increase. The change in MEP amplitude and accommodation half-time supports the reduction of cortical and axonal hyperexcitability with mexiletine.
All Science Journal Classification (ASJC) codes
- Clinical Neurology
- Cellular and Molecular Neuroscience
- Physiology (medical)