Overexcitation (hyperexcitability) of motor neurons appears to be an early process in amyotrophic lateral sclerosis (ALS) and could lead to cell death. Dr. Michael D. Weiss, from the University of Washington School of Medicine, reviews the objective of this phase II study which is to determine the effects of mexiletine, a cardiac anti-arrhythmic medication, on cortical hyperexcitability in ALS subjects using transcranial magnetic stimulation, a device which employs magnetic fields to target the motor cortex of the brain to determine their level of excitation, and on peripheral nerve excitability using threshold tracking, a technique that stimulates the nerves with low levels of electricity. Reduction of hyperexcitability may suggest that a larger and longer phase III study is warranted to determine whether mexiletine slows progression of the disease.
