Percutaneous epidural spinal cord stimulation immediately reduces clonus in an individual with multiple sclerosis

Clonus is a disabling symptom of upper motor neuron dysfunction in patients with multiple sclerosis (MS). We report immediate termination of mechanically evoked clonus by epidural lumbosacral spinal cord stimulation (ES) in a 58-year-old man with secondary progressive MS. This observation was captured during training using video and skin surface electromyography of soleus muscle activity. ES immediately reduced mechanically evoked clonus duration and cycle count compared to trials without stimulation, as determined by a Kruskal-Wallis test (p < 0.05, n = 2-3 trials), and reverted to baseline status when stimulation was off.