Safety and preliminary efficacy of deep transcranial magnetic stimulation in MS-related fatigue

Background:

MS is the most common autoimmune inflammatory and neurodegenerative disease of the CNS. Fatigue is one of the most frequent symptoms experienced in MS, affecting up to 90% of patients. Neuroimaging studies suggest that structural and functional connectivity alterations, particularly to interconnections between the basal ganglia and the prefrontal cortex (PFC), the posterior cingulate cortex and cortical motor areas, may contribute to fatigue in MS. A potential treatment of functional connectivity impairment is noninvasive neuromodulation by means of repetitive transcranial magnetic stimulation (rTMS).

Objective:

To conduct a randomized, sham-controlled phase I/IIa study to evaluate the safety and preliminary efficacy of deep brain H-coil repetitive transcranial magnetic stimulation (rTMS) over the prefrontal cortex (PFC) and the primary motor cortex (MC) in patients with MS with fatigue or depression.

Methods:

Thirty-three patients with MS were recruited to undergo 18 consecutive rTMS sessions over 6 weeks, followed byfollow-up (FU) assessments over 6weeks. Patients were randomized to receive high-frequency stimulation of the left PFC, MC, or sham stimulation. Primary end pointwas the safety of stimulation. Preliminary efficacy was assessed based on changes in Fatigue Severity Scale (FSS) and Beck Depression Inventory scores. Randomization allowed only analysis of preliminary efficacy for fatigue.

Results:

No serious adverse events were observed. Five patients terminated participation during treatment due to mild side effects. Treatment resulted in a significant median FSS decrease of 1.0 point (95%CI [0.45,1.65]), which was sustained during FU.

Conclusions:

H-coil rTMS is safe and well tolerated in patients with MS. The observed sustained reduction in fatigue after subthreshold MC stimulation warrants further investigation.