Multifocal Noninvasive Magnetic Stimulation of the Primary Motor Cortex in Type 1 Myotonic Dystrophy –A Proof of Concept Pilot Study

Abstract

Background: Repeated neuromuscular electrical stimulation in type 1 Myotonic Dystrophy (DM1) has previously been shown to cause an increase in strength and a decrease in hyperexcitability of the tibialis anterior muscle. Objective: In this proof-of-principle study our objective was to test the hypothesis that noninvasive repetitive transcranial magnetic stimulation of the primary motor cortex (M1) with a new portable wearable multifocal stimulator causes improvement in muscle function in DM1 patients. Methods: We performed repetitive stimulation of M1, localized by magnetic resonance imaging, with a newly developed Transcranial Rotating Permanent Magnet Stimulator (TRPMS). Using a randomized within-patient placebo-controlled double-blind TRPMS protocol, we performed unilateral active stimulation along with contralateral sham stimulation every weekday for two weeks in 6 adults. Methods for evaluation of muscle function involved electromyography (EMG), hand dynamometry and clinical assessment using the Medical Research Council scale. Results: All participants tolerated the treatment well. While there were no significant changes clinically, EMG showed significant improvement in nerve stimulus-evoked compound muscle action potential amplitude of the first dorsal interosseous muscle and a similar but non-significant trend in the trapezius muscle, after a short exercise test, with active but not sham stimulation. Conclusions: We conclude that two-week repeated multifocal cortical stimulation with a new wearable transcranial magnetic stimulator can be safely conducted in DM1 patients to investigate potential improvement of muscle strength and activity. The results obtained, if confirmed and extended by future safety and efficacy trials with larger patient samples, could offer a potential supportive TRPMS treatment in DM1.

The Effects of Testosterone and Transcutaneous Muscle Stimulation on Strength and Muscle Mass in Myotonic Dystrophy

“…Chloroquine led to functional improvement in drosophila and mouse models of DM1 (51). In terms of improving symptoms, novel approaches are also being explored, such as with robotics and transcranial magnetic stimulation (52,53). With advances in robotics, exoskeleton assisted rehabilitation training was trialed in one patient with DM1 that showed improvement in strength and functional status (53).…”

Electric field characteristics of rotating permanent magnet stimulation

“…Applying the TRPMS device to brain regions that modulate voiding initiation significantly improved bladder emptying symptoms [15,17,18]. Additionally, a proof-of-concept pilot study suggests that the TRPMS device may offer potential benefits for muscle function in individuals with type 1 myotonic dystrophy [16]. Yet another system that uses a magnet array is a wide-bore, low-frequency magnetic spinner comprised of approximately 1300 Alnico permanent magnets [19].…”

“…Recent studies showed the safety and potential effectiveness of the TRPMS device in treating voiding dysfunction in patients with multiple sclerosis (MS) [15][16][17][18]. In a feasibility and safety study, the microstimulators from the TRPMS device were individually placed over predetermined regions of interest (ROI) during voiding initiation [15,17,18].…”

Electric Field Characteristics of Rotating Permanent Magnet Stimulation

“…Recent studies have shown the safety and potential effectiveness of the TRPMS device in treating voiding dysfunction in patients with multiple sclerosis (MS) [ 15 , 16 , 17 , 18 ]. In a feasibility and safety study, the microstimulators from the TRPMS device were individually placed over predetermined regions of interest (ROI) during voiding initiation [ 15 , 17 , 18 ].…”

“…Applying the TRPMS device to brain regions that modulate voiding initiation significantly improved bladder emptying symptoms [ 15 , 17 , 18 ]. Additionally, a proof-of-concept pilot study suggests that the TRPMS device may offer potential benefits for muscle function in individuals with type 1 myotonic dystrophy [ 16 ].…”