Neuromuscular Magnetic Stimulation Counteracts Muscle Decline in ALS Patients

Background: Amyotrophic lateral sclerosis (ALS) is a multi-factorial and multi-systemic pathology associated with motor neuron degeneration, muscle atrophy and paralysis. Mounting evidence suggests that the earliest presymptomatic functional and pathological changes are occurring distally in axons and at the neuromuscular junction (NMJ). These changes precede, and can be independent of the loss of cell bodies or alterations in other cell types already linked to the ALS disease process. In line with these studies, we found that in human ALS muscles the acetylcholine receptors (AChRs) are less sensitive to ACh than denervated non-ALS muscles. It has been also reported that muscle specific expression of mutant superoxide dismutase (SOD1) gene induces muscle atrophy, significant reduction in muscle strength, mitochondrial dysfunction, microgliosis, and neuronal degeneration, suggesting that retrograde signals from muscle to nerve may contribute to synapse and axon damage. This suggests that skeletal muscle is an important target for therapeutic intervention. Neuromuscular system may be artificially stimulated either by an electrical stimulation (ES) or by time-varying electromagnetic fields. Neuromuscular magnetic stimulation (NMMS) has been proposed as an alternative, non-invasive, stimulation technique.

Objective: aim of the study is to verify whether neuromuscular magnetic stimulation can improve muscle function in spinal-onset Amyotrophic Lateral Sclerosis (ALS) patients. We will study if neuromuscular magnetic stimulation can counteract muscle atrophy by promoting the modulation of factors associated with muscle catabolism and/or increasing the efficacy of nicotinic acetylcholine receptors.

Methods: At the baseline visit, ALS patients will be randomized in two groups to receive daily real neuromuscular magnetic stimulation in one arm and sham neuromuscular magnetic stimulation in the opposite arm for two weeks. All patients will undergo median nerve conduction study and a clinical examination, including handgrip strength test and evaluation of upper limbs muscle strength by Medical Research Council Muscle Scale. At the end of the stimulation procedures, a needle muscle biopsy will be performed bilaterally from flexor carpi radialis muscle. Muscle samples will be used to perform histomorphometric and molecular analysis and electrophysiological recordings of acetylcholine evoked currents.