Clinical Neurophysiology - Studies of the neuromuscular synapse and myasthenia gravis

Disorders of disturbed neuromuscular transmission include the autoimmune disorder Myasthenia Gravis (MG), in which antibodies attack the receptors of the neuromuscular synapse. The symptoms manifest as fatigable weakness of skeletal muscles in the face, in the neck, arms and legs and often cause droopy eyelids, difficulty in swallowing and chewing etc.

In many patients, there is also a subsequent muscle wasting, in particular in patients with antibodies against the receptor muscle specific tyrosine kinase (MuSK).

Our main research interest is to elucidate pathogenic mechanisms underlying neuromuscular disorders, and establishment of biomarkers, with focus on myasthenia gravis (MG). Ultimately we aim at finding new therapeutic interventions against the muscle wasting following chronic neuromuscular disorders. Additionally, we aim to discover novel circulating and neurophysiological biomarkers for improved diagnostics, prognosis and treatment in conditions of disturbed neuromuscular transmission and other neuromuscular disorders.  We work both with preclinical models (experimental autoimmune MG) and in the clinical setting with MG patients.

During the past year we have found that different muscle signaling pathways are differentially regulated in various muscles in the preclinical model of  MuSK antibody seropositive (MuSK+) EAMG. This finding also gives a broader understanding of the clinical spectrum of muscle wasting in muscular dystrophies.

We also managed to link certain microRNAs to subgroups of MG. Ongoing studies now aim at studying the role of microRNA in the autoimmune process and neuromuscular transmission. Eventually, microRNAs may serve as predictive biomarkers in judging disease states of autoimmune neuromuscular disorders.

Development of electrophysiological methods and markers for the study of neuromuscular disorders continues. In the past year, our focus has been on new electrodes for jitter analysis with single-fiber EMG and collection of new referece values. The macro EMG technique has a proven value to study and follow reinnervation processes, and is superior to the conventional needle-EMG in these respects. In the future, we plan to apply neuromuscular ultrasound as an additional method in these disorders. Further, neurophysiological parameters to assess the safety and efficacy upon intramuscular injection of botulinum toxin in the facial muscles have been established.