Sodium and chloride channelopathies with myositis: coincidence or connection?

INTRODUCTION

A proximal myopathy develops in some patients with muscle channelopathies, but the causative molecular mechanisms are unknown.

METHODS

We reviewed retrospectively all clinical and muscle biopsy findings of 3 patients with channelopathy and additional myositis. Direct DNA sequencing was performed.

RESULTS

Pathogenic mutations were identified in each case. Biopsies demonstrated inflammatory infiltrates.

CONCLUSIONS

Clinicians should consider muscle biopsy in channelopathy patients with severe myalgia and/or subacute weakness and accompanying elevated creatine kinase. Chance association of myositis and channelopathy is statistically unlikely. An alternative hypothesis suggests that inflammatory insults could contribute to myopathy in some patients.