What's in the literature

The spectrum of congenital myasthenic syndromes continues to expand, and recent studies found mutations in enzymes that glycosylate peptides. Affected patients have early onset of a limb-girdle pattern of weakness, and the disorder is treatment responsive. Another article addressed quinine use for slow channel syndrome. There is an additional report on the use of rituximab in acquired myasthenia gravis, and the risk of developing cancer with azathioprine therapy for myasthenia gravis is also covered. Regarding amyotrophic lateral sclerosis, we review articles addressing the utility and safety profile of botulinum injections for sialorrhea and possible associations with autoimmune diseases. Moving to peripheral nerve, we address reports on small fiber neuropathy as a cause of muscle cramps, reexamine clinical and electrodiagnostic features of childhood Guillain-Barré syndrome, and review a recent article on an unusual syndrome of postirradiation lower motor neuron syndrome affecting the cauda equina. Finally, recent reports show that mutations in the skeletal muscle ryanodine receptor may be a common cause of rhabdomyolysis and exertional myalgias and another cause of axial myopathy. Advances in clinical and basic science concepts of myotonic dystrophy are also reviewed.