Myasthenia and the neuromuscular junction.

PURPOSE OF REVIEW

Myasthenic syndromes are distinct disorders at the neuromuscular junction, most often with well characterized autoimmune or genetic pathology. New aspects of the dysfunctions give insight into the normal neuromuscular function in addition to giving therapeutic clues and tailoring the therapy to the pathophysiology in individual patients.

RECENT FINDINGS

Patients with myasthenia gravis and congenital myasthenic syndromes should be further classified into distinct subgroups. Myasthenia gravis with low-affinity acetylcholine receptor (AChR) antibodies and myasthenia gravis with antibodies to the postsynaptic low-density lipoprotein receptor-related protein 4 represent new groups, whereas a myasthenia gravis subgroup without any detectable antibodies still persists. Myasthenia gravis with antibodies against muscle-specific kinase (MuSK) is, due to new reports, now as established as AChR-myasthenia gravis regarding disease mechanisms and recommended therapy.

SUMMARY

Myasthenic syndromes and myasthenia gravis are well characterized disorders. The prognosis is generally good, apart from paraneoplastic Lambert-Eaton myasthenic syndrome. However, patients need long-term symptomatic and immunoactive treatment, this treatment to be balanced against present and potential side effects. New and more selective treatment is needed, especially for severe generalized disease. Well controlled long-term studies of sufficient power are much wanted, but new therapy has often to be tried in patients before high-class evidence of effect on myasthenia gravis has been published.