Disorders affecting the neuromuscular junction (NMJ) are generally pure motor syndromes that usually affect the extraocular muscles but also the proximal limb and bulbar or respiratory function. They can be classified into autoimmune, acquired, toxic, and inherited disorders of the NMJ.
The most common NMJ disorders are autoimmune and therefore respond to immunosuppressive therapy. These include myasthenia gravis (MG) and, rarely, the Lambert-Eaton myasthenic syndrome (LEMS). A number of genetically determined disorders of neuromuscular transmission, the congenital myasthenic syndromes, are seen in childhood but may rarely present in adult life
Botulism is a toxin-mediated disorder of the NMJ. All NMJ disorders cause generalized weakness and fatigability with a propensity for oculobulbar involvement. Electrophysiologic studies can detect an impairment of neuromuscular transmission in most of these disorders.
Once diagnosis is established treatments are generally long term under a specialist. Several drugs must be avoided in myasthenia gravis (please obtain list from treating neurologist).