MYASTHENIA GRAVIS: MEDICAL ASPECTS

Abstract

The diagnosis of myasthenia gravis is often difficult and calls for a broader use of pharmacological and electrodiagnostic tests. The decamethonium-edrophonium test, which has proved superior to other procedures for this purpose, is based on neurophysiological principles and depicts the behaviour of the neuromuscular junction. A state of resistance to depolarizing agents in the limited form of myasthenia and a state of a non-depolarizing (competitive) block in advanced cases has been shown. This test has demonstrated that the neuromuscular defect exists throughout the skeletal musculature, including muscles clinically unaffected. It produced no false-positive results either in normal or neurasthenic persons or in patients with neurological diseases with myasthenic symptoms. In a patient with botulism and in a patient with ocular palsies from brain-stem encephalitis the edrophonium test gave a false-positive result, while the decamethonium-edrophonium test was negative.Diagnosis, treatment and management of myasthenic emergencies are described.