Perioperative evaluation of myasthenia gravis

Abstract

Myasthenia gravis (MG) is the prototype of antibody mediated autoimmune disease and results from the production of autoantibodies against the acetylcholine receptor (AChR) of the neuromuscular synapse. Adequate preoperative evaluation of the myasthenic patient must be carried out carefully. Age, sex, onset and duration of the disease as well as the presence of thymoma may determine the response to thymectomy. Specific attention should be paid to voluntary and respiratory muscle strength. The preoperative preparation of MG patients is essential for the success of surgery. It depends on the severity of clinical status and changes if myasthenic patients receive anticholinesterase therapy. Myasthenic patients may have little respiratory reserve, and hence depressant drugs for preoperative premedication should be used with caution and avoided in patients with bulbar symptoms. The anaesthetic management of myasthenic patient must be individualized in according to the severity of the disease and the type of surgery required. The use of regional or local anaesthesia seems warranted whenever possible. General anaesthesia can be performed safely when patient is optimally prepared and neuromuscular transmission is adequately monitored during and after surgery. Adequate postoperative pain control, pulmonary toilet, and avoidance of drugs that interfere with neuromuscular transmission will facilitate tracheal extubation. Myasthenia gravis is a disease with many implications for the safe administration of anaesthesia. The potential for respiratory compromise in these patients requires the anaesthesiologist to be familiar with the underlying disease state, as well as the interaction of anaesthetic and non-anaesthetic drugs with MG.