Surgery and the onset of MG

Spinal anesthesia cannot cause myasthenia gravis (MG), which is an autoimmune disease. However, spinal anesthesia (or any anesthesia/surgery) can act as a physiological stressor that may trigger an exacerbation or crisis of pre-existing, and sometimes undiagnosed, myasthenia gravis in susceptible individuals.
Key Points
Cause vs. Trigger: Myasthenia gravis is an autoimmune disorder where the body produces antibodies against acetylcholine receptors at the neuromuscular junction. Anesthesia and surgery do not cause this underlying autoimmune condition.
Exacerbation Risk: The physiological stress of surgery and anesthesia is a known precipitating factor for a myasthenic crisis, a life-threatening condition involving severe muscle weakness and potential respiratory failure.
Anesthetic Management: For patients known to have MG, anesthesiologists take special precautions. Regional anesthesia techniques like spinal or epidural anesthesia may be preferred over general anesthesia in some cases, as they can help avoid the need for certain muscle-relaxing agents that MG patients are highly sensitive to.
Caution with Local Anesthetics: While regional anesthesia is often considered safer, caution is still needed because high levels of local anesthetics can potentially cause muscle weakness and exacerbate symptoms in MG patients.
Undiagnosed Cases: In rare instances, an acute myasthenic event after anesthesia can be the first clinical presentation of an undiagnosed case of myasthenia gravis.
Therefore, while spinal anesthesia cannot initiate the disease, it can reveal or worsen an existing condition due to the body's heightened sensitivity to the physiological stress of the procedure.