Myasthenia gravis in the West of Scotland
Myasthenia gravis (MG) is a relatively rare acquired neurological disorder that is potentially life-threatening. Characteristically it results in fatigable weakness of any muscle but typically involves ocular (eyes), limb, facial and bulbar (speech and swallowing) muscles and in severe cases the respiratory muscles. Patients with myasthenia gravis (MG) often have an antibody in their blood to a protein present at the muscle surface called the acetylcholine receptor. This receptor is present at the junction between nerve and muscle and allows the translation of electrical nerve messages into muscle contraction and movement. The antibody is present in about 85% of patients with generalised muscle weakness and around 50% of patients with weakness isolated to the eye muscles (referred to as ocular MG). In a minority of patients, there may be an antibody to an alternative protein called MuSK (which stands for muscle specific tyrosine kinase) or may have no detectable antibody at all (referred to as seronegative MG). Treatment for MG consists of symptomatic treatment with a drug called pyridostigmine and immunosuppressive agents (usually corticosteroids and a drug called azathioprine). “Rescue” treatments available to manage MG crises include intravenous immunoglobulin or plasma exchange. Removal of the thymus gland is indicated in cases where there is an associated tumour of the thymus (thymoma) or in younger (<45 years) MG patients.