IMMUNE DISORDERS ASSOCIATED WITH MYASTHENIA GRAVIS

myopathies (malignant hyperthermia, acute alcoholic myopathies). 2. EMG and n. conduction studies -confirm the diagnosis of either a myopathy anchor neuropathy. Abundant single-fibre activity in inflammatory myopathy, can also occur in adult form of acid maltase deficiency. 3. Muscle biopsy -provides conclusive evidence whether a motor unit disease is of myopathic or neuropathic origin 4 Molecular genetic analysis - of blood cells, muscle tissue or cultured muscle cells can diagnose symptomatic and presymptomatic hereditary diseases. It can also detect carriers and be suitable for prenatal diagnosis. 5. Muscle imaging by CT or MRI - can establish the distribution and degree of involvement in individual ire This may be diagnostic ally helpful or indicate a suitable site for biopsy. In vivo 32P or proton-based magnetic resonance spectroscopy are particularly useful to differentiate some cases of metabolic myopathies from chronic fatigue syndrome and fibromyalgia. 6. Miscellaneous tests -Biochemical methods to analyse deficiency states (e.g. glycogenolytic enzyme defects, carnitine deficiency). Immunlogical and serological studies - for investigating inflammatory myopathies or retroviral diseases. Management 1. Treatment of cause where possible - e.g. cessation or reduction of corticosteroids together with high protein diet in steroid myopathy, correction of endocrinopathy. 2. Drug therapy - In DMD, muscle destruction can be slowed and clinical course stabilised by oral prednisolone or deflazacort 0.76 mg/kg/day. Mexiletine controls myotonia in myotonia congenita and paramyotonia congenita. Acetazolamide or spironolactone for preventing acute attacks of hypokalemic periodic paralysis. Dantrolene for prevention and treatment of malignant hyperthermia crisis. Some mitochondria! myopathies respond to graded m conditioning aided by oral dichloroacetate. 23. MYASTHENIA GRAVIS Definition: An acquired autoimmune disorder causing skeletal muscle fatigability and weakness which can present at any age. Under age of 40, the disease predominantly affects females, in older age group men predominate. It is associated with a serum IgG antibody that binds acetylcholine receptors (AChR) in the. postsynaptic membrane of the neuromuscular junction and causes receptor loss. Symptoms and Signs: MUSCULAR WEAKNESS - following repetitive contraction with a tendency to recovery of motor power after a period of inactivity. a) Ocular muscles - first to be involved causing double vision or ptosis Symptoms are asymmetrical. b) Limb weakness - may involve proximal or distal muscles. (c) Bulbar muscle weakness - leads to loss of facial expression, inability to whistle, difficulty with speech, chewing and swallowing. Weakness of neck muscles and jaw causes patient to use a hand to support his jaw. (d) Respiratory muscle involvement - can lead to shortness of breath and ventilator/ failure in severe cases Other precipitating factors - Emotional stress, pregnancy and infection apart from exercise can lead to exacerbation of symptoms IMMUNE DISORDERS ASSOCIATED WITH MYASTHENIA GRAVIS - Rheumatoid arthritis, hyperthyroidism, hypothyroidism, polymyositis, SLE, pernicious anaemia, Sjogren's syndrome, pemphigus. Clinical types _ 1. Neonatal myasthenia -Transient illness in babies born to myasthenic mothers. 2. Juvenile myasthenia - in younger age group. 3 Eaton-Lambert