INVESTIGATION OF A CASE OF MUSCULAR WASTING

repeated after 2-3 years in those who are positive for anti-AChR and anti-striated muscle antibody Differential Diagnosis 1 Conditions manifested as fluctuating excessive muscular fatigability (a) Eaton-Lambert syndrome (b) Drug-induced myasthenia (e g Penicillamine) 2. Ocular manifestations (a) External ophthalmoplegia Hyperthyroid ophthaimopathy Mitochondrial myopathies (b) Pseudo internuclear ophthalmoplegia Multiple sclerosis Brainstem stroke (c) Ptosis Ocular myopathies 3 Others Botulinism Snake bite B syndrome Organophosphate toxicity Management: Treatment options Indications 1 Cholinesterase Inhibitors Pyridostigmine First line reatment for every pt. Neostigmine Side-effects (due to parasympathetic stimulation) Pupillary constriction, colic diarrhoea, increased salivation and sweating, lacrimation, bronchial secretions 2. Thymectomy Associated with thymoma Generalised MG (especially in young pts with poor response to choline-esterase inhibitors) 3. Prednisolone Initial 10 mg Seriously ill pts increased by or insufficient week improvement after till symptoms thymectomy are controlled Ocular myasthenia or dose of 120 mg is reached, then reduced to minimum effective level 4 Root lesions - (a) Cervical spondylosis. (b) Injury or tumour or cervical enlargement of spinal cord (c) Hypertrophic cervical pachymeningitis (d) Vertebral metastasis. 5 Brachial plexus or peripheral nerve lesions -e.g. - (a) Thoracic inlet syndrome. (b) Inflammation of spinal nerve (neuralgic amyotrophy) (c) Carpal tunnel syndrome (d) Diphtheritic and lead paralysis. (e) Leprosy.(f) Neoplasms of vertebrae. (g) Trauma. (h) Peroneal muscular atrophy G Myoneural junction disorder - Myasthenia gravis (muscular wasting very rare) B. Disuse atrophy - (a) Arthritic - Rheumatoid arthritis. (b) Post-paralytic - Hemiplegia and paraplegia. (c) Therapeutic immobilization - fracture. (d) Psychogenic (hysterical paralysis) C Systemic wasting - Tuberculosis, malignancy, thyrotoxicosis. INVESTIGATION OF A CASE OF MUSCULAR WASTING I. History - 1. Family history - constant in muscular dystrophy and peroneal muscular atrophy. Absent in motor neurone disease. 2 Age of onset - Muscular dystrophy, poliomyelitis and diphtheritic paralysis in infancy and childhood; motor neurone disease in second half of life, peroneal muscular atrophy and wasting of cervical rib pressure in early adult life, cervical spondylosis usually after 45 3 Mode of onset - Rapid in poliomyelitis and acute radiculitis More gradual in diphtheritic paralysis, cervical spondylosis or tumour, and infective polyneuritis In spinal lesions, atrophy usually precedes weakness, in polyneuritis, weakness precedes atrophy 4. Symmetry - Muscle weakness may be symmetrical which usually indicates myopathic disease, or asymmetrical, suggesting neurogenic disease 5 Episodic or progressive - Progressive weakness is usually associated with one of the limb girdle, fascioscapulohumeral or scapuloperoneal syndrome. Episodic weakness if accompanied by fatigue, suggests a disorder of neuromuscular transmission Episodic weakness following exercise or heavy meal suggests periodic paralysis G Associated discomfort - Muscle pain - at rest can occur in polymyositis, polymyalgia in myopathies of metabolic bone disease Episodic pain, which may at times be associated with weakness, suggests a metabolic disorder Pain that develops during exercise is