fibre size and selective atrophy of type I fibres. Treatment - Quality of speech may be improved by

fibre size and selective atrophy of type I fibres. Treatment - Quality of speech may be improved byprocainamide 250 mg t.d.s. or phenytoin 100 mg t.d.s. 2. MYOTONIA CONGENITA - (i) Thomsen's disease (AD) - begins in infancy and affects entire voluntary, musculature giving rise to generalized muscular stiffness. (ii) Becker type (AR) - usually begins later in childhood and is characterised by striking muscular hypertrophy giving the patient a Herculean appearance 'Startle' myotonia may often be present 3. CONGINITAL MYOTONIC DYSTROPHY - Can occur in an infant born of a mother with myotonic dystrophy. Features are marked hypotonia, feeding difficulties, areflexia and respiratory insufficiency. About half die in infancy, and those who survive show classical picture of myotonic dystrophy before age of 10.4. PARAMYOTONIA CONGENITA - Generalised myotonia accentuated by cold and accompanied by episodes of weakness related to a disturbance of potassium metabolism. III. Specific congenital myupathies - are rare disorders which present with undue floppiness in infancy - (1) Central core disease - is characterised by presence of one or more cores which run axially along the fibres. The disease is compatible with a normal ambulant life. Risk of developing malignant hyperpyrexia. (2) Nemaline myopathy - runs a benign course in childhood but may later progress. Skeletal abnormalities such as scoliosis, high arched palate, arachnodactyly. IV. Metabolic myopathics - Clinical patterns: (1) Infantile hypotonia ,(Floppy infant syndrome) due to acid maltase deficiency. (a) Infantile form - Heart, liver and muscles involved with failure to thrive and death within first year. (b) Childhood and adult varieties – Glycogen accumulation only in skeletal muscle Slowly progressive limb-girdle syndrome, often with hypertrophy of lower limbs Respiratory muscle involvement in 50%, and often causes death. (2) Limb girdle myopathies - Relatively late-onset myopathy. a) Benign acid maltase deficiency - with glycogen storage in childhood, adolesence or early adulthood. (b) Carnitine deficiency - (i) Systemic deficiency - Intermittent attacks of hepatic enlargement and insufficiency, associated with hypoglycemia and encephalopathy. Pre-myopathic phase of 2-10 years before onset of muscle weakness. (ii) Muscle carnitine deficiency - Presents as limb- girdle syndrome in childhood or early adult life, and is progressive Cardiac involvement is cause of death in later stages. (c) Mitochondrial disorders - usually result of disorders of respiratory chain function Late- onset limb girdle myopathy sometimes accompanied by prolonged paralytic attacks (at times involving bulbar and ventilatory functions) and precipitated by exercise, exposure to cold or excessive alcohol intake. 'Ragged red' fibre apparance on muscle biopsy. 3) Exercise-induced cramps with myoglobinuria- at rest or on exertion. Types - (i) Myophosphorylase deficiency with defect in glycolysis (McArdles disease). Cramping pains on exercise. (ii) Carnitine palmytil transferases (CPTI and II) deficiency -causing defective fatty acid oxidation. Late onset carmps (more than 3 hours after exercise). (iii) AMP deaminase deficiency -Disorder of purine nucleotide metabolism Occasional cases (including families). (4) Chronic progressive ophthalmoplegia plus (CPEC+) - Most disorders associated with 'mosaic' cytochrome oxidase deficiency Generalised disorder with involvement of extra-ocular muscles and limb girdles (mildly) Mitochondria!