Neuromuscular disorders in infancy and childhood.

Thirty five floppy children seen during two year period, were subjected to clinical examination, electroneuromyography and muscle biopsy. The muscle biopsy was sent for routine histology, histochemistry and electron microscopy. Using muscle pathology as the 'gold standard' for diagnosis, the aetiological entities were spinal muscular atrophy (16), congenital muscular dystrophy (6), mitochondrial myopathy (3), congenital fibre type disproportion (2), acid mutase deficiency (1) and benign congenital hypotonia (6). Mental subnormality, seizures, ptosis and ophthalmoplegia suggested mitochondrial disease (n=2). Macroglossia, hepatomegaly and cardiomegaly along with the dive bomber effect on electromyography were useful clues to the diagnosis of Pompe's disease (n=1). Positive decremental test established the diagnosis of congenital myasthenia in one patient. Contrary to most previously published reports, infantile onset of spinal muscular atrophy did not always spell a poor prognosis on follow up. 'Floppy infant syndrome' has varied etiology. Comprehensive evaluation including clinical, electrophysiological and detailed histological examination is necessary for proper diagnosis and prognosis of this heterogenous entity.