The myopathology of floppy and hypotonic infants in Singapore.
OBJECTIVE
This study attempts to determine the type and relative frequency of muscle diseases contributing to floppy and hypotonic infants in Singapore.


METHODS
Eighty consecutive muscle biopsies in the Department of Pathology, National University of Singapore, in the period 1978-2000, in which a clinical diagnosis of floppy or hypotonic infant was made, were reviewed.


RESULTS
The commonest cause of severe hypotonia in infancy was spinal muscular atrophy, which accounted for 33% of cases followed by congenital muscular dystrophy (13%). Eight cases (10%) of infantile type II glycogenosis (Pompe's disease) were encountered. There were seven cases of congenital myopathy, of which four were centronuclear myopathy, and one each of central core myopathy, nemaline myopathy and congenital fibre type disproportion. One case of centronuclear myopathy was associated with type I fibre smallness. Type II atrophy, which is generally considered a non-specific change, was encountered in five cases. Of interest is the relatively large number of muscle biopsies (29%) in which no significant pathological features were encountered at the light microscopic, histochemical as well as ultra-structural level.


CONCLUSIONS
The study has revealed a great variety of pathology affecting the muscle of children presenting as floppy infants or with hypotonia. The muscle diseases included spinal muscular atrophy, congenital muscular dystrophies, congenital myopathies and metabolic myopathies. However, 23 (29%) cases showed no significant pathology. For this group of floppy and hypotonic infants further studies are needed.
Premasiri
Mapalagama K
MK
Department of Pathology, National University of Singapore.
Lee
Yoke-Sun
YS
D002681:China / Q000208:ethnology; D005260:Female; D006801:Humans; D007194:India / Q000208:ethnology; D007223:Infant; D007231:Infant, Newborn; D008296:Malaysia / Q000208:ethnology; D008297:Male; D009123:Muscle Hypotonia / Q000151:congenital / Q000208:ethnology / Q000473:pathology*; D018482:Muscle, Skeletal / Q000378:metabolism / Q000473:pathology*; D009135:Muscular Diseases / Q000151:congenital / Q000208:ethnology / Q000473:pathology*; D017678:Sex Distribution; D012846:Singapore / Q000453:epidemiology; D014897:Spinal Muscular Atrophies of Childhood / Q000208:ethnology / Q000378:metabolism / Q000473:pathology