Centronuclear myopathy.

Abstract

The patient (CM), a black girl aged 7 years, is the only child of a non-consanguineous marriage. Pregnancy and delivery were normal. In the early neonatal period, transient jaundice was present. A generalised floppiness was noted soon after birth with reportedly normal limb movements. There were no feeding difficulties and bulbar function appeared to be good. Considerable difficulty in lifting the head, especially when in the prone position, was noted after a few months. She was able to sit unaided at the age of 4 months, but was never able to crawl. She walked at the age of 4 years. The patient was first seen at the age of 4 years 9 months because of increasing difficulty with walking. Increasing difficulty had also been experienced in changing from a lying to a sitting position. Her (Fig. 1). Amarkedgeneralised hypotonia was present. The strength was markedly reduced in the limbs, the upper limbs being slightly weaker than the lower limbs with the proximal muscles being most involved. The neck musculature was diffusely weakened. She was unable to stand from a lying position, could not climb stairs, and walked with a slow waddling gait. Prominent facial weakness resulted in an expressionless appearance. A mild ptosis and proptosis were present. She was unable to raise the eyes, and horizontal upward and downward eye movements were limited to a few degrees. Pupillary reflexes were normal. The masticatory muscles were weakened, and at rest the patient presented an open-mouthed appearance (Fig. 2). The tongue and pharyngeal muscles were normal. The trunk musculature was similarly involved, resulting in an exaggerated lumbar lordosis with protuberant abdomen. Respiration was mainly abdominal. The tendon reflexes were absent and plantar responses flexor. Sensation was normal. Over the vertex of the head there was a patch of white hair.

Centronuclear myopathy: histopathological aspects in ten patients with chilfhood onset

“…Type I fiber predominance, one of the main findings in CNM [3][4][5]11,12,15,16 , was seen in all our muscle samples. Four patients disclosed only type I fibers.…”

“…Only one patient of our series had a severe increase and in the other patients it was absent or insignificant. Other authors have found an increase in the endomysial, or perifascicular adipose tissue 2,3,4,14,30 . Only an increase in the perifascicular adipose tissue we have found in our patients.…”

“…Such histochemical alterations were observed in our study but with variable intensity from case to case. Fiber type differentiation is very poor using these staining procedures 4,14,20 , a fact we observed possibly due to internal architectural alterations.…”

“…Also, a radiated aspect of the myofibrils, of spoke-like appearance, may be observed surrounding the nucleus 14,34 , and in some cases there are intense alterations in the internal architecture where areas with absence of oxidative activity can be observed throughout the whole muscle fiber 4,20 . Such histochemical alterations were observed in our study but with variable intensity from case to case.…”

“…Another frequent finding in CNM is the increased variability in fiber size where there are hypotrohied fibers usually in a great number adjacent to normal size and hypertrophied ones 4,5,12,14,15,16 . This variability occurred in 80% of our cases.…”