A 5 month old with cardiomegaly, hepatomegaly and hypotonia

Dr Ira Shah

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A 5 month old with cardiomegaly, hepatomegaly and hypotonia.

Dr Ira Shah.

Medical Sciences Department, Pediatric Oncall, Mumbai, India.

ADDRESS FOR CORRESPONDENCE
Dr Ira Shah, Medical Sciences Department, Pediatric Oncall, 1, B Saguna, 271, B St. Francis Road, Vile Parle {W}, Mumbai 400056.

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Clinical Problem
A 5 month old male child born of non consanguineous marriage presented with breathlessness since 2 months, loss of weight since 1 month and fever since 3 days. He was a full term normal delivery without antenatal or postnatal complications. His older brother had died at 9 months of age due to a heart disease. On examination, he had tachycardia with heart rate of 180 beats/min. His peripheral pulses were well felt and respiratory rate was 40/minute. There were no dysmorphic features. On cardiovascular system examination, he had cardiomegaly without a murmur. Heart sounds were normal. He had a firm hepatomegaly. He was hypotonic with power 3/5 in all 4 limbs. Deep tendon reflexes were absent. Sensations to pain & touch appeared normal.

Investigations: X Ray chest revealed right lower zone haziness with cardiomegaly. His S.CPK was high [(485 IU/L (Normal = 20-125 IU/L)] and CPK-MB fraction was also elevated [(28 IU/L (Normal = 0-18 IU/L)]. His serum was lipemic and liver enzymes were elevated (SGOT = 1010 IU/L, SGPT = 404 IU/L) though S. albumin was normal. His blood gases, ammonia, blood sugar and renal function tests were normal.
2 D Echo was suggestive of infiltrative cardiomyopathy with poor left ventricular function and diastolic dysfunction. His ejection fraction was 30% with fractional shortening of 15%. His EMG was suggestive of myogenic lesion with decreased motor units in amplitude and duration and denervation diphasics were present at rest. Nerve conduction velocity was normal. ECG was suggestive of sinus tachycardia with inferior myocardial wall infarct.

What is the diagnosis?

Discussion
Glycogen storage disease type II (GSD type II) also termed as “acid maltase deficiency” or “Pompe’s disease” is an inherited disorder of glycogen metabolism resulting from defects in activity of the lysosomal hydrolase acid alpha - glucosidase in all tissues of affected individuals. It is an autosomal recessively inherited disorder. It results in 2 major presentations – Infantile and Juvenile onset. The infantile variety presents as massive cardiomegaly, macroglossia, hepatomegaly progressive muscle weakness (including respiratory muscles) and marked hypotonia. Patients often present with feeding difficulties and pneumonias. Echocardiography reveals a markedly enlarged heart with increased thickness of the walls of both ventricles and interventricular septum with marked dimunition in size of ventricular cavities. The cardiomegaly is progressive. Mental development is normal. Death usually occurs before 1 year of age and is usually due to cardio respiratory failure.
Juvenile onset disease presents predominantly with progressive proximal muscle weakness including major impairment of respiratory functions. Onset in infants is called “Muscular variant”, onset in older children is called “Juvenile variant” and onset in adults is called adult onset disease. In adults, is seen in second to sixth decade of life. Death occurs due to respiratory failure.
The enzyme deficiency results in intralysosomal accumulation of glycogen markedly in cardiac, skeletal muscle and hepatic tissues in infants with generalized disorder. In adult onset, accumulation of glycogen is limited to skeletal muscle and is of lesser magnitude.
Electromyography reveals a myopathic pattern in all types. Myotonic discharges without clinical myotonia are common. Serum CPK (creatine phosphokinase) is elevated upto tenfold in infantile onset patients and SGOT & LDH are also somewhat increased. There are no abnormalities of glucose metabolism. Muscle biopsy shows presence of vacuoles that stain positively for glycogen as well as for lysosomal enzyme acid phosphatase.
The clinical diagnosis is confirmed by virtual absence (infantile onset) or markedly reduced activity (adult onset) of acid alpha - glucosidase in muscle biopsies & cultured fibroblasts. Prenatal diagnosis is by determination of acid alpha- glucosidase deficiency in cultured amniotic cells and chorionic villus biopsies.
Definitive therapy is not available though enzyme replacement is theoretically possible. Supportive measures for respiratory functions are required.

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Funding: None

Conflict of Interest: None

Cite this article as:
Shah I. A 5 month old with cardiomegaly, hepatomegaly and hypotonia. Pediatr Oncall J. 2004;1.