An unusual cause of hypertrophic cardiomyopathy in an infant: A case report

Abstract

Introduction: Nemaline myopathy (NM), also known as Nemalinosis, is a rare congenital muscle disease with an incidence of 1 in 50000. It is characterized by nemaline rods in muscle fibers, leading to muscle weakness. We reported a case of NM revealed by cardiac involvement, and we highlighted the challenges in diagnosing this condition as well as its poor prognosis.

Observation: The patient is a 7.5-month-old infant from a consanguineous marriage, with a history of bronchiolitis and psychomotor retardation. The infant was admitted to the paediatric intensive care unit due to respiratory distress, which necessitated intubation and mechanical ventilation. A chest X-ray revealed cardiomegaly and bilateral bronchial syndrome, while an electrocardiogram showed left ventricle hypertrophy. Emergency echocardiography revealed biventricular hypertrophy. Laboratory tests indicated significant rhabdomyolysis, hepatic cytolysis, microcytic hypochromic anaemia, negative troponins, and respiratory acidosis. The enzymatic activity of acid alpha-glucosidase was inconclusive. Genetic analysis for mutations in exon 2 associated with Pompe disease and congenital muscular dystrophy, the most common differential diagnoses, returned negative results. Given the presence of rhabdomyolysis, the emergence of tongue fasciculations, and pronounced axial and peripheral hypotonia, a muscle biopsy was performed. This revealed the presence of nemaline rods, confirming the diagnosis of NM. The patient’s condition deteriorated, marked by extubating failure due to severe muscle weakness. The infant passed away after 50 days of hospitalization.

Conclusion: This case underscores the severity and complexity of NM revealed by hypertrophic cardiomyopathy, emphasizing the importance of early diagnosis and prenatal genetic counseling.