INTRODUCTION

Congenital methemoglobinemia is a rare hereditary condition which may present with neurological manifestations and persistent cyanosis. In the literature only 80-100 cases have been reported till date.

CASE REPORT

An 18-months girl was brought to us with severe respiratory distress, stridor and cyanosis requiring intubation and ventilation. Child was undernourished, hemodynamically stable, irritable and had spasticity, microcephaly without focal deficit. Rest of the examination was unremarkable.

Till now child was managed by her primary pediatrician and was referred to us for PICU management. Birth and neonatal period were uneventful. At 3 months, she was detected with cyanosis for which x-ray-chest, 2D echo and CT pulmonary angiography done, were normal. At 6-month, child was referred to neurologist for neurodevelopmental delay. MRI brain done showed inferior cerebellar vermis hypoplasia and large posterior fossa CSF space which was reported as Dandy Walker variant. Since then she is on anticonvulsant, gabapentin and physiotherapy.

On present admission, it was noticed that blood was chocolate brown and ABG by co-oximetry showed methemoglobin of 47%. Hence diagnosis of hereditary methemoglobinemia type 2 was entertained and vitamin C was started. Methemoglobin gradually declined and was 5% on discharge. Child was sent home on day seven with no cyanosis. She was advised to continue levetiracetam, vitamin C and syndopa.  Genetic analysis for CYB5R3 gene is awaited.

KEY MESSAGES

Hereditary methemobinemia type 2 presents with neurological manifestations and is often mislabelled as cerebral palsy. Co-oximetry is a valuable diagnostic tool for cyanosis of uncertain cause.