February 2026

CASE HISTORY

A term, appropriate-for-gestational-age neonate with normal APGAR scores and no history of perinatal hypoxia presented with seizures on day 2 of life. There were no antenatal or perinatal complications. Initial consideration was hypoxic–ischemic encephalopathy (HIE); however, the clinical history was discordant with this diagnosis.

CASE CONTRIBUTED BY

Dr Thapasya, DNB resident, KMCH, Coimbatore

DWI: Diffuse, symmetric cortical thickening with widespread diffusion restriction, involving bilateral cortical and subcortical regions, basal ganglia, thalami, and cerebral peduncles.

SWI: Susceptibility-weighted imaging shows no hemorrhage

MRI Spectrum

Acute: Diffuse white matter and caudate T2 hyperintensity with widespread diffusion restriction; MRS shows elevated lactate and reduced NAA.
Subacute: T1/T2 shortening of basal ganglia, mimicking HIE, with relative thalamic sparing.
Chronic: Severe volume loss of basal ganglia and white matter with cystic degeneration.

Imaging Differentials:

HIE-like metabolic disorders (MoCD/ISOD)
Epileptic encephalopathy
Mitochondrial cytopathy.

Diagnosis: Targeted metabolic evaluation followed by genetic testing confirmed molybdenum cofactor deficiency.

LIKELY COMPOUND HETEROZYGOUS VARIANTS TO BE CAUSATIVE OF THE REPORTED PHENOTYPE WERE IDENTIFIED

“Reclassification of these variants could be considered based on parental testing.”

Discussion:

Hypoxic–ischemic encephalopathy (HIE) is the most common cause of neonatal encephalopathy. MoCD leads to toxic sulfite accumulation, resulting in severe excitotoxic neuronal injury and HIE-like imaging patterns, often in the absence of a hypoxic insult.

Conclusion:

MoCD is a HIE-like imaging patterns that are discordant with clinical history, thucritical metabolic mimic of HIE. Imaging plays a pivotal role in identifying molybdenum cofactor deficiency by recognizing s guiding timely metabolic and genetic testing, preventing misdiagnosis.