Introduction:

Hypoglycaemia: blood glucose level below 54 mg/dL (3.3mmol/L). Cerebral cortex, hippocampus, and basal ganglia are commonly affected, while cerebellum and brain stem are spared. While we are familiar with Magnetic Resonance Imaging (MRI) brain in neonatal hypoglycaemia, there is scarce literature on infantile hypoglycemia. It also needs to be differentiated from hypoxic-ischemic-injury, which can be co-associated with hypoglycaemia. Most cases present with encephalopathy, which could be due to hypoxia, hypoglycaemia or meningitis. The pattern of neuroimaging can help in early diagnosis.

Methods: 2 cases were evaluated with a detailed history, examination, and investigations.

Results: Case-1: 1-year-8-month-old girl, with skin-hyperpigmentation, presented with fever and lethargy. Blood sugar- 30mg/dL. MRI brain: diffusion restriction in right hemi-cortex and left frontal cortex (Fig-1). Based on adrenocorticotropic hormone stimulation test and exome sequencing (NNT gene), Addison’s disease was diagnosed.

Case-2: 5-month-old boy, moderate preterm, presented with fever, irritability, and lethargy for 2 days. Blood sugar was low. MRI: diffusion restriction in fronto-temporal, and occipital regions (Fig-2).

Cerebrospinal fluid analysis and arterial blood gas ruled out infection and hypoxia as the cause of encephalopathy in both cases. Thalami, basal ganglia, and splenium were spared. Both cases succumbed.

Conclusion: Diffusion-weighted imaging is the best modality for early diagnosis of hypoglycaemic encephalopathy and helps in prognostication. Hypoglycaemic brain injury is different beyond the neonatal period- splenial involvement may be uncommon and involvement of occipital lobe is lesser. Extensive cortical involvement can be a predictor of poor prognosis. Sparing of thalami helps in differentiating hypoglycaemic from hypoxic encephalopathy.

Thanuja Basavanagowda
Jawaharlal Nehru Medical College
India

Mahesh Kamate
Jawaharalal Nehru medical College
India