A nutritionally compromised infant with severe lactic acidosis and basal ganglia hyperintensities

Thiamine, a water-soluble and heat-labile vitamin, plays a crucial role in metabolism and energy production. Whole-grain food, rice bran, nuts and legumes provide this vital nutrient; however, processed foods like milled cereals (including polished rice) and refined oils are poor in thiamine.1, 2 Also, improper food preparation (e.g., discarding cooking water, overcooking, etc.) can lead to substantial thiamine loss.3 Infants exclusively breastfed by thiamine-deficient mothers or those on thiamine-deficient formula are at risk of developing vitamin B1 deficiency.1, 2 Infantile beriberi may have a varied clinical presentation ranging from non-specific symptoms (irritability, anorexia, emesis) to cellular/organ dysfunction (cardiac failure, severe lactic acidosis, encephalopathy/seizures).2 Patients presenting with neurological dysfunction (Infantile Wernicke's encephalopathy) exhibit T2-weighted hyperintensities in regions with high energy/oxidative demand on MRI (including corpus striatum, thalami, hypothalamus, etc.).4 As typical clinical features of Wernicke's encephalopathy (altered mental status, ataxic gait, ophthalmoplegia) are difficult to demonstrate in infants, recognition of these characteristic neuroimaging findings is imperative. Although diagnosis of thiamine deficiency can be confirmed biochemically (erythrocyte transketolase activity; unavailable in our region), brisk clinical response to intravenous thiamine administration substantiates the diagnosis in patients with typical clinicoradiological features (including dietary history).5, 6 Inborn errors of metabolism (IEMs) are important differentials in infants presenting with lactic acidosis and basal ganglia/cortical hyperintensities on MRI. In our patient, blood tandem mass spectrometry and urinary gas chromatography/mass spectrometry were non-contributory. Besides, the infant remained well on follow-up favouring the diagnosis of thiamine deficiency (over IEMs) in our case. Lastly, from an epidemiological perspective, infantile beriberi may be rarely encountered in routine clinical practice in well-nourished societies. However, in the context of increasing food insecurity issues globally and locally prevalent food fads, consideration of beriberi amongst the differential diagnosis seems prudent in infants presenting with compatible clinicoepidemiological profiles.7 Relevant data utilised in the preparation of this manuscript are provided in the main manuscript.