Bilateral sixth nerve palsy with subdural hematoma: a unique presentation of B12 deficiency.

Vitamin B12 is inextricably associated with the development and maintenance of neuronal functions. It is classically associated with subacute combined degeneration and peripheral neuropathy; however, cranial neuropathy is uncommon. We observed the rarest neurological manifestation of B12 deficiency. A 12 months infant had history of lethargy, irritability, anorexia, paleness, vomiting, and neurodevelopmental delay for 2 months. He also developed inattention and altered sleep pattern. His mother noticed bilateral inward rotation of both eyes. On examination, the infant had bilateral lateral rectus palsy. The infant was found to have anemia (7.7g/dL) and severe B12 deficiency (74pg/mL). On MRI, there was cerebral atrophy, subdural hematoma (SDH) and wide cisternal spaces and sulci. On supplementation with cobalamin, he improved clinically though mild restriction of lateral gaze on the left side persists. Follow up MRI showed significant improvement in cerebral atrophy with resolution of SDH. To date, such clinical presentation of B12 deficiency has never been reported. The authors suggest B12 supplementation for at risk population esp at antenatal stage and lactating mothers in national programs. The treatment of this condition should be initiated early to prevent long term sequelae.