Homonymous hemianopia: An unusual presentation of vitamin B 12 deficiency

Abstract

A 24 years male presented with a headache for one year, recent memory loss and loss of left hemifield of vision for three months. Upon examination, visual acuity was found to be 20/20 in both eyes. Automated perimetry revealed left homonymous hemianopia with sparing of the macula. Right thalamic infarct and subacute infarct in the territory of the right posterior cerebral artery (PCA) were the findings on CT scan. Except for decreased vitamin B12 level and increased homocysteine level in serum, rest of the serological, biochemical, hormonal and immunological investigations were within normal limits. MRI of the brain showed right PCA infarct and few ischemic foci in bilateral periventricular regions. MR Angiogram revealed relatively reduced flow in the right PCA and right vertebral artery. The patient was managed with antiplatelet drugs and supplementation of vitamin B12. Marked improvement was noticed in a headache and memory loss and there was normalization of field defect after 6 months of treatment. Cases of homonymous hemianopia in neuro-ophthalmology are not unusual, but the etiology and course of this case report make an interesting variation. Keywords: Homonymous hemianopia, Vitamin B12 deficiency, Posterior Cerebral artery infarct.