Vitamin B12 deficiency presenting with an acute reversible extrapyramidal syndrome

Vitamin B12 deficiency usually presents with pernicious anemia or various neuropsychiatric manifestations. Commonly seen neuropsychiatric manifestations include large fiber neuropathy, myelopathy (subacute combined degeneration of the spinal cord), dementia, cerebellar ataxia, optic atrophy, psychosis and mood disorders. The present report highlights an unusual presentation of vitamin B12 deficiency- acute onset extrapyramidal syndrome in a 55-year-old man. The patient presented with a 10-day history of slowness of all activities including a slow gait, mild tremors of hands and low volume speech. On examination, he had features of mask-like facies, reduced blink rate and cogwheel rigidity. He was investigated for the possible causes and was found to have laboratory features of vitamin B12 deficiency. Other causes for acute onset parkinsonism were excluded by appropriate investigations. He showed a dramatic improvement following treatment with intramuscular vitamin B12 injections. At a five-year follow up, he was found to be functionally independent with no neurological deficits.