Clinical case of cyanocobalamin-deficient polyneuropathy

Introduction. Cyanocobalamin (vitamin B12) deficiency is an important but often overlooked cause of neurological disorders, including polyneuropathy, especially in the absence of classic hematological signs.

The objective was to describe a clinical case of B12-deficient polyneuropathy induced by occupational exposure to nitrous oxide and to discuss the features of diagnosis and treatment.

A clinical case of a 27-year-old female patient with complaints of weakness, paresthesia, and ataxia is presented. Clinical and neurological examination, laboratory tests (complete blood count, biochemical analysis, B12 level), and instrumental methods (electroneuromyography) were performed. The patient was found to have severe B12-deficient polyneuropathy (B12 level – 90 pg/ml) against the background of occupational contact with nitrous oxide. Neurological status was characterized by sensory ataxia and impaired deep sensitivity of the polyneuropathic type. ENMG confirmed mixed axonal-demyelinating lesion.

Conclusion. Occupational exposure to nitrous oxide can be a cause of severe vitamin B12 deficiency with dominant neurological manifestations. Timely diagnosis and replacement therapy with cyanocobalamin lead to significant clinical improvement, emphasizing the importance of a thorough occupational history in patients with polyneuropathy.

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