Pyridoxine (vitamin B6) is an essential vitamin playing a crucial role in amino acid metabolism. Pyridoxine is used for isoniazid side-effects prevention, pyridoxine-dependent epilepsy treatment and cystathionine beta-synthase deficiency (homocystinuria) treatment. However, vitamin B6 hypervitaminosis is neurotoxic and may provoke a progressive sensory neuronopathy (sensory ganglionopathy), usually when daily uptake is above 50 mg. We describe the case of a 30-year-old patient with homocystinuria who was treated with pyridoxine 1250–1750 mg/day for 20 years and developed progressive sensory neuropathy with ataxia and impaired sensation in the extremities. Electrodiagnostic testing demonstrated non-length-dependent abnormalities of sensory nerve potentials, and sensory ganglionopathy was diagnosed. Pyridoxine dosage was reduced to 500 mg/day, resulting in the disappearance of sensory symptoms and ataxia, and the normalisation of sensory nerve potentials. Our case indicates that pyridoxine-induced sensory ganglionopathy may be reversible, even after prolonged ingestion of high doses of vitamin B6 for more than 20 years.
- contraindications and precautions
- peripheral nerve disease
- vitamins and supplements
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Contributors AE-L was responsible for the conception and design and drafting the article. RM-C, EN and J-BC were responsible for the acquisition, analysis and interpretation of data and revising it critically for important intellectual content. All authors contributed to the final approval of the version published and agreed to be accountable for the article and to ensure that all questions regarding the accuracy or integrity of the article are investigated and resolved.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests J-BC reports hospitality fees from LFB laboratories, CSL-Behring, Biogen, Grifols.
Patient consent Obtained.
Provenance and peer review Not commissioned; externally peer reviewed.
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