Characteristics of patients with vitamin B12-responsive neuropathy: a case series with systematic repeated electrophysiological assessment

ABSTRACT

Background: Vitamin B12 (B12) has a fundamental role in both central and peripheral nervous system function at all ages. Neurologic manifestations may be the earliest and often the only manifestation of B12 deficiency. Mostly because of the poor sensitivity of methods of determination for B12 levels, peripheral neuropathy remains a classical but underdiagnosed complication of B12 deficiency. So the clinical and electrophysiological characteristics of B12-responsive neuropathy are not well known.

Methods: A retrospective study of patients with B12-responsive neuropathy was conducted at our hospital on a 3-year period. The criteria for inclusion were: (a) neuropathy confirmed by the electrophysiological study (nerve conduction study); and (b) improvement of at least 1 point of the total Overall Neuropathy Limitations Scale score after vitamin B12 treatment.

Results: Nine patients were identified. Serum B12 level was low in only four. Four patients had sensorimotor (predominantly sensory) axonal polyneuropathy while five had only sensory neuronopathy. Six improved in less than 1 month after B12 supplementation.

Conclusion: B12-responsive neuropathy is a more heterogeneous group of neuropathy than previously described. B12 deficiency is a cause of peripheral neuropathy and should systematically be ruled out in the clinical setting of idiopathic neuropathy or sensory neuronopathy because of potential reversibility.

Abbreviations: B12: vitamin B12; CMAP: compound muscle action potentials; DRG: dorsal root ganglia; ENMG: electroneuromyography; MCCT: motor central conduction time; MEP: motor evoked potentials; MMA: methylmalonic acid; MMCoAM: L-methylmalonyl–CoenzymeA mutase; ONLS: overall neuropathy limitations scale; SCV: sensory conduction velocities; SNAP: sensory nerve action potentials; SNN: sensory neuronopathy; SSS: SNAP sum score

KEYWORDS:

• B12
• Cobalamin deficiency
• Sensory neuropathy
• Neuronopathy
• Electrophysiological
• Electromyography

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

this research did not receive any specific grant from funding agencies in the public, commercial or not-for-profit sectors.

Notes on contributors

Jérôme Franques

Jérôme Franques, is neurologist in Marseille Hospital. He got MD degree at Hospice civil Hospital, Strasbourg France. He has several publications about cobalamin deficiency neuropathy.

Laurent Chiche

Laurent Chiche, is internist in Marseille. He got MD, PHD degree at Conception Hospital, Marseille France. He currently work at Hospital European and has several publications about B12 deficiency.

André Maues De Paula

André Maues De Paula, is a pathologist in Marseille Hospital. He got MD,PhD degree at Timone Hospital, Marseille France. He has several publications about neuropathy.

Aude Marie Grapperon

Aude Marie Grapperon, is a neurologist pathologist in Marseille Hospital. She got MD degree at Timone Hospital, Marseille France. she has several publications about neuropathy.

Shahram Attarian

Shahram Attarian, is neurologist in Marseille Hospital. He got PhD degree at Timone Hospital, Marseille France. He has several publications about neuropathy.

Jean Pouget

Jean Pouget, is neurologist in Marseille Hospital. He got MD degree at Timone Hospital, Marseille France. He has several publications about neuropathy.

Stephane Mathis

Stephane Mathis, is neurologist in Bordeaux Hospital. He got PhD degree at Pellegrin Hospital, Bordeaux France. He has several publications about neuropathy.