Les troubles neurologiques par carence en vitamine B12 : étude rétrospective de 26 cas

Abstract

Purpose. – Neurological symptoms of B12 vitamin deficiency are polymorph. Causes are dominated by Biermer's disease and B12 vitamin non dissociation that is frequent in the elderly. Methods. – We realized a retrospective study during 11 years. Patients with neurological symptoms associated to megaloblastosis were included. Treatment with B12 vitamin lead to haematological manifestation regression. Results. – 26 cases were analyzed. Mean age was 50 ± 14.5 years and there were 11 women and 15 men. Neurological signs included combined medullar sclerosis ( N = 10), peripheral neuropathy ( N = 10), isolated paresthesia ( N = 5) and inferior limb pyramidal syndrome ( N = 1). Neurological signs revealed vitamin B12 deficiency in 4 cases. Mean haemoglobin rate was 6.2 ± 2.6 g/dl, mean MCV was 109 ± 56 fl. Eight patients had macrocytic anaemia, nine bicytopenia and eight deep pancytopenia. Electromyography ( N = 8) confirmed neuropathy and medullar MRI ( N = 2) showed antero-posterior cordonal demyelisation of cervico-dorsal medulla. Causes of B12 vitamin deficiency were Biermer's disease ( N = 11), non dissociation of B12 vitamin's syndrome ( N = 8) and partial gastrectomy ( N = 1). In 6 patients, no aetiology was found. Treatment with parenteral vitamin B12 induced neurological symptoms regression in 14 cases. Patient with neurological disorder had significantly higher platelet count and haemoglobin level as compared with patients without neurological disorder. Reticulocyte crisis was more precocious in patients with neurological disorders. Conclusion. – Neurological symptoms in vitamin B12 deficiency are frequent. We insist on isolated forms, inaugural forms and on the interest of medullar MRI for early diagnosis.