Biermer's anemia is an auto immune disease that can lead to neurological manifestations. Medullary combined sclerosis accounts for only 10% of neurological complications. There are few reports of documented bone marrow involvement by magnetic resonance imaging (MRI). Observation: We report a case of combined sclerosis of the cervical spinal cord assessed by cerebro-medullary MRI in a context of vitamin B12 deficiency in a 36-year-old patient who was hospitalized in the intensive care unit for septic shock with respiratory starting point, requiring the use of mechanical ventilation for 13 days and the discovery in post-extubation of pancytopenia with macrocytic anemia and flasquo-spasmodic tetraparesis prompting an emergency MRI showing combined sclerosis of the spinal cord , with vitamin B12 deficiency and megaloblastic anemia at the myelogram. The patient had benefited of vitamin therapy combined with a physical rehabilitation and the evolution was marked by a recovery of walking and normalization of biology after 2 months. Conclusion: The advantage of medullary MRI in a severe clinical form with neurological impairment of vitamin B12 deficiency to guide the diagnosis. The treatment is based on vitamin therapy with a good evolution.