Cobalamin deficiency: clinical picture and radiological findings

Abstract

Vitamin B12 deficiency causes a wide range of hematological, gastrointestinal, psychiatric and neurological disorders. Hematological presentation of cobalamin deficiency ranges from the incidental increase of mean corpuscular volume and neutrophil hypersegmentation to symptoms due to severe anemia, such as angor, dyspnea on exertion, fatigue or symptoms related to congestive heart failure, such as ankle edema, orthopnea and nocturia. Neuropsychiatric symptoms may precede hematologic signs and are represented by myelopathy, neuropathy, dementia and, less often, optic nerve atrophy. The spinal cord manifestation, subacute combined degeneration (SCD), is characterized by symmetric dysesthesia, disturbance of position sense and spastic paraparesis or tetraparesis. The most consistent MRI finding is a symmetrical abnormally increased T2 signal intensity confined to posterior or posterior and lateral columns in the cervical and thoracic spinal cord. Isolated peripheral neuropathy is less frequent, but likely overlooked. Vitamin B12 deficiency has been correlated negatively with cognitive functioning in healthy elderly subjects. Symptoms include slow mentation, memory impairment, attention deficits and dementia. Optic neuropathy occurs occasionally in adult patient. It is characterized by symmetric, painless and progressive visual loss. Parenteral replacement therapy should be started soon after the vitamin deficiency has been established.

Figure 1

Bone marrow aspiration; May-Grunwald-Giemsa staining; magnification (600×) shows a hypercellular marrow with a reduced myeloid-to-erythroid ratio of about 1:1 (normal 3:1). Megaloblastic basophilic and polychromatophilic erythroblast are prominent, with their reticular and finely dense chromatin. Progenitor myeloid cells also display large dimensions and fine chromatin. Cytoplasmic granulation occurs regularly.

Figure 2

Cervical spinal cord MRI in a 49-year-old male presenting with subacute combined degeneration due to a deficit of B12. (A) The midsagittal T2 weighted image shows linear hyperintensity in the posterior portion of the cervical tract of the spinal cord (black arrows). (B) Axial T2 weighted images reveal the selective involvement of the posterior columns.

Figure 3

Brain MRI of a 45-year-old female presenting with slowly progressive cognitive impairment. Axial attenuated inversion recovery (FLAIR) images disclose diffuse and symmetric white matter signal hyperintensity.