SUBACUTE COMBINED DEGENERATION
IntroductionVitamin B12 deficiency may result spinal cord lesions, known as subacute combined degeneration. B12 deficiencey can occur in conditions such as, intrinsic factor deficiency, gastrectomy, blind loop syndrome, celiac disease, Crohn's disease, chronic pancreatic insufficiency or Diphyllobothrium latum infestation. Strict vegetarians may also develop B12 deficiencies. Pathologic results of B12 deficiency in spinal cord are demyelination, wallerian degeneration and gliosis. These changes have hyperintense signal properties in T2-weighted MRI images.
Case ReportA 55 year old female patient was referred with a history of numbness and tingling in both hands for a month. MRI showed bilateral symmetrical T2-hyperintense signal changes involving the dorsal columns of the cervical spinal cord (Fig-1, 2 and 4). The lesion was isointense on T1-weighted images (Fig-3) MRI findings were consistent with subacute combined degeneration of cervical spinal cord. Furthermore, the cobalamine level (65 pg/ml) was found to be markedly decreased (normal: 98.5-1200 pg/ml). Further examination of gastrointestinal system with gastroscopy revealed both gastritis and duodenitis. After B12 supplementation treatment, the complaints of the patient disappeared.
There are several reports describing typical symmetrical high T2 signal bilaterally in the posterior columns of the spinal cord. Neuropathological studies of SCD show that the main lesions are present in the posterior and lateral columns, involving the corticospinal and spinocerebellar tracts. Most of the cases are reported to show improvement of MRI findings after B12 supplementation treatment.
Differential diagnoses of posterior column lesions include infectious or post-infectious myelitis, radiation myelitis, peripheral neuropathy, carcinomatous radiculopathy, multiple sclerosis, ischemia, traumatic cord injury, metabolic disease and acute transverse myelitis . Involvement of the posterior columns may be seen in these conditions, therefore the radiological finding of posterior column involvement is not specific for SCD.
It is important to distinguish B12 deﬁciency from other causes of myelopathy, so that patients may be treated before significant cord damage has occurred. A correct diagnosis of subacute combined degeneration should based on the clinical, laboratory and imaging findings.
References1) D. A. Shrier, H. Tanaka, Y. Numaguchi, K. Yamada. A case of subacute combined degeneration: MRI findings. Neuroradiology (1998) 40: 398-400.
2) S. S. Bassi, K. K. Bulundwe, G. P. Greeff, J. H. Labuscagne, R. F. Gledhill. MRI of the spinal cord in myelopathy complicating vitamin B12 deficiency: two additional cases and a review of the literature. Neuroradiology (1999) 41: 271-274.
3) B. Ravina, L. A. Loevner, W. Bank. MR Findings in Subacute Combined Degeneration of the Spinal Cord: A Case of Reversible Cervical Myelopathy. AJR (2000) 174:863–865.
Figure-1: Sagittal TSE T2-weighted image shows hyperintensity in posterior parts of spinal cord (arrows)
Figure-2: Sagittal TSE T2-weighted image shows hyperintensity in posterior parts of spinal cord (arrows)
Figure-4: Axial GRE T2-weighted image reveals bilateral symmetrical hyperintensity of posterior columns (arrows).
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