Subacute necrotizing myelopathy: MR imaging in four pathologically proved cases

This report describes the MR and correlative imaging findings of four histologically proved cases of subacute necrotizing myelopathy in which there was no evidence of a spinal dural arteriovenous fistula. Subacute necrotizing myelopathy is characterized clinically by progressive motor and sensory deterioration, and pathologically by necrosis in the spinal cord. Initial MR imaging showed focal enlargement of the spinal cord and nonspecific T1 and T2 lengthening. Rimlike enhancement was demonstrated in one case. Clinically, steroid therapy failed in all four patients. Follow-up MR scans showed two slightly enlarged lesions, one stable thoracolumbar lesion, and atrophy of a cervical lesion. Open spinal cord biopsies revealed foci of necrosis and abnormal parenchymal vessels with thickened hyalinized walls. A prolonged course distinguishes subacute necrotizing myelopathy from acute transverse myelitis, but the clinical course and imaging appearance are similar to those of intramedullary tumor. Rimlike rather than solid contrast enhancement may be a distinguishing feature. In the absence of a demonstrable spinal dural arteriovenous fistula, the radiologic differentiation of subacute necrotizing myelopathy from tumor is probably impossible, and biopsy establishes the correct diagnosis.