DELAYED RADIATION MYELOPATHY - SERIAL MR-IMAGING AND PATHOLOGY

Clinical data, MR-scans, time-dose fractionation schemes and neuropath ologic findings of two cases of delayed radiation myelopathy (DRM), ar e presented. Both patients, a 72-year-old diabetic woman with cervical lymphnode metastasis from a squamous cell carcinoma and a 46-year-old woman with tonsillar carcinoma, developed paraparesis followed by qua driplegia, at 7 and at 10 months following radiation. The spinal cord received 46 and 49 Gy. (Fraction dose 2.25 Gy and 2.0 Gy, 4 times/week ). Serial MR-scans showed spinal cord enlargement and focally increase d signal intensity (T1-gd). The second patient survived and stabilized following therapy with coumarins. The first patient died 13 months af ter radiotherapy. At autopsy necrosis, local calcium deposits, lipid m acrophages and swollen astrocytes were observed in the white matter. T here was slight hyalinosis of the intramedullary vessel walls. We conc lude that serial MRI may be helpful to distinguish DRM from other caus es of spinal cord injury. DRM may occur at a total dose less than 50 G y. Additional risk factors (diabetes, hypertension), and fraction dose s above 2 Gy contribute to the development of DRM.