MRI in chronic progressive radiation myelopathy.

Objective: Our goal was to assess medullary lesions in patients suffering from chronic progressive radiation myelopathy (CPRM) using MRI.
Materials and Methods: In a group of 10 patients suffering from CPRM, MRI findings (11 examinations), radiation protocols, and patient prognoses were reviewed.
Results: A cord enlargement was demonstrated in five cases, whereas four cases presented with medullary atrophy. As demonstrated by MRI, radiation-induced medullary lesions progressed toward cord atrophy in one patient. When MRI and/or comparison myelogram were performed within 8 months following the onset of the myelopathy, a cord enlargement was usually encountered. When the patient was evaluated > 8 months after the first neurological symptoms, a cord atrophy was always demonstrated. Medullary lesions extended beyond the boundaries of the radiation field in 67% of the cases. However, with the exception of one case, the main focus of the cord damage was included within an irradiated cord segment. An enlarged cord was often associated with a neurologic deterioration and a fatal outcome. In patients with cord atrophy, the neurologic deficit was often static and survival rates were better.
Conclusion: These results suggest a revision of classic criteria used for the diagnosis of CPRM. By demonstrating cord lesions, MRI helps to establish disease prognosis.