In a review of the literature, Jabbour et al.2004 described a 33-year-old

patient who had received radiation to the chest and abdomen at 4 years of age for treatment of Wilm’s tumor. Interestingly, this patient was asymptomatic and his subsequent MRI findings were discovered incidentally. Labauge et al.2006 described a 62-year-old male who had received para-aortic radiation for Hodgkin’s disease 26 years prior to presenting with progressive bilateral lower extremity weakness, muscle wasting, and fasciculations. Ducray et al2008 described a 52-year old who had also received para-aortic BKM120 in vitro radiation for Hodgkin’s disease 13 years prior to presenting with progressive right lower extremity weakness and associated gait abnormality. Subsequent MRI in all 3 of these patients demonstrated multiple nodular areas of enhancement coating the nerve roots of the cauda equina mimicking carcinomatous meningitis. Biopsy was then performed and was consistent with

cavernous malformation in all three cases. The pathophysiology of radiation-induced cavernous malformations of the CNS is not well understood. Various hypotheses exist, specifically in regards to cerebral cavernous malformations. One such hypothesis describes a release of vascular endothelial Cisplatin chemical structure growth factor (vEGF) in response Fludarabine to vessel lumen narrowing, which occurs as a result of radiation-induced adventitial fibrosis and endothelial edema.1999 The release of vEGF then results in the induction of angiogenesis and presumably the formation of endothelial-lined vascular sinusoids, as seen in cavernous malformations. Alternatively, some propose that there may be preexisting tiny cavernous malformations, which undergo growth

and/or hemorrhage as a result of radiation, only then resulting in clinical symptomatology and eventual detection on CT or MRI. This finding of multiple nodular areas of enhancement coating the nerve roots of the cauda equina has been associated with a specific set of differential diagnostic considerations. Foremost among this list is leptomeningeal carcinomatosis, which can either represent drop metastases from a primary CNS malignancy or metastases from a distant primary such as lung or breast carcinoma. Infection is also a key differential consideration for this imaging finding including fungal infection, tuberculosis, and HIV-related polyradiculopathy secondary to cytomegalovirus (CMV). Other less common considerations include neurosarcoidosis, Guillan-Barré syndrome, chronic inflammatory demyelinating polyneuropathy (CIDP), and the congenital hypertrophic polyneuropathies.