OCCULT CEREBROVASCULAR MALFORMATIONS AFTER IRRADIATION

OBJECTIVE: It has recently been found that patients receiving cerebral irradiation can develop hemorrhagic dysangiogeneses simulating occult vascular malformations. To analyze this connection, we report on five patients with occult cerebrovascular malformations occurring after '' standard'' or focused irradiation performed for brain tumors in four p atients and for a deep-seated cavernous angioma in one patient. METHOD S: All lesions were within the radiation ports. The time interval betw een irradiation and the detection of the occult vascular malformations varied from 3 to 9 years; the ratio of female to male patients was 4: 1. Four patients were <15 years old when first irradiated. Four patien ts presented with acute symptoms (headache, vomiting, focal signs) and one was asymptomatic when the lesions were first detected. Serial mag netic resonance imaging scans were available in four patients and a co mputed tomographic scan in the other patient. RESULTS: The initial app earance was that of a hypointense T1-T2 focus; magnetic resonance imag ing then revealed focal or multifocal T1 hyperintensity and T2 mixed s ignal intensity followed by a late ring of decreased signal intensity. Four patients were operated on and one was under neuroradiological mo nitoring. Histological features of these lesions included clusters of closely packed vascular spaces resembling cavernous malformations some times associated with a thrombosed thick-walled vein with intense hemo siderin deposition and fibroblastic proliferation; telangiectasic chan ges were also seen in the adjacent brain. CONCLUSION: Increased awaren ess of occult cerebrovascular malformations is necessary, because thei r occurrence is not infrequent and they have hemorrhagic potential. Ch ildren receiving cerebral irradiation are at greater risk of this comp lication.