Hemorrhagic encephalitis produced by selective non-occlusive intracarotid BCNU injection in dogs

A selective non-occlusive technique was developed for administration of BCNU (1,3-bis(2-chloroethyl)-1-nitrosourea) into the internal carotid artery of the dog, and the neuropathological effects in the brain were studied. One out of three dogs showed ipsilateral hemorrhagic necrotizing encephalitis at doses of 102 mg/sq m, and all of three dogs showed similar but more severe pathology at doses of 215 to 232 mg/sq m. This study and previous studies in the dog and monkey suggest definite thresholds above which cerebral toxicity occurs when BCNU is administered via the intracarotid route. Greater dilution of drug in the larger territory of supply of the human internal carotid artery allows somewhat higher doses in man. The pathology of the lesion induced by BCNU suggests a primary vascular injury as a pathogenic mechanism, consonant with similar findings following high-dose systemic BCNU administration in man. Investigators conducting ongoing and future trials of intracarotid BCNU in the human for the treatment of intracranial neoplasms should be especially vigilant for a similar toxic effect.