ABSTRACT
Authors analyzed the post-operative subdural hygroma using radioisotope(RI) cisternography in 30 cases following aneurysmal surgery with pterional approach from October, 1995 to March, 1996. Age, CSF flow from basal cisterns, and etent of opening of Liliequist's membrane during operation were significantly related to the development of post-operative subdural hygroma. Computed tomography(CT) scan of brain and RI cisternography were performed in all patients at three weeks following operations. RI diffusion time from the interpeduncular cistern to the cerebral convexity of ipsilateral side with surgically opened Liliequist's membrane was compared with contralateral nonoperated normal side. Diffusion time of ipsilateral side(mean 5.2+/-8.4hr) was faster than that of contralateral one. Age, cerebrospinal fluid(CSF) from basal cistern, and extent of opening of Liliequist's membrane during operation were significantly related to development of post-operative subdural hygroma. Development of subdural hygroma after pterional approach for aneurysmal operations in our series is believed to be caused by stagnation of CSF in the convexity until its absorption into the arachnoid villi. Increased CSF flow from the infratentorial space to the supratentorial space through extensively opened Liliequist's membrane is considered to contribute development of its formation.