[Temporal lobe damage as pitfalls at subtemporal transtentorial approach (author's transl)].

It is essential to make a proper approach to the lesion site and retract brain, thereby securing an adequate field of vision, upon performing operations on patients for lesions of deep temporal lobe and tentorium. Although subtemporal transtentorial approaches to tumors in the tentorium, pyramis and cerebellopontine angle have been described by a number of workers, further studies have to be made on temporal lobe damage as a pitfall since only a few reports have been published to date. We have therefore examined the possible factors which are responsible for temporal lobe damage and brain swelling in six cases in which subtemporal transtentorial approaches were made. We have encountered two cases of meningioma of the pyramis and tentorium growing in the middle and posterior fossa, one case each of acoustic neurinoma and trigeminal neurinoma located in the middle and posterior fossa, one case of aneurysm at a marginal branch of the superior cerebellar artery and one case of arteriovenous malformation of the deep temporal lobe. Temporal lobe damage was observed in two of these cases during operation and in post-operative CT scans. Although no particular symptoms were noted, CT scan revealed temporal lobe damage in one case. One of the main factors responsible for temporal lobe damage is cutting major veins, namely inferior cerebral vein, transverse sinus, etc. However, no damage was resulted from cutting superior petrosal sinus. Intermittent release of the brain retractor and repeated use of hyperosmotic solution including ventricular drainage are recommended for preventing temporal lobe damage.