Author: Mahmoud,Ahmed Darwish./ Title: SURGIC.AL APPROACHES FOR TENTORIAL HIATUS LESIONS \

الموضوع

The neurovascul ar relationships in the region of the tentorial incisura are among the complex in the cranium . The incisura! area is related to the depths of the cerebrum and the cerebellum, six cranial nerves, the upper brain stem, the cricle of Willis and the convergence of the deep intracranial venous system to form the vein of Galen. It is exposed during many operations for aneurysms, deep tumours, arteriovenous malformations, trigeminal neuralgia and epilepsy. The incisura! area is subdivided according to the relation to the brain stem into four spaces : anterior, paired middle and posterior incisura! spaces. Prior to the development of microsurgical techniques, the operative mortality rate for surgical treatment of different incisura! lesions was extremely high. Even with the • operating microscope and advanced microneurosurgical instrumentation . It still remains technically challanging for the neurosurgeon. With the advent of improved imaging tools and techniques such as computerized tomography CT and magnetic resonance imaging MRI . Lesions of the tentorial incisura are diagnosed earlier and more precisely than in the pre CT era. An accurate preoperative localisation of the lesion IS necessary before an operative approach and possible recostruction can be planned .The essential issues that guide the evaluation of incisura! lesions include; the anatomical localisation and extent , the lesion composition and biology, its rela