6533b86cfe1ef96bd12c8252

RESEARCH PRODUCT

Neural conservation in skull base surgery

subject

description

Surgical treatment of lesions of the skull base carries significant risk to the functioning of the cerebral hemispheres, brainstem, and cranial nerves. This risk is due to both (1) problems associated with maintaining an adequate blood flow while exposing and removing the tumor and (2) direct or indirect trauma to the brain, perineural tissues, and cranial nerves. These risks may be reduced if information about possible implications of surgical maneuvers on the cerebral blood flow and on the function of the patient’s CNS and cranial nerves is available and can be monitored during surgery of the skull base. The use of EMG neuromonitoring for the facial nerve and of brainstem evoked response audiometry monitoring for the auditory nerve have been described and are now standard methods to achieve these goals [50,52,54]. For acoustic tumors, in addition to preservation of the function of the facial nerve, hearing preservation has been one of the primary goals in acoustic neuroma surgery in the past several years, especially for patients with small tumors [4–6]. Computer-assisted surgery and intraoperative imaging for lateral skull base surgery are still in their infancy but promise to allow for further improvement of neural conservation [7–10]. Cerebral blood supply In some patients with advanced tumors of the skull base, CT scanning and MR imaging show that the internal carotid artery is surrounded or infiltrated by tumor eventually requiring resection with or without reconstruction, so several tests have been developed to determine whether it would be safe to occlude or even resect the carotid artery. Most tests fail to detect patients who are at risk for delayed stroke in cases in which the carotid artery is permanently occluded [11].