[Intraoperative identification of oculomotor, trochlear and abducent nerves in surgery of invasive cranioorbital tumors (new technique)].

BACKGROUND: Aim of the study was to evaluate effectiveness of intraoperative identification of oculomotor nerves (OMN) in resection of skull base tumors invading superior orbital fissure and cavernous sinus. MATERIALS AND METHODS: 69 patients with cranioorbital tumors operated in Burdenko Neurosurgical Institute (Moscow, Russia) since 2000 until 2005 were included in the study. They were divided into 2 groups: 19 patients treated with intraoperative identification of OMN and 50 patients in the control group. Craniorbital meningiomas were in the majority among all cases. Intraoperative identification of OMN was performed using coaxial electrode while muscular response was registered through electrodes inserted in m. levator palpebrae superioris, m. obliquus superior and m. rectus lateralis (for III, IV and VI cranial nerves, respectively). Identification of IMN trunci was repeated throughout the whole stage of tumor resection for their preservation. RESULTS: comparison of dynamics of oculomotor dysfunction in early postoperative period in patients of both groups demonstrated that intraoperative identification of OMN allowed to decrease the frequency of oculomotor deficit. The rates in main and control groups were: for III and IV nerves--37% and 68% (p < 0.05), for VI nerve--47% and 54% (p > 0.05), respectively. CONCLUSION: application of intraoperative identification of OMN allows to decrease the risk of oculomotor deterioration due to III and IV nerve dysfunction by 1.8 times. Technically the method is quite simple and not time-consuming procedure.

[Skull base meningiomas spreading into the infratemporal fossa: clinical picture, diagnosis, and treatment policy]. / Meningiomy osnovaniia cherepa, rasprostraniaiushchiecia v podvisochnuiu iamku: klinika, diagnostika, taktika lecheniia.

From 1997 to 2004, the Academician N. N. Burdenko Research Institute of Neurosurgery has operated on 54 patients with intracranial meningiomas spreading into the infratemporal fossa. Fifteen patients were operated on for the first time. Thirty-nine patients had undergone surgical interventions on the average 3 times (from 2 to 8). All the patients were operated on via different orbitozygomatic approaches depending on the extent of the process. Opening the upper and lower palpebral fissures and the round foramen with resection, if required, the pterygoid processes suffice to remove tumors from the areas of the upper and lower palpebral fissures, which spread into the sphenoid and maxillary sinuses. If there are tumors at the site of the base of the anterior surface of the pyramid, and the articular bursa, it is expedient to open the oval and spinous foramens, to resect the external portions of the fundus of the middle cranial fossa and, if required, the articular process of the lower jaw. By taking into account the X-ray and histological patterns, it may be stated that invasion of meningiomas is not always accompanied by the development of hyperostosis. According to our findings, extracranial growth of meningiomas points to the invasion of osseous structures of the middle cranial fossa. Furthermore, if meningiomas grow into the infratemporal fossa, they frequently involve the muscles, nerves, and mucosa. After removing the tumors spreading to the infratemporal fossa, the optimum plastic repairs of defects of the base of the skull are as follows: hermetic closure of basal defect of the dura mater with a free fat flap, by fixing it with sutures and fibrin-thrombin glue with additional plastic repair of skull base defect with local displaced tissues on a pedicle (with a temporal muscular fascioperiosteal flap, a Bisch fat flap). Further policy of management of these patients is a complicated problem. It depends on the radicalism of an operation and the invasiveness of the process. The histobiological features of infiltrative meningiomas should be studied and this will determine management policy. Conceivably, the use of postoperative radiation therapy will be substantiated in a definite group of patients.