In the anterior skull base surgery, deteriorations of the olfactory function due to the nerve damage can occur under several conditions of surgical procedures. The surgical procedures include : (1) preservation of the olfactory nerve in cases of bilateral subfrontal, basal interhemispheric, and transbasal approaches, and (2) dissection of the olfactory nerve from anterior skull base tumors. In this article, I show a series of surgical procedures and several tips of preserving the olfactory nerve under these conditions.

  Recently, endovascular interventions such as coil embolization and flow-diverting stenting are usually used to manage paraclinoid carotid artery aneurysms due to anatomical location and visual complications. However, all paraclinoid carotid artery aneurysms cannot be treated with the endovascular approach. To prevent visual complications, clipping surgery for paraclinoid carotid artery aneurysm, skull base technique, retrograde suction decompression method, intraoperative electrophysiological monitoring, and indocyanine green videoangiography have been developed. In this report, the functional anatomies of the ophthalmic artery and the superior hypophyseal artery feeding the optic apparatus and originating from the paraclinoid carotid artery are summarized. Moreover, the direct surgical procedure used for paraclinoid carotid artery aneurysm is presented.

  Although stereotactic radiosurgery is a basic treatment for cavernous sinus tumors, surgical excision is required in patients with symptomatic tumors or recurrent tumors after radiotheraphy. Here, we present detailed anatomical knowledge of the cavernous sinus and surgical techniques for preservation of the third, fourth and sixth cranial nerves. Our surgical procedure for cavernous sinus tumor is an option for the treatment of cavernous sinus tumors.

  Trigeminal schwannomas can develop anywhere along the course of the trigeminal root, ganglion, and nerve branches. The most frequent tumor site is Meckel’s cave. The tumor, is dumbbell in shape, often extends to the posterior cranial fossa. A series of surgical approaches, which primarily include skull base extradural approaches, used for the management of trigeminal schwannomas has been discussed based on tumor site. More recently, an endoscopic endonasal approach has been used for lesions in Meckel’s cave, pterygoid palatine fossa, and infratemporal fossa. This article describes anatomy-based surgical approaches for the management of trigeminal schwannoma and surgical approaches aimed at functional preservation.

  Vestibular schwannomas are one of the most common types of tumor in the cerebellopontine angle. The treatment of vestibular schwannomas has evolved over several decades to the point where the main goal is no longer merely saving life through a hazardous surgical procedure : now it is possible to aim at preserving facial and/or hearing functions while achieving optimal tumor control. In order to accomplish this challenge safely, various diagnostic and/or treatment modalities have been developed, including radiological imaging, neuromonitoring, radiosurgery, and interventional radiology. Needless to say, such treatment requires much of the surgeon in terms of multiple skill sets and a wide range of knowledge, but the authors believe that a detailed knowledge of microsurgical anatomy is also essential in utilizing the plethora of treatment modalities available. In this article, the microsurgical anatomy of the cerebellopontine angle is reviewed with respect to its relevance for vestibular schwannoma surgery. Anatomical variations in the cranial nerves and vascular structures encountered intraoperatively in more than 1,200 vestibular schwannoma surgeries are introduced.

  Jugular foramen schwannoma is a relatively rare form of schwannoma and accounts for 2.9% of all intracranial schwannomas. Most of the jugular foramen schwannomas form dumbbell-shaped tumors that extend from the intracranial lesion toward the extracranial location to different degrees. Because these tumors grow slowly, a surgical indication should be determined by considering multiple factors such as the patient’s age, performance status, symptoms, and the volume of the tumor. In this paper, microsurgical anatomy around the jugular foramen, the surgical approach, and the outcome were discussed.

  The glossopharyngeal nerve, the vagus nerve, and the accessory nerve run in the lateral medullary cistern toward the jugular foramen and turn at the foramen just medial to the jugular bulb. After exiting from the foramen, these nerves run toward the caudal direction in front of the axis.

  A transjugular approach is mandatory to perform resection of intra- and extradural tumors. In addition, high cervical exposure is required when the tumor is extending toward the ventral location of the cervical spine. For the intradural part of the tumor, total resection is performed to release the compression of the brain stem and the nerves in the lateral medulla. For the extradural part, an intracapsular removal is considered for preserving the function of the lower cranial nerves.

  Analysis of the postoperative symptoms demonstrated that the function of the nerve which was the origin of the schwannoma was not preserved. However, the neurological impairments that were caused by the compression by the tumor tended to recover after the surgery.

  In conclusion, meticulous surgical resection of jugular foramen schwannoma based on the precise microsurgical anatomy may result in the functional recovery of the compressed neural structures.

  We have many reports of recurrent risk factors for chronic subdural hematomas (CSDHs). However, the case report associated with dural arteriovenous fistula (dAVF) is rare.

  An 86-year-old man with hemiparesis was referred to our hospital. CT scan showed bilateral CSDHs and we treated the right CSDH with burr-hole irrigation, but the hematoma was progressed. After the third surgery, angiography was performed and dAVF near the transverse sinus was found. The fistula was treated with transvenous embolization and the CSDH was cured.

  The CSDH is a common disease for neurosurgeons. However it is sometimes difficult to treat recurrent CSDH. We should consider the possibility of the dAVF when CSDHs recur in a short period.