Skull Base Surgical Techniques Research Articles

未破裂脳動脈りゅうの治療指針

An increasing number of cases of incidental cerebral aneurysms are currently being reported. However, the indications for surgery of unruptured asymptomatic cerebral aneurysms are still unclear. The benefit of treatment ultimately depends on the relative risk of subsequent aneurysm rupture in untreated patients versus the risk involved in surgery. We report a series of 90 cases of unruptured aneurysms, admitted and treated over a period of 6 years and 1 month (1993. 12. 1-1999. 12. 31). General information about the natural history of incidentally discovered aneurysms was given to the patients and their relatives. Informed consent was based on the fact that subarachnoid hemorrhage was associated with a poor prognosis, while excellent operative results were common in patients with unruptured aneurysms. Sixty-six patients underwent surgery, and the remaining 24 patients who did not receive surgery were followed up at periods ranging from 1.5 months to 5 years and 9 months. Of the 66 patients who were operated on, there were 11 (17%) cases of postoperative complications, including 5 venous infarctions, 2 memory disturbance, 1 recurrent cerebral infarction, 1 visual disturbance, 1 cerebral embolism and 1 intraoperative rupture. Three patients (4.5%) did not recover. The remaining 8 patients, however, recovered with time or through treatment. Among the 24 patients who were treated conservatively, only 2 developed rupture of the aneurysms (0.4% annual rupture rate) and both made an uneventful recovery. It is our clinical impression, however, that they harbor an unruptured aneurysm with at least mild trepidation. Aneurysm size, location, and number were risk predictors for surgical morbidity in patients with unruptured aneurysms. This experience suggests that if intact aneurysms are treated surgically, careful preoperative evaluation and precise microsurgical techniques are essential. An endovascular approach or some skull base surgical techniques should be considered to obtain better results.

Fibrous dysplasia of the sinuses and orbit: Surgical techniques

Symptomatic fibrous dysplasia of the orbits and paranasal sinuses causing deformity or functional impairment is best treated with total or near total resection and reconstruction. Modern craniofacial and skull base surgical techniques permit this approach with relatively little patient morbidity. Autogenous split cranial bone grafts are optimal for reconstruction with allogenic cortical bone and hydroxyapatite cement providing additional contouring materials. If computed tomography imaging reveals optic canal encroachment and ophthalmologic evaluation shows visual disturbance from fibrous dysplasia involvement, then 3-wall optic nerve decompression should be performed concurrently with resection of the dysplasia. Careful and long-term follow-up of these young patients is essential for documenting the advantageous outcome of these treatment approaches.

Tentorial dural arteriovenous fistula obliterated using the petrosal approach

Background Tentorial dural arteriovenous fistulas (AVFs) are uncommon lesions usually treated surgically using a subtemporal exposure with division of the tentorium. This exposure requires significant retraction of the temporal lobe and has the possibility of significant arterialized venous bleeding if a draining vein is accidentally cut during division of the tentorium. Skull base surgical techniques may provide alternate approaches for the surgical treatment of tentorial dural AVFs. Methods A tentorial dural arteriovenous fistula supplied by the tentorial artery and drained by the petrosal vein was exposed and obliterated using the petrosal (subtemporal-presigmoid) approach. Results The petrosal approach allowed the exposure and division of the superior petrosal sinus and tentorium with direct visualization of the supratentorial and the infratentorial compartments, avoiding accidental damage to the draining veins. The dural fistula was easily obliterated after its venous drainage was interrupted and the tentorial artery occluded. Conclusions Tentorial dural AVFs can be safely treated with interruption of the venous drainage. The exposure can be enhanced with a petrosal approach, decreasing the possibility of uncontrolled bleeding during the procedure.

Neurosurgical considerations on the anatomy of the medial canthus in children.

Craniofacial surgery and anterior skull base surgical techniques require an intimate knowledge of periorbital structures. The medial orbital anatomy is especially important for midline approaches to nasion encephalocele, midline trauma, surgery for hypertelorism as well as midline approaches to anterior skull base lesions. The medial canthal tendon is of primary importance in anchoring the eyelid medially in a cosmetic and functional fashion. This review will summarize the anatomic features of the medial canthus and its surrounding structures, including vascular and muscular components. The intimate relationship of the three components of the medial canthal tendon to the nasal lacrimal apparatus is emphasized. Techniques to prevent injury as well as to repair abnormalities in this area will be discussed.

Meningiomas of the cranial base.

Treatment objectives for meningiomas of the cranial base include relief of neurologic disability and prevention of clinical progression or recurrence with the least morbidity. Recent advances in skull base surgical techniques, through an appreciation of skull base anatomy and institutional specialization, have contributed major improvements to the outlook for patients with these tumors, and previously inoperable cases may now often be removed completely with acceptable risk. Since significant morbidity may be incurred during surgical resection of these difficult lesions, especially in terms of cranial nerve dysfunction, the value of aggressive surgical resection must be weighted against the often indolent natural history of these lesions, and must be individualized in each patient. Completeness of resection is the major prognostic factor determining the outcome of patients with typical benign meningiomas in terms of length of survival, risk of recurrence, and neurological disability. Various means of prognosticating the growth potential of a given tumor are being investigated, though none have yet been confirmed for their predictive value in typical, histologically benign meningiomas. The role of external beam radiotherapy has not been subjected to adequately controlled, prospective studies, and there is currently insufficient followup to assess the risks and benefits of stereotactic radiosurgery. Advances in the clinical management of tumors of the skull base has had perhaps the greatest impact for patients with meningiomas who constitute a large portion of tumors seen in these locations. Although the majority have benign histological features, skull base meningiomas can present a formidable challenge due to their proximity to vital structures, surgical inaccessibility, and occasional aggressive features. The combination in recent years of advances in skull base surgical techniques, adjuvant therapy, and rehabilitation methods have dramatically improved the outcome for these tumors.