Technical aspects and recent trends in the management of large and giant midbasilar artery aneurysms.

OBJECTIVE: Cranial base approaches that involve radical petrosectomy are associated with significant rates of morbidity. We have sought alternative approaches to the midbasilar artery to reduce the extent of temporal bone removal and correspondingly to reduce complications while still providing adequate surgical exposure. The extended orbitozygomatic and far-lateral approaches are two such approaches. We compared our experience with these approaches to our experience with the standard transpetrosal approaches in the treatment of midbasilar artery aneurysms. METHODS: Between 1990 and 1995, 28 patients with large and giant midbasilar artery aneurysms were treated with approaches involving either radical or conservative petrosectomy. RESULTS: Overall, good outcomes (Glasgow Outcome Scale scores of 1 and 2) were observed in 21 patients (75%), and three patients (11%) had permanent treatment-associated neurological deficits. Four patients died. Later in the series, the pterional-subtemporal approach (four patients) was supplanted by the orbitozygomatic approach (six patients). The increased use of hypothermic circulatory arrest involved exposure of the midbasilar region from above (orbitozygomatic approach) and below (far-lateral approach, 13 patients). Concomitantly, the use of transpetrosal approaches (five patients) decreased. CONCLUSION: Modified orbitozygomatic and far-lateral approaches adequately expose the midbasilar region and can replace transpetrosal approaches in some cases. These extended approaches can be associated with lower morbidity rates than can transpetrosal approaches. Hypothermic circulatory arrest is critical to clipping large and giant midbasilar artery aneurysms directly when approaches that conserve the temporal bone are used.

The far lateral-combined supra- and infratentorial approach: clinical experience.

Four patients underwent a far lateral-combined craniotomy procedure for extensive tumors of the clivus and craniocervical junction. Their presentation, operative, and clinical course are discussed. All patients had improved at their follow-up examination (mean follow-up, 10.7 months). This approach can now be applied to extensive tumors of the petroclival region and craniocervical junction to decrease morbidity.

The far lateral/combined supra- and infratentorial approach. A human cadaveric prosection model for routes of access to the petroclival region and ventral brain stem.

A far lateral approach to the ventral brain stem, lower clivus, and anterior foramen magnum is described. Methods for further exposure of the superior petroclival region by incorporating a subtemporal craniotomy and posterior petrosectomy are also demonstrated. Eight sequentially illustrated steps depict this technique. The far lateral/combined supra- and infratentorial exposure is a comprehensive surgical approach that provides direct access to the entire anterior and lateral brain stem and craniovertebral junction. It minimizes brain-stem retraction and maximizes visualization of the neurovascular structures.

The combined supra- and infratentorial approach for lesions of the petrous and clival regions: experience with 46 cases.

The combined supra- and infratentorial approach has been subdivided into three variations: the retrolabyrinthine technique (petrous bone resection with preservation of hearing); the translabyrinthine technique (greater petrous bone resection and sacrifice of hearing); and the transcochlear technique (maximum petrous drilling, sacrifice of hearing, and transposition of the facial nerve). These three variations maximize temporal bone drilling and therefore provide exquisite exposure of the clivus and petrous regions with minimal or no brain retraction. The superior petrosal sinus is always sacrificed and the tentorium completely cut. The sigmoid sinus can be transected or kept intact, depending on the venous drainage and the degree of exposure required. A series of 46 patients who underwent the combined approach is presented.

Combined approach for lesions involving the cerebellopontine angle and skull base: experience with 20 cases--preliminary report.

Skull base tumors involving the clivus, petrous bone, and adjacent areas can be formidable lesions to successfully remove without causing significant neurologic deficits. At our institution in the last 5 years, twenty patients out of 103 patients with skull base tumors have undergone the supratentorial-infratentorial combined approach for removal of a neoplasm (nine schwannomas, six meningiomas, two epidermoids, one extensive basal cell carcinoma, one pontine cavernous malformation, and one basilar artery aneurysm). The average patient age was 43 years. The combined approaches in conjunction with the subtemporal exposure were retrosigmoid-retrolabyrinthine, retrosigmoid-translabyrinthine, or retrosigmoid-transcochlear. The choice depended upon the type and location of the lesion and the deficits noted preoperatively. Basically, the approach allowed communication of the middle fossa and posterior fossa by totally dividing the tentorium as much as necessary for effective surgical manipulations. Both sigmoid and superior petrosal sinuses are divided. There were no deaths. Postoperative neurologic deficits included temporary seventh nerve paralysis, sixth nerve weakness, fifth nerve sensory deficits, cerebrospinal fluid leaks, and hydrocephalus requiring a shunt. Overall, the results were very gratifying, considering the difficulties encountered in the surgical removal of these lesions.

Reanimation of the paretic eyelid using gold weight implantation. A new approach and prospective evaluation.

Sixty-one lid-loading procedure, performed by the author, were evaluated prospectively. Simple, gold weight implantation, combined with lower lid retractor recession, placement of fascia lata, and lateral tarsal strip tightening is effective for promoting voluntary closure and correction of lower lid paralytic ectropion. Placement of a heavier gold weight, in combination with mullerectomy, is a reliable new approach for mimicking involuntary blink without ptosis.

Combined approach for lesions involving the cerebellopontine angle and skull base: experience with 30 cases.

This article presents a series of 30 patients who underwent a combination of the subtemporal and posterior fossa approaches for exposure of lesions in the clivus or medial petrous region. This combined supra- and infratentorial approach is divided into three variations with progressively greater petrous bone resection to increase exposure of the clivus and medial petrous region. The approach has been divided into petrous bone resection with preservation of hearing (retrolabyrinthine), greater petrous bone resection with sacrifice of hearing (translabyrinthine), and finally maximum petrous drilling with sacrifice of hearing along with transposition of the facial nerve (transcochlear). Ninety-three percent of the cases returned to their premorbid occupations.

Synovial chondromatosis of the temporomandibular joint with intracranial extension. Case report.

The authors report the unusual presentation of an intracranial extension of synovial chondromatosis of the temporomandibular joint. The patient presented with a peripheral facial nerve paralysis and anacusis. Computerized tomography revealed the lesion, but fine-needle biopsy was inconclusive. Craniotomy with removal of the tumor was performed, and pathological studies confirmed the diagnosis. The facial nerve dysfunction was thought to be secondary to direct neural compression.

Otolaryngologic manifestations of posterior fossa arachnoid cysts.

Posterior fossa arachnoid cysts are more common than previously reported. While they may present with symptoms of hearing loss, vertigo, and tinnitus, often they are associated with vague, nonspecific complaints such as headache, dizziness, or generalized unsteadiness. We present five cases of posterior fossa arachnoid cysts discovered in adult patients. Four of the five patients had nonlocalizing symptoms (three of those sought medical evaluations for persistent dizziness and/or headache). Two patients had prolonged symptoms despite medical evaluation and normal audiometric testing before the correct diagnosis was made. We describe the case of our senior author (C.P.D.) in detail and include computerized tomographic and nuclear magnetic resonance studies outlining his pathology. A review of the management of these lesions is included. Dizzy patients and those patients with nonspecific complaints referable to the inner ear or posterior fossa who have normal audiometric testing, and in whom the index of suspicion is high, should have high resolution computerized tomography of the posterior fossa.

Monitoring of intraoperative auditory brain stem responses.

We believe that our initial experience establishes the fact that ABRs can be routinely and reliably performed in an operating room environment. There was no added risk to the patient, and operative delays were minimal. We did note transient fluctuation in latency values up to 1.5 msec. These changes would revert to baseline levels within five to ten minutes. Changes noted during drilling were probably related to the random noise produced. Case 3 was worrisome in that hearing was lost after maintenance of the ABRs during the surgical procedure. Evidently the vestibule was damaged, and a labyrinthitis caused the hearing loss. We feel that this procedure will be most useful in those situations in which the cochlear nerve and blood vessels are at risk. Such procedures as acoustic tumor removal with attempts to preserve hearing, vestibular nerve sections, and facial nerve problems in the IAC should be routinely monitored. Further experience will, of course, be most helpful in explaining and recognizing these changes.

Diagnosis of perilymph fistula using ENG and impedance.

The presence of perilymph fistula has been difficult to determine because of the lack of efficient and reliable testing methods. The condition is suspected on the basis of history alone and confirmed by surgery. This paper details a quick, reliable procedure called the ENG fistula test, using impedance bridge for pressure change and electronystagmography to aid the establishment of nystagmus and dizziness. To evaluate this procedure, a combination of tests were performed, including Valsalva maneuver, tragal compression, and pneumatic otoscopy, which were previously considered helpful in the diagnosis of fistula. Of them, Valsalva maneuver and tragal compression proved inconclusive; pneumatic otoscopy proved to be helpful. In comparison, however, the ENG fistula test proved most valuable, with results surgically confirmed in 90.8% of cases in this series. This study involved 74 patients whose primary complaint was dizziness. Only some patients simultaneously experienced hearing lows. Included are 5 patients whose positive ENG fistula test results and 15 whose negative test results were confirmed by surgery. Selected case histories are presented.