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Ian F. Dunn, Wenya Linda Bi, Kadir Erkmen, Paulo A. S. Kadri, David Hasan, Chi-Tun Tang, Svetlana Pravdenkova and Ossama Al-Mefty

Object

Medial acoustic neuroma is a rare entity that confers a distinct clinical syndrome. It is scarcely discussed in the literature and is associated with adverse features. This study evaluates the clinical and imaging features, pertinent surgical challenges, and treatment outcome in a large series of this variant. The authors postulate that the particular pathological anatomy with its arachnoidal rearrangement has a profound implication on the surgical technique and outcome.

Methods

The authors conducted a retrospective analysis of 52 cases involving 33 women and 19 men who underwent resection of medial acoustic neuromas performed by the senior author (O.A.) over a 20-year period (1993–2013). Clinical, radiological, and operative records were reviewed, with a specific focus on the neurological outcomes and facial nerve function and hearing preservation. Intraoperative findings were analyzed with respect to the effect of arachnoidal arrangement on the surgeon's ability to resect the lesion and the impact on postoperative function.

Results

The average tumor size was 34.5 mm (maximum diameter), with over 90% of tumors being 25 mm or larger and 71% being cystic. Cerebellar, trigeminal nerve, and facial nerve dysfunction were common preoperative findings. Hydrocephalus was present in 11 patients. Distinguishing intraoperative findings included marked tumor adherence to the brainstem and frequent hypervascularity, which prompted intracapsular dissection resulting in enhancement on postoperative MRI in 18 cases, with only 3 demonstrating growth on follow-up. There was no mortality or major postoperative neurological deficit. Cerebrospinal fluid leak was encountered in 7 patients, with 4 requiring surgical repair. Among 45 patients who had intact preoperative facial function, only 1 had permanent facial nerve paralysis on extended follow-up. Of the patients with preoperative Grade I–II facial function, 87% continued to have Grade I–II function on follow-up. Of 10 patients who had Class A hearing preoperatively, 5 continued to have Class A or B hearing after surgery.

Conclusions

Medial acoustic neuromas represent a rare subgroup whose site of origin and growth patterns produce a distinct clinical presentation and present specific operative challenges. They reach giant size and are frequently cystic and hypervascular. Their origin and growth pattern lead to arachnoidal rearrangement with marked adherence against the brainstem, which is critical in the surgical management. Excellent surgical outcome is achievable with a high rate of facial nerve function and attainable hearing preservation. These results suggest that similar or better results may be achieved in less complex tumors.

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Ahmed Nageeb M. Taha, Kadir Erkmen, Ian F. Dunn, Svetlana Pravdenkova and Ossama Al-Mefty

Object

Juxtasellar meningiomas frequently extend into the optic canal. Removing these meningiomas from the optic canal is crucial for favorable visual outcome.

Methods

The authors performed a retrospective analysis of 45 patients with anterior and middle fossa meningiomas with involvement of the optic pathway in whom surgery was performed by the senior author (O.A.M.) during the period from 1993 to 2007. Extent of resection and recurrence rates were determined by pre- and postoperative MR imaging studies. Visual outcomes were evaluated with full ophthalmological examinations performed before and after surgery.

Results

Forty-five patients (31 women and 14 men) were involved in this study; their mean age was 51.6 years. Patients were followed for a mean of 29.8 months (range 6–108 months). No surgery-related death occurred. The average tumor size was 3.1 cm. Total resection of the tumor (Simpson Grade I) was achieved in 32 patients (71.1%). Gross-total resection (Simpson Grades II and III) was achieved in 13 patients (28.9%). Only 1 patient harboring a left cavernous sinus meningioma had tumor recurrence and underwent repeat resection. Meningiomas extended into 58 optic canals in these cases; 13 patients showed extension into both optic canals. Visual disturbance was the main presenting symptom in 37 patients (82.2%); 8 patients had normal vision initially. Visual improvement after surgery was seen in 21 (57%) of 37 patients and in 27 (34.6%) of 78 affected eyes. Vision remained unchanged in 48 (61.5%) of 78 eyes. Transient postoperative visual deterioration occurred in 2 eyes (2.6%), with recovery to baseline over time. Only 1 (1.3%) of 78 eyes had permanent visual deterioration after surgery. The visual outcome was affected mainly by the tumor size, the preoperative visual status, and the duration of symptoms.

Conclusions

Involvement of the optic canal in meningiomas is frequent. It occurs in a wide variety of anterior skull base meningiomas and it can be bilateral. It is a prominent factor that affects the preoperative visual status and postoperative recovery. Decompression of the optic canal and removal of the tumor inside is a crucial step in the surgical management of these tumors to optimize visual recovery and prevent tumor recurrence.

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Kadir Erkmen, Svetlana Pravdenkova and Ossama Al-Mefty

Petroclival meningiomas remain one of the most challenging intracranial tumors to treat surgically. This is attributable to their location deep within the skull base and their association with multiple critical neural and vascular structures. Over the years, many skull base approaches have been described that are meant to improve resection and decrease patient morbidity. Appropriate selection of the surgical approach requires a thorough preoperative evaluation of clinical and radiological factors. In this paper the authors retrospectively reviewed 97 patients treated surgically for petroclival meningiomas by the senior author (O.A.M.) between 1995 and 2005 to assess the factors used to determine the choice of surgical approach, and to assess complication rates based on the approach selected. The skull base approaches used in these patients included the middle fossa anterior petrosal, posterior petrosal, and combined petrosal approaches, and complete petrosectomy. Factors found to be important in determining the selection of approach included the size, location, and extension of the tumor, preoperative hearing evaluation, and venous sinus anatomy.