Extra-Arachnoidal Dissection and Limited Meatal Drilling for Excision of Giant Vestibular Schwannomas: Improved Facial Nerve Preservation

BACKGROUND

Surgical excision of giant (>4 cm size) vestibular schwannomas (VS) with preservation of facial nerve (FN) function remains a challenge.

OBJECTIVE

Our surgical technique using an extra-arachnoid plane of dissection and limited meatal drilling is described with the goal of improving FN preservation.

METHODS

Surgical results with respect to FN preservation were analyzed for two groups of giant VS patients: Group A-operated between 2002 and 2009 using "standard" surgical technique, group B-operated between 2009 and 2016 using extra-arachnoidal dissection and limited meatal drilling. All patients had a minimum follow-up of 1 year.

RESULTS: GROUP A

Of the 115 patients, total excision was possible in 103 (89.5%), near-total in 7 (6%), and subtotal in 5 (4.3%) patients. At a >6-month follow-up, 68 (59.1%) patients had good FN function (House-Brackmann [H&B] grades 1-2), while 21 (18.3%) patients had poor function (H&B grade 3-5). Grade 6 involvement was seen in 26 (22.6%). Five patients had lower cranial nerve impairment necessitating tracheostomy.

GROUP B

Of the 98 patients, total excision was achieved in 70 (71.4%) patients, near-total in 9 (9.2%), and subtotal in 19 (19.4%). Four patients had repeat surgery; 14 underwent gamma-knife radiosurgery. At >6-month follow-up, 78 (79.5%) patients had good FN function (H&B grades 1-2), while 20 (20.4%) had poor function (H&B grade 3-5).

CONCLUSIONS

With our 'modified' surgical technique of extra-arachnoidal dissection of VS throughout surgery and limited meatal drilling, an improved rate of functional FN preservation was observed.

What factors influence treatment decision making in acoustic neuroma? Our experience on 103 cases

Acoustic Neuromas (AN) are benign tumors of the vestibulocochlear nerve with symptomatology that includes unilateral sensorineural hearing loss, tinnitus, dizziness, facial and/or trigeminal neuropathy. There are different treatment options of AN: watchful waiting, microsurgical resection, stereotactic radiation and the choice depends by many variables such age, health and hearing of patients as size, location and growing status of tumor. The objective of this retrospective study is to better understand the differences in demographic, hearing status, symptoms, tumor characteristics in patients affected by AN presenting at our clinic and analyze the factors that influence the therapeutic choice. One-hundred three patients affected by AN were included in the study. All subjects underwent a detailed clinical interview and audio-vestibular examination, and Magnetic Resonance Imaging (MRI). Tumor status, growing or stable was estimated comparing new size to any previous MRI with at least a 6-month interval. Descriptive statistics were used for clinical and demographic features of patients. Therapeutic choices related to subjective symptoms were assessed with the chi-square test. Treatment options in our sample included watchful waiting, surgical resection and stereotactic radiosurgery. Overall, 17 patients (16.5%) pursued surgical resection via the retrosigmoid approach, 3 patients (2.9%) were treated with gamma knife stereotactic radiosurgery and 83 patients (80.6%) underwent watchful waiting. The decision-making process for AN treatment was based on size of tumor, age, and hearing loss; a statistically significant difference was found at Z test about size of tumor and PTA of patients that underwent retrosigmoid surgery. No statistically significant difference was found at chi-square test between the type of treatment and symptoms (p=0.719). The analysis of the data showed that the main elements taken into consideration for surgery were the size of tumor (p<0.000004) and, secondly, the PTA threshold; the latter may be due to the fact that patients with bigger tumors had greater hearing impairment (p<0.001). Disease progression influenced the therapeutic decision making with a positive correlation between tumor progression and surgery (p<0.001). In our sample, active surveillance was the most adopted option for small tumor, slow growth and old age. Microsurgical resection was the preferred treatment in patients with large tumors, hearing deterioration and rapid growth. Stereotactic radiation has been proposed in a few cases of elderly patients with slow growing tumor and mild hearing loss.

Surgical Treatment of Secondary Trigeminal Neuralgia Induced by Cerebellopontine Angle Tumors: A Single-Center Experience

OBJECTIVE

Secondary trigeminal neuralgia (TN) caused by cerebellopontine angle (CPA) tumors are rare, although TN may be a primary manifestation in the neurosurgery department. In this study, we aimed to retrospectively assess patients with CPA tumor-induced TN from a single center.

METHODS

Of 819 consecutive patients with TN treated at our center between 2007 and 2017, 36 with CPA tumor-induced TN were enrolled, and their medical and surgical records were analyzed.

RESULTS

The 36 patients accounted for 4.4% of all patients with TN. A comparison of patients with classic and tumor-induced TN indicated significant intergroup differences in the mean age at surgery (58.94 vs. 49.33 years, P = 0.000), the mean age at onset of TN (52.01 vs. 38.04 years), and affected side (298/485 vs. 22/14 in left/right, P = 0.006); no such difference was noted in the sex ratio (0.598 vs. 0.385, P = 0.214). The rates of excellent, good, and fair clinical outcomes were 80.56%, 13.89%, and 2.78%, respectively. The offending vessels found during surgery included the superior and anterior inferior cerebellar arteries in 3 and 4 cases, respectively. Postoperative complications included aseptic meningitis (1 case), facial numbness (2 cases), hearing disturbance (3 cases), facial palsy (4 cases), hemorrhage (1 case), and diplopia (2 cases).

CONCLUSIONS

Secondary TN caused by CPA tumors is not as frequent as classic TN. Compared with classic TN, tumor-induced TN is characterized by symptom onset and surgery at a younger age. Direct compression rather than chemical irritation is the cause of secondary TN.

Cystic acoustic neuromas

Predominantly cystic acoustic neuromas are rare and they usually present with clinical and radiological features different from their more common solid counterparts. Two cases of cystic acoustic neuromas are reported here.