The extracisternal approach in vestibular schwannoma surgery and facial nerve preservation

Factors Associated with Acute Obstructive Hydrocephalus After Retrosigmoid Approach for Extra-Axial Cerebellopontine Angle Tumors

BACKGROUND

This study aimed to identify the risk factors for acute obstructive hydrocephalus (AOHCP) after extra-axial cerebellopontine angle (CPA) tumor surgery using the retrosigmoid (RS) approach.

METHODS

This retrospective study assessed 154 patients (100 vestibular schwannomas, 34 CPA meningiomas [MNGs], 9 trigeminal schwannomas, and 11 petroclival MNGs) who underwent surgical resection using the RS approach by a single surgeon between August 2010 and September 2019. AOHCP was defined as postoperative ventricular enlargement due to cerebrospinal fluid flow obstruction caused by surgery-related cerebellar injury within 1 week. The radiological characteristics of the tumors were classified, and the surgical outcomes were reviewed. We analyzed the impact of different factors on the development of AOHCP after surgery.

RESULTS

AOHCP developed in 17 (11%) patients, all of whom were treated with external ventricular drain insertion. Multivariate analysis showed that CPA MNGs (odds ratio [OR], 37.98), grade of tumor extension beyond the petroclival junction (grade 1: OR, 16.42; grade 2: OR, 17.47), major fourth ventricle compression (OR, 17.77), and surgery-related hemorrhage (OR, 7.64) were associated with AOHCP. Surgery-related hemorrhage was observed in 17 (11%) patients. 9 (6%) patients underwent ventriculoperitoneal shunt surgery because of persistent HCP.

CONCLUSIONS

An increased risk of AOHCP after the RS approach was observed in patients with extra-axial CPA tumors with clival extension and major fourth ventricle compression. Compulsive and meticulous hemostasis must be achieved because postoperative hemorrhage is associated with AOHCP.

Application of Subperineural Resection Technique in Vestibular Schwannomas: Surgical Efficacy and Outcomes in 124 patients

Objective

We aimed to explore the application and prospects of the subperineural resection technique for tumor separation and removal under the perineurium during surgery for vestibular schwannomas (VSs).

Methods

This study retrospectively analyzed 124 patients with VSs who underwent surgery via a retrosigmoid approach from July 2015 to October 2020 in the Department of Neurosurgery, Tangdu Hospital, Air Force Military Medical University. The data will be discussed with regard to the following aspects: clinical features, surgical strategies, tumor resection extent, facial-acoustic function preservation, and postoperative complications.

Results

Gross total resection (GTR) of the tumor was achieved in 104 patients, with a GTR rate of 83.9%, and subtotal resection (STR) of the tumor was achieved in 20 patients. There was no significant difference in facial and acoustic nerve functional preservation between GTR and STR, as well as in tumor resection between solid and cystic tumors. The retention rate reached 97.6% in terms of complete anatomical facial nerve preservation. Facial nerve function was assessed using the House-Brackmann (HB) grading score. Consequently, HB grades of I-II, III-IV, and V-VI were determined for 96 (77.4%), 25 (20.2%), and 3 (2.4%) cases, respectively, 1 week postoperatively and accounted for 110 cases (88.7%), 13 cases (10.5%), and 1 case (0.8%), respectively, at 6 months. Fifteen of 35 (42.9%) patients with serviceable hearing before the operation still had serviceable hearing at 6 months postoperatively. There were 5 cases of cerebellar or brainstem bleeding after the operation, and one patient died. Multivariate logistic regression analysis showed that older age (≥60 years, p = 0.011), large tumor (>3 cm, p = 0.004), and cystic tumor (p = 0.046) were independent risk factors associated with the extent of adhesion between the tumor and the brainstem and facial-acoustic nerve.

Conclusion

We successfully applied the subperineural resection technique to a large series of patients with VSs and achieved satisfactory results. Accurate identification of the perineurium and subperineural resection of the tumor can effectively reduce the disturbance of the facial-acoustic nerve during the operation and provide an intuitive basis for judging the tumor boundary. The subperineural resection technique may be conducive to improving the rate of total tumor resection and facial-acoustic nerve functional preservation in the surgical treatment of VSs.

Vestibular schwannoma: care for soft tissues and subperineural dissection: how I do it

BACKGROUND

Recognition of the right surgical cleavage plane of a vestibular schwannoma is mandatory to preserve the facial nerve function.

METHOD

We describe here our surgical technique that is focused on soft tissues preservation and on subperineural dissection, avoiding direct exposure of the acoustico-facial complex in order to preserve facial nerve function.

CONCLUSION

Soft tissue dissection helps in reducing patient's postoperative discomfort. Meticulously keeping a subperineural plan of dissection enables to preserve facial nerve function while offering satisfying resection rates.

Radiologic Features of Spontaneous Regression of Vestibular Schwannomas

BACKGROUND

Vestibular schwannoma (VS) is the most common benign tumor originating in the cerebellopontine angle. In most cases, tumors tend to grow and deserve proper treatment. Sometimes they stabilize, and rarely they decrease in size spontaneously.

METHODS

We evaluated retrospectively the images of patients with spontaneous tumor regression. We describe the common neuroimage findings of patients with spontaneous tumoral regression.

RESULTS

Four patients with diagnosis of VS were followed with magnetic resonance imaging (MRI). There were some relevant features in MRI: a heterogeneous contrast enhancement in the outer layer of the tumor and presence of a cerebrospinal fluid column between the tumor and the entrance of the internal auditory canal. The percentage of tumor diameter reduction ranged from 20% to 40%.

CONCLUSIONS

Some MRI features may demonstrate a spontaneous involution of VS and may be closely followed in asymptomatic or oligosymptomatic patients.