Near Total Versus Gross Total Resection of Large Vestibular Schwannomas: Facial Nerve Outcome

Prevalence and patterns of cerebral venous sinus thrombosis following vestibular schwannoma surgery: a systematic review and meta-analysis

PURPOSE

Cerebral venous sinus thrombosis (CVST) is a potentially serious complication following surgical treatment of vestibular schwannoma, a benign tumor originating from Schwann cells of the vestibulocochlear nerve. This study aimed to determine the prevalence of CVST following surgical treatment of vestibular schwannoma and the factors contributing to its occurrence.

METHOD

Two independent researchers searched the global databases of PubMed, Web of Science, Scopus, and the Cochrane Library up to September 01, 2023. We employed a random-effects model for data analysis. Heterogeneity was evaluated using the I2 test. To assess the quality of the studies meeting our inclusion criteria, we employed the Joanna Briggs Institute Critical Appraisal Checklist.

RESULTS

We included 23 articles in this meta-analysis. The pooled prevalence of CVST after vestibular schwannoma surgery was 6.4% (95%CI 3.4-11.5%). The pooled prevalence of CVST following the retrosigmoid (RS), translabyrinthine (TL), and middle cranial fossa (MCF) approaches was 4.8% (95%CI 2.0-11.0%), 9.6% (95%CI 4.3-20.3%) and 9.9% (95%CI 1.6-42.2%), respectively, revealing a significant difference between the TL and the RS approaches (Odds ratio = 2.10, 95%CI 1.45-3.04, P < 0.001). The sigmoid sinus exhibited the highest post-operative thrombosis rate (7.9%), surpassing the transverse sinus (3.7%) and involvement of both sigmoid and transverse sinuses (1.6%), respectively. No significant associations were found with demographic or surgical factors.

CONCLUSION

In the current meta-analysis, we identified a 6.4% CVST prevalence following vestibular schwannoma surgery, with varying rates depending on the surgical approach. No significant associations with patient or surgical factors were found, emphasizing the need for heightened clinical vigilance and further research in this context.

TRAIL REGISTRATION

PROSPERO ID: CRD42023453513.

Evaluating growth trends of residual sporadic vestibular schwannomas: a systematic review and meta-analysis

BACKGROUND

Gross total resection remains the gold-standard approach for vestibular schwannomas (VS) when surgery is indicated. In select cases, incomplete resection (IR) becomes a desired alternative to preserve the facial nerve function and the patient's quality of life. While a lot of earlier studies described incompletely resected sporadic VSs as dormant, more recent studies reported a higher growth rate following IR, therefore an evaluation of the residual VS growth rates could have important implications for the follow-up treatment protocols and provide relevant information for neurosurgeons, neuro-otologists, neuropathologists, and radiologists. Although prognostic factors predicting preoperative VS growth have been previously investigated, these factors have not been investigated following IR. Our review aims to examine the growth rate of residual sporadic VS following IR and to examine variables associated with the regrowth of residual VS.

METHODS

The review was conducted in accordance with the PRISMA guidelines. Six databases (MEDLINE (Ovid), Embase (Ovid), CINAHL Plus (EBSCO), Cochrane Central Register of Controlled Trials (CENTRAL), WHO International Clinical Trials Registry Platform and UK Clinical Trials Gateway (WHO ICTRP) were searched. Full-text articles analysing growth rates in at least ten patients who had residual VS after IR were assessed. We conducted a meta-analysis using a random-effects model via RevMan.

RESULTS

14 studies totalling 849 patients were included in the analysis. The mean planimetric growth rate was 1.57 mm/year (range 0.16-3.81 mm/year). The mean volumetric growth rate was 281.725 mm³/year (range 17.9-530.0 mm³/year). Age, sex, pre-operative tumour size/volume, cystic tumour sub-type, MIB-1 index, and intracanalicular tumour location were not associated with residual growth. Residual tumour size/volume was statistically significant to growth (OR = 0.65, 95% CI 0.47-0.90, p = 0.01). Radiological re-growth occurred in an average of 26.6% of cases (range 0-54.5%).

CONCLUSION

From our analysis, only the residual tumour volume/size was associated with residual VS growth. Therefore, close postoperative surveillance for the first year, followed by an annual MRI scan for at least 5 years, and subsequently extended interval surveillance remains of utmost importance to monitor disease progression and provide timely surgical and adjuvant interventions. Our study shows that future work should be aimed at molecular and histological characteristics of residual VSs to aid prognostic understanding of growth.

Preoperative Facial Nerve Palsy in Patients With Vestibular Schwannoma: Clinical Features and Postoperative Functional Prognosis in a Case Series of 34 Among 1228 Consecutive Patients

BACKGROUND

Facial nerve palsy is a rare presenting symptom of vestibular schwannomas and has not been investigated in detail.

OBJECTIVE

To investigate the incidence, clinical features, and postoperative long-term outcomes of facial nerve function in patients with vestibular schwannomas causing preoperative facial nerve palsy.

METHODS

After excluding patients with neurofibromatosis type 2 and those with prior treatment, 1228 consecutive patients who underwent vestibular schwannoma surgery were retrospectively investigated. Patients with and without preoperative facial nerve palsy were compared statistically to clarify their clinical features.

RESULTS

Preoperative tumoral facial nerve palsy was seen in 34 patients (2.8%). Their clinical features included older age, having large cystic tumors with significant meatal extension, and showing abnormal electrogustometric responses, compared with patients without preoperative facial nerve palsy. Owing to the frequent insufficient intraoperative responses on facial nerve electromyography, the tumor resection rate was lower in the group with preoperative facial nerve palsy (mean: 95.2%). Among the 33 patients with sufficient follow-up data (mean: 63.9 mo), additional treatment was required only in 1 patient and facial nerve function improved in 25 patients (75.8%) within 2 yr postoperatively.

CONCLUSION

Facial nerve palsy is a rare preoperative symptom that occurs in less than 3% of patients with vestibular schwannoma. Tumor resection in such patients tends to be challenging owing to their advanced age, having large cystic tumors with significant meatal extension, and difficulties in intraoperative facial nerve monitoring, but surgical decompression of the facial nerve can assist in the improvement of their long-term functions.

Microsurgical treatment of symptomatic vestibular schwannomas in patients under 40: different results before and after age of 30

In 10-15% of cases of vestibular schwannoma (VS), age at diagnosis is 40 years or less. Little is known about the differences in natural history, surgical findings, and postoperative outcomes of such younger patients as compared to those of greater age. To analyze clinical and surgical and imaging data of a consecutive series of n = 50 patients with unilateral sporadic VS, aged 40 years or younger - separated in a very young group (15-30 years) and a moderately young group (31-40 years). Retrospective case series. Fifty consecutive patients under 40 years of age underwent microsurgical resection of unilateral sporadic VS via the retrosigmoid approach. The study cohort was subdivided into two groups according to the age range: group A, age range 15-30 years (n = 23 patients), and group B, age range 31-40 years (n = 27 patients). The adherence of VS capsule to surrounding nervous structures and the tendency of the tumors to bleed were evaluated by reviewing video records; the course of the FN in relation to the tumor's surface was assessed in each case. Microsurgical removal of tumor was classified as total (T), near total (residual tumor volume < 5%), subtotal (residual tumor volume 5-10%), or partial (residual tumor volume > 10%). Mean tumor size of entire cohort was 2.53 (range: 0.6-5.8) cm: 2.84 cm in group A and 2.36 cm in group B (p = NS). Facial nerve course and position within the cerebellopontine angle did not differ significantly between the two groups. At 6-month follow-up, FN functional outcome was HBI-II in 69.5% in group A, versus 96.3% in group B (p < .001). Hearing preservation was achieved in 60.0% of patients of group A and in 58.3% of group B (p = NS). Total and near-total resection was feasible in 95.6% of cases of group A and in 88.9% of group B (p = NS). Tumor capsule was tightly adherent to nervous structures in 69.6% patients of group A and in 22.2% of group B (p < .05). Significant bleeding was encountered in 56.5% of group A tumors, and in 29.6% of group B tumors (p < .01). Microsurgery of VS in patients aged 40 or less is associated with good functional results, and with high rates of total and near total tumor removal. Patients < 30 years of age have more adherent tumor capsules. Furthermore, their tumors exhibit a tendency to larger sizes, to hypervascularization, to profuse intraoperative bleeding and they present worse long-term functional FN results when compared to patients in their fourth decade of life. Our limited experience seems to suggest that a near total resection in very young VS patients with large tumors should be preferred in adherent and hypervascularized cases, in order to maximize resection and preserve function.