Removal of large acoustic neurinomas (vestibular schwannomas) by the retrosigmoid approach with no mortality and minimal morbidity

Functional outcomes after retrosigmoid approach to the cerebellopontine angle: Observations from a single-center experience of over 13 years

Introduction

Accessing the posterior base of the skull is complex because of the vital neurovascular structures in the area. However, the retrosigmoid approach (RSA) offers a solution to this challenge.

Research question

To analyze surgical outcome of RSA.

Material and methods

This study involved a retrospective review of patient charts from a single center, focusing on the surgical procedure and outcomes following the operation.

Results

The study included 517 patients suffering from conditions like vestibular schwannomas (VS), metastatic cancers, and trigeminal neuralgia. The most frequent symptoms reported were balance disorders (42.7%), hearing loss (36.5%), walking difficulties (21.2%), headaches (18.9%), facial pain (17.1%), issues with trigeminal nerve function (14.1%), cerebellar dysfunction (13.5%), and facial nerve paralysis (10.2%). The rate of complications stood at 21.1%, with 11.3% of patients needing revision surgery. The median score on the Clavien-Dindo scale was 2, and the rate of mortality related to surgery was 1.0%. Permanent symptom improvement was seen in 72.1% of cases. Temporary new deficits occurred in 43.2% of patients, with facial nerve paralysis being the most common (14.1%). No significant correlation was found between the size of the craniotomy and the extent of tumor resection (p = 0.155), except in the case of VS (p = 0.041). Larger craniotomy sizes were associated with higher rates of complications (p = 0.016), especially CSF leaks (p = 0.006). Complications significantly affected the likelihood and number of new deficits (p < 0.001 for both), particularly postoperative bleeding (p = 0.019, p = 0.001), CSF leaks (p = 0.026, p = 0.039), and hydrocephalus (p = 0.050, p = 0.007).

Conclusions

The potential for complications related to the surgical approach cannot be overlooked. The size of the tumor should not dictate larger surgical approaches due to the associated increase in postoperative complications; a tailored approach that considers the precise tumor location and pathology is crucial for optimizing postoperative outcomes.

Retrosigmoid versus middle fossa approach for hearing and facial nerve preservation in vestibular schwannoma surgery: A systematic review and comparative meta-analysis

BACKGROUND

Vestibular schwannomas (VS) are benign tumors arising from vestibular nerve's Schwann cells. Surgical resection via retrosigmoid (RS) or middle fossa (MF) is standard, but the optimal approach remains debated. This meta-analysis evaluated RS and MF approaches for VS management, emphasizing hearing preservation and Cranial nerve seven (CN VII) outcomes stratified by tumor size.

METHODS

Systematic searches across PubMed, Cochrane, Web of Science, and Embase identified relevant studies. Hearing and CN VII outcomes were gauged using the American Academy of Otolaryngology-Head and Neck Surgery, Gardner Robertson, and House-Brackmann scores.

RESULTS

Among 7228 patients, 56 % underwent RS and 44 % MF. For intracanalicular tumors, MF recorded 38 % hearing loss, compared to RS's 54 %. In small tumors (<1.5 cm), MF showed 41 % hearing loss, contrasting RS's lower 15 %. Medium-sized tumors (1.5 cm-2.9 cm) revealed 68 % hearing loss in MF and 55 % in RS. Large tumors (>3cm) were only reported in RS with a hearing loss rate of 62 %.

CONCLUSION

Conclusively, while MF may be preferable for intracanalicular tumors, RS demonstrated superior hearing preservation for small to medium-sized tumors. This research underlines the significance of stratified outcomes by tumor size, guiding surgical decisions and enhancing patient outcomes.

The outcome of the retrosigmoid approach in the decompression of vestibular schwannomas - a retrospective cohort study of 60 consecutive cases

This multicenter retrospective cohort study aimed to evaluate the effectiveness of the retrosigmoid surgical approach in decompressing vestibular schwannomas, focusing on tumor decompression, neurological function preservation, and postoperative complications. A cohort of 60 patients, operated between 2016 and 2019, was analyzed for age, sex, symptoms, tumor size, surgery duration, complications, mortality, and facial/auditory functions using established criteria. Hearing loss was observed in 80% of patients, mainly progressive, with tumor size emerging as a critical prognostic factor. Facial weakness affected 10% of patients preoperatively; postoperatively, 35% of patients had affected facial nerve function, with 10% exhibiting poor or no facial nerve function, linked to resection extent rather than tumor size. Tinnitus was more prevalent with larger tumors, whereas headaches were common irrespective of size. Balance disorders improved after surgery, especially in case of larger tumors. Functional recovery varied, with 41.67% of patients returning to their previous activity within 4 months, 25% within 4-12 months, and 33.33% remaining inactive. The mortality rate was low at 3.3 %, with two deaths out of 60 patients after surgery. This analysis highlights surgery risks for vestibular schwannomas (e.g., facial nerve decline, tinnitus, headaches), but also emphasizes benefits like improved balance and low mortality. Many patients regain professional activity, stressing the importance of informed treatment decisions for this condition.

Two-Stage Surgical Management for Acutely Presented Large Vestibular Schwannomas: Report of Two Cases

The surgical management of vestibular schwannomas should be based on their presentation, neuro-imaging findings, surgeons' expertise, and logistics. Multi-stage surgery can be beneficial for large-sized lesions with acute presentations. Herein, we highlighted the indications for two cases managed initially through the retrosigmoid and, subsequently, translabyrinthine approaches. The first case presented with acute balance and gait issues and a long history of hearing loss and blurred vision. Neuroimaging findings revealed a cerebellopontine angle lesion, resembling a vestibular schwannoma, with significant brainstem compression and hydrocephalus. Due to the rapidly deteriorating clinical status and large-sized tumor, we first proceeded with urgent decompression via a retrosigmoid approach, followed by gross total resection via a translabyrinthine approach two weeks later. The second case presented with gradually worsening dizziness and hemifacial numbness accompanied by acute onset severe headaches and hearing loss. Neuroimaging findings showed a large cerebellopontine angle lesion suggestive of a vestibular schwannoma with acute intratumoral hemorrhage. Given the acute clinical deterioration and large size of the tumor, we performed urgent decompression with a retrosigmoid approach followed by gross total resection through a translabyrinthine approach a week later. Post-surgery, both patients showed excellent recovery. When managing acutely presented large-sized vestibular schwannomas, immediate surgical decompression is vital to avoid permanent neurological deficits.

Growth potential of small residual tumors after vestibular schwannoma surgery: comparison between remnants and the natural history of small tumors

OBJECTIVE

Due to the heterogeneous definitions of tumor regrowth and various tumor volume distributions, the nature of small remnants after vestibular schwannoma (VS) surgery and the appropriate timing of adjuvant stereotactic radiosurgery for these remnants remain unclear. In this study, the growth potential of small remnants (< 1 cm3) after VS surgery was compared with that of treatment-naïve (TN) small VSs.

METHODS

This retrospective single-center study included 44 patients with VS remnants following subtotal resection (STR) of a large VS (remnant group) and 75 patients with TN VS (< 1 cm3; TN group). A 20% change in tumor volume over the imaging interval indicated radiographic progression or regression. Tumor progression-free survival (TPFS) rates were estimated using the Kaplan-Meier method.

RESULTS

In the remnant group, the mean preoperative tumor volume was 13.8 ± 9.0 cm3 and the mean tumor resection rate was 95% ± 5%. The mean tumor volume at the start of the observation period did not differ significantly between the two groups (remnant vs TN: 0.41 ± 0.29 vs 0.34 ± 0.28 cm3, p = 0.171). The median periods until tumor progression was detected were 15.1 (range 4.9-76.2) months and 44.7 (range 12.6-93.2) months in the TN and remnant groups, respectively. In the remnant group, the TPFS rates were 74% and 70% at 3 and 5 years after the surgery, respectively, compared with 59% and 47% in the TN group. The log-rank test demonstrated a significant difference (p = 0.008) in the TPFS rates between the two groups. Furthermore, 42 patients each from the remnant and TN groups were matched based on tumor volume. TPFS was significantly longer in the remnant group than in the TN group (3-year rates, 77% vs 62%; 5-year rates, 73% vs 51%; p = 0.02). In the remnant group, 18% of the tumor remnants demonstrated regression during follow-up, compared with 9% in the TN group, but this intergroup difference was not significant (p = 0.25).

CONCLUSIONS

This study demonstrated that the growth potential of small VS remnants was lower than that of TN tumors. Observing for small remnants may be appropriate after STR of a large VS. Given the risk of tumor regrowth, careful observation using MRI should be mandatory during follow-up.

A Large Residual Vestibular Schwannoma Following Incomplete Resection: A Case Report With Literature Review

Vestibular schwannomas (VSs), also known as acoustic neuromas, are benign, slow-growing tumors. If not detected early or treated appropriately, these tumors can lead to complications such as pressure on adjacent intracranial structures that can affect vital functions. The present report discusses a rare case of a residual VS in a 46-year-old female patient. The patient was a known case of left-sided VS who underwent partial excision of the tumor four years ago and had complete hearing loss on the left side since then. She reported to the clinic with progressive headaches and imbalance while walking. Magnetic resonance imaging of the brain revealed a large left residual VS compressing the brainstem and cerebellum, which was completely excised, and the patient did well postoperatively. Incomplete resection of VS carries a significant risk of tumor regrowth, necessitating the importance of complete resection with periodic follow-ups.

Direct cochlear nerve stimulation monitoring through evoked muscle responses during retrosigmoid vestibular schwannoma resection surgery: technical note

OBJECTIVE

Cochlear nerve preservation during surgery for vestibular schwannoma (VS) may be challenging. Brainstem auditory evoked potentials and cochlear compound nerve action potentials have clearly shown their limitations in surgeries for large VSs. In this paper, the authors report their preliminary results after direct electrical intraoperative cochlear nerve stimulation and recording of the postauricular muscle response (PAMR) during resection of large VSs.

METHODS

The details for the electrode setup, stimulation, and recording parameters are provided. Data of patients for whom PAMR was recorded during surgery were prospectively collected and analyzed.

RESULTS

PAMRs were recorded in all patients at the ipsilateral vertex-earlobe scalp electrode, and in 90% of the patients they were also observed in the contralateral electrode. The optimal stimulation intensity was found to be 1 mA at 1 Hz, with a good cochlear response and an absent response from other nerves. At that intensity, the ipsilateral cochlear response had an initial peak at a mean (± SEM) latency of 11.6 ± 1.5 msec with an average amplitude of 14.4 ± 5.4 µV. One patient experienced a significant improvement in his audition, while that of the other patients remained stable.

CONCLUSIONS

PAMR monitoring may be useful in mapping the position and trajectory of the cochlear nerve to enable hearing preservation during surgery.

Management of Vestibular Schwannoma with Normal Hearing

INTRODUCTION

This work aimed to study the management of vestibular schwannoma (VS) patients with normal hearing (NH).

METHODS

A retrospective study was undertaken in a Quaternary referral center for skull base pathologies. Among 4,000 VS patients 162 met our strict audiological criteria for NH. These patients were divided into 2 management groups, wait and scan (W&S) (45/162, 25%) and operated patients (123/162, 75%), and 6 patients were included in both groups.

RESULTS

Our management strategy achieved the goals for treatment of VS. First goal, all tumors were completely removed except for 2 intentional residuals. Second goal, facial nerve (FN) function preservation (House Brackmann I, II, and III) was 95.9%. Third goal, possible hearing preservation (HP) attempts occurred in (50/122) (40.9%) with an HP rate in 44% of the patients. Additionally, there were only 2 cases of postoperative complications with no CSF leakage. The prospect of HP in NH patients did not differ with respect to tumor size. However, patients with normal preoperative ABR seemed to have better chances of HP and good FN function and vice versa. HP rate was superior for the MCFA as opposed to the RS + RLA. W&S group demonstrated hearing stability in 88.9% of the patients and FN function stability of HB I in 100% of the patients.

CONCLUSIONS

Surgical resection is a reasonable and definitive management option for VS with NH. Nevertheless, choosing to manage cases with observation remains an appropriate management option for NH patients. ABR might be considered as an adjuvant tool indicating better prognosis for HP.

Large Vestibular Schwannoma: A Two-Stage Surgery

Treatment of large vestibular schwannoma (VS) has historically centered on total resection of the lesion. Staged surgery has been used for VS that is highly vascularized, unexpected events during surgery, and thinned and stretched facial nerve with serious adherence causing difficult dissection. We present a case of a patient with a large VS resected through a two-stage surgery through the same retrosigmoid craniotomy.

Hypofractionated stereotactic radiotherapy for large vestibular schwannomas and the impact of pre-radiation debulking surgery on dosimetry and clinical outcomes

Introduction:

This study was aimed to evaluate the outcomes of patients with large (>2 cm in great diameter) vestibular schwannomas (VSs) treated with hypofractionated stereotactic radiotherapy (HFSRT) compared to small (<2 cm) ones and the impact of debulking surgery prior to radiation for large VSs.

Methods:

Fifty-nine patients with VSs treated with HFSRT (25 Gy in 5 fractions) were evaluated by tumour size and surgical status. Patients were divided based on tumour size: small VSs (n = 42) and large VSs (n = 17). The large group was further divided into the groups of pre-treatment debulking surgery (n = 8) and no surgery (n = 9). Rates of tumour control, brainstem necrosis and neurologic dysfunction were assessed following treatment. Pre-surgical magnetic resonance imaging (MRI) were used to generate hypothetical HFSRT plans to compare the effect of debulking surgery on dosimetry. Normal tissue complication probability (NTCP) modelling was performed to compare toxicity probabilities with and without surgical debulking in large VSs.

Results:

There was no statistical difference of tumour control rate between small and large VSs with 100% for small tumours and 94·1% for large tumours (p = 0·12), respectively. In large VSs patient, the tumour control rate of HFSRT was 100% (8/8) for surgically debulked patients and 89% (8/9) for non-surgically debulked patients (p = 0·35). There were no patients who experienced brainstem necrosis or progression of facial and trigeminal nerve symptoms after HFSRT in the entire groups of patients. Surgical debulking large VSs did not change the maximum point dose of brainstem (p = 0·98), but significantly decreased volumes of VSs and changed the minimum dose to the hottest 0·5 cc of tumour (p = 0·016) as well as the volume receiving at least 23 Gy (p = 0·023). NTCP modelling revealed very low rates (average < 1%) of brainstem toxicity with or without surgical debulking, but there was a significant difference favoring surgery (p < 0·05).

Conclusions:

HFSRT is a safe and effective treatment for both small and large VSs and is a viable option for patients with large VSs who cannot undergo surgery, if NTCP of pre-debulking HFSRT dosimetry is lower.

Surgical Outcomes After Total or Subtotal Resection of Large Vestibular Schwannoma: A Single-Institution Experience

BACKGROUND

Patients with large vestibular schwannomas have various surgical outcomes. The aim of this study is to evaluate facial nerve outcome and surgical complications in patients who underwent total and subtotal resection.

METHODS

Between October 2008 and September 2020, 72 patients underwent surgery in Rajavithi Hospital. Of these, 48 had total or subtotal resection. We classified these participants into two groups: VS ≥3 cm (Group A, n=30); and VS <3 cm (Group B, n=18). Both groups were compared in terms of clinical presentation, imaging data, facial nerve outcomes, and surgical complications. The retrosigmoid approach was used in each case, and all patients had follow-up for at least 1 year. Chi-square and Fisher's exact test were used for statistical analysis.

RESULTS

The mean tumor size in Group A was 3.8 cm compared with 1.5 cm in Group B. In Group A, clinical signs of hearing dysfunction, gait ataxia, and facial paresthesia were present in 96.7%, 66.7%, 50% of patients respectively, compared with 100%, 5.6%, and 11.1% respectively in Group B. Radiographic signs of hydrocephalus were observed in 56.7% of Group A subjects, and 5.6% of those in Group B. At 1 year follow-up, 40% of patients with large VS and 94.4% of patients with small to medium size VS had good facial nerve outcomes (House-Brackmann [HB] facial grading scale grade I-III). Significant differences between the two groups were found only in gait ataxia (p<0.001), facial paresthesia (p=0.006), radiographic signs of hydrocephalus (p=0.002), facial nerve outcome 1 month (p<0.001) and facial nerve outcome 1 year (p<0.001).

CONCLUSION

In patients with large size VS, microsurgical resection had poor facial nerve outcomes compared with those of their counterparts with small to medium size VS. Planned subtotal resection with postoperative radiosurgery might attain superior facial nerve outcomes and result in better quality of life in subjects with large VS.

Infra-tentorial brain tumor subtypes in children and adults-surgical outcome in an ethnic population with a single regional tertiary center

BACKGROUND

To analyze clinically and radiologically the surgical outcome like residual disease, progression of disease, recurrence, disabilities, event-free survival (EFS), and mortality of different infra-tentorial tumor subtypes in children and adults of a strictly non-migratory and ethnic population.

METHODS

The 410 histologically proved, out of 589, infra-tentorial brain tumor patients were analyzed clinically and by the imaging post-surgically in a single tertiary center for an ethnic region. In this analytico-observational study, retrospectively postoperative records of 589 infra-tentorial brain tumors from November 1998 to December 2018 (20 years) were retrieved, scrutinized, and compiled. The post-operative clinic-radiological records of 410 patients with proved histopathological examination results were included. Statistical law of variance was applied where-ever necessary.

RESULTS

The 63.2% of the all 410 operated infra-tentorial brain tumors were males while females predominated in meningiomas and pineoblastomas. About 31.7% infra-tentorial tumors were children (below 18 years). About 54.1% cases were histologically malignant. The residual tumors comprised 40.2% and symptoms of disease-progression occurred in 10.9%. The tumor recurrence occurred in 14.3% while 6.0% patients developed severe disability. The overall mortality was 11.4% but 18.9% in malignant tumors. The event-free survival (EFS) for all the patients was 66.0%, patients with malignancies had 47.7% and benign group had 87.7%.

CONCLUSION

The study, surgical outcome of infra-tentorial brain tumor subtypes in children and adults (approx. 1/3rd of patients being children), conducted in a tertiary center at a remote land-locked location with non-migratory ethnic population as its catchment area, has a significant epidemiological value for the community and the region.

Treatment for vestibular schwannoma: Systematic review and single arm meta-analysis

OBJECTIVE

Vestibular schwannoma is a benign tumor in the schwannoma cells of the 8th cranial nerve. It causes symptoms like tinnitus, vertigo and end up with loss of hearing so the appropriate treatment is very important. There are many treatment techniques including conservative, surgery and radiosurgery. We aimed to systematically review and single arm meta-analysis the different treatment techniques of vestibular schwannoma.

METHODS

A comprehensive literature search using thirteen databases including PubMed, Scopus, and Web of Science was performed. All clinical trials about treatment vestibular schwannoma were included and single arm meta-analyzed. We assessed the risk of bias using ROBIN-I's tool and scale of Council Australia's Cancer Guidelines Wiki. The protocol was registered in PROSPERO (CRD42018089784) and has been updated on 17 April 2019.

RESULTS

A total of 35 clinical trials studies were included in the final analysis. The pooled proportion of stable hearing capability in patients receiving gamma knife radiosurgery (GKRS) was 64% (95% CI: 52%-74%). GKRS favored increased hearing capability 10% (95% CI: 7%-16%). Regarding tumor size, GKRS is the most protective method 53% (95% CI: 37%-69%). Complications occurred most commonly in single fractional linac stereotactic radiosurgery (SFSRT) 37% (95% CI: 12%-72%).

CONCLUSION

Our analysis suggested gamma knife radiosurgery could be the most ideal treatment for vestibular schwannoma based on stabilizing hearing capability, increasing hearing capability, decreasing tumor size and complications.

Accuracy and outcomes of diffusion tensor imaging tractography in resection for vestibular schwannoma for facial nerve preservation

BACKGROUND

Impairment of facial nerve (FN) function is a common postoperative complication in surgical resections of Vestibular Schwannomas (VS). Diffusion tensor imaging (DTI) tractography creates in vivo imaging of the anatomical location of white matter tracts that can be preoperatively used to visualize the displaced FN. We present an analysis of patients who underwent DTI tractography imaging prior to VS resection.

METHODS

Patient charts were reviewed from March 2012 to April 2015 who underwent DTI tractography prior to surgical resection for VS. Reliability of this measure was compared to the intraoperative FN location as determined by the surgeon. House Brackmann (HB) score was used to assess facial nerve function.

RESULTS

A total of 11 patients were included with a mean age of 43 years (range: 19-64) and mean follow-up length of 11.9 months (range: 3.1-34.2). The average maximum tumor diameter was 2.82 cm (range: 1.7-4.2). DTI tractography was accurate in 90.9% (10/11) of patients. Postoperatively, 72.7% (8/11) had a HB score of I or II, 18.2% (2/11) had a HB score of III, and 9.1% (1/11) had a HB score of IV.

CONCLUSIONS

Facial nerve visualization for VS resection can be accurately visualized using DTI tractography. This modality may lead to reduction of postoperative FN damage.

An aberrant venous channel mimicking the perilabyrinthine cells in the petrous bone of a patient with vestibular schwannoma: illustrative case

BACKGROUND

Anatomical variations, such as high jugular bulbs and air cell development in the petrosal bone, should be evaluated before surgery. Most bone defects in the internal auditory canal (IAC) posterior wall are observed in the perilabyrinthine cells. An aberrant vascular structure passing through the petrous bone is rare.

OBSERVATIONS

A 48-year-old man presented with a right ear hearing disturbance. Magnetic resonance imaging revealed a 23-mm contrast-enhancing mass in the right cerebellopontine angle extending into the IAC, consistent with a right vestibular schwannoma. Preoperative bone window computed tomographic scans showed bone defects in the IAC posterior wall, which ran farther posteroinferiorly in the petrous bone, reaching the medial part of the jugular bulb. The tumor was accessed via a lateral suboccipital approach. There was no other major vein in the cerebellomedullary cistern, except for the vein running from the brain stem to the IAC posterior wall. To avoid complications due to venous congestion, the authors did not drill out the IAC posterior wall or remove the tumor in the IAC.

LESSONS

Several aberrant veins in the petrous bone are primitive head sinus remnants. Although rare, their surgical implication is critical in patients with vestibular schwannomas.

[Trigeminal radiculopathy in vestibular schwannomas]

OBJECTIVE

To evaluate the correlation of trigeminal radiculopathy with anatomical relationships of trigeminal nerve root, brainstem, tumors and vessels in patients with vestibular schwannomas.

MATERIAL AND METHODS

A retrospective analysis included 153 patients (106 females and 47 males aged 22-82 years) with vestibular schwannomas who underwent surgery via retromastoid approach. Preoperative trigeminal radiculopathy (facial pain and sensory disturbances) was examined after microsurgical resection. Brainstem compression was analyzed by comparison of transverse size of contralateral to vestibular schwannoma half of brainstem and ipsilateral side.

RESULTS

Tumor-induced brainstem and trigeminal nerve compression was found in 115 cases. Sixty-four of these patients had trigeminal radiculopathy symptoms. Degree of brainstem compression was significantly higher in trigeminal radiculopathy group. Facial hypoesthesia was found in 61patients, trigeminal neuralgia - in 5 cases, neuropathic pain - in 3 patients. Thirty-seven patients without brainstem compression had no trigeminal nerve involvement. One patient had trigeminal neuralgia following compression by superior cerebellar artery. Total resection with brainstem and trigeminal nerve decompression were performed in all cases. Isolated or combined compression of trigeminal nerve root was noted in 9 patients with trigeminal neuralgia and neuropathic pain, in 2 with facial numbness and in 2 patients without trigeminal symptoms. In case of trigeminal neuralgia following compression by superior cerebellar artery, vascular decompression was performed only in patients with facial pain and numbness. Facial pain completely resolved in all patients. Complete or partial sensory restoration was noted in 25 cases. No facial sensory disorders were noted in 26 cases, transient sensory deterioration - in 10 patients.

CONCLUSION

Trigeminal radiculopathy is caused by severe brainstem compression following vestibular schwannomas and usually results sensory disturbances and rarely facial pain. The impact of tumor on trigeminal nerve root and brainstem trigeminal pathways can be accompanied by vascular compression by superior cerebellar artery. Regression of trigeminal radiculopathy symptoms after resection of vestibular schwannoma is caused by decompression of trigeminal nerve root and brainstem. In case of concomitant neurovascular syndrome, vascular decompression is indicated.

Clinical Studies and Pre-clinical Animal Models on Facial Nerve Preservation, Reconstruction, and Regeneration Following Cerebellopontine Angle Tumor Surgery-A Systematic Review and Future Perspectives

Background and purpose: Tumorous lesions developing in the cerebellopontine angle (CPA) get into close contact with the 1st (cisternal) and 2nd (meatal) intra-arachnoidal portion of the facial nerve (FN). When surgical damage occurs, commonly known reconstruction strategies are often associated with poor functional recovery. This article aims to provide a systematic overview for translational research by establishing the current evidence on available clinical studies and experimental models reporting on intracranial FN injury.

Methods: A systematic literature search of several databases (PubMed, EMBASE, Medline) was performed prior to July 2020. Suitable articles were selected based on predefined eligibility criteria following the Preferred Reporting Items for Systematic Reviews and Meta Analyses (PRISMA) guidelines. Included clinical studies were reviewed and categorized according to the pathology and surgical resection strategy, and experimental studies according to the animal. For anatomical study purposes, perfusion-fixed adult New Zealand white rabbits were used for radiological high-resolution imaging and anatomical dissection of the CPA and periotic skull base.

Results: One hundred forty four out of 166 included publications were clinical studies reporting on FN outcomes after CPA-tumor surgery in 19,136 patients. During CPA-tumor surgery, the specific vulnerability of the intracranial FN to stretching and compression more likely leads to neurapraxia or axonotmesis than neurotmesis. Severe FN palsy was reported in 7 to 15 % after vestibular schwannoma surgery, and 6% following the resection of CPA-meningioma. Twenty-two papers reported on experimental studies, out of which only 6 specifically used intracranial FN injury in a rodent (n = 4) or non-rodent model (n = 2). Rats and rabbits offer a feasible model for manipulation of the FN in the CPA, the latter was further confirmed in our study covering the radiological and anatomical analysis of perfusion fixed periotic bones.

Conclusion: The particular anatomical and physiological features of the intracranial FN warrant a distinguishment of experimental models for intracranial FN injuries. New Zealand White rabbits might be a very cost-effective and valuable option to test new experimental approaches for intracranial FN regeneration. Flexible and bioactive biomaterials, commonly used in skull base surgery, endowed with trophic and topographical functions, should address the specific needs of intracranial FN injuries.

Gross-total versus near-total resection of large vestibular schwannomas. An institutional experience

OBJECTIVE

We will report our experience of the surgical treatment of large vestibular schwannomas (VSs).

PATIENTS, MATERIALS AND METHODS

We conducted a retrospective study of patients operated on for Koos grade IV VS between 2007 and 2015 at the Department of Neurosurgery, Emergency County Hospital, Târgu Mureş, Romania. We studied the general preoperatory clinical data, the preoperative and postoperative facial nerve status, preoperative hearing on the affected side, and any postoperative complications, including death.

RESULTS

Sixty-six cases were included in our study. The mean age was 52.95 years and 66.7% (n=44) of the sample were female. All patients had suffered from tinnitus and this had been followed by loss of serviceable hearing on the affected side in 89.4% (n=59) of cases. Preoperative facial palsy was found in 53% (n=35) of patients. The mean tumor size was 40.35 mm. Gross-total resection (GTR) was achieved in 24 (36.36%) cases, while near-total resection (NTR) was obtained in 42 (63.64%) cases. New-onset facial palsy or degradation of the preoperative facial deficit occurred in 12 (18.18%) cases, most of whom were patients with a GTR (n=9, 37.5%). This was statistically significant. There were no significant postoperative differences between the GTR and NTR groups. There was one death in the GTR group.

CONCLUSIONS

We conclude that near-total tumor removal provides good surgical results and better postsurgical quality of life for patients when compared to gross-total tumor resection. Therefore, this should be the end goal of the resection of large VSs.

Retrosigmoid Approach in the Supine Position Using ORBEYE: A Consecutive Series of 14 Cases

One of the merits of recently introduced exoscopes, including ORBEYE, is that they are superior to a conventional microscope in terms of ergonomic features. Taking advantage of it, the retrosigmoid approach can be performed in the supine position using ORBEYE. We report a consecutive series of 14 operations through the retrosigmoid approach in the supine position using ORBEYE. Fourteen consecutive patients who underwent surgery through the retrosigmoid approach for cerebellopontine (CP) angle lesions in the supine position using ORBEYE were targeted, and surgical outcomes and complications were examined. We evaluated the posture of the operator and the surgical field during this approach compared with those using a conventional microscope. In all 14 cases, all operative procedures were accomplished only using the ORBEYE. There were no operative complications due to this approach. Using ORBEYE, even when the angle of the operative visual axis was horizontal, the operators could manipulate in a comfortable posture. They were not forced to be in an uncomfortable posture that extended their arms, as is often the case with a conventional microscope. Therefore, they could use shorter surgical instruments. As the cerebellum shifted downward with gravity even using slight retraction during this approach, the working space of the surgical field was easily secured. Through this approach, the operators can perform stable microsurgery of CP angle lesions in a comfortable posture. This approach can reduce the burden on the operator and the patient, leading to a refined surgical procedure.

Surgical management for large vestibular schwannomas: a systematic review, meta-analysis, and consensus statement on behalf of the EANS skull base section

BACKGROUND AND OBJECTIVE

The optimal management of large vestibular schwannomas continues to be debated. We constituted a task force comprising the members of the EANS skull base committee along with international experts to derive recommendations for the management of this problem from a European perspective.

MATERIAL AND METHODS

A systematic review of MEDLINE database, in compliance with the PRISMA guidelines, was performed. A subgroup analysis screening all surgical series published within the last 20 years (January 2000 to March 2020) was performed. Weighted summary rates for tumor resection, oncological control, and facial nerve preservation were determined using meta-analysis models. This data along with contemporary practice patterns were discussed within the task force to generate consensual recommendations regarding preoperative evaluations, optimal surgical strategy, and follow-up management.

RESULTS

Tumor classification grades should be systematically used in the perioperative management of patients, with large vestibular schwannomas (VS) defined as > 30 mm in the largest extrameatal diameter. Grading scales for pre- and postoperative hearing (AAO-HNS or GR) and facial nerve function (HB) are to be used for reporting functional outcome. There is a lack of consensus to support the superiority of any surgical strategy with respect to extent of resection and use of adjuvant radiosurgery. Intraoperative neuromonitoring needs to be routinely used to preserve neural function. Recommendations for postoperative clinico-radiological evaluations have been elucidated based on the surgical strategy employed.

CONCLUSION

The main goal of management of large vestibular schwannomas should focus on maintaining/improving quality of life (QoL), making every attempt at facial/cochlear nerve functional preservation while ensuring optimal oncological control, thereby allowing to meet patient expectations. Despite the fact that this analysis yielded only a few Class B evidences and mostly expert opinions, it will guide practitioners to manage these patients and form the basis for future clinical trials.

Management von Patienten mit Vestibularisschwannomen Typ IV

Hintergrund Vestibularisschwannome (VS) sind benigne Tumoren, die anhand der Hannover-Klassifikation bzw. der Koos-Klassifizierung eingeteilt werden. Trotz der umfangreichen Literatur sind die Klinik und die Behandlungskonzepte speziell bei großen VS selten beschrieben.

Material und Methoden Zwischen 2003 und 2018 wurden 61 Patienten mit VS Typ IV durch die Arbeitsgruppe Schädelbasischirurgie am Klinikum Dortmund behandelt. Die radiologischen und klinischen Daten wurden retrospektiv ausgewertet. Zudem erfolgte eine Subgruppenanalyse zwischen Patienten mit und ohne Kompression des IV. Ventrikels.

Ergebnisse Neben einer Hörminderung bei 55 Patienten (90 %) hatten die meisten Patienten multiple Symptome wie eine Trigeminusaffektion bei 16 (26 %), eine Fazialisparese bei 7 (12 %), eine Ataxie bei 27 (45 %) und Symptome eines Hirndruckanstiegs durch einen Hydrozephalus bei 4 Patienten (7 %). Bei Patienten mit einem VS Typ IVb wurde signifikant häufiger eine Ataxie, eine tonsilläre Herniation bzw. ein Hydrozephalus festgestellt. Eine komplette Resektion wurde in 48 Patienten (78 %) erreicht und eine weitestgehende Tumorentfernung in 12 Patienten (20 %). In der Langzeituntersuchung zeigten 90 % einen günstigen Outcome bezüglich des Nervus facialis (House-und-Brackman-Grad I–III). 6 Patienten (10 %) benötigten einen dauerhaften ventrikulo-peritonealen Shunt. Mehr als 90 % der Patienten erzielten einen Karnofsky-Index > 70 %.

Diskussion VS Typ IV sind häufig assoziiert mit Hydrozephalus, Ataxie, multiplen Hirnnervenausfällen und gelegentlich Zeichen eines intrakraniellen Druckanstiegs. Die primäre mikrochirurgische Resektion ist weiterhin eine entscheidende Therapieoption.

Keyhole retrosigmoid approach for large vestibular schwannomas: strategies to improve outcomes

OBJECTIVE There are numerous treatment strategies in the management for large vestibular schwannomas, including resection only, staged resections, resections followed by radiosurgery, and radiosurgery only. Recent evidence has pointed toward maximal resection as being the optimum strategy to prevent tumor recurrence; however, durable tumor control through aggressive resection has been shown to occur at the expense of facial nerve function and to risk other approach-related complications. Through a retrospective analysis of their single-institution series of keyhole neurosurgical approaches for large vestibular schwannomas, the authors aim to report and justify key techniques to maximize tumor resection and reduce surgical morbidity. METHODS A retrospective chart review was performed at the Centre for Minimally Invasive Neurosurgery. All patients who had undergone a keyhole retrosigmoid approach for the resection of large vestibular schwannomas, defined as having a tumor diameter of ≥ 3.0 cm, were included in this review. Patient demographics, preoperative cranial nerve status, perioperative data, and postoperative follow-up were obtained. A review of the literature for resections of large vestibular schwannomas was also performed. The authors' institutional data were compared with the historical data from the literature. RESULTS Between 2004 and 2017, 45 patients met the inclusion criteria for this retrospective chart review. When compared with findings in a historical cohort in the literature, the authors' minimally invasive, keyhole retrosigmoid technique for the resection of large vestibular schwannomas achieved higher rates of gross-total or near-total resection (100% vs 83%). Moreover, these results compare favorably with the literature in facial nerve preservation (House-Brackmann I-II) at follow-up after gross-total resections (81% vs 47%, p < 0.001) and near-total resections (88% vs 75%, p = 0.028). There were no approach-related complications in this series. CONCLUSIONS It is the experience of the senior author that complete or near-complete resection of large vestibular schwannomas can be successfully achieved via a keyhole approach. In this series of 45 large vestibular schwannomas, a greater extent of resection was achieved while demonstrating high rates of facial nerve preservation and low approach-related and postoperative complications compared with the literature.

Adaptive hybrid surgery analysis (AHSA) for adjuvant gamma knife radiosurgery treatment of vestibular schwannoma residuals

OBJECTIVES

Adaptive Hybrid Surgery Analysis (AHSA, Brainlab, Munich, Germany) is a software application generating in real-time conceptual dose plans for tumor residuals but has so far not been assessed for usability in a Gamma Knife (Elekta, Stockholm, Sweden) radiosurgery practice. We aimed to compare AHSA stereotactic radiosurgery dose plans with Leksell Gamma Plan (LGP, Elekta, Stockholm, Sweden) plans for adjuvant radiosurgical treatment of Vestibular Schwannoma (VS) residuals.

PATIENTS AND METHODS

In this retrospective comparative study, we compared the automatically calculated AHSA dose plans with clinical LGP treatment plans in 13 patients radiosurgically treated for VS residuals. We first created an LGP template based on our specific constraints to organs at risk (OAR), and a tumor prescription volume coverage of minimum 98%. As most proximal anatomy at risk is not manually contoured in our practice, OARs (i.e. brainstem, optic apparatus and cochlea) in the planning images were automatically segmented in Elements Anatomical Mapping and imported into the AHSA software for re-planning and comparison with the LGP dose plans.

RESULTS

There was no significant difference in tumor coverage and conformity index between the LGP and AHSA dose planning data, with the mean and maximal dose to the brainstem slightly higher in the latter.

CONCLUSION

The AHSA dose plans for adjuvant radiosurgical treatment of VS residuals were comparable to those of LGP used in our Gamma Knife practice, confirming the usability of AHSA in the management of Vestibular Schwannoma in a Gamma Knife practice.

De Novo Vestibular Schwannoma: A Report of Three Cases

The reported growth rate of vestibular schwannoma varied widely in the literature. However, emergence of vestibular schwannoma remains unsolved. We presented three patients who had undergone previous magnetic resonance imaging (MRI) confirming the absence of tumor and were diagnosed with a unilateral vestibular schwannoma with a diameter of 18–30 mm, 6–9 years after the initial MRI. One patient had solid tumor and experienced stereotactic radiosurgery. Following stereotactic radiosurgery, continuous tumor growth led to hydrocephalus and trigeminal dysfunction, resolved by surgical removal. Other two patients had the tumor with cystic component and experienced surgical removal as first treatment. All tumors were pathologically diagnosed as schwannomas without evidence of high potential of proliferation. This is the first report of three patients with de novo vestibular schwannoma, showing tumor emergence and rapid growth in a short period. Considering a de novo aspect, the “wait and scan” policy may not be appropriate for the subset of VS such as de novo VS.

Vestibular Schwanomma: An Experience in a Developing World

Background

Tumors related to the acoustic nerves represent 90% of cerebellopontine angle diseases and have been in the picture for at least 200 years. Famous as acoustic neuromas and vestibular neuromas, these are usually benign, slow-growing tumors of Schwann cells of the myelin sheath. Surgery is the treatment of choice though some authors have suggested "wait and watch" policy. The aims of our study were to study the clinical presentation and management of the tumors, and to evaluate the perioperative outcomes of the surgery.

Methods

A retrospective review of the datasheet of 33 patients diagnosed with vestibular schwanomma who had undergone surgery from January 2014 to January 2017 was performed in National Academy of Medical Sciences, Bir Hospital, Kathmandu, Nepal. Analysis of the demographic data and perioperative outcomes was performed.

Results

Hearing loss was the main presenting symptom in 72% cases followed by tinnitus, dizziness, facial numbness and sudden sensorineural hearing loss. Mean tumur size was 39.7 ± 3 mm. The mean age of the patients was 46 ± 3 years with a female preponderance (1.2:1). In particular, the retrosigmoid route was preferred in all the cases since it was the most employed approach at our center and 63% of the tumors presented to us were grade 5. The surgical techniques allowed safe preservation of the facial function which was 93%. The hearing loss did not improve after the surgery in 94% while it worsened in 6% of cases. We did not find any significant relation between outcome and size, age, gender or laterality of the tumor (P > 0.05). There was no perioperative mortality.

Conclusions

The benign and slow-growing nature of vestibular schwanomma usually poses problems for the early diagnosis and treatment especially in a poor resource setting like ours. Likewise, there are very few studies so far done in the country regarding the incidence and management of the disease. Thus, this study might be helpful in providing insight into the occurrence of the disease in the present scenario and the need for much more studies in the future.

Lateral Semi-sitting Position: A Novel Method of Patient's Head Positioning in Suboccipital Retrosigmoid Approaches

Background

The most common methods of positioning patients for suboccipital approaches are the lateral, lateral oblique, sitting, semisitting, supine with the head turn, and park bench. The literature on the positioning of patients for these approaches does not mention the use of lateral semisitting position. This position allows utilization of the benefits of both semisitting and lateral position without causing any additional morbidity to the patient.

Aims

The aim of the present study is to highlight the advantages of the lateral semisitting position while operating various cerebellopontine angle (CPA) and posterior fossa lesions.

Materials and Methods

The position involved placing the patient in a lateral position with torso flexed to 45° and head tilted toward opposite shoulder by 20°. The most common approach taken was retrosigmoid suboccipital craniotomy.

Results

The advantages of lateral semisitting position were early decompression of cisterna magna, and the surgical field remained relatively clear, due to gravity-assisted drainage of blood and irrigating fluid. We could perform all the surgeries without the use of any retractors. The position allowed better delineation of surrounding structures resulting in achieving correct dissection plane and also permitted early caudal to cranial dissection of tumor capsule, thereby increasing chances of facial nerve preservation. Importantly, there is less engorgement of the cerebellum as the venous outflow is promoted. We have not experienced any increased rate of complications, such as venous air embolism, tension pneumocephalus with this lateral semisitting position.

Conclusions

Lateral semisitting position is a relatively safe modification, which combines the benefits of semisitting and lateral position, and avoids the disadvantages of sitting position in operating CPA tumors. This position can provide quick and better exposure of the CPA without any significant complications.

Primary Dural Closure for Retrosigmoid Approaches

Object  Primary closure of posterior fossa dura can be challenging, and postoperative cerebrospinal fluid (CSF) leaks continue to represent a common complication of the retrosigmoid approach. We describe a simple technique to allow for primary closure of the dura following retrosigmoid approaches. The incidence of CSF leaks using this method is reported.

Methods  A retrospective chart review was conducted on all cases of retrosigmoid craniotomies performed by the senior surgeon from February 2009 to February 2015. The primary outcome was development of postoperative CSF leak or pseudomeningocele. Length of stay, lesion type, and other surgical complications were also reported.

Results  Eighty-six patients underwent a retrosigmoid craniotomy during the study period. The most common indications for retrosigmoid craniotomy were microvascular decompression (58%) and tumor resection (36%). No allo- or autografts to repair the dural defect were needed, and no lumbar drains were used. No patients developed CSF otorrhea, rhinorrhea, or incisional leak postoperatively.

Conclusion  Primary dural closure is possible in retrosigmoid approaches without the use of allo- or autografts and may prevent postoperative CSF leaks when combined with other posterior fossa closure techniques. Careful attention to the handling of the dural flap is necessary to achieve this.

Could IGF-I levels play a neuroprotective role in patients with large vestibular schwannomas?

Aim

To evaluate the possible superiority of outcome in patients with elevated IGF-I levels after vestibular schwannoma (VS) resection.

Patients & methods

This retrospective study included 65 patients (34 male, 52.3%) with VS operated in between January 2009 and April 2014 (follow-up 3.2 ± 0.7 years). Preoperative or postoperative IGF-I levels were identified for each patient.

Results

Patients were divided into two groups: Group A (small size tumor), 56 patients; and Group B (large size tumor), 9 cases. IGF-I levels in Group A (195.8 ± 32.9 ng/ml) were compared with those of Group B (242.2 ± 22.2 ng/ml) and were found to have statistically significant difference (p = 0.001).

Conclusion

Increased IGF-I levels could hold a key role in nerve recovery in patients undergoing surgical resection of large VS.

Clinical features, microsurgical treatment, and outcome of vestibular schwannoma with brainstem compression

Background:

Presenting symptoms, treatment considerations, and outcome are strongly related to the extension of vestibular schwannomas (VS). The aim of the current retrospective study was to analyze the clinical features, microsurgical treatment, and outcome of VS with brainstem compression.

Methods:

Forty-nine patients presented with VS (Hannover grading scale T4a or T4b) in our department. A subgroup analysis was performed among patients without (T4a) and with (T4b) compression and dislocation of the fourth ventricle.

Results:

Patients with type T4b VS presented significantly more often with long tract signs/ataxia (P < 0.05), tonsillar herniation (P < 0.001), and preoperative hydrocephalus (P < 0.01). No significant difference was found between the groups regarding hearing loss and facial nerve, trigeminal nerve, and lower cranial nerve function. Gross total resection was achieved in 83% of the cases, near total resection was achieved in 15% of the cases, and subtotal resection was performed in 2% of the cases. One patient died after massive postoperative bleeding caused by a coagulopathy. At last follow-up, 69% of the patients had excellent facial nerve function (Grade I–II) and the remaining 31% a fair outcome. Six patients (12%) required permanent ventriculoperitoneal shunting. Hearing was preserved in two patients. Forty-six patients (94%) were independent without occasional assistance (Karnofsky scale 70–100%).

Conclusions:

VS with brainstem compression is frequently associated with hydrocephalus, ataxia, long tract signs, multiple cranial nerve disorders, and occasionally, signs of intracranial hypertension. Primary microsurgical resection is an appropriate management option for large VS.

Morphometric analysis of posterior fossa in Indian CP angle acoustic schwannoma patients

AIM

To study the morphometry of posterior fossa in Indian CP angle schwannoma patients in order to know its influence on the extent of excision of the CP angle acoustic schwannomas.

MATERIALS AND METHODS

One hundred cases of cerebellopontine angle schwannomas treated surgically by the senior author and 20 controls between January 2006 and June 2011 were consecutively investigated with computed tomography (CT) using the high-resolution CT bone windows before surgery. Evaluation of anatomic parameters of the petrous bone and posterior fossa cavity were done in all patients and controls. Data were entered in Excel software and were analyzed using NCSS software. All possible regression analysis was done to select the important variables to be included in the model to predict the excision of tumor with these variables. A prediction model was developed defining the binary outcome as total excision or subtotal excision as dependent variable and the morphometric data and grading of tumor as independent variables.

RESULTS

Interpetrous distance (IP) is the distance between the two petrous apices. Sigmoid distance (IS) distance is the distance between the two sigmoid points. Sigmoid point is the point at which the scalloped impression of the sigmoid sinus straightens to join the occipital bone posteriorly. SAG is the distance between the mid IP point and the mid-point on the inner wall of the occipital bone. The PM angle was 47.8±4.14 degrees (38-58), the PA angle was 42.68±4.47 degrees (34-53), the IP distance was 2.07±0.13 cm (1.5-2.8), the sagittal diameter of posterior fossa was 6.22±0.73 cm (5.1-9.8) and the intersigmoid distance was 9.45±0.73 cm (7.4-11). There was no significant gender difference in the posterior fossa morphometry between patients and controls. Inter-sigmoid distance and the petrous-apex angle were more in the Indians when compared to the European population mentioned in the Mathies and Samii study.

CONCLUSIONS

The posterior fossa morphological parameters of the Indian and European population differ significantly. Inter-sigmoid distance and the petrous-apex angle were more in the Indians when compared to the Europeans. There is no significant gender difference in the morphometry of the Indians. There is no significant difference between the patients and the control groups. In our study the adhesions with surrounding structures along with the posterior fossa morphometry significantly affect the extent of excision.

Surgical outcome in cystic vestibular schwannomas

Background:

Cystic vestibular schwannomas (VS) form a rare subgroup that differs from the solid variant clinically, radiologically, and histopathologically. These tumors also vary in their surgical outcome and carry a different risk of post-operative complications. We analyzed our series of 64 patients with cystic VS and discuss the technical difficulties related to total excision of these tumors and focus on complication avoidance.

Materials and Methods:

A retrospective review of cystic VS surgically managed over a span of 11 years. The case records were evaluated to record the clinical symptoms and signs, imaging findings, surgical procedure, complications, and follow-up data. Post-operative facial nerve palsy was analyzed with respect to tumor size and tumor type.

Results:

Progressive hearing impairment was the most common initial symptom (76.6%). Atypical initial symptoms were present in 15 patients (23.4%). Preoperatively, 78% patients had good facial nerve function (HB grade 1, 2) and 22% had intermediate (HB grade 3, 4) to poor (HB grade 5 and 6) function. Mean tumor size was 4.1 cm. Complete tumor removal was achieved in 53 patients (83%). The facial nerve was anatomically intact but thinned out after tumor excision in 38 patients (59.4%). Ninety percent patients had either intermediate or poor facial nerve function at follow-up. Poor facial nerve outcome was associated with giant tumors and peripherally located, thin-walled cystic tumors.

Conclusion:

Resection of cystic VS is complicated by peritumoral adhesions of the capsule to the nerve. Extensive manipulation of the nerve in order to dissect the tumor–nerve barrier results in worse facial nerve outcome. The outcome is worse in peripherally located, thin-walled cystic VS as compared to centrally located, thick-walled cystic tumors. Subtotal excision may be justified, especially in tumors with dense adhesion of the cyst wall to the facial nerve in order to preserve nerve integrity.

Clinical comparison of two subtypes of cystic vestibular schwannoma: surgical considerations and outcomes

Cystic vestibular schwannoma (CVS) is classified as Type A and Type B based on the overall cyst location and cyst wall thickness in magnetic resonance imaging. A retrospective analysis was performed to compare surgical considerations and outcomes between Type A and Type B groups of CVS. We selected 188 patients diagnostic for CVS with surgical resection, and divided them into Type A and Type B groups. General information, preoperative symptoms, the result of neuroimaging, and audiological tests were recorded. Surgical approach, completeness of tumor resection, and intraoperative facial nerve (FN) integrity were taken down. After operation, the short-term and long-term FN functions, complications, and recurrence rate were evaluated. The total tumor removal rate in Type A group was higher than that in Type B group (86.1 vs 72.5 %, p = 0.021). Anatomical FN integrity was preserved in 173 patients (92.0 %), with no significant differences between Type A and Type B. FN function was better in Type A group at hospital discharge. Besides, a good FN function rate was inversely proportional to the tumor size. The long-term FN function and all of the complications had no significant differences between the two groups. Patients in the Type B group are prone to have a lower total tumor removal rate and transient FN dysfunction. The long-term FN function was similar in both groups. Tumor size is another important indication of FN function. All postoperative complications occurred in patients with a tumor larger than grade 3, regardless of the subtypes of CVS.

Facial functional outcome in monitored versus not-monitored patients in vestibular schwannomas surgery

Objective:

Even though advances in surgical techniques have improved facial nerve outcomes, functional preservation is still an issue because injury to the facial nerve has significant physical and psychological consequences for the patient. We retrospectively review our data in VS surgery to compare the facial outcome in intraoperative facial monitored versus not-monitored patients.

Materials and Methods:

51 consecutive patients with unilateral vestibular schwannoma in the period from 2005 to 2010 were treated in our Institution. In according to the type of neurophysiological tool used during surgical procedures, two patients groups were identified: Group 1 (facial stimulator only) and Group 2 (stimulator and facial monitoring). Statistical comparison of the two groups was made with the t- test, and facial function results were evaluated with the Fisher's exact test.

Results:

In the Group 1, of the 22 patients with anatomically preserved facial nerves, 3 (13.6%) showed excellent facial nerve function, 14 (63.6%) showed intermediate function, and 5 (22.7%) showed poor function. In the Group 2, all the 27 patients got anatomically preserved facial nerves, and 18 (66.7%) showed excellent facial nerve function, 9 (33.3%) showed intermediate function, and no one showed poor function.

Conclusions:

We found that retrosigmoid approach associated with continuous EMG facial monitoring combined with the use of bipolar stimulation is a safe and effective treatment for vestibular schwannomas.

Head movements in patients with vestibular lesion: a novel approach to functional assessment in daily life setting

OBJECTIVES

(1) To determine if head movements in patients with vestibular deficiency differ from those in normal subjects during daily life activities. (2) To assess if these differences can be correlated with patients' perception of dizziness-induced handicap.

STUDY DESIGN

Prospective matched-pairs study

SETTING

Tertiary referral center

PATIENTS

Thirty-one vestibular schwannoma patients with documented postoperative unilateral vestibular loss and their age-, gender-, and physical activity level-matched controls with symmetric vestibulo-ocular reflexes.

INTERVENTIONS

Head movements during 10 tasks from daily life were recorded using body-worn movement sensors.

MAIN OUTCOME MEASURES

The time to complete the task, the average head velocity and acceleration during each task, and the number of head turns performed were compared between cases and controls. These measures were then correlated with the self-reported Dizziness Handicap Inventory (DHI) scores of the patients.

RESULTS

Patients with a unilateral vestibular deficit took significantly longer to perform most daily life activities compared to controls. Their head movements, however, were not always slower. They adopted a different movement strategy, in certain instances less efficient and more disorganized. Dimensions of movement are not all affected equally after a unilateral vestibular loss with evidence of clear clustering of the differences within dimensions across tasks. There was no correlation between the DHI and patients' performance in those tasks.

CONCLUSION

Vestibular loss, even when compensated, affects patients' movements, which can be measured in an ambulatory setting of daily life activities. The differences in movements associated with vestibular loss do not correlate with the degree of self-reported handicap.

Large vestibular schwannoma resection through the suboccipital retrosigmoid keyhole approach

OBJECTIVE

The objective of this study was to retrospectively study the outcomes of large vestibular schwannoma resection through the suboccipital retrosigmoid keyhole approach and emphasize technical details and advantages of surgical resection of large vestibular schwannomas via this approach.

METHODS

From January 2010 to September 2012, 37 consecutive patients (16 men and 21 women) with vestibular schwannoma, 4 cm or greater, received surgical resection through the suboccipital retrosigmoid keyhole approach in our department. Clinical records, radiographic findings, operative summaries, and follow-up data were analyzed retrospectively.

RESULTS

The mean age of these patients was 45.1 ± 11.6 years. Thirty-six patients underwent primary keyhole surgical removal, and 1 underwent surgery for residual tumor after gamma knife. Gross total tumor removal was accomplished in 35 patients (94.6%), near total resection in 1 (2.7%), and subtotal resection in 1 patient (2.7%). The facial nerve was anatomically intact in all 37 patients (100%). Facial nerve function was assessed in 6 to 12 months after operation. Good function (House-Brackmann facial nerve grade I-II) was present in 81.1% of the patients, whereas acceptable function (grade III) was present in 11.1%. Cerebrospinal fluid (CSF) leakage that required surgical intervention occurred in only 5.4% of the patients, and meningitis occurred in 8.1%. In addition, 3 patients (8.1%) had hydrocephalus requiring a temporary ventricular diversion. There were no deaths.

CONCLUSIONS

The suboccipital retrosigmoid keyhole approach is a valid choice for removing large vestibular schwannomas. Through this approach, cerebellopontine angle can be effectively exposed. Skills to protect facial nerve and extensive experience in microsurgical techniques can significantly improve the total resection rate and postoperative facial nerve function. The authors recommend this approach for patients with vestibular schwannomas larger than 3 to 4 cm.

Multicystic vestibular schwannomas with fluid-fluid levels: A report of three cases

The present study reported three rare cases of multicystic vestibular schwannoma with fluid-fluid levels. These three tumors exhibited apparent fluid-fluid levels that demonstrated a radiological appearance of two fluid levels in the cystic area. Two cases had an acute history, whereas one case presented with a chronic progression. A suboccipital retrosigmoid approach was used for access to the tumors and gross total resection was achieved in all the cases. During the surgical procedures, unclotted blood was observed, and the tumors were adhered to the facial nerve, other cranial nerves or the brain stem. In each case, the facial nerve function of the patients was impaired following surgery. The present study discussed the possible mechanism of the formation of the fluid-fluid levels, the effect of the fluid-fluid levels and the therapeutic strategy employed.

Facial Nerve Outcome after Vestibular Schwannoma Resection: A Comparative Meta-Analysis of Endoscopic versus Open Retrosigmoid Approach

The minimal access retrosigmoid endoscopic approach to vestibular schwannoma (VS) resection has been used with promising results. However, it has not been compared with the standard open approach in the literature. We performed a meta-analysis review for all articles describing both approaches for VS from 1996 to 2011. We found 1861 articles. After review and discussion, we narrowed our study to 25 articles, 4 endoscopic and 21 open. The total number of patients was 3026 for open and 790 for endoscopic. The mean tumor sizes in the open and endoscopic series were 2.5 cm and 2.7 cm, respectively. Good facial nerve outcome was achieved in 67% of the open series patients and in 94% of the endoscopic series patients. Other outcomes in the open and endoscopic series were the following: gross total resection, 91% versus 97%; functional hearing, 22.6% versus 46%; wound infection, 1.3% versus 2.6%; and recurrence, 5.4% versus 2.2%. We acknowledge the limitations of our study, but we can state that the endoscopic approach is not inferior to the standard open approach. In expert hands the endoscopic approach can offer as good a result as the open, with potential benefits such as less pain and a shorter length of stay in the hospital. There is a need for more controlled studies for a definitive comparison.

Comparison of outcomes following complex posterior fossa surgery performed in the sitting versus lateral position

The sitting position during surgery is thought to provide important advantages, yet it remains controversial. We compared surgical and neurological outcomes for patients operated on in the sitting versus lateral position. Technically difficult procedures performed from the years 2001-2008 for complex lesions in the posterior fossa (vestibular schwannomas, other cerebellopontine angle tumors, foramen magnum meningiomas, brainstem cavernomas, pineal region tumors) were included. Outcomes in the two surgical positions were compared for all 243 patients (93 sitting, 38.3%; 150 lateral, 61.7%) and for 130/243 patients with vestibular schwannomas (50 sitting, 38.5%; 80 lateral, 61.5%). Sitting and lateral patient subgroups were clinically comparable. There were no surgical mortalities. The extent of removal and surgical and neurological outcomes were comparable. We found no advantage in surgical or neurological outcomes for use of the sitting or lateral surgical positions in technically difficult posterior fossa procedures. In vestibular schwannoma surgeries facial nerve preservation (House-Brackmann score 1-2) was related to extent of resection but not to surgical position. The choice of operative position should be based on lesion characteristics and the patient's preoperative medical status as well as the experience and preferences of the surgeons performing the procedure.

Reconstruction after retrosigmoid approaches using autologous fat graft-assisted Medpor Titan cranioplasty: assessment of postoperative cerebrospinal fluid leaks and headaches in 60 cases

BACKGROUND

Postoperative cerebrospinal fluid (CSF) leaks and headaches remain potential complications after retrosigmoid approaches for lesions in the posterior fossa and cerebellopontine angle. The authors describe a simple repair technique with an autologous fat graft-assisted Medpor Titan cranioplasty and investigate the incidence of postoperative CSF leaks and headaches using this technique.

METHODS

A retrospective chart review was conducted on all cases (n = 60) of retrosigmoid craniectomy from September 2009 to May 2014 in patients who underwent fat graft-assisted cranioplasty. After obtaining a watertight dural closure and sealing off any visible mastoid air cells with bone wax, an autologous fat graft was placed over the dural suture line and up against the waxed-off air cells. The fat graft filled the retrosigmoid cranial defect and was then bolstered with a Medpor Titan (titanium mesh embedded in porous polyethylene) cranioplasty. A postoperative mastoid pressure dressing was applied for 48 h, and prophylactic lumbar drainage was not used. Factors examined in this study included postoperative CSF leak (incisional, rhinorrhea, otorrhea), pseudomeningocele formation, incidence and severity of postoperative headache, length of hospital stay, and length of follow-up.

RESULTS

No patients developed postoperative CSF leaks (0 %), pseudomeningoceles (0 %), or new-onset postoperative headaches (0 %) with the described repair technique. There were no cases of graft site morbidity such as hematoma or wound infection. Mean duration of postoperative hospital stay was 3.8 days (range 2-10 days). Mean postoperative follow-up was 12.4 months (range 2.0-41.1 months).

CONCLUSIONS

Our multilayer repair technique with a fat graft-assisted Medpor Titan cranioplasty appears effective in preventing postoperative CSF leaks and new-onset postoperative headaches after retrosigmoid approaches. Postoperative lumbar drainage may not be necessary.

Retrosigmoid removal of small acoustic neuroma: curative tumor removal with preservation of function

Object

Management of small acoustic neuromas (ANs) consists of 3 options: observation with imaging follow-up, radiosurgery, and/or tumor removal. The authors report the long-term outcomes and preservation of function after retrosigmoid tumor removal in 44 patients and clarify the management paradigm for small ANs.

Methods

A total of 44 consecutively enrolled patients with small ANs and preserved hearing underwent retrosigmoid tumor removal in an attempt to preserve hearing and facial function by use of intraoperative auditory monitoring of auditory brainstem responses (ABRs) and cochlear nerve compound action potentials (CNAPs). All patients were younger than 70 years of age, had a small AN (purely intracanalicular/cerebellopontine angle tumor ≤ 15 mm), and had serviceable hearing preoperatively. According to the guidelines of the Committee on Hearing and Equilibrium of the American Academy of Otolaryngology–Head and Neck Surgery Foundation, preoperative hearing levels of the 44 patients were as follows: Class A, 19 patients; Class B, 17; and Class C, 8. The surgical technique for curative tumor removal with preservation of hearing and facial function included sharp dissection and debulking of the tumor, reconstruction of the internal auditory canal, and wide removal of internal auditory canal dura.

Results

For all patients, tumors were totally removed without incidence of facial palsy, death, or other complications. Total tumor removal was confirmed by the first postoperative Gd-enhanced MRI performed 12 months after surgery. Postoperative hearing levels were Class A, 5 patients; Class B, 21; Class C, 11; and Class D, 7. Postoperatively, serviceable (Class A, B, or C) and useful (Class A or B) levels of hearing were preserved for 84% and 72% of patients, respectively. Better preoperative hearing resulted in higher rates of postoperative hearing preservation (p = 0.01); preservation rates were 95% among patients with preoperative Class A hearing, 88% among Class B, and 50% among Class C. Reliable monitoring was more frequently provided by CNAPs than by ABRs (66% vs 32%, p < 0.01), and consistently reliable auditory monitoring was significantly associated with better rates of preservation of useful hearing. Long-term follow-up by MRI with Gd administration (81 ± 43 months [range 5–181 months]; median 7 years) showed no tumor recurrence, and although the preserved hearing declined minimally over the long-term postoperative follow-up period (from 39 ± 15 dB to 45 ± 11 dB in 5.1 ± 3.1 years), 80% of useful hearing and 100% of serviceable hearing remained at the same level.

Conclusions

As a result of a surgical technique that involved sharp dissection and internal auditory canal reconstruction with intraoperative auditory monitoring, retrosigmoid removal of small ANs can lead to successful curative tumor removal without long-term recurrence and with excellent functional outcome. Thus, the authors suggest that tumor removal should be the first-line management strategy for younger patients with small ANs and preserved hearing.

Endoscope-assisted retrosigmoid resection of a medium size vestibular schwannoma tumor model: a cadaveric study

OBJECTIVE

To demonstrate a flexible endoscope assisted technique to perform microsurgical resection using a retrosigmoid approach of an artificial polymer tumor model that mimics a medium size (15-20mm diameter) vestibular schwannoma.

METHODS

Twelve bilateral retrosigmoid dissections were performed in 6 glutaraldehyde embalmed, colored silicone injected, adult cadaveric heads. Using a standard retrosigmoid approach, we first implanted the tumor model at the cerebellopontine angle (CPA) and then we resected the tumor under simultaneous endoscopic and microscopic visualizations. The resection was performed by first creating a corridor by removing the lower portion of the tumor and then by inserting through the same corridor the flexible endoscope mounted on a surgical instrument in order to accomplish early visualization of the VII-VIII complex. This early visualization of the VII-VIII complex made possible expeditious removal of the model with preservation of the VII-VIII complex.

RESULTS

We were able to successfully implant the artificial tumor in all the specimens. The post-tumor implantation CT scan confirmed the optimal CPA location of the model with its intra-porus extension. The exposure of the facial and the adjoining neuro-vascular structures was excellent during all stages of the surgical removal and was accomplished with minimal cerebellar retraction, under intermittent endoscopic-assisted control. Early visualization of the facial and vestibular cochlear nerves complex led to unhindered removal of the tumor model.

CONCLUSIONS

The endoscopic-assisted microsurgical removal of a tumor model simulating a medium size vestibular schwannoma was feasible in our tumor model study emulating real surgery. Visualization of the acousticofacial bundle at the early stage of the surgical removal should theoretically decrease the risk of its inadvertent injuries as well as facilitate complete removal of the tumor. Clinical studies to validate this laboratory study are necessary.

Facial nerve preservation with preoperative identification and intraoperative monitoring in large vestibular schwannoma surgery

BACKGROUND

Microsurgery is an option of choice for large vestibular schwannomas (VSs). Anatomical and functional preservation of facial nerve (FN) is still a challenge in these surgeries. FNs are often displaced and morphologically changed by large VSs. Preoperative identification of FN with magnetic resonance (MR) diffusion tensor tracking (DTT) and intraoperative identification with facial electromyography (EMG) may be desirable for improving functional results of FN.

METHOD

In this retrospective study, eight consecutive cases with large VS (≥30 mm in maximal extrameatal diameter) were retrospectively studied. FN DTT was performed in each case preoperatively. All the cases underwent microsurgical resection of the tumor with intraoperative FN EMG monitoring. Correctness of prediction for FN location by DTT was verified by the surgeon's inspection. Postoperative FN function of each patient was followed up.

RESULTS

Preoperative identification of FN was possible in 7 of 8 (87.5 %) cases. FN location predicted by preoperative DTT agreed to surgical finding in all the 7 cases. FN EMG was helpful to locate and protect the FN. Total resection was achieved in 7 of 8 (87.5 %). All FNs were anatomically preserved. All cases had excellent facial nerve function (House-Brackmann Grade I-II).

CONCLUSIONS

FN DTT is a powerful technique in preoperatively identification of FN in large VS cases. Continuous intraoperative FN EMG monitoring is contributive to locating and protecting FNs. Radical resection of large VSs as well as favorable postoperative FN outcome is available with application of these techniques.

Functional outcome and postoperative complications after the microsurgical removal of large vestibular schwannomas via the retrosigmoid approach: a meta-analysis

For large (≥30 mm) or giant (≥40 mm) vestibular schwannomas (VSs) for which microsurgical removal is the main treatment option, complete tumour resection and the preservation of acceptable facial nerve function can be safely and successfully achieved via the retrosigmoid approach. We performed a meta-analysis to provide a reliable estimate of functional outcome and postoperative complications for patients treated surgically for large VSs. We conducted a comprehensive search in Pubmed, Embase and the Chinese National Knowledge Infrastructure (CNKI) databases to identify publications that included only patients in whom the VSs were >3.0 cm in maximal diameter and microsurgically removed by a retrosigmoid approach. Pooled estimates of proportions with corresponding 95 % confidence intervals were calculated using the Freeman-Tukey double arcsine transformation. This meta-analysis revealed that the pooled proportion of gross total resections was 79.1 % (95 % CI, 64.2-90.8 %; I (2) = 95.4 %). By combining microsurgical techniques with continuous electrophysiological monitoring, the anatomical preservation of the facial nerve at the end of surgery was achieved in 88.8 % (95 % CI, 83.6-93.2 %; I (2) = 76.1 %) of the patients. The pooled proportion of good postoperative facial nerve function (House-Brackmann (HB) grades I-II) was 62.9 % (95 % CI, 50.0-74.9 %; I (2) = 91.1 %). Cerebrospinal fluid leakage was reported in 7.8 % (95 % CI, 4.8-11.4 %; I (2) = 49.8 %) of the patients. The mortality rate was 0.87 % (95 % CI, 0.22-1.78 %; I (2) = 4.9 %). Our meta-analysis revealed that for large VSs, very favourable results can be obtained using the retrosigmoid approach with minimal mortality, especially with respect to anatomical and functional facial nerve preservation.

Surgical management of vestibular schwannoma: attempted preservation of hearing and facial function

BACKGROUND

Vestibular schwannomas are benign tumours which usually originate from the vestibular portion of the VIIIth cranial nerve. Treatment options include observation with serial imaging, stereotactic radiation and microsurgical removal.

AIM

The goal of surgery was complete eradication of tumour with preservation of hearing and facial nerve function.

METHODS

A retrospective review was undertaken of 24 cases of vestibular schwannoma jointly operated upon by a team of neurosurgeons and otologists at the Suez Canal University Hospital, with assessment of VIIth and VIIIth cranial nerve function, tumour size, and extent of growth. All surgery utilised a retromastoid, suboccipital approach.

RESULTS

Complete tumour removal was achieved in 19 patients. Anatomical preservation of the facial nerve was possible in 66.6 per cent of patients. Pre-operative, useful hearing was present in four patients, and preserved in 80 per cent. Cerebrospinal fluid leakage was diagnosed in two (8.3 per cent) patients, who responded to conservative therapy.

CONCLUSION

The retromastoid, suboccipital surgical approach to the skull base can be safely and successfully achieved using a microsurgical technique, with minimal or no damage to neurovascular structures, even for large tumours.

Extent of resection and early postoperative outcomes following removal of cystic vestibular schwannomas: surgical experience over a decade and review of the literature

OBJECT

Vestibular schwannomas (VSs) are benign tumors of the eighth cranial nerve sheath, representing approximately 6%-8% of all newly diagnosed brain tumors, with an annual incidence of 2000-2500 cases in the US. Although most of these lesions are solid, cystic vestibular schwannomas (CVSs) compose 4%-20% of all VSs and are commonly larger at the time of presentation. The authors present their experience with the operative management of CVSs, including surgical approach, extent of resection, and postoperative facial nerve outcomes. The literature pertaining to clinical and histopathological differences between CVSs and their solid counterparts is reviewed.

METHODS

The University of Southern California Department of Neurosurgery database was retrospectively reviewed to identify patients who had undergone resection of a VS between 2000 and 2010. One hundred seventy-nine patients with VS were identified. Patients with CVSs were the subject of the present analysis. Diagnosis of a CVS was made based on MRI findings. Clinical and neuroimaging data, including pre- and postoperative assessments and operative notes, were collected and reviewed.

RESULTS

Twenty-three patients, 14 men (61%) and 9 women (39%), underwent 24 operations for CVSs. These patients composed 12.8% of all cases of VS. Patient ages ranged from 28 to 78 years (mean 55 years), and the mean maximal tumor diameter was 3.6 cm (range 2.0-4.0 cm). Patients most frequently presented with headache, hearing loss, vertigo, and dizziness. Preoperative facial numbness was reported in 44% of patients. Among the 24 cases, 13 were treated with retrosigmoid craniotomy and 11 via a translabyrinthine approach. Complete resection was achieved in 11 patients (48%), subtotal resection (STR) in 8 patients (35%), and near-total resection (NTR) in 4 patients (17%). Facial nerve outcomes were available in all except one case. Good facial nerve outcomes (House-Brackmann [HB] Grades I-III) were achieved in 82% of the patients who had undergone either NTR or STR, as compared with 73% of patients who had undergone gross-total resection (GTR; p > 0.05, Fisher exact test). In comparison, 83% of patients with solid VSs had a good HB grade (p = 0.38, Fisher exact test), although this finding did not reach statistical significance. Complications included wound infection (2 patients), delayed CSF leakage (1 patient), and a delayed temporal encephalocele following a translabyrinthine approach and requiring surgical repair (1 patient).

CONCLUSIONS

Cystic vestibular schwannoma represents a clinical and surgical entity separate from its solid counterpart, as demonstrated by its more rapid clinical course and early surgical outcomes. Facial nerve grades may correlate with the degree of tumor resection, trending toward poorer grades with more significant resections. Although GTR is recommended whenever possible, performing an STR when facial nerve preservation is in jeopardy to improve facial nerve outcomes is the preferred strategy at the authors' institution.