Microsurgical Removal Of Vestibular Schwannomas Research Articles

Prophylactic nimodipine treatment for hearing preservation after vestibular schwannoma surgery: study protocol of a randomized multi-center phase III trial\u2014AkniPro 2

BackgroundA previously performed phase III trial on 112 subjects investigating prophylactic nimodipine treatment in vestibular schwannoma (VS) surgery showed no clear beneficial effects on preservation of facial and cochlear nerve functions, though it should be considered that protection of facial nerve function was the primary outcome. However, the risk for postoperative hearing loss was halved in the nimodipine group compared to the control group (OR 0.49; 95% CI 0.18–1.30; p = 0.15). Accordingly, this phase III extension trial investigates the efficacy and safety of prophylactic nimodipine for hearing preservation in VS surgery.MethodsThis is a randomized, multi-center, two-armed, open-label phase III trial with blinded expert review and two-stage with interim analysis. Three hundred thirty-six adults with the indication for microsurgical removal of VS (Koos I–IV) and serviceable preoperative hearing (Gardner-Robertson scale (GR) 1–3) are assigned to either the therapy (intravenous nimodipine 1–2 mg/h from the day before surgery until the fifth postoperative day and standard of care) or the control group (surgery only and standard of care). The primary endpoint of the trial is postoperative cochlear nerve function measured before discharge according to GR 1–3 versus GR 4–5 (binary). Hearing function will be determined by pre- and postoperative audiometry with speech discrimination, which will be evaluated by a blinded expert reviewer. Furthermore, patient-reported outcomes using standardized questionnaires will be analyzed.DiscussionProphylactic parenteral nimodipine treatment may have a positive effect on hearing preservation in VS surgery and would improve patient’s quality of life. Further secondary analyses are planned. Except for dose-depending hypotension, nimodipine is known as a safe drug. In the future, prophylactic nimodipine treatment may be recommended as a routine medication in VS surgery. VS can be considered as an ideal model for clinical evaluation of neuroprotection, since hearing outcome can be classified by well-recognized criteria. The beneficial effect of nimodipine may be transferable to other surgical procedures with nerves at risk and may have impact on basic research.Trial registrationEudraCT 2019-002317-19, DRKS00019107. 8th May 2020.

Degree of preoperative hearing loss predicts time to early mobilization following vestibular schwannoma microsurgery

ObjectiveTo test the hypothesis that severe to profound preoperative hearing loss predicts less acute postoperative vestibulopathy following microsurgical removal of vestibular schwannoma (VS) allowing for earlier postoperative mobilization and hospital discharge. MethodsPatients with VS who underwent microsurgery and were found to have preoperative severe to profound hearing loss (pure tone average [PTA] > 70 dB HL) were matched 1:1 by age and tumor size to a group of randomly selected controls with preoperative serviceable hearing. ResultsA total of 57 patients met inclusion criteria and were matched to controls. Median age at the time of microsurgery was 56 years. The median PTA and WRS for cases were 91 dB HL (interquartile range [IQR] 78–120) and 0% (IQR 0–0), respectively. Median tumor size was 14.2 mm (IQR 10.9–20.9). A total of 35 (61%) patients exhibited nystagmus after surgery associated with acute vestibular deafferentation. Median time to ambulation in the hallway was 2 days. Controls exhibited similar tumor size (12.7 mm, p = 0.11) and age (57 years, p = 0.52). Preoperative hearing loss did not predict severity or duration of postoperative nystagmus or days to discharge; however, those with Class D hearing exhibited a shorter time to ambulation (p = 0.04). ConclusionFollowing microsurgical removal of VS, preoperative profound hearing loss was associated with a shorter time to postoperative mobilization; however, there were no observed associations with duration or severity of nystagmus and time to hospital discharge. Although not a predictor of nystagmus, preoperative profound hearing loss may portend quicker recovery from clinically significant postoperative vestibulopathy.

Koos grade IV vestibular schwannomas: considerations on a consecutive series of 60 cases-searching for the balance between preservation of function and maximal tumor removal.

Koos grade IV vestibular schwannomas (VS) (maximum diameter > 3 cm) compress the brainstem and displace the fourth ventricle. Microsurgical resection with attention to the right balance between preservation of function and maximal tumor removal is the treatment of choice. Our series consists of 60 consecutive patients with unilateral VS, operated on from December 2010 to July 2019. All patients underwent microsurgical removal via the retrosigmoid approach. The adherence of VS' capsule to the surrounding nervous structures and the excessive tendency of tumor to bleed during debulking, because of a redundant vascular architecture, was evaluated by reviewing video records. Microsurgical removal of tumor was classified as total (T), near-total (NT: residue < 5%), subtotal (ST: residue 5-10%), or partial (P: residue > 10%). Maximal mean tumor diameter was 3,97 cm (SD ± 1,13; range 3,1-5,8 cm). Preoperative severely impaired hearing or deafness (AAO-HNS classes C-D) was present in 52 cases (86,7%). Total or NT resection was accomplished in 46 cases (76,7%), 65,8% in cases with, and 95,4% without tight adhesion of capsule to nervous structures (p < 0,001). Endoscopic-assisted microsurgical removal of VS in the IAC was performed in 23 patients: in these cases, a T resection was obtained in 78,3% versus 45,9% of microsurgery only (p < 0,001). The capsule of VS was tightly adherent to nervous structures in 63,3% of patients, whereas hypervascular high-bleeding tumors represented 56,7%. Hearing preservation was possible in 2 out of 8 patients with preoperative class B hearing. At last follow-up, 34 (56,7%) patients had a normal postoperative FN outcome (HBI), 9 (15,0%) were HBII, 8 (13,3%) HBIII, and 9 (15,0%) HBIV. The total NT resection of solid and low-bleeding VS, without tight capsule adhesion, was associated with better FN outcome. Mortality was zero; permanent complications were observed in 2 cases (diplopia, hydrocephalus), transient in 9. Microsurgery of Koos grade IV VS seems to be associated with more than acceptable functional results, with high rate of T and NT removal of tumor. Long-term FN results seem to be worse in patients with cystic Koos grade IV VS, in cases with tight capsule adherences to nervous structures and in high-bleeding tumors.

Microsurgical removal of vestibular schwannomas with flexible hand-held 2μ-Thulium-fiber laser. Personal experience in 78 consecutive cases

Abstract Aims We performed a retrospective non-randomized study to analyze the results of microsurgery of vestibular schwannomas (VS) using 2μ-Thulium flexible hand-held laser fiber (Revolix jr®). Methods From September 2010 to November 2018, 180 patients suffering from VS have been operated on with microsurgical technique via retrosigmoid (RS) approach in our Department. From July 2012 to April 2018, tumor resection was performed in 78 cases with the assistance of 2μ-Thulium-fiber hand-held flexible laser. Facial nerve function was assessed with the House-Brackmann (HB) scale preoperatively, 1 week postoperatively, and 6-month after surgery. Results Overall time from incision to skin suture changed in relation to size of tumor (185–575 min) and was not affected by the use of laser. In 5 out of 78 cases preoperative facial nerve palsy HB2 and in one case HB4 (permanent) was observed. On considering 77 cases (excluding 1 permanent HB4) with a minimum 6-month follow-up, facial nerve preservation rate (HB1) was 92,2%. Hearing preservation rate (AAO-HNS A/B classes) was possible in 17 out of 30 cases (56,7%). Adopting a 0–3-scale, the mean surgeon satisfaction rate of usefulness of laser fiber was 2,75. Conclusions The use of 2μ-Thulium-fiber hand-held flexible laser in VS-microsurgery seems to be safe and to facilitate tumor resection, especially in “difficult” conditions (e.g., highly vascularized and hard tumors). In this retrospective trial, the good functional outcome following conventional microsurgery had not further improved, nor the surgical time reduced by laser. Focusing its use on “difficult” (large and vascularized) cases may lead to different results in future.

What is the Role of Endoscopy during Microsurgical Removal of Vestibular Schwannomas?

What is the Role of Endoscopy during Microsurgical Removal of Vestibular Schwannomas?

Assessing the Threshold for Vestibular Schwannoma Resection and the Behavior of Residual Tumor

In vestibular schwannoma surgery postoperative facial nerve function is generally described as being related to tumor size, with 20 mm extrameatal diameter suggested as the threshold at which facial nerve function deteriorates. Near-total resection is accepted if the risk to nerve function becomes unacceptably high. We sought to review outcomes of vestibular schwannoma resection and follow residual tumor fragments. Second, we pooled data to quantify the risk of regrowth and need for subsequent intervention. Prospectively collected data on all patients undergoing microsurgical removal of vestibular schwannoma by the senior author over the past 15 years. Approximately 247 patients were identified, the spread of tumors was 74 intracanalicular, 120 15 mm or lesser, 57 between 16 and 30 mm, and 6 greater than 30 mm. Overall, 91.5% recovered to House-Brackmann Grade 1 or 2, with no difference between the groups with 15 mm or lesser and greater than 15 mm (p > 0.05); 26 had incomplete resection, and 3 showed regrowth. Pooled data: 193 near total resections with 12% regrowing; 181 subtotal resections with 30% regrowing. Of 108 growing fragments, 78% had intervention. The present series suggests that the threshold for preservation of good facial nerve function may be moved to a tumor of 30-mm extrameatal diameter. Although historically tumor fragments were felt to have a low growth potential, the cumulative data would suggest that a significant proportion of fragments do grow and may need intervention.

Cerebrospinal Fluid Leak after Microsurgical Surgery in Vestibular Schwannomas via Retrosigmoidal Craniotomy

Objective: Cerebrospinal fluid leak (CSF) is still a common complication in surgery of vestibular schwannoma (VS), increasing morbidity. Our study was performed to determine the incidences of CSF leaks after microsurgical removal of vestibular schwannoma via a retrosigmoidal approach with two different surgical closure techniques. Methods: Between January 2003 and December 2009, microsurgical tumor resection using a suboccipital approach was performed in 81 patients. In 41 cases, the dural closure was done using a sandwich technique: Subdural closure with TissuFleece, respectively Spongostan, and after that, dural suture and epidural TachoSil were fixed on. In 40 cases, the dura was sealed epidurally with TachoSil after suture. In 65 cases, the posterior wall of the petrosus bone was drilled. The closure was performed using muscle and Fibrin glue. All patients had a minimal follow-up of 1 year. Results: Seven patients (8.6%) developed a CSF fistula. Three patients (3.7%) underwent surgical procedure because of persisting CSF fistula, and in four cases (4.9%) spontaneous closure under lumbar drain was observed. Comparing the different techniques of dura sealing, we found three CSF leaks (7.3%) in 41 patients who underwent the sandwich technique, whereas there were four CSF leaks (10%) in 40 patients who underwent a single epidurally sealed dura closure (P = 0.69). No rhinorrhea or otorhinorrhea was observed. No intracranial infection or meningitis occurred. Conclusion: Suture and occlusion of the dura is an important step for preventing CSF leak and postoperative infection. A comparison of the sandwich technique and single-layer dural sealing revealed no significant difference between the two procedures.

Usefulness of Endoscope-Assisted Microsurgery for Removal of Vestibular Schwannomas

The usefulness of endoscope-assisted microsurgical removal of vestibular schwannomas in the internal auditory canal (IAC) was evaluated. Microsurgical removal using the endoscope was done in 28 procedures and microsurgical removal without an endoscope was done in 43 procedures. A retrosigmoid approach was used. The tumor location in the IAC was classified as grade 1 (located up to the mid-portion), 2, 3, or 4 (located up to the fundus with bony destruction) according to the tumor extent, and residual tumor in the IAC was evaluated as grade A (remnant tumor was not observed), B, C, or D (remnant tumor was observed over the mid-portion) according to the extent of remnant tumor. The residual tumor in the IAC was less in the endoscope-assisted group than in the microsurgery group. There was a significant difference only in grade 2, that is, tumor located beyond the mid-portion of the IAC. There was no significant difference in the results of preservation of useful hearing, facial nerve function, and tumor recurrence between the two groups. The benefit of endoscope-assistance microsurgery was shown for those patients whose tumors extended beyond the mid-portion of the IAC but did not reach the fundus.

Cerebrospinal fluid leak after microsurgical surgery in vestibular schwannomas via retrosigmoidal craniotomy

Objective: Cerebrospinal fluid (CSF) leak is still a common complication in surgery of vestibular schwannoma, increasing morbidity and prolonging hospital stay. Our single center study was performed to determine the incidences of CSF leaks after microsurgical removal of vestibular schwannoma via a retrosigmoidal approach with two different surgical closure techniques.Methods: Between January 2003 and December 2009 in 81 patients, microsurgical tumor resection using a suboccipital, retrosigmoidal approach was performed with an interdisciplinary ENT and neurosurgical management was performed. In 41 cases, the dural closure was done using a sandwich technique: subdural closure with TissuFleece® respectively Spongostan®, and after that dural suture and epidural Tachosil® were fixed on. In 40 cases, the dura was sealed epidurally with Tachosil after suture. In 65 cases, the posterior wall of the petrous bone was drilled. The closure was performed using muscle and FibrinGlue®. All patients had a minimal follow-up of 1 year.Results: Seven patients (8·6%) developed a CSF fistula. Three patients (3·7%) underwent surgical procedure because of persisting CSF fistula while in four cases (4·9%) spontaneous closure under lumbar drain was observed. Comparing the different techniques of dural sealing, we found in 41 patients with sandwich technique three CSF leaks (7·3%) while there were four CSF leaks (10%) in 40 patients with a single epidurally sealed dural closure (P=0·69). No rhinorrhea or otorhinorrhea was observed. No intracranial infection or meningitis in case of CSF leak occurred.Conclusion: Suture and occlusion of the dura is an important step to prevent CSF leak and postoperative infection. By comparing sandwich technique and single-layer dural sealing, no significant difference could be shown.

Exercise with visual feedback improves postural stability after vestibular schwannoma surgery

We analyzed the effect of 2-week individualized visual feedback-based balance training on the postural control of patients undergoing retrosigmoid microsurgical removal of vestibular schwannoma. We performed prospective evaluation of 17 patients allocated into two groups: feedback group (9 patients, mean age 37 years) and standard physiotherapy group (8 patients, mean age 44 years). Patients in both the groups were treated once per day by intensive rehabilitation from 5th to 14th postoperative day. Rehabilitation of patients in the feedback group was performed using the visual feedback and force platform. Results were evaluated on the beginning and at the end of rehabilitation program (e.g. 5th and 14th postoperative day). Outcome measures included posturography during quiet stance under four different conditions by the modified Clinical Test for Sensory Interaction of Balance. Body sway was evaluated from center of foot pressure. Compensation of Center of pressure (CoP) parameters in stance on firm surface was similar in the control and feedback groups. However, in stance on foam surface with eyes closed the patients from the feedback group were better compensated and CoP parameters differed significantly (p < 0.05). This prospective clinical study suggests that specific exercises with visual feedback improve vestibulospinal compensation in patients after vestibular schwannoma surgery and thus can improve their quality of life.

An electrophysiological study on the safety of the endoscope-assisted microsurgical removal of vestibular schwannomas

Background Endoscopy is being increasingly used in skull base surgery. The issue of its safety, however, has not been definitely solved. Methods We evaluated the risk of thermal or mechanical iatrogenic nerve injury related to endoscope application during microsurgical removal of vestibular schwannomas (VS) in a prospective group of 30 patients (Group A). Main analysed parameters were electrophysiological monitoring data (auditory evoked potentials and EMG) during and after endoscopic observation. The structural and functional preservation of facial and cochlear nerves, radicality of tumour removal, and CSF leak rate were evaluated and compared to historical group of 50 patients (Group B), operated consecutively with classical microsurgical technique. Results No electrophysiological changes directly related to endoscope were registered. The rate of loss of waves I, II, and V did not depend on application of endoscope and was similar in both groups. The functional and general outcome was also similar. Endoscopic inspection provided early and detailed view of anatomical relations within cerebellopontine angle and internal auditory canal and confirmed completeness of tumour removal. Total tumour removal was achieved in all patients from Group A and in 49/50 from Group B. Useful hearing after the surgery had 17/30 patients in Group A and 26/50 in Group B. Conclusions The application of endoscope during microsurgical removal of VS is a safe procedure that does not lead to heat-related or mechanical neural or vascular injuries. The actual significance of this additional endoscopic information, however, is related to the particular operative technique and experience of the surgeon.

Expression of neuregulin and activation of erbB receptors in vestibular schwannomas: possible autocrine loop stimulation.

We sought to determine whether vestibular schwannomas are capable of producing and responding to the glial growth factor neuregulin. Neuregulin is a neuronally derived trophic factor that interacts with erbB2 and erbB3 receptors on Schwann cells and is required for normal Schwann cell proliferation, survival, and development. Vestibular schwannomas grow several millimeters or even centimeters away from adjacent axons, suggesting that vestibular schwannomas do not depend critically on axons for their proliferation or survival. This raises the possibility that vestibular schwannomas themselves produce and respond to trophic factors in an autocrine fashion. Pathologic specimens from eight patients undergoing microsurgical removal of vestibular schwannomas and one patient undergoing vestibular nerve section were immunostained with anti-neuregulin, anti-erbB2, anti-erbB3, and anti-phosphorylated-erbB2 antibodies. Three patients had received previous gamma knife radiation therapy and two patients had neurofibromatosis Type 2. The Scarpa ganglion neurons express neuregulin, and normal vestibular Schwann cells express erbB2 and erbB3. Vestibular schwannomas from all eight patients demonstrated neuregulin, erbB2, and erbB3 immunoreactivity. In addition, all vestibular schwannomas demonstrated immunoreactivity to anti-phosphorylated-erbB2 antibody that only recognizes erbB2 when it is phosphorylated, or activated. These results demonstrate that vestibular schwannomas express neuregulin and its receptors, erbB2 and erbB3. Because erbB2 exists in an activated state, as evidenced by phosphorylated-erbB2 immunoreactivity, it likely responds to the locally produced neuregulin. This suggests the possibility that vestibular schwannomas produce and respond to neuregulin in an autocrine fashion.

Incidence of cerebrospinal fluid leak after microsurgical removal of vestibular schwannomas.

Cerebrospinal fluid (CSF) leak still remains an unresolved problem after microsurgical removal of vestibular schwannomas (VS). 14 (6%) Cases of cerebrospinal fluid rhinorrhea and 3 cases with subcutaneous retro-auricular CSF collection, occurring in a series of 224 patients operated on by the senior author (JMG) on VS between 1989-2000 via the suboccipital retrosigmoidal approach were studied retrospectively. Prophylaxis of CSF leak was usually attempted by packing the unroofed posterior wall of internal acoustic meatus with muscle. The mastoid air cells were packed first with collagen then with muscle and bone dust. All CSF leaks were diagnosed within 2-7 days after surgery. We found no relation to tumour size. Treatment was initiated in all patients with continuous external lumbar cerebrospinal fluid drainage (CELCFD) for 7 days. In 11 cases with CSF rhinorrhea and all cases with retro-auricular CSF collection, the CSF leak was stopped. However, in 3 cases the CSF leak persisted despite the lumbar drain. These patients were operated on again with sealing the IAM and the mastoid cells again with muscle and collagen. No recurrence of CSF leak was noted after the second operation. There was no case of late onset CSF leak during the follow-up of one year. Although CSF leak is a common complication (6%) after vestibular schwannoma removal, aggressive treatment is required only in a few cases (1%). Most of the cases are successfully treated by (CELCFD). The suboccipital approach offers an advantage of opening only a part of mastoid air cells, which are in our opinion the second most common site of CSF leakage.

Incidence of Cerebrospinal Fluid Leak after Microsurgical Removal of Vestibular Schwannomas

Incidence of Cerebrospinal Fluid Leak after Microsurgical Removal of Vestibular Schwannomas