Prophylactic nimodipine treatment and improvement in hearing outcome after vestibular schwannoma surgery: a combined analysis of a randomized, multicenter, Phase III trial and its pilot study

Factors associated with hearing outcomes after a middle fossa approach in 131 consecutive patients with vestibular schwannomas

OBJECTIVE

The middle fossa approach is an effective option for the treatment of small (Koos grade I and II) vestibular schwannomas (VSs) when the goal is hearing preservation. The authors evaluated the rates of hearing preservation and examined the factors associated with improved hearing outcomes after the middle fossa approach for VSs.

METHODS

In this retrospective, single-center cohort study evaluating the clinical outcomes after resection of small VSs using the middle fossa approach, consecutive adult patients (> 18 years) who underwent surgery between January 2000 and December 2021 were included. Clinical and imaging characteristics were analyzed, including baseline hearing status, duration of surgery, anesthetic parameters, and imaging characteristics of the surgically treated tumors.

RESULTS

Among the 131 included patients, 102 had valid and discoverable pre- and postoperative audiology assessments. The mean follow-up was 26 months (range 1-180 months). There were 85 patients with serviceable hearing preoperatively, defined as American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) class A or B, of whom 78% retained class A or B hearing at the last follow-up. Binary logistic regression demonstrated that preoperative hearing AAO-HNS class (OR 0.19, 95% CI 0.05-0.77; p = 0.02), overlap between fundus and cochlea (OR 0.32, 95% CI 0.11-0.96; p = 0.04), and duration of anesthesia (OR 0.98, 95% CI 0.97-0.99; p = 0.03) were independent predictors of hearing outcomes. Additionally, 75% of patients with high diffusion-weighted imaging signal in the tumor (p = 0.009) and 67% of patients with the tumor originating at the modiolus of the cochlea (p = 0.004) had poor hearing outcomes.

CONCLUSIONS

The hearing preservation rates after microsurgical resection of small VSs using the middle fossa approach are high, with 78% of patients maintaining AAO-HNS class A or B hearing. Poor hearing status at baseline, longer duration of anesthesia, and large overlap between the fundus of the internal auditory canal and the cochlea were independently associated with unfavorable hearing outcomes. Imaging characteristics can be used to stratify patients' risk of hearing loss.

Nimodipine Treatment Protects Auditory Hair Cells from Cisplatin-Induced Cell Death Accompanied by Upregulation of LMO4

Ototoxicity is one of the main dose-limiting side effects of cisplatin chemotherapy and impairs the quality of life of tumor patients dramatically. Since there is currently no established standard therapy targeting hearing loss in cisplatin treatment, the aim of this study was to investigate the effect of nimodipine and its role in cell survival in cisplatin-associated hearing cell damage. To determine the cytotoxic effect, the cell death rate was measured using undifferentiated and differentiated UB/OC−1 and UB/OC−2 cells, after nimodipine pre-treatment and stress induction by cisplatin. Furthermore, immunoblot analysis and intracellular calcium measurement were performed to investigate anti-apoptotic signaling, which was associated with a reduced cytotoxic effect after nimodipine pre-treatment. Cisplatin’s cytotoxic effect was significantly attenuated by nimodipine up to 61%. In addition, nimodipine pre-treatment counteracted the reduction in LIM Domain Only 4 (LMO4) by cisplatin, which was associated with increased activation of Ak strain transforming/protein kinase B (Akt), cAMP response element-binding protein (CREB), and signal transducers and activators of transcription 3 (Stat3). Thus, nimodipine presents a potentially well-tolerated substance against the ototoxicity of cisplatin, which could result in a significant improvement in patients’ quality of life.

Evolution in Surgical Treatment of Vestibular Schwannomas

Purpose of Review

Management of vestibular schwannomas (VSs) is multimodal and include watchful observation, radiation treatment, and surgery. Over the past decades, a shift in treatment strategy toward radiation treatment has gradually displaced surgery from the main treatment option for VS. In recent years, however, surgery has been further refined by developments of microsurgical and endoscopic techniques and advances in intraoperative application of neuroprotective drugs. This article presents outcomes of modern surgical treatment of VS in the era of radiosurgery and reviews recent published advancements relevant to VS management.

Recent Findings

Following VS surgery, excellent tumor resection rates and cranial nerve outcomes were achieved in a consecutive series of 572 adult patients with mean postoperative follow up of 4 years. Innovations in surgical technique include endoscopic technique as additional tool to microsurgery, exploration of semi-sitting position for large tumors, and intraoperative use of vasoactive agents as neuroprotective strategy.

Summary

Despite great developments in radiation treatment of VS, surgery remains the key solution for the majority of the cases in order to achieve cure of the disease, long-term tumor control, and preservation of cranial nerve function at long-term.

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

Background

A 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.

Methods

This 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.

Discussion

Prophylactic 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 registration

EudraCT 2019-002317-19, DRKS00019107. 8th May 2020.

Perioperative Nimodipine to Improve Cranial Nerve Function: A Systematic Review and Meta-Analysis

OBJECTIVE

Nimodipine has emerged as a promising strategy for protection of cranial nerves following vestibular schwannoma (VS) resections. Our goal was to conduct a comprehensive analysis of clinical studies to determine the therapeutic efficacy of nimodipine in improving facial nerve and cochlear nerve function.

DATABASE REVIEWED

We searched PubMed, Scopus, Cochrane Clinical Trial Registry, Clinicaltrials.gov, World Health Organization's International Clinical Trials Registry Platform, and EU Clinical Trials Registry to identify clinical studies up to May 11, 2020.

METHODS

We included studies evaluating perioperative administration of nimodipine as a strategy to prevent or treat facial nerve or cochlear nerve dysfunction following VS resections. Primary outcomes included preservation or recovery of House-Brackman scale for facial nerve function and Hearing and Equilibrium Guidelines for cochlear nerve function at the latest follow-up visit. Secondary outcomes included adverse events and administration strategies of nimodipine.

RESULTS

Nine studies (603 patients) met inclusion, of which seven studies (559 patients) were included in the quantitative analysis. Overall, nimodipine significantly increased the odds of cranial nerve recovery compared with controls (odds ratio [OR] 2.87, 95% confidence intervals [CI] [2.08, 3.95]; I2 = 0%). Subgroup analysis demonstrated that nimodipine was only effective for cochlear nerve preservation (OR 2.78, 95% CI [1.74, 4.45]; I2 = 0%), but not for facial nerve function (OR 4.54, 95% CI [0.25, 82.42]; I2 = 33%).

CONCLUSION

Although there is evidence supporting the perioperative role of nimodipine for VS resections, more studies are warranted to help clarify the effects of nimodipine therapy on cranial nerve preservation.

Nimodipine-Dependent Protection of Schwann Cells, Astrocytes and Neuronal Cells from Osmotic, Oxidative and Heat Stress Is Associated with the Activation of AKT and CREB

Clinical and experimental data assumed a neuroprotective effect of the calcium channel blocker nimodipine. However, it has not been proven which neuronal or glial cell types are affected by nimodipine and which mechanisms underlie these neuroprotective effects. Therefore, the aim of this study was to investigate the influence of nimodipine treatment on the in vitro neurotoxicity of different cell types in various stress models and to identify the associated molecular mechanisms. Therefore, cell lines from Schwann cells, neuronal cells and astrocytes were pretreated for 24 h with nimodipine and incubated under stress conditions such as osmotic, oxidative and heat stress. The cytotoxicity was measured via the lactate dehydrogenase (LDH) activity of cell culture supernatant. As a result, the nimodipine treatment led to a statistically significantly reduced cytotoxicity in Schwann cells and neurons during osmotic (p ≤ 0.01), oxidative (p ≤ 0.001) and heat stress (p ≤ 0.05), when compared to the vehicle. The cytotoxicity of astrocytes was nimodipine-dependently reduced during osmotic (p ≤ 0.01), oxidative (p ≤ 0.001) and heat stress (not significant). Moreover, a decreased caspase activity as well as an increased proteinkinase B (AKT) and cyclic adenosine monophosphate response element-binding protein (CREB) phosphorylation could be observed after the nimodipine treatment under different stress conditions. These results demonstrate a cell type-independent neuroprotective effect of the prophylactic nimodipine treatment, which is associated with the prevention of stress-dependent apoptosis through the activation of CREB and AKT signaling pathways and the reduction of caspase 3 activity.

Differential Recovery in Early- and Late-Onset Delayed Facial Palsy Following Vestibular Schwannoma Resection

BACKGROUND

Delayed facial palsy (DFP) after resection of vestibular schwannomas (VS) is worsening of facial nerve function after an initially normal postoperative result.

OBJECTIVE

To characterize different types of DFP, compare recovery rates, and review of series of outcomes in patients following resection of VS.

METHODS

Between 2001 and 2017, 434 patients (51% female) with VS underwent resection. We categorized the patients who developed facial palsy into groups based on timing of onset after surgery, immediate facial palsy (IFP), early-onset DFP (within 48 h), and late-onset DFP (after 48 h). Introduction of facial nerve motor-evoked potentials (fMEP) in 2002 and a change of practice utilizing perioperative minocycline in 2005 allowed for historical analysis of these interventions.

RESULTS

Mean age of study cohort was 49.1 yr (range 13-81 yr), with 19.8% developing facial palsy. The late-onset DFP group demonstrated a significantly faster recovery than the early-onset DFP group (2.8 ± 0.5 vs 47 ± 8 wk, P < .0001), had prolonged latency to palsy onset after initiating perioperative minocycline (7.3 vs 12.5 d, P = .001), and had a nonsignificant trend towards faster recovery from facial palsy with use of minocycline (2.6 vs 3.4 wk, P = .11).

CONCLUSION

Given the timings, it is likely axonal degeneration is responsible for early-onset DFP, while demyelination and remyelination lead to faster facial nerve recovery in late-onset DFP. Reported anti-apoptotic properties of minocycline could account for the further delay in onset of DFP, and possibly reduce the rate and duration of DFP in the surgical cohort.

Nimodipine for the treatment of otolaryngic indications

PURPOSE

The uses of nimodipine for otolaryngic indications are reviewed, and recommendations for its use in clinical practice are provided.

SUMMARY

Nimodipine is currently indicated for the improvement of neurologic outcomes in adult patients with aneurysmal subarachnoid hemorrhage (aSAH). However, other oral and i.v. calcium channel blockers have not exhibited the same beneficial effects in patients with aSAH, leading clinicians to believe that nimodipine possesses unique neuroprotective effects in addition to its calcium channel-blocking and vasodilatory properties. Consequently, clinical investigations of nimodipine have been conducted for cochlear and facial nerve preservation after vestibular schwannoma (VS) surgery, symptomatic management of Ménière's disease and peripheral vertigo, and recovery of vocal cord paralysis after laryngeal nerve injury. Three prospective randomized studies have investigated nimodipine for hearing and/or nerve preservation in patients undergoing VS resection, the results of which have suggested a potential benefit of initiating nimodipine during the perioperative period. Several studies of Ménière's disease and/or peripheral vertigo have reported improved symptom control with nimodipine. For vocal fold paralysis associated with recurrent laryngeal nerve (RLN) injury, nimodipine may increase the recovery rate based on the results of 1 nonrandomized prospective study that used nimodipine in a protocolized manner. One small pilot study found that nimodipine improved facial nerve function after maxillofacial surgery.

CONCLUSION

Due to its proposed vasoactive and neuroprotective effects, nimodipine may play a role in the treatment of a number of otolaryngic pathologies including VS, Ménière's disease, peripheral vertigo, RLN injury, and facial weakness after maxillofacial surgery. Small studies have shown improved symptom control and recovery after surgery. Since all of the aforementioned indications are still considered off label, clinicians and patients should collaboratively assess the risks and benefits before initiating treatment.

[Neuroprotective medication in vestibular schwannoma surgery]

BACKGROUND

Except for glucocorticoids there is a lack of neuroprotective medication in neurosurgical interventions.

OBJECTIVE

An overview of clinical trials investigating administration of the calcium antagonist nimodipine and hydroxyethyl starch (HES) in vestibular schwannoma (VS) surgery is given. Basic research is addressed and potential neuroprotective effect mechanisms are discussed, as are perspectives for application of the concept to other types of surgery with a risk postoperative impairment of nerve function.

MATERIALS AND METHODS

A selective PubMed search was performed and all 10 clinical trials corresponding to the search criteria were included.

RESULTS

Four trials with an intraoperative start of the medication showed a positive effect for the preservation of facial nerve function and hearing preservation. A pilot study showed superiority of prophylactic treatment over intraoperative application. There were no significant results in a prospective multicenter phase III trial. After 1 year, postoperative facial nerve preservation rates were excellent in both groups. However, the risk of hearing loss was twice as high in the control group. A combined analysis of the phase III trial with its pilot study showed significant results for better hearing preservation rates in the treatment group (probably by increasing the case load).

CONCLUSION

Prophylactic nimodipine can be recommended in VS surgery in patients with good preoperative hearing. The effect mechanisms of nimodipine and modifications to prophylaxis should be clarified in basic research.