Prophylactic nimodipine treatment for cochlear and facial nerve preservation after vestibular schwannoma surgery: a randomized multicenter Phase III trial

Evaluating calcium channel blockers and bisphosphonates as otoprotective agents in cochlear implantation hearing preservation candidates

OBJECTIVES

Evaluate potential effects of calcium channel blockers (CCB) and bisphosphonates (BP) on residual hearing following cochlear implantation.

METHODS

Medications of 303 adult hearing preservation (HP) candidates (low frequency pure tone average [LFPTA] of 125, 250, and 500 Hz ≤80 dB HL) were reviewed. Postimplantation LFPTA of patients taking CCBs and BPs were compared to controls matched by age and preimplantation LFPTA.

RESULTS

Twenty-six HP candidates were taking a CCB (N = 14) or bisphosphonate (N = 12) at implantation. Median follow-up was 1.37 years (range 0.22-4.64y). Among subjects with initial HP, 29% (N = 2 of 7) CCB users compared to 50% (N = 2 of 4) controls subsequently lost residual hearing 3-6 months later (OR = 0.40, 95% CI = 0.04-4.32, p = 0.58). None of the four BP patients with initial HP experienced delayed loss compared to 50% (N = 2 of 4) controls with initial HP (OR = 0.00, 95% CI = 0.00-1.95, P = 0.43). Two CCB and one BP patients improved to a LFPTA <80 dB HL following initial unaided thresholds that suggested loss of residual hearing.

DISCUSSION

There were no significant differences in the odds of delayed loss of residual hearing with CCBs or BPs.

CONCLUSION

Further investigation into potential otoprotective adjuvants for maintaining residual hearing following initial successful hearing preservation is warranted, with larger cohorts and additional CCB/BP agents.

Skull Base Registries: A Roadmap

Hospitals, payors, and patients increasingly expect us to report our outcomes in more detail and to justify our treatment decisions and costs. Although there are many stakeholders in surgical outcomes, physicians must take the lead role in defining how outcomes are assessed. Skull base lesions interact with surrounding anatomy to produce a complex spectrum of presentations and surgical challenges, requiring a wide variety of surgical approaches. Moreover, many skull base lesions are relatively rare. These factors and others often preclude the use of prospective randomized clinical trials, thus necessitating alternate methods of scientific inquiry. In this paper, we propose a roadmap for implementing a skull base registry, along with expected benefits and challenges.

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.

Learning from EMG: semi-automated grading of facial nerve function

The current grading of facial nerve function is based on subjective impression with the established assessment scale of House and Brackmann (HB). Especially for research a more objective method is needed to lower the interobserver variability to a minimum. We developed a semi-automated grading system based on (facial) surface EMG-data measuring the facial nerve function of 28 patients with vestibular schwannoma surgery. The sEMG was recorded preoperatively, postoperatively and after 3–12 months. In addition, the HB grade was determined. After manual selection and preprocessing, the data were subjected to machine learning classificators (Logistic regression, SVM and KNN). Lateralization indices were calculated and multivariant machine learning analysis was performed according to three scenarios [differentiation of normal (1) and slight (2) vs. impaired facial nerve function and classification of HB 1-3 (3)]. The calculated AUC for each scenario showed overall good differentiation capability with a median AUC of 0.72 for scenario 1, 0.91 for scenario 2 and multiclass AUC of 0.74 for scenario 3. This study approach using sEMG and machine learning shows feasibility regarding facial nerve grading in perioperative VS-surgery setting. sEMG may be a viable alternative to House Brackmann regarding objective evaluation of facial function especially for research purposes.

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.

Intraoperative Auditory Brainstem Response Results Predict Delayed Sensorineural Hearing Loss After Middle Cranial Fossa Resection of Vestibular Schwannoma

OBJECTIVE

To identify intraoperative neurophysiologic measures predictive of delayed progressive sensorineural hearing loss in the operative ear after a middle fossa approach (MCF) for resection of vestibular schwannoma (VS).

STUDY DESIGN

Retrospective review.

SETTING

Academic, tertiary referral center.

PATIENTS

Subjects with vestibular schwannoma who underwent a MCF microsurgical resection of VS were analyzed for individuals whose hearing was initially preserved but subsequently developed progressive sensorineural hearing loss in the operative ear. Thirty-seven patients were identified for whom audiologic and neurophysiologic data was available.

INTERVENTION

Intraoperative neurophysiologic changes will correlate with delayed sensorineural hearing loss in the operative ear.

MAIN OUTCOME MEASURES

Audiometric evaluations, intraoperative electrocochleography (ECoG), and auditory brainstem response (ABR) measures.

RESULTS

Twenty-five subjects experienced stable hearing or hearing loss in the operative ear comparable to the contralateral ear. Twelve subjects suffered a significant increase in the hearing asymmetry between ears. Deterioration in the amplitude of wave V of the ABR persisting at the close of tumor resection correlated with delayed sensorineural hearing loss in the operative ear (p 0.02, 5% mean improvement in the stable hearing group, versus a 14% decline with progressive asymmetry), but changes in ECoG or other auditory brainstem response parameters (p > 0.05) were not predictive.

CONCLUSIONS

Persisting amplitude reduction of wave V of the intraoperative ABR best correlates with delayed progressive sensorineural hearing loss in the operative ear. Neither persistent changes in ECoG, other ABR parameters, nor transient changes, correlated with delayed progressive sensorineural hearing loss in the operative ear.

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.

Prophylactic nimodipine treatment improves hearing outcome after vestibular schwannoma surgery in men: a subgroup analysis of a randomized multicenter phase III trial

A 2016 published randomized multicenter phase III trial of prophylactic nimodipine treatment in vestibular schwannoma surgery showed only a tendency for higher hearing preservation rates in the treatment group. Gender was not included in statistical analysis at that time. A retrospective analysis of the trial considering gender, preoperative hearing, and nimodipine treatment was performed. The treatment group received parenteral nimodipine from the day before surgery until the seventh postoperative day. The control group was not treated prophylactically. Cochlear nerve function was determined by pure-tone audiometry with speech discrimination preoperatively, during in-patient care, and 1 year after surgery and classified according to the Gardner-Robertson grading scale (GR). Logistic regression analysis showed a statistically significant effect for higher hearing preservation rates (pre- and postoperative GR 1–4) in 40 men comparing the treatment (n = 21) and the control (n = 19) groups (p = 0.028), but not in 54 women comparing 27 women in both groups (p = 0.077). The results were also statistically significant for preservation of postoperative hearing with pre- and postoperative GR 1–3 (p = 0.024). There were no differences in tumor sizes between the treatment and the control groups in men, whereas statistically significant larger tumors were observed in the female treatment group compared with the female control group. Prophylactic nimodipine is safe, and an effect for hearing preservation in 40 men with preoperative hearing ability of GR 1–4 was shown in this retrospective investigation. The imbalance in tumor size with larger tumors in females of the treatment group may falsely suggest a gender-related effect. Further investigations are recommended to clarify whether gender has impact on nimodipine’s efficacy.

Electrospun Nimodipine-loaded fibers for nerve regeneration: Development and in vitro performance

Nimodipine is a 1,4-Dihydropyridine type calcium antagonist routinely used to control blood pressure and reduce the risk of secondary ischemia after aneurismal subarachnoid hemorrhage. Additionally, Nimodipine has unique neuroprotective properties. With respect to brain related applications, the full potential of the desired local effect can often not be realized after systemic administration due to systemic side effects. Therefore, it was our aim to develop a biodegradable drug delivery system for the local controlled release of the drug inside the brain. As a suitable and biodegradable system we successfully electrospun PLGA fibers containing 1 and 10% drug. The results of DSC and X-Ray diffractometry measurements indicate that Nimodipine was incorporated in the polymer matrix in the amorphous state. No drug recrystallization was detected for up to 6 months. Electron-beam sterilization was tried but reduced the drug content of the fiber mats considerably. A sustained drug release over 4-8 days was observed, highly depended on release conditions. The Nimodipine fiber mats exhibited no cell toxicity. In contrast, the electrospun fibers were able to significantly reduce cell death in in vitro cell models of oxidative, osmotic and heat-induced cell stress in Schwann cells, neuronal cells as well as immortalized and primary astrocytes. Therefore, electrospun Nimodipine loaded PLGA fibers represent a promising drug delivery system to realize the druǵs benefits for its intracranial use.

Nimodipine Reappraised: An Old Drug With a Future

Nimodipine is a dihydropyridine calcium channel antagonist that blocks the flux of extracellular calcium through L-type, voltage-gated calcium channels. While nimodipine is FDAapproved for the prevention and treatment of neurological deficits in patients with aneurysmal subarachnoid hemorrhage (aSAH), it affects myriad cell types throughout the body, and thus, likely has more complex mechanisms of action than simple inhibition of cerebral vasoconstriction. Newer understanding of the pathophysiology of delayed ischemic injury after a variety of acute neurologic injuries including aSAH, traumatic brain injury (TBI) and ischemic stroke, coupled with advances in the drug delivery method for nimodipine, have reignited interest in refining its potential therapeutic use. In this context, this review seeks to establish a firm understanding of current data on nimodipine's role in the mechanisms of delayed injury in aSAH, TBI, and ischemic stroke, and assess the extensive clinical data evaluating its use in these conditions. In addition, we will review pivotal trials using locally administered, sustained release nimodipine and discuss why such an approach has evaded demonstration of efficacy, while seemingly having the potential to significantly improve clinical care.

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.

The Nimodipine-Sparing Effect of Perioperative Dexmedetomidine Infusion During Aneurysmal Subarachnoid Hemorrhage: A Prospective, Randomized, Controlled Trial

Background: Nimodipine can block the influx of calcium into the vascular smooth muscle cell and prevent secondary ischemia in patients with aneurysmal subarachnoid hemorrhage. However, the reduction of blood pressure after long-term intravenous administration of nimodipine has been associated with neurological deterioration. Yet, no effective solutions have been suggested to address this phenomenon. The use of neuroprotective drug combinations may reduce the risk of sudden blood pressure loss. This prospective, randomized, controlled trial was performed to evaluate the nimodipine-sparing effect of perioperative dexmedetomidine infusion during aneurysmal subarachnoid hemorrhage.

Methods: One hundred nine patients who underwent aneurysm embolization were divided into three groups: group C (n = 35, infused with 0.9% sodium chloride at the same rate as other two groups), group D1 (n = 38, dexmedetomidine infusion at 0.5 µg·kg^–1 for 10 min, then adjusted to 0.2 µg·kg^–1·h^–1), and group D2 (n = 36, dexmedetomidine infusion at 0.5 µg·kg^–1 for 10 min, then adjusted to 0.4 µg·kg^–1·h^–1). Patient-controlled analgesia was given for 48 h after surgery. The primary outcome measure was the total consumption of nimodipine during the first 48 h after surgery. The secondary outcome measures were recovery time at post-anesthesia care unit (PACU), postoperative pain intensity scores, dexmedetomidine and sufentanil consumption, hemodynamic, satisfaction of patients and neurosurgeon, neurologic examination (Glasgow Coma Scale, GCS), Bruggemann comfort scale, and adverse effects. Intraoperative hemodynamics were recorded at the following time-points: arrival at the operating room (T1); before intubation (T2); intubation (T3); 5 min (T4), 10 min (T5), and 15 min (T6) after intubation; suturing of femoral artery (T7); end of surgery (T8); extubation (T9); and 5 min (T10), 10 min (T11), and 15 min (T12) after arrival at the PACU. The level of sedation was recorded at 15 min, 30 min, 1 h, and 2 h after extubation. We also recorded the incidence of symptomatic cerebral vasospasm during 7 days after surgery, Glasgow Outcome Score (GOS) at 3 months, and incidence of cerebral infarction 30 days after surgery.

Results: The consumption of nimodipine during the first 48 h after surgery was significantly lower in group D2 (P < 0.05). Compared with group C, HR and MAP were significantly decreased from T2 to T12 in group D1 and D2 (P < 0.05). Patients in group D2 showed a significantly decreased MAP from T5 to T9 compared with group D1 (P < 0.05). The consumption of sevoflurane, remifentanil, dexmedetomidine, and nimodipine were all significantly reduced in groups D1 and D2 during surgery (P < 0.05). Compared with group C, MAP was significantly decreased in groups D1 and D2 during the first 48 h after surgery (P < 0.05). Compared with group C, consumption of sufentanil and dexmedetomidine at 1 h, pain intensity at 1 h, and 8 h after surgery were significantly decreased in groups D1 and D2 (P < 0.05). FAS was significantly higher in group D2 at 8 h, 16 h, and 24 h after surgery. LOS was significantly lower only in group D2 at 0.5 h after surgery (P < 0.05). Compared with group C, BCS was significantly higher group D2 at 4 h and 8 h after surgery (P < 0.05). There were no significant differences among the three groups in consumption of propofol, cisatracurium, fentanyl, and vasoactive drugs during operation, recovery time at PACU, satisfaction of patients and neurosurgeon, and number of applied urapidil and GCS during the first 48 h after surgery. The incidence of symptomatic cerebral vasospasm during 7 days after surgery, GOS of 3 months, and cerebral infarction after 30 days were also comparable among the three groups.

Conclusions: Dexmedetomidine (infusion at 0.5 µg·kg^–1 for 10 min, then adjusted to 0.4 µg·kg^–1·h^–1 during the surgery) significantly reduced the total consumption of nimodipine during the first 48 h after surgery and promoted early rehabilitation of patients although the incidences of symptomatic cerebral vasospasm, GOS, and cerebral infarction were not reduced.

A critical comparison between the semisitting and the supine positioning in vestibular schwannoma surgery: subgroup analysis of a randomized, multicenter trial

OBJECTIVE

Patient positioning in vestibular schwannoma (VS) surgery is a matter of ongoing discussion. Factors to consider include preservation of cranial nerve functions, extent of tumor resection, and complications. The objective of this study was to determine the optimal patient positioning in VS surgery.

METHODS

A subgroup analysis of a randomized, multicenter trial that investigated the efficacy of prophylactic nimodipine in VS surgery was performed to investigate the impact of positioning (semisitting or supine) on extent of resection, functional outcomes, and complications. The data of 97 patients were collected prospectively. All procedures were performed via a retrosigmoid approach. The semisitting position was chosen in 56 patients, whereas 41 patients were treated while supine.

RESULTS

Complete resection was obtained at a higher percentage in the semisitting as compared to the supine position (93% vs 73%, p = 0.002). Logistic regression analysis revealed significantly better facial nerve function in the early postoperative course in the semisitting group (p = 0.004), particularly concerning severe facial nerve paresis (House-Brackmann grade IV or worse; p = 0.002). One year after surgery, facial nerve function recovered. However, there was still a tendency for better facial nerve function in the semisitting group (p = 0.091). There were no significant differences between groups regarding hearing preservation rates. Venous air embolism with the necessity to terminate surgery occurred in 2 patients in the semisitting position (3.6%). Supplementary analysis with a 2-tailed permutation randomization with 10,000 permutations of treatment choice and a propensity score matching showed either a tendency or significant results for better facial nerve outcomes in the early postoperative course and extent of resection in the semisitting group.

CONCLUSIONS

Although the results of the various statistical analyses are not uniform, the data indicate better results concerning both a higher rate of complete removal (according to the intraoperative impression of the surgeon) and facial nerve function after a semisitting as compared to the supine position. These advantages may justify the potential higher risk for severe complications of the semisitting position in VS surgery. The choice of positioning has to consider all individual patient parameters and risks carefully.

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.

[Intraoperative monitoring of cochlear nerve function during cerebello-pontine angle surgery]

BACKGROUND

Surgical procedures in the cerebello-pontine angle (CPA), e. g. for vestibular schwannoma, have an increased risk for damage to the cochlear nerve. Consequently, hearing deterioration up to complete deafness may result with severe impact on quality of life. Methods for intraoperative monitoring of function may minimize such risks.

OBJECTIVE

Review of current methods for intraoperative monitoring of the cochelar nerve and summary of new developments.

MATERIALS AND METHODS

Analysis and summary of literature, discussion of new methods.

RESULTS

Early auditory evoked potentials using click stimuli remain the standard method for intraoperative monitoring of cochlear nerve function. Amplitude and latency changes indicate a risk of postoperative hearing deterioration; however demonstrate only limited further differentiation of hearing quality. As novel methods, near-field recordings may allow faster feedback and auditory steady state responses potentially enable frequency specific testing.

CONCLUSIONS

Intraoperative monitoring of the cochlear nerve is an integral component of CPA surgery. It enables detection of potential nerve damage and thus contributes to avoiding postoperative functional deficits. Development and implementation of novel and additional approaches may further improve its clinical value.

Microvascular Brainstem Ischemia After Vestibular Schwannoma Surgery: A Clinical and Microanatomic Study

OBJECTIVE

To identify a potential microvascular etiology in patients who underwent vestibular schwannoma surgery (VSS) complicated by postoperative microvascular brainstem ischemia.

METHODS

Charts were retrospectively reviewed of all patients who had an MRI within 14 days of VSS in years 2005-2016. Patient characteristics, preoperative and postoperative imaging features, clinical course and potential predictors of brainstem ischemia were recorded. Cadaveric dissections of 4 cerebellopontine angle (CPA) cisterns with focus on the anterior inferior cerebellar artery (AICA) microvascular were also performed to identify candidate vessels and potential etiology.

RESULTS

Fifty-four of 258 patients had an MRI within 14 days of VSS. Retrosigmoid approach was used in 61.1% of patients, translabyrinthine approach in 25.9%, and middle fossa approach in 13.0%. Four patients (7.4%) had acute microvascular ischemia involving the middle cerebellar peduncle (MCP) adjacent to the cranial nerve (CN) VII-VIII complex demonstrated on postoperative MRI. A statistically significant association was found between the translabyrinthine approach and acute brainstem ischemia (odds ratio, 10.6; 95% confidence interval, 1.004-112.7). Dissection of CPAs revealed 10-20 perforating arteries per specimen originating from the lateral pontine and the flocculopeduncular segments of the AICA. Most microvessels travelled in retrograde fashion along the anteroinferior surface of the CN VII-VIII complex to perforate the cisternal surface of the MCP. No patient had residual or delayed neurologic deficits related to brainstem ischemia at final follow-up.

CONCLUSIONS

While effort should be made to preserve perforating vessels, microvascular brainstem ischemia is often asymptomatic and did not lead to permanent neurologic deficits in our series.

[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.

Nimodipine but Not Nifedipine Promotes Expression of Fatty Acid 2-Hydroxylase in a Surgical Stress Model Based on Neuro2a Cells

Nimodipine is well characterized for the management of aneurysmal subarachnoid hemorrhage and has been shown to promote a better outcome and less delayed ischemic neurological deficits. Animal and clinical trials show neuroprotective efficacy following nerve injuries. We showed a neuroprotective effect on Neuro2a cells. Subsequent microarray analysis revealed—among others—fatty acid 2-hydroxylase (FA2H) upregulated by nimodipine in vitro, which is a component of myelin synthesis. Differentiated Neuro2a cells were analyzed for nimodipine-mediated survival considering stress treatment in comparison to nifedipine-treatment. Cell survival was determined by measurement of LDH activity in the culture medium. Nimodipine decreased surgery-like stress-induced cell death of differentiated Neuro2a cells. Neuro2a cell culture was analyzed for changes in FA2H expression induced by nimodipine or nifedipine in surgery-like stress conditions. We analyzed expression levels of FA2H mRNA and protein by qPCR using fa2h specific primers or a FA2H-specific antibody in nimodipine or nifedipine non- and pre-treated Neuro2a cell culture, respectively. Nimodipine but not nifedipine increases FA2H protein levels and also significantly increases mRNA levels of FA2H in both undifferentiated and differentiated Neuro2a cells. Our findings indicate that higher expression of FA2H induced by nimodipine may cause higher survival of Neuro2a cells stressed with surgery-like stressors.

Interobserver variability of the House-Brackmann facial nerve grading system for the analysis of a randomized multi-center phase III trial

BACKGROUND

Evidence of a high interobserver variability of the subjective House-Brackmann facial nerve grading system (HBGS) would justify cost- and time-consuming technological enhancements of objective classifications for facial nerve paresis.

METHOD

A total of 112 patients were recruited for a randomized multi-center trial to investigate the efficacy of prophylactic nimodipine treatment in vestibular schwannoma (VS) surgery. For the present investigation both treatment groups were pooled for the assessment of facial nerve function preoperatively, in the early postoperative course and 1 year after the surgery. Facial nerve function was documented photographically at rest and in motion and classified according to the HBGS by three independent observers (neurosurgeon, neurologist, ENT) and by the investigator of each center.

RESULTS

Interobserver variability was considerably different with respect to the three time points depending upon the severity of facial nerve paresis. Preoperative facial nerve function was normal or only mildly impaired (HB grade I or II) and was assessed consistently in 97%. Facial nerve function deteriorated during the early postoperative course and was subsequently documented without dissent in only 36%, with one grade difference in 45%, two grade difference in 17% and three grade difference in 2%. One year after surgery, facial nerve function predominantly improved resulting in a consistent assessment in 66%. Differing ratings were observed in 34% with one grade deviation in 88% and of two grades in 12%. Patients with differing ratings of two or more grades exhibited considerably worse facial nerve function (p < 0.001).

CONCLUSIONS

The HBGS produced comparable results between different observers in patients with normal or only mildly impaired facial nerve function. Interobserver variability increased depending on the severity of facial nerve paresis. The results suggest that the HBGS does not promote uniformity of reporting and comparison of outcomes in patients with moderate or severe facial nerve paresis.

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

OBJECTIVE In clinical routines, neuroprotective strategies in neurosurgical interventions are still missing. A pilot study (n = 30) and an analogously performed Phase III trial (n = 112) pointed to a beneficial effect of prophylactic nimodipine and hydroxyethyl starch (HES) in vestibular schwannoma (VS) surgery. Considering the small sample size, the data from both studies were pooled. METHODS The patients in both investigator-initiated studies were assigned to 2 groups. The treatment group (n = 70) received parenteral nimodipine (1-2 mg/hour) and HES (hematocrit 30%-35%) from the day before surgery until the 7th postoperative day. The control group (n = 72) was not treated prophylactically. Facial and cochlear nerve functions were documented preoperatively, during the inpatient care, and 1 year after surgery. RESULTS Pooled raw data were analyzed retrospectively. Intent-to-treat analysis revealed a significantly lower risk for hearing loss (Class D) 12 months after surgery in the treatment group compared with the control group (OR 0.46, 95% CI 0.22-0.97; p = 0.04). After exclusion of patients with preoperative Class D hearing, this effect was more pronounced (OR 0.38, 95% CI 0.17-0.83; p = 0.016). Logistic regression analysis adjusted for tumor size showed a 4 times lower risk for hearing loss in the treatment group compared with the control group (OR 0.25, 95% CI 0.09-0.63; p = 0.003). Facial nerve function was not significantly improved with treatment. Apart from dose-dependent hypotension (p < 0.001), the study medication was well tolerated. CONCLUSIONS Prophylactic nimodipine is safe and may be recommended in VS surgery to preserve hearing. Prophylactic neuroprotective treatment in surgeries in which nerves are at risk seems to be a novel and promising concept. Clinical trial registration no.: DRKS 00000328 ( https://drks-neu.uniklinik-freiburg.de/drks_web/ ).

Exam 1 Questions

Which of the following is the most common form of incomplete spinal cord injury?A.

Central cord syndrome

B.

Cauda equina syndrome

C.

Anterior spinal cord syndrome

D.

Posterior spinal cord syndrome

E.

Brown-Sequard lesion

A 64-year-old male with a history of chronic alcohol abuse and congestive heart failure is currently recovering from excision of a large right shoulder lesion suspicious for melanoma. Postoperatively, he is experiencing bleeding and oozing from his surgical site that has persisted despite suture repair and direct pressure for an extended period of time. His labs are drawn, and are as follows: platelets 141 × 10³/mL, INR 1.2, fibrinogen 90 mg/dL. Which of the following blood products should be administered next?A.

Fresh frozen plasma

B.

Cryoprecipitate

C.

Prothrombin complex concentrate

D.

Recombinant activated factor VII

E.

Aminocaproic acid

A 75-year-old, 90 kg male with a history of peripheral vascular disease, coronary artery disease, and epilepsy following a recent cerebral infarction presents to the emergency department after having three witnessed seizures at home. He was intubated at the scene by the paramedics, and received 8 mg of intravenous lorazepam and 1 g of phenytoin. While you are evaluating him, he has another generalized tonic-clonic seizure, and the nurse asks if you would like to initiate a continuous propofol infusion. His blood pressure is 94/42 mmHg, and he is having numerous premature ventricular contractions (PVCs) on the electrocardiographic monitor. He has no history of platelet or liver dysfunction. Which of the following should be performed next?A.

Complete the phenytoin load to attain 20 mg/kg, then start propofol infusion

B.

Complete the phenytoin load to attain 20 mg/kg only

C.

Administer valproate, 30 mg/kg over 10 min, as well as midazolam 0.2 mg/kg

D.

Start immediate midazolam infusion at 2 mg/kg/h

E.

Give a 1 L normal saline bolus, and start a norepinephrine infusion to normalize blood pressure

A 38-year-old male is brought to the emergency department after a motor vehicle accident. He is found to have significant ecchymoses on his chest and face, with multiple apparent rib fractures. He is in mild respiratory distress, with an oxygen saturation of 89% on room air, and hypotensive, with a systolic blood pressure of 88 mmHg. He has absent breath sounds on the right side. There is currently a delay in obtain a bedside portable chest x-ray. Which of the following should be performed next?A.

28-French chest tube placement

B.

16-French chest tube placement

C.

Obtain computed tomography (CT) of the chest

D.

Administer 30 cc/kg crystalloid

E.

Obtain urgent cardiothoracic surgery consult

Stress ulcer prophylaxis is often undertaken to prevent clinically important upper gastrointestinal (GI) bleeding. Which of the following factors puts patients at highest risk for such bleeding episodes?A.

Respiratory failure

B.

History of alcohol abuse

C.

NPO status

D.

Diverticulitis

E.

All of the above

In an intact heart, the Frank-Starling mechanism describes contractility increases in responses to:A.

Decreased preload

B.

Increased afterload

C.

Decreased left ventricular end-diastolic pressure

D.

Increased left ventricular end-diastolic volume

E.

Increased pulmonary vascular resistance

A 68-year-old female with a history of hyperlipidemia, hypothyroidism, and gastric cancer on total parenteral nutrition is currently in the ICU following a small traumatic subdural hemorrhage. On hospital day 5, the patient begins to spike fevers that persist despite broad spectrum antibiotic coverage with vancomycin and piperacillin-tazobactam. She is otherwise hemodynamically stable. The lab calls you to notify you that multiple sets of blood cultures display budding yeast forms and pseudohyphae. Which of the following should be administered next?A.

Fluconazole

B.

Posaconazole

C.

Anidulafungin

D.

Caspofungin

E.

Amphotericin B

A 56-year-old male with a past medical history of hypertension, hyperlipidemia, and morbid obesity is currently intubated in the ICU following a left middle cerebral artery infarct. The respiratory therapist alerts you the fact that the patient has become markedly dysynchronous with the ventilator, including breath holding episodes, breath stacking, and resisting ventilator-delivered breaths. A variety of pressure- and volume-regulated ventilator modes have been attempted without improvement, as well as boluses of both fentanyl and midazolam. The most recent arterial blood gas is as follows: pH 7.19, PaCO₂ 78 mmHg, PaO₂ 61 mmHg. The patient is now hypotensive to 91/66 mmHg with sinus tachycardia at 117 beats/min. A recent bedside chest x-ray shows no consolidation or pneumothorax. Which of the following should be performed next?A.

Prone the patient

B.

Administer nitric oxide at 10 parts per million

C.

Administer 10 mg of cisatracurium

D.

Administer a mixture of 60% helium/40% oxygen

E.

Administer a continuous infusion of phenobarbital

Compared to lactulose for the treatment of hepatic encephalopathy, polyethylene glycol (PEG) has been shown to:A.

Decrease in-hospital mortality

B.

More rapidly improve symptoms

C.

Increase the rate of gastrointestinal complications

D.

Increase the incidence of major electrolyte abnormalities

E.

None of the above

Which of the following neurologic insults is the least likely to cause central (non-infectious) fever in the ICU?A.

Intracranial neoplasm

B.

Intraventricular hemorrhage

C.

Normal pressure hydrocephalus

D.

Subarachnoid hemorrhage

E.

Traumatic brain injury

A 57-year-old male with a history of epilepsy and medication noncompliance is admitted to a small community hospital after a brief tonic-clonic seizure. A non-contrast head CT on admission is normal. On the second hospital day, the patient begins to complain of severe substernal chest pressure, and an urgent bedside EKG shows evidence of an acute inferior myocardial infarction (MI). The nearest percutaneous coronary intervention (PCI) capable center is approximately 150 min away by the fastest transport method available. Which of the following is the most appropriate next step in this patient’s care?A.

Arrange for transport to the closest PCI center with anticipated balloon time within 30 min of arrival

B.

Prepare to administer fibrinolytic therapy

C.

Consult cardiothoracic surgery for possible coronary artery bypass grafting (CABG)

D.

Place the patient on a continuous nitroglycerine infusion and administer aspirin, clopidogrel, and heparin

E.

Await serum cardiac biomarkers and repeat EKG in 1 h

A 62-year-old male with unknown past medical history who recently immigrated from El Salvador is currently in the stroke unit after suffering from an acute left middle cerebral artery infarction. The patient is aphasic; his wife states that he been in his usual state of health lately, and denies any recent weakness, dizziness, chest pain, cough, shortness of breath, or fevers. On reviewing this patient’s belongings, the nurse discovers a bottle of isoniazid, as well as paperwork demonstrating a positive quantiferon gold test performed at a local clinic approximately 3 weeks ago. He does not appear to be on any other medications. A bedside portable chest x-ray is performed, which preliminarily appears normal. Which of the following should be performed next?A.

Move the patient to a negative pressure isolation room, continue isoniazid

B.

Isolate the patient, continue isoniazid, add rifampin

C.

Isolate the patient, continue isoniazid, add rifampin and pyrazinamide

D.

Isolate the patient, continue isoniazid, add rifampin, pyrazinamide and ethambutol

E.

None of the above

A 56-year-old, 70 kg female patient in oliguric renal failure would be expected to have a daily urine output of:A.

No more than 50 mL

B.

No more than 400 mL

C.

No more than 800 mL

D.

Less than 70 mL/h

E.

Less than 35 mL/h

A 37-year-old female with a history of epilepsy is admitted to the ICU with status epilepticus. She required several doses of lorazepam in the emergency department in addition to fosphenytoin, intubation, and a continuous propofol infusion. There was concern for aspiration in the prehospital setting. Approximately 3 days after being admitted to the hospital, her respiratory status has worsened; she is increasingly hypoxic, and her chest x-ray demonstrates diffuse bilateral interstitial infiltrates. The patient is afebrile with minimal secretions. Her most recent arterial blood gas is as follows: pH 7.21, PaO₂ 107 mmHg, PCO₂ 55 mmHg, 100% FiO₂, and a positive end-expiratory pressure (PEEP) of 8 cm H₂O. According to the Berlin criteria, how would you categorize this patient’s acute respiratory distress syndrome (ARDS)?A.

Acute lung injury (ALI)

B.

Mild ARDS

C.

Moderate ARDS

D.

Severe ARDS

E.

None of the above

An 80-year-old male presents to the emergency department with multiple episodes of bright red blood per rectum. He is on aspirin and clopidogrel for a history of coronary artery disease and a previous transient ischemic attack. He underwent aortic graft surgery for repair of an abdominal aortic aneurysm 2 years ago. A complete blood count and coagulation profile are all within normal limits. His vital signs are as follows: blood pressure 102/58 mmHg, heart rate 98 beats/min, respiratory rate 18 breaths/min, oxygen saturation 98% on room air, and temperature 98.3 °F. Which of the following is the next best step in the care of this patient?A.

Transfuse platelets, fresh frozen plasma, and recombinant factor VIIa

B.

Consult gastroenterology for emergent upper endoscopy

C.

Consult gastroenterology for emergent colonoscopy

D.

CT angiogram of the abdomen and pelvis

E.

Expectant management with fluids and blood transfusions

A thrombus in which of the following veins would not be considered a deep vein thrombosis (DVT)?A.

Popliteal vein

B.

Soleal vein

C.

Femoral vein

D.

Gastrocnemius vein

E.

Greater saphenous vein

After partial resection of the pituitary stalk, secretion of which of the following hormones will be most affected?A.

Oxytocin

B.

Adrenocorticotrophic hormone

C.

Melanocyte-stimulating hormone

D.

Thyroid-stimulating hormone

E.

All will be equally affected

A 58-year-old female with a history of hypertension, rheumatoid arthritis, metastatic ovarian cancer, and bilateral deep venous thrombosis status post recent inferior vena cava filter placement presents to the emergency department with right flank pain. She states the pain began approximately 1 h ago when bending down to pick something off the floor, and that it is constant and severe in nature. She denies dysuria or hematuria. Her vital signs are as follows: blood pressure 108/62 mmHg, heart rate 121 beats/min, respiratory rate 20 breaths/min, oxygen saturation 99% on room air, and temperature 99.6 °F. A CT scan of the abdomen is obtained (see Image 1). Which of the following is the next best step in this patient’s management?A.

Administer vancomycin and cefepime, and draw two sets of blood cultures

B.

Urgent vascular surgery consult

C.

Immediately place the patient on her left side

D.

Rapid sequence intubation with mechanical ventilation

E.

Perform bedside diagnostic peritoneal lavage

Auditory Monitoring in Vestibular Schwannoma Surgery: Intraoperative Development and Outcome

OBJECTIVE

The auditory brainstem response (ABR) may be a predictor of postoperative cochlear nerve function. In this study, the course of intraoperative ABR monitoring was analyzed to find predictive markers for postoperative hearing function.

PATIENTS AND METHODS

From 2010 to 2012, 46 patients who had had vestibular schwannoma surgery were investigated by intraoperative ABR monitoring. The type of ABR development was identified: type A, improved or stable ABR; type B, fluctuating or deteriorated ABR; and type C, slow or sudden ABR loss. Hearing function was correlated with ABR monitoring.

RESULTS

The different types of ABR development showed a strong correlation with postoperative hearing (P < 0.001). ABR quality after 60% tumor removal was independently significant for hearing outcome. Possible interpretations are: 1) Independent of positive factors at the start of surgery at the final phase of tumor resection, what mattered for hearing outcome was the ABR quality (P < 0.001). 2) Dependence on ABR quality in the last phase might be a result of what the cochlear nerve has endured during resection. 3) The importance of ABR quality in the last phase might be because the tumor capsule is dissected from the nerves in that final phase.

ANALYSIS

of critical actions with incidence of ABR impairment showed that dissection in the internal auditory canal and drilling were most critical.

CONCLUSIONS

Intraoperative ABR development is a predictive factor for postoperative hearing outcome. Deterioration should be avoided, because ABR improvement as a result of good status at the beginning of surgery could not be assumed.