A Combined Analysis of a Randomized, Multicenter, Phase III Trial and Its Pilot Study
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CLINICAL ARTICLE 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 Christian Scheller, MD,1,2 Andreas Wienke, PhD,3 Marcos Tatagiba, MD,4 Alireza Gharabaghi, MD,4 Kristofer F. Ramina, MD,4 Oliver Ganslandt, MD,5 Barbara Bischoff, MD,5 Johannes Zenk, MD,6 Tobias Engelhorn, MD,7 Cordula Matthies, MD,8 Thomas Westermaier, MD,8 Gregor Antoniadis, MD,9 Maria Teresa Pedro, MD,9 Veit Rohde, MD,10 Kajetan von Eckardstein, MD,10 Thomas Kretschmer, MD,11 Malte Kornhuber, MD,12 Jörg Steighardt, PhD,13 Michael Richter, PhD,13 Fred G. Barker II, MD,14 and Christian Strauss, MD1 Departments of 1Neurosurgery and 12Neurology, 3Institute of Medical Epidemiology, Biostatistics, and Informatics, and 13Coordi- nation Centre for Clinical Trials, University of Halle-Wittenberg, Halle (Saale); 2Translational Centre for Regenerative Medicine, University of Leipzig; 4Department of Neurosurgery, University of Tübingen; Departments of 5Neurosurgery, 6Otorhinolaryngol- ogy, Head and Neck Surgery, and 7Neuroradiology, University of Erlangen-Nuremberg, Erlangen; 8Department of Neurosurgery, Würzburg University Hospital, Würzburg; 9Department of Neurosurgery, Bezirkskrankenhaus Günzburg, University of Ulm, Gün- zburg; 10Department of Neurosurgery, University of Göttingen; and 11Department of Neurosurgery, Evangelisches Krankenhaus, University of Oldenburg, Germany; and 14Department of Neurosurgery, Massachusetts General Hospital, Boston, Massachusetts OBJECT 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. Prophy- lactic 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/) https://thejns.org/doi/abs/10.3171/2016.8.JNS16626 KEY WORDS facial nerve; cochlear nerve; nimodipine; hydroxyethyl starch; vestibular schwannoma; neuroprotection ABBREVIATIONS AAO-HNS = American Academy of Otolaryngology–Head and Neck Surgery; HB = House-Brackmann; HES = hydroxyethyl starch; ITT = intent to treat; RCT = randomized controlled trial; VS = vestibular schwannoma. ACCOMPANYING EDITORIAL DOI: 10.3171/2016.11.JNS162189. SUBMITTED March 11, 2016. ACCEPTED August 23, 2016. INCLUDE WHEN CITING Published online February 24, 2017; DOI: 10.3171/2016.8.JNS16626. ©AANS, 2017 J Neurosurg February 24, 2017 1 C. Scheller et al. HE incidence of diagnosed vestibular schwan- randomized, Phase III trial with blinded expert review nomas (VSs) has been estimated to range from (performed 2010–2013). Design and sample size planning 1–2/100,000/year;18 VSs comprise 6%–8% of all were based on the data of the single-center pilot study (n Tintracranial tumors. Vestibular schwannomas most fre- = 30, performed 2004–2006), which was randomized as quently present with hearing loss. Depending on the size well. The aim of both studies was to investigate the effi- of the tumor, facial nerve weakness may be additionally cacy and safety of prophylactic parenteral nimodipine and recognized. Other symptoms include tinnitus, vertigo, HES treatment in VS surgery. Parenteral administration headache, facial numbness, and change in taste percep- of nimodipine for several days requires the use of a cen- tions.5 Possible options are wait and scan, radiotherapy, tral line. It was not considered ethical to impose this on and microsurgery. In case of surgery, the objective should control patients. Therefore a blinded design was not used. be complete tumor removal with preservation of facial and possibly cochlear nerve functions.18 So far, application of Study Participants neuroprotective strategies from basic research to clinical 26 Adults 18 years of age or older with an indication for VS practice in neurosurgical procedures has been elusive. surgery were included. Reasons for exclusion were contra- Nimodipine, a dihydropyridine calcium antagonist, re- indications against nimodipine or HES, surgery for recur- duces the risk of poor outcome and secondary ischemia 4 rent VS, pregnancy and lactation period, neurofibromatosis after aneurysmal subarachnoid hemorrhage. Besides pre- Type 2, tumor inoperability, and participation in other clin- venting vasospasm, a neuroprotective effect of nimodipine 17 ical trials within the last 30 days. Considering that facial has been proposed. The beneficial impact of nimodipine nerve function 12 months after surgery was the primary on protection and regeneration of nerve tissue is support- 1,6,10,13,15 outcome of the multicenter trial, preoperative facial nerve ed by animal experiments, and it has been used in function Grade VI according to the House-Brackmann combination with hydroxyethyl starch (HES) by several (HB) grading scale was an additional exclusion criterion.17 retrospective and prospective clinical trials.3,19,20,27,28 A pi- lot study showed superiority of prophylactic nimodipine Surgical and Neuroprotective Interventions compared with an intraoperative start or no treatment.19 A Phase III trial with facial nerve function assessed 12 The pilot study was performed at a single center. Seven months after surgery as the primary outcome showed German university hospitals participated in the multi- no significant results.22 However, the risk for postop- center trial. The aim of all surgeries done by experienced erative hearing loss was 2 times lower in the treatment surgeons was to preserve facial and cochlear nerve func- group compared with the control group. Several factors tions and to achieve gross-total resection via a retrosig- are known to have an impact on the outcome of both the moid approach. Intraoperative neurophysiological moni- facial and cochlear nerves following VS surgery. There- toring including brainstem auditory evoked potentials, fore, the efficacy of an additionally applied neuroprotec- continuous facial nerve electromyography, and direct fa- tive drug is difficult to quantify. However, it is possible to cial nerve stimulation was used in all surgeries, and histo- determine objectively the slightest alterations of hearing pathological examinations were performed. One hundred ability by pure-tone audiometry with speech discrimina- forty-two patients were randomly assigned to treatment (n tion. Considering the small sample size, the results of the = 70) and control groups (n = 72), respectively. Neuropro- only 2 analogously performed randomized controlled tri- tective prophylaxis was started the day before surgery and als (RCTs) were pooled. was continued until the 7th postoperative day. The medi- cation consisted of parenteral nimodipine (1–2 mg/hour; Nimotop, Bayer) and HES 6% (aiming at a hematocrit be- Methods tween 30% and 35%; Voluven 6%, Fresenius Kabi) and Trial Design was preoperatively administered via a peripheral venous A combined analysis using the raw data from the only 2 catheter with a dose of 1 mg/hour for 2 hours. Thereafter RCTs of prophylactic nimodipine and HES in VS surgery the dose was increased to 2 mg/hour. conducted so far was performed retrospectively. Treat- In the treatment group, 2 patients were not treated 1 ment, follow-up, and data acquisition were identical in both day before surgery but before skin incision. In 11 patients studies. However, expert review was different between the the duration of nimodipine and HES therapy was reduced studies (see Outcomes, Follow-Ups, and Blinding). and in 2 patients the therapy was prolonged. Thirty-three Both the pilot study and the multicenter trial were in- patients tolerated the full dose of 2 mg/hour. Symptomatic vestigator-initiated trials conducted in compliance with hypotension with headaches or dizziness was observed in the principles of the Declaration of Helsinki and Good 28 patients, resulting in a dose reduction to 1 mg/hour. Clinical Practice guidelines. The multicenter trial was ap- These symptoms