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Preservation of hearing following awake surgery via the retrosigmoid approach for vestibular schwannomas in eight consecutive patients

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Nobusada Shinoura
Nobusada Shinoura
Nobusada Shinoura
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Akira Midorikawa at Chuo University
Akira Midorikawa
Kentaro Hiromitsu at Advanced Telecommunications Research Institute International
Kentaro Hiromitsu
Shoko Saito
Shoko Saito
Shoko Saito
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Abstract and Figures

Background: Hearing preservation in patients with vestibular schwannomas remains difficult by microsurgery or radiosurgery. Method: In this study, awake surgery via the retrosigmoid approach was performed for vestibular schwannomas (volume, 11.6 ± 11.2 ml; range, 1.3-26.4 ml) in eight consecutive patients with preoperative quartering of pure tone audiometry (PTA) of 53 ± 27 dB. Results: After surgery, hearing was preserved in seven patients and improved in one patient. The postoperative quartering PTA was 51 ± 21 dB. Serviceable hearing (class A + B + C) using the American Association of Otolaryngology-Head and Neck Surgery (AAO-HNS) classification was preserved in all patients. Preoperative useful hearing (AAO-HNS class A + B) was observed in three patients, and useful hearing was preserved in all three of these patients after surgery. In addition, useful facial nerve function (House-Blackmann Grade 1) was preserved in all patients. Conclusions: These results suggest that awake surgery for vestibular schwannomas is associated with low patient morbidity, including with respect to hearing and facial nerve function.
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ORIGINAL ARTICLE - NEUROSURGICAL TECHNIQUES
Preservation of hearing following awake surgery via
the retrosigmoid approach for vestibular schwannomas
in eight consecutive patients
Nobusada Shinoura
1
&Akira Midorikawa
2
&Kentaro Hiromitsu
2
&Shoko Saito
2
&
Ryoji Yamada
1
Received: 14 December 2016 /Accepted: 31 May 2017 /Published online: 3 July 2017
#Springer-Verlag GmbH Austria 2017
Abstract
Background Hearing preservation in patients with vestibular
schwannomas remains difficult by microsurgery or
radiosurgery.
Method In this study, awake surgery via the retrosigmoid ap-
proach was performed for vestibular schwannomas (volume,
11.6 ± 11.2 ml; range, 1.3–26.4 ml) in eight consecutive pa-
tients with preoperative quartering of pure tone audiometry
(PTA) of 53 ± 27 dB.
Results After surgery, hearing was preserved in seven patients
and improved in one patient. The postoperative quartering
PTA was 51 ± 21 dB. Serviceable hearing (class A + B + C)
using the American Association of Otolaryngology-Head and
Neck Surgery (AAO-HNS) classification was preserved in all
patients. Preoperative useful hearing (AAO-HNS class A + B)
was observed in three patients, and useful hearing was pre-
served in all three of these patients after surgery. In addition,
useful facial nerve function (House-Blackmann Grade 1) was
preserved in all patients.
Conclusions These results suggest that awake surgery for
vestibular schwannomas is associated with low patient
morbidity, including with respect to hearing and facial
nerve function.
Keywords Awake surgery .Vestibular schwannomas .Facial
nerve .Hearing
Introduction
Postoperative preservation of hearing following surgery for
vestibular schwannomas is still not good, although the tech-
nique of microsurgery (MS) for these tumors has recently
evolved. According to recent reports, as for preservation of
hearing after MS for vestibular schwannomas, serviceable
hearing (class A + B + C) using the American Association
of Otolaryngology-Head and Neck Surgery (AAO-HNS) clas-
sification was obtained in 61.6% of patients, and useful hear-
ing (class A + B) was preserved in 33.5% after MS in a series
of 1,006 patients [2,24]. In a series of 80 consecutive cases,
serviceable hearing was preserved in 36% of patients after MS
for small vestibular schwannomas (less than 20 mm in diam-
eter) [3]. As for the retrosigmoid approach of MS, 43% of 64
patients maintained serviceable hearing after surgery [1], and
in another series of 592 cases, 74.1% of patients preserved
serviceable hearing [20].
Awakecraniotomyisassociatedwithimprovedneurologi-
cal outcomes in functional areas with maximal removal of
lesions when compared with surgery under general anesthesia.
Improved outcomes are mainly attributed to the ability to im-
mediately identify the deterioration of neurological function
during surgery and to alter or terminate the surgical procedure
accordingly [5,11,15,17]. Similarly, we assumed that awake
surgery would be useful to preserve hearing and other func-
tions in patients undergoing MS for vestibular schwannomas.
The present report describes the use of awake surgery for MS
via the retrosigmoid approach in eight consecutive patients,
resulting in successful preservation of hearing, as well as of
facial nerve function, in all patients.
*Nobusada Shinoura
shinoura@cick.jp
1
Department of Neurosurgery, Komagome Metropolitan Hospital,
3-18-22 Hon-komagome, Bunkyo-ku, Tokyo 113-8677, Japan
2
Department of Psychology, Faculty of Letters, Chuo University,
742-1 Higashi-nakano, Hachioji City, Tokyo 192-0393, Japan
Acta Neurochir (2017) 159:1579–1585
DOI 10.1007/s00701-017-3235-8
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
... There are a few case reports and case series on AC for posterior fossa lesions such as acoustic schwannoma to preserve the functions of lower cranial nerves especially seventh and eighth cranial nerves [12,13]. Shinoura et al. published a case series of eight cases of vestibular schwannoma where surgery was conducted after infiltration of local anesthetic agents at pin and incision sites along with surgical field block (infiltration). ...
... Shinoura et al. published a case series of eight cases of vestibular schwannoma where surgery was conducted after infiltration of local anesthetic agents at pin and incision sites along with surgical field block (infiltration). The degree of tumor resection after surgery was observed to be 86 ± 16%, and the values for preoperative and postoperative hearing were 53 ± 27 and 51 ± 21 dB, respectively [12]. They concluded that awake surgical resection of vestibular schwannomas helped preserving hearing and other cranial nerves functions. ...
... The most serious complications and their step-wise management are listed in Table 5. As per a previous study, the incidence of various complications during AC is approximately 16.5% [8], and in an approximately 6.4% of patients, mapping procedure could not be completed [12]. The reasons for failure include seizures, loss of cooperation due to severe somnolence or restlessness, and dysphasia [24]. ...
Anesthesia for Awake Craniotomy: What Is New?
Article
Full-text available
  • Sep 2018
Purpose of Review The purpose of this article is to review the current evidence on perioperative management for awake craniotomy (AC). Recent Findings With the advancement of diagnostic modalities, newer intraoperative monitoring technologies, and safer and shorter-acting anesthetic agents, the indications of AC are expanding beyond epilepsy surgery. Anesthesia techniques including asleep-awake-asleep and monitored anesthesia care are generally safe and without any serious side effects when performed by experienced providers; however, data regarding awake-awake-awake technique is limited. Currently, an α-2 agonist, dexmedetomidine, is gaining popularity both as a sole agent as well as an adjunct for AC as it provides analgesia with minimal respiratory depression and it minimally interferes with electrocorticography and cortical mapping. The use of dexmedetomidine allows reduction of opioid and propofol doses while preserving hemodynamic stability. Summary The success of AC is based on the appropriate patient selection, detailed preoperative evaluation, adequate preparation, and prevention, timely detection, and efficient management of the intraoperative complications.
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... 6,19,37,[45][46][47][48] Two studies included tumor sizes in terms of volume rather than diameter. 49,50 Others reported tumor sizes based on the Koos grading system. [51][52][53] For our purposes, small tumors were defined as those with intracisternal diameters of 0 to 20 mm. ...
... Three authors included both subtotal and gross total resections in their reported data, 22,28,43 5 included data from gross total resections, 13,26,27,47,52 while 2 studies included only cases involving subtotal resection. 44,49 In addition, VS can be bilateral and aggressive. These are caused by a deletion on chromosome 22q11, which codes for tumor suppressor gene, Merlin. ...
Postoperative Hearing Preservation in Patients Undergoing Retrosigmoid Craniotomy for Resection of Vestibular Schwannomas: A Systematic Review of 2034 Patients
Article
  • May 2019
  • NEUROSURGERY
Background: Vestibular schwannomas (VS) are benign tumors derived from Schwann cells ensheathing the vestibulocochlear nerve. The retrosigmoid (RS) surgical approach is useful to resect tumors of multiple sizes while affording the possibility of preserving postoperative hearing. Objective: To conduct a systematic review of published literature investigating hearing preservation rates in patients who underwent the RS approach for VS treatment. Methods: The PubMed, Scopus, and Embase databases were surveyed for studies that reported preoperative and postoperative hearing grades on VS patients who underwent RS treatment. Hearing preservation rates were calculated, and additional patient demographic data were extracted. Tumor size data were stratified to compare hearing preservation rates after surgery for intracanalicular, small (0-20 mm), and large (>20 mm) tumors. Results: Of 383 deduplicated articles, 26 studies (6.8%) met eligibility criteria for a total of 2034 patients with serviceable preoperative hearing, for whom postoperative hearing status was evaluated. Aggregate hearing preservation was 31% and 35% under a fixed and random effects model, respectively. A mixed effects model was used to determine hearing preservation rates depending on tumor size, which were determined to be 57%, 37%, and 12% for intracanalicular, small, and large tumors, respectively. Significant cross-study heterogeneity was found (I2 = 93%, τ2 = .964, P < .01; Q = 287.80, P = < .001), with rates of hearing preservation ranging from 0% to 100%. Conclusion: Tumor size may have an effect on hearing preservation rates, but multiple factors should be considered. Discussion of a patient's expectations for hearing preservation is critical when deciding on VS treatment plans.
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... Dear Editor, With great interest I read the article of Shinoura et al. [4], reporting on their experience in the attempt to preserve hearing in microsurgery for vestibular schwannoma using awake craniotomy. The authors reported hearing preservation and useful facial nerve function in all of the patients in whom they have used intraoperative testing of the hearing level and facial nerve function. ...
... When the facial nerve was identified, its functionality was tested by electrical stimulation [2]. The authors Shinoura et al. do not mention that the study is the first report on awake craniotomy for vestibular schwannoma surgery [4]. A reference to previous experiences with awake surgery in the history of neurosurgery, however, would have been appropriate. ...
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... In addition, some acute symptoms in the present study might have occurred due to differences in patients' pathological backgrounds and/or surgical procedures. All of the participants had undergone awake craniotomy, which uses intraoperative stimulation mapping to maximize the extent of resection while avoiding severe deficits (21,22). ...
Sensory hypo- and hypersensitivity in patients with brain tumors
Article
  • Aug 2022
Objectives Hyper- and hyposensitivity in multiple modalities have been well-documented in subjects with autistic spectrum disorder (ASD) but not in subjects with acquired brain injury (ABI). The purpose of this study was to determine whether subjects with ABI experience altered sensory processing in multiple sensory modalities, and to examine the relationships between impaired sensory processing and the emotional state. Methods and procedures Sixty-eight patients with brain or spinal cord tumors participated in the study. Cognitive ability and emotional function were tested, and subjective changes were evaluated in two directions (hyper- and hyposensitivity) and five modalities (visual, auditory, tactile, olfactory, and gustatory) at two time points (after disease onset and after surgery). Results One-fifth of the participants complained of hypersensitivity in the visual domain, and a similar proportion complained of hyposensitivity in the auditory and tactile domains. Additionally, one-third of participants complained of two or more sensory abnormalities after disease onset. A hierarchical regression analysis indicated that auditory and tactile sensory changes predicted a depressive state. Conclusion In conclusion, multimodal sensory changes occurred in patients with brain tumors, manifesting as hyper- or hyposensitivity. Sensory changes might be related to depressive state, but the results were inconclusive.
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... Awake craniotomy is usually performed to maximize resection of tumors near the eloquent area [3,4]. It can reduce anesthetic interference with brain mapping [5]. Awake craniotomy for posterior fossa surgery reminds a number of significant challenges for the anesthesiologist. ...
Awake craniotomy for auditory brainstem implant in patients with neurofibromatosis type 2: Four case reports
Article
Full-text available
  • Sep 2021
Background: The auditory brainstem implant (ABI) is a significant treatment to restore hearing sensations for neurofibromatosis type 2 (NF2) patients. However, there is no ideal method in assisting the placement of ABIs. In this case series, intraoperative cochlear nucleus mapping was performed in awake craniotomy to help guide the placement of the electrode array. Case summary: We applied the asleep-awake-asleep technique for awake craniotomy and hearing test via the retrosigmoid approach for acoustic neuroma resections and ABIs, using mechanical ventilation with a laryngeal mask during the asleep phases, utilizing a ropivacaine-based regional anesthesia, and sevoflurane combined with propofol/remifentanil as the sedative/analgesic agents in four NF2 patients. ABI electrode arrays were placed in the awake phase with successful intraoperative hearing tests in three patients. There was one uncooperative patient whose awake hearing test needed to be aborted. In all cases, tumor resection and ABI were performed safely. Satisfactory electrode effectiveness was achieved in awake ABI placement. Conclusion: This case series suggests that awake craniotomy with an intraoperative hearing test for ABI placement is safe and well tolerated. Awake craniotomy is beneficial for improving the accuracy of ABI electrode placement and meanwhile reduces non-auditory side effects.
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... The notable progress obtained by the use of awake craniotomy in the removal of glial brain tumors has stimulated the use of this approach in other areas. For instance, among the articles published during the last year, we found case reports or small series of awake craniotomy in multiple particular clinical situations: clipping of cerebral aneurisms [10], vestibular schwannomas removal [11,12], resection of tumors in conjunction with optic radiation [13], in a patient with congenital heart disease [14], in an 8-year-old child [15], in a pregnant patient [16], and even in a deaf patient who communicated in sign language [17]. ...
Anesthesia for awake craniotomy
Article
  • Jul 2018
Purpose of review: The current review reports on current trends in the anesthetic management of awake craniotomy, including preoperative preparation, sedation schemes, pain management, and prevention of intraoperative complications. Recent findings: Both approaches for anesthesia for awake craniotomy, asleep-awake-asleep and monitored anesthesia care (MAC), have shown equal efficacy for performing intraoperative brain mapping. Choice of the appropriate scheme is currently based mainly on the preferences of the particular anesthesiologist. Dexmedetomidine has demonstrated high efficacy and safety in MAC for awake craniotomy and has become a rational alternative to propofol. Despite the high efficacy of scalp block and opioids, pain remains a common compliant in awake craniotomy. Appropriate surgical tactics can reduce pain and even prevent postoperative neurological complications. Although the efficacy of prophylaxis of intraoperative seizures with anticonvulsants remains doubtful, levetiracetam can be superior to other drugs for this purpose. Summary: Following a great deal of progress in anesthetic management, awake craniotomy, which had been a relatively rare approach, is now a commonly performed procedure for neurosurgical intervention. Modern anesthesia techniques can provide for successful brain mapping in almost any patient. Management of awake craniotomy in high-risk patients is a central task for future research.
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... Это совсем свежая публикация в Acta Neurochirurgica японских нейрохирургов, в которой анализируются результаты удаления неврином слухового нерва в условиях местной анестезии [87]. В серии всего 8 наблюдений и радикальность удаления существенно ниже, но функциональные результаты оказались лучше, даже в виде сохранения слуха. ...
Neurosurgery in conscious patients: Forward to the past
Article
  • Jan 2018
  • Vopr Neirokhir
We present an analytical review of various neurosurgical interventions in conscious patients. An analysis of the literature indicates growing interest in this problem. Craniotomy in conscious patients has been extensively used in resection of space-occupying cerebral lesions in the eloquent hemispheric areas and in epilepsy surgery. In recent years, there have been a number of reports on interventions in conscious patients with other neurosurgical pathologies, which may be regarded as a new emerging tendency in neurosurgery and neuroanesthesiology. Neurosurgery in conscious patients provides a special advantage because it enables highly functional neuromonitoring without use of complex devices.
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... In the present issue of Acta Neurochirurgica, Shinoura and colleagues [9] report, as a first, awake craniotomy for a series of eight patients operated on for vestibular schwannoma. They managed to save some hearing in all, and even improved it in one patient. ...
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Patient Selection for Awake Craniotomy
Chapter
  • Jul 2023
The first awake craniotomy (AC) applications were found in archaeological excavations in Peru. The successful healing rate was 55% of trephinations in 214 skulls. Coca leaves were used as a local anesthetic before the general anesthesia (GA) era. The first recorded case of AC was the epilepsy surgery performed by Sir Victor Horsley in 1886 [1]. He resected an epileptogenic lesion from a 22-year-old man. Wilder Penfield popularized the procedure in the first half of the twentieth century [2]. Compared with GA, AC has the following advantages after tumor resection: improved outcome; greater extent of tumor resection; fewer late neurological deficits, and shorter hospital stay [3–5].
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Preservation of cranial nerve function following awake surgery for benign brain tumors in 22 consecutive patients
Article
  • Oct 2018
  • J CLIN NEUROSCI
Background Preservation of cranial nerve function in patients with benign tumors such as meningiomas and vestibular schwannomas remains difficult following microsurgery. Methods In this study, awake surgery was performed in 22 consecutive patients with meningiomas or vestibular schwannomas that compressed cranial nerves (I–XII). Improved, unchanged, or deteriorated cranial nerve function after surgery was evaluated. Results The function of 44 cranial nerves in 22 consecutive patients who underwent awake surgery for meningiomas or vestibular schwannomas improved, was unchanged, or deteriorated in eight, 35, and one nerves, respectively. Regarding the function of the olfactory (Ist) nerve, which is difficult to preserve, hyposmia improved after surgery in two patients with olfactory groove meningiomas. Regarding the auditory (VIIIth) nerve, which is also difficult to preserve, the function was improved, unchanged, or deteriorated after surgery in two, 11, and one patients, respectively, with cerebello-pontine angle meningiomas or vestibular schwannomas. In all patients with serviceable auditory function before surgery, function was preserved after surgery. In the same patients, the function of the facial (VIIth) nerve was also preserved after surgery in all patients. Conclusions These results suggest that awake surgery for benign brain tumors such as meningiomas and vestibular schwannomas is associated with low patient morbidity regarding cranial nerve function.
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Surgical treatment of sporadic vestibular schwannoma in a series of 1006 patients
Article
Full-text available
  • Sep 2016
  • Acta Otorhinolaryngol Ital
The management of sporadic vestibular schwannoma (VS) has evolved in the last decades. The aim of this study was to analyse the evolution in surgical outcomes of VSs operated by a neurotological team between 1990 and 2006 by different approaches. A monocentric retrospective review of medical charts of 1006 patients was performed. In order to assess eventual changes and progress, the 17-years period was divided in three periods, each one comprehending 268 VS (1990-1996), 299 VS (1997-2001), and 439 VS (2002-2006). Mean follow-up was 5.9 ± 2.4 years. Overall, complete VS removal was achieved in 99.4% of cases. Mortality rate was 0.3%, meningitis and CSF leaks were observed in 1.2 % and 9 % of the cases, respectively. CSF leakage decreased from 11.6% to 7.1% between the first and last period (p < 0.01) as well as revision surgery from 3.4 % to 0.9 % (p < 0.05). Facial nerve was anatomically preserved in 97.7% of cases. At one year, a good facial nerve function was observed in 85.1% of patients (grade I and II of House-Brackmann grading scale), which ranged between the first and last period from 78.4% to 87.6% (p <0.05). At one year, hearing preservation was obtained in 61.6% of patients, which increased from the first period to the last one from 50.9% to 69.0% (p < 0.05) (class A+B+C from the AAO-HNS classification). Useful hearing (class A+B) was observed in 33.5% of cases overall, with 21.8% and 42% in the first and last period, respectively (p < 0.01). Surgical outcomes of sporadic vestibular schwannoma have improved concerning facial nerve function outcomes, hearing preservation and cerebrospinal fluid (CSF) leaks, mainly due to the neuro-otological team's experience. Functional results after complete microsurgical removal of large VS depend on experience gained on small VS removal. © Copyright by Società Italiana di Otorinolaringologia e Chirurgia Cervico-Facciale, Rome, Italy.
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A matched cohort comparison of clinical outcomes following microsurgical resection or stereotactic radiosurgery for patients with small- and medium-sized vestibular schwannomas
Article
Full-text available
  • Apr 2016
OBJECTIVE A randomized trial that compares clinical outcomes following microsurgery (MS) or stereotactic radiosurgery (SRS) for patients with small- and medium-sized vestibular schwannomas (VSs) is impractical, but would have important implications for clinical decision making. A matched cohort analysis was conducted to evaluate clinical outcomes in patients treated with MS or SRS. METHODS The records of 399 VS patients who were cared for by 2 neurosurgeons and 1 neurotologist between 2001 and 2014 were evaluated. From this data set, 3 retrospective matched cohorts were created to compare hearing preservation (21 matched pairs), facial nerve preservation (83 matched pairs), intervention-free survival, and complication rates (85 matched pairs) between cases managed with SRS and patients managed with MS. Cases were matched for age at surgery (± 10 years) and lesion size (± 0.1 cm). To compare hearing outcomes, cases were additionally matched for preoperative Class A hearing according to the American Academy of Otolaryngology-Head and Neck Surgery guidelines. To compare facial nerve (i.e., cranial nerve [CN] VII) outcomes, cases were additionally matched for preoperative House-Brackmann (HB) score. Investigators who were not involved with patient care reviewed the clinical and imaging records. The reported outcomes were as assessed at the time of the last follow-up, unless otherwise stated. RESULTS The preservation of preoperative Class A hearing status was achieved in 14.3% of MS cases compared with 42.9% of SRS cases (OR 4.5; p < 0.05) after an average follow-up interval of 43.7 months and 30.3 months, respectively. Serviceable hearing was preserved in 42.8% of MS cases compared with 85.7% of SRS cases (OR 8.0; p < 0.01). The rates of postoperative CN VII dysfunction were low for both groups, although significantly higher in the MS group (HB III–IV 11% vs 0% for SRS; OR 21.3; p < 0.01) at a median follow-up interval of 35.7 and 19.0 months for MS and SRS, respectively. There was no difference in the need for subsequent intervention (2 MS patients and 2 SRS patients). CONCLUSIONS At this high-volume center, VS resection or radiosurgery for tumors ≤ 2.8 cm in diameter was associated with low overall morbidity. The need for subsequent intervention was the same in both groups. SRS was associated with improved hearing and facial preservation rates and reduced morbidity, but with a shorter average follow-up period. Facial function was excellent in both groups. Since patients were not randomly selected for surgery, different clinical outcomes may be of different value to individual patients. Both anticipated medical outcomes and patient goals remain the drivers of treatment decisions.
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Gamma Knife radiosurgery for vestibular schwannoma: clinical results at long-term follow-up in a series of 379 patients
Article
Full-text available
  • Dec 2014
Object: Since the 1990 s, Gamma Knife radiosurgery (GKRS) has become the first-line treatment option for small- to medium-size vestibular schwannomas (VSs), especially in patients without mass effect-related symptoms and with functional hearing. The aim of this study was to assess the safety and efficacy of GKRS, in terms of tumor control, hearing preservation, and complications, in a series of 379 consecutive patients treated for VS. Methods: Of 523 patients treated at the authors' institution for VS between 2001 and 2010, the authors included 379 who underwent GKRS as the primary treatment. These patients were not affected by Type 2 neurofibromatosis and had clinical follow-up of at least 36 months. Clinical follow-up (mean and median 75.7 and 69.5 months, respectively) was performed for all patients, whereas audiometric and quantitative radiological follow-up examinations were obtained for only 153 and 219 patients, respectively. The patients' ages ranged from 23 to 85 years (mean 59 years). The mean tumor volume was 1.94 ± 2.2 cm(3) (median 1.2 cm(3), range 0.013-14.3 cm(3)), and the median margin dose was 13 Gy (range 11-15 Gy). Parameters considered as determinants of the clinical outcome were long-term tumor control, hearing preservation, and complications. A statistical analysis was performed to correlate clinical outcomes with the radiological features of the tumor, dose-planning parameters, and patient characteristics. Results: Control of the tumor with GKRS was achieved in 97.1% of the patients. In 82.7% of the patients, the tumor volume had decreased at the last follow-up, with a mean relative reduction of 34.1%. The rate of complications was very low, with most consisting of a transient worsening of preexisting symptoms. Patients who had vertigo, balance disorders, or facial or trigeminal impairment usually experienced a complete or at least significant symptom relief after treatment. However, no significant improvement was observed in patients previously reporting tinnitus. The overall rate of preservation of functional hearing at the long-term follow-up was 49%; in patients with hearing classified as Gardner-Robertson (GR) Class I, this value was 71% and reached 93% among cases of GR Class I hearing in patients younger than 55 years. Conclusions: Gamma Knife radiosurgery is a safe and effective treatment for VS, achieving tumor control in 97.1% of cases and resulting in a very low morbidity rate. Younger GR Class I patients had a significantly higher probability of retaining functional hearing even at the 10-year follow-up; for this reason, the time between symptom onset, diagnosis, and treatment should be shortened to achieve better outcomes in functional hearing preservation.
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Operative Strategies during Awake Surgery Affect Deterioration of Paresis a Month after Surgery for Brain Lesions in the Primary Motor Area
Article
  • Oct 2016
Introduction We analyzed factors associated with worsened paresis at 1-month follow-up in patients with brain tumors located in the primary motor area (M1) to establish protocols for safe awake craniotomy for M1 lesions. Methods Patients with M1 brain tumors who underwent awake surgery in our hospital (n = 61) were evaluated before, during, and immediately and 1 month after surgery for severity of paresis, tumor location, extent of resection, complications, preoperative motor strength, histology, and operative strategies (surgery stopped or continued after deterioration of motor function). Results Worsened paresis at 1-month follow-up was significantly associated with worsened paresis immediately after surgery and also with operative strategy. Specifically, when motor function deteriorated during awake surgery and did not recover within 5 to 10 minutes, no deterioration was observed at 1-month follow-up in cases where we stopped surgery, whereas 6 of 13 cases showed deteriorated motor function at 1-month follow-up in cases where we continued surgery. Conclusion Stopping tumor resection on deterioration of motor function during awake surgery may help prevent worsened paresis at 1-month follow-up.
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Optimal outcomes for hearing preservation in the management of small vestibular schwannomas
Article
  • May 2016
Objective: To undertake a systematic review of the role of microsurgery, in relation to observation and stereotactic radiation, in the management of small vestibular schwannomas with serviceable hearing. Methods: The Medline database was searched for publications that included the terms ‘vestibular schwannoma’ and/or ‘acoustic neuroma’, occurring in conjunction with ‘hearing’. Articles were manually screened to identify those concerning vestibular schwannomas under 1.5 cm in greatest dimension. Thereafter, only publications discussing both pre-operative and post-operative hearing were considered. Results: Twenty-six papers were identified. Observation is an acceptable strategy for small tumours with slow growth where hearing preservation is not a consideration. In contrast, microsurgery, including the middle fossa approach, may provide excellent hearing outcomes, particularly when a small tumour has begun to cause hearing loss. Immediate post-operative hearing usually predicts long-term hearing. Recent data on stereotactic radiation suggest long-term deterioration of hearing following definitive therapy. Conclusion: In patients under the age of 65 years with small vestibular schwannomas, microsurgery via the middle fossa approach offers durable preservation of hearing.
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Middle Fossa Approach for Vestibular Schwannoma: Good Hearing and Facial Nerve Outcomes with Low Morbidity
Article
  • May 2016
Objective: The middle fossa approach (MFA) is not used as frequently as the traditional translabyrinthine and retrosigmoid approaches for accessing vestibular schwannomas (VSs). Here, MFA was used to remove primarily intracanalicular tumors in patients in whom hearing preservation is a goal of surgery. Methods: The authors performed a retrospective chart review to identify consecutive adult patients who underwent MFA for VS. Demographic profile, perioperative complications, pre- and postoperative hearing, and facial nerve outcomes were analyzed with linear regression analysis to identify factors predicting hearing outcome. Results: Among 78 identified patients (mean age 49 years, 53% female, mean tumor size 7.5 mm), 78% had functional hearing preoperatively (American Academy of Otolaryngology-Head and Neck Surgery class A/B). Follow-up audiological data was available for 60 patients overall (mean follow-up 15.1 months). The hearing preservation rate was 75.5% (37/49) at last known follow-up for patients with functional hearing preoperatively. Other than preoperative hearing status (p<0.001), none of the factors assessed, including demographic profile, size of tumor and fundal fluid cap, predicted hearing preservation (p>0.05). Good functional preservation of the facial nerve (House-Brackmann class I/II) was achieved in 90% of patients. The only operative complications were 3 wound infections (3.8%). Conclusion: Preliminary results from this single-center retrospective study of patients undergoing MFA for resection of VS showed that good hearing preservation and facial nerve outcomes could be achieved with few complications. These results suggest that resection via the MFA is a rational alternative to watchful waiting or stereotactic radiosurgery.
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Small Vestibular Schwannomas: Does Surgery Remain a Viable Treatment Option?
Article
  • Oct 2015
Background Surgery for small vestibular schwannomas (Koos grade I and II) has been increasingly rejected as the optimal primary treatment, instead favoring radiosurgery and observation that offer lower morbidity and potentially equal efficacy. Our study assesses the outcomes of contemporary surgical strategies including tumor control, functional preservation, and implications of pathologic findings. Design Retrospective review. Setting/Participants Eighty consecutive patients (45 women, 35 men; mean: 47 years of age). Main Outcomes Measures Approaches included retrosigmoid approach (52%), translabyrinthine (40%), and middle fossa (8%). Operated on by the same surgical team, we analyzed presentation, radiographic imaging, surgical data, and outcomes. Results At last follow-up (mean: 34 months), 95% had good facial nerve function (House-Brackmann grade I or II); 36% who presented with serviceable hearing retained it; and 93% who presented with vestibular dysfunction reported resolution. Pathology identified two grade I meningiomas. Conclusions As one of the largest contemporary surgical series of small vestibular schwannomas, we discuss some nuances to help refine treatment algorithms. Although observation and radiosurgery have established roles, our results reinforce microsurgery as a viable, safe option for a subgroup of patients.
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Functional Preservation After Planned Partial Resection Followed by Gamma Knife Radiosurgery for Large Vestibular Schwannomas
Article
  • Mar 2015
The treatment goal for vestibular schwannomas (VS) has been changed from total removal of the tumor to functional preservation with long-term tumor growth control. The small to medium sized VSs can be treated by stereotactic radiosurgery, but large VSs require surgical decompression for the relief of cerebellar dysfunction and increased intracranial pressure. We have been performing planned partial surgical resections followed by gamma knife radiosurgery (GKS) for large VSs. Here, we evaluate a recent series of such cases from the standpoint of functional outcomes. From January 2000 to May 2013, we treated 40 patients with large unilateral VSs (maximum tumor diameter: at least 25 mm) with planned partial tumor removal followed by GKS for functional preservation. The median maximum diameter of the tumors was 32.5 mm (range 25 - 52 mm). All patients were operated using the retrosigmoid approach, and tumors situated on the ventral and in the internal auditory canal were intentionally not removed, thus preserving cranial nerve functions. GKS was performed 1 to 12 months after surgical resection (median interval 3 months). The median tumor volume at GKS was 3.3 cm(3) (range 0.4 - 10.4 cm(3)) and the median prescribed dose was 12 Gy (range 10 - 12 Gy). The median follow-up period after GKS was 65 months (18- 156 months). At the final follow-up, facial nerve preservation (House-Brackmann, HB grade I - II) was achieved in 38 patients (95%; HB grade I: 92.5%, II: 2.5%). Among the 14 patients with preoperative pure tone average (PTA) below 50 dB, 6 of them (42.9%) maintained PTA below 50 dB at the last follow-up. Two patients improved from severe hearing loss to PTA below 50 dB (one patient after surgery and one patient one and half years after GKS). Five- and 10-year tumor growth control occurred in 86% of patients. Four patients (10%) required salvage surgery; the predictive factor being tumor volume above 6 cm(3) at GKS (p=0.01). Planned partial removal of large VSs followed by GKS achieved a high rate of facial nerve and hearing preservation. To achieve long-term tumor growth control, the tumor volume at GKS after planned partial surgical resection should be smaller than 6 cm(3). Our results revealed that patients with hearing preservation postoperatively have a chance of maintaining hearing function, even though the possibility exists of deterioration by long-term follow-up after surgical intervention and GKS. Furthermore, some patients with severe hearing loss before treatment have the chance of hearing improvement, even those with large VSs. Copyright © 2015 Elsevier Inc. All rights reserved.
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Long-term vestibulocochlear functional outcome following retro-sigmoid approach to resection of vestibular schwannoma
Article
  • Feb 2015
The objective of this study was to evaluate long-term vestibulocochlear functional outcomes of patients operated for unilateral vestibular schwannoma via the retro-sigmoid approach. Patients who underwent vestibular schwannoma resection via retro-sigmoid approach between 2004 and 2008 at our institution, without prior surgical or radio-surgical therapy were considered to be eligible for this study. Preoperative auditory and vestibular symptoms were assessed retrospectively. Postoperative symptoms were prospectively assessed using a standardised questionnaire, pure tone audiometry, video-oculography, and rotary chair testing. Out of a total of 203 patients, 120 were eligible for this study, of whom 64 responded to follow-up requests and could be enrolled. Serviceable hearing was reported in 42 patients (66 %) preoperatively and was maintained in 18 (43 %) postoperatively. While no significant change in rate of tinnitus and balance impairment between pre- and postoperative periods was detected, vertigo decreased significantly (40 to 28 %, p < 0.001). Postoperative video-oculography demonstrated vestibular paresis in 80 %. Rotary chair testing demonstrated normal or central compensation in 84 %. Absence of central compensation was associated with postoperative balance disturbance (p = 0.035). Increasing tumour size and patient age, also decreasing quality of preoperative hearing were independent factors predictive of a postoperative non-serviceable hearing (p = 0.020, p = 0.039 and p = 0.002, respectively). Resection of vestibular schwannoma via the retro-sigmoid approach is associated with improvement in postoperative vertiginous symptoms. Absence of central compensation leads to increased postoperative balance disturbances. Preservation of serviceable postoperative hearing is associated with good preoperative hearing status, younger age, and smaller tumours.
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