Acoustic neuroma surgery: absent auditory brainstem response does not contraindicate attempted hearing preservation.

OBJECTIVE: Absence of auditory brainstem response (ABR) waveforms has been associated with a poor likelihood of hearing preservation following resection of acoustic neuromas. Our experience is reviewed for patients with absent preoperative ABR regarding hearing preservation, hearing improvement, and return of ABR. STUDY DESIGN: Retrospective review of 22 cases of acoustic neuroma resection. Nine patients with absent preoperative ABR were identified. All underwent tumor resection utilizing intraoperative cochlear nerve action potential (CNAP) monitoring. Postoperative hearing results and ABR waveforms were examined. METHODS: Charts were reviewed and tabulated for age, sex, tumor side, tumor size, preoperative and postoperative audiometric and ABR results, intraoperative monitoring results by ABR and CNAP, and surgical complications. RESULTS: Hearing preservation was achieved in seven of nine patients (78%) with absent preoperative ABR, as well as six of seven patients (86%) with tumors less than or equal to 20 mm in greatest dimension. Although intraoperative ABR monitoring was not possible in any of these patients, CNAP monitoring was successful in all. Return of ABR waveforms was observed in four of the six patients (67%) tested from 3 to 22 months postoperatively. Four of the seven patients (57%) enjoyed improvement in hearing class as defined by the guidelines of the American Academy of Otolaryngology-Head and Neck Surgery. CONCLUSIONS: Absent ABR waveforms have not been a negative prognostic sign regarding hearing preservation. CNAP monitoring is possible in these patients and likely helps to minimize iatrogenic cochlear nerve trauma. Patients with no ABR waveforms have hope of hearing preservation and even improvement following acoustic neuroma resection performed utilizing CNAP monitoring and hearing preservation surgical techniques.     

两种听觉监护在听神经瘤术中的联合应用及评价

目的　探讨听神经瘤手术中听觉监护的意义。比较听性脑干反应（ABR）和蜗神经动作电位（cochlear nerve action potential,CNAP）在听觉监护应用中的价值。方法　回顾性分析我中心12例保留听力手术的听神经瘤患者资料及术中情况,患者术前均有实用听力（AAO-HNS分级A级、B级）,可引出ABR波形,V波分化可,所有手术均采取乙状窦后径路摘除肿瘤。所有患者均全程ABR监护,术中打开脑膜后联合监测CNAP。结果　手术过程中所有患者ABR波形较术前基线均有不同程度的变化,可记录到V波潜伏期均较基线延长（0.68±0.41）ms。CNAP波幅个体差异性较大,可记录到的P1潜伏期均较基线延长（0.25±0.16）ms。12例中有8例（66.7%）患者术后保留可用听力;另外4例（33.3%）术后达不到可用听力,此4例患者ABR表现为3例V波消失,1例V波潜伏期延长。CNAP表现为2例CNAP的P1消失,2例P1延长。电钻钻磨造成的震动和噪声、手术时神经被牵拉或热损伤后等急性损伤后ABR和CNAP波幅均出现短时间急剧下降,手术暂停5 min后,部分患者波幅可在一定程度恢复。结论　听神经瘤手术中ABR和CNAP对于听觉监护均有一定意义。ABR波形稳定可靠,但叠加时间相对较长;CNAP叠加快速,可提升监测灵敏度,但波形变异度较大。电钻钻磨造成的震动和噪声、操作过程中对神经组织的牵拉以及热损伤均被及时监控,两者联合应用可提升听神经瘤手术的听觉功能保留率。     

A comparison of direct eighth nerve monitoring and auditory brainstem response in hearing preservation surgery for vestibular schwannoma.

OBJECTIVE: The objective of this study was to compare the effectiveness of direct eighth nerve monitoring (DENM) and auditory brainstem response (ABR) in facilitating hearing preservation during vestibular schwannoma resection. STUDY DESIGN: This was a retrospective study. SETTING:: Tertiary referral center. METHODS: We conducted a retrospective clinical study of the use of ABR and DENM during vestibular schwannoma removal. Tumors were removed through a retrosigmoid craniotomy. The rate of hearing preservation between the two monitoring modalities was compared. The additional outcome measures of facial nerve function and cerebral spinal fluid leak rate were also evaluated. RESULTS: Hearing preservation was attempted in 77 patients with vestibular schwannomas. Tumor sizes ranged from 0.5 cm to 2.5 cm. Hearing was preserved in 71% of patients with tumors 1 cm or less and in 32% of patients with tumors between 1 and 2.5 cm when direct eighth nerve monitoring was used. Hearing preservation rates with ABR for tumors 1 cm or less were 41% and 10% in patients with tumors between 1 and 2.5 cm (p=0.03) Facial nerve preservations rates were 94% (House-Brackmann 1-2) for tumors less than 2 cm. CONCLUSIONS: DENM provides significantly higher rates of hearing preservation during vestibular schwannoma resection when compared with ABR.     

Steroid and vasoactive treatment for acute deafness after attempted hearing preservation acoustic neuroma surgery

OBJECTIVE: To investigate whether intravenous steroid and vasoactive therapy in the acute postoperative period improves hearing outcome in patients who develop acute deafness after attempted hearing preservation surgery for acoustic neuroma (AN) through a retrosigmoid or a middle cranial fossa approach. STUDY DESIGN AND SETTING: Retrospective controlled study in a tertiary care center. Thirty-six patients who had developed acute deafness after hearing preservation surgery for treatment of an AN were reviewed. Preoperative AAOHNS hearing class was A in 2, B in 2 and D in 32 patients. Twenty-seven patients were treated with prednisolone, hydroxyethyl starch 3% and pentoxifylline intravenously for a period of at least 5 days. Nine patients (controls) did not receive any specific steroid or vasoactive therapy. RESULTS: All patients in both groups remained deaf. CONCLUSIONS: Intravenous therapy with prednisolone, hydroxyethyl starch 3% and pentoxifylline in the acute postoperative period does not improve hearing in patients who develop acute deafness after attempted hearing preservation surgery for AN.     

听神经瘤术中听力监测及术后听力保留影响因素分析

目的探讨听神经瘤术中听力监测的应用及术后听力保留的可能影响因素。方法16例采用乙状窦后入路手术切除听神经瘤的成年患者,分为两组,术中采用听性脑干反应(auditory brainstem response,ABR)和耳蜗电图(electrocochleogram,ECochG)联合监测为监测组(8例),未监测者为未监测组(8例),比较两组患者术后听力保留情况,采用单因素分析,分析影响听力保留的可能因素,包括:年龄、病程、肿瘤大小、术前纯音听阈和言语识别率、术中是否行ABR和ECochG联合监测、内听道是否扩大、肿瘤和神经是否粘连等。结果前庭诱发肌源性电位(VEMP)提示16例患者肿瘤来源于前庭上神经,监测组中6例术中及术毕ABR波Ⅰ、Ⅴ和复合动作电位(CAP)持续存在,术后听力保留;1例术中ABR波Ⅰ、Ⅴ和ECochG CAP持续存在,但术后无可用听力;1例术中切除肿瘤时ECochG与基线重复性良好,ABR波V消失,手术结束波V仍未恢复;监测组术后听力保留率为75.0%(6/8),未监测组术后无一例保留听力,差异有统计学意义(P=0.007)。单因素分析显示,年龄、病程、肿瘤大小、术前纯音听阈以及内听道扩大与术后听力保留率无关(P>0.05),术前言语识别率、术中ABR和ECochG联合监测、肿瘤和神经粘连与否与术后听力保留率相关(P<0.05)。结论听神经瘤切除术中ABR和ECochG连续监测对指导手术和提高术后听力保留率有重要意义,肿瘤与神经粘连是术后听力保留的重要影响因素,手术技巧、术前听力、肿瘤大小、内听道扩大等是否是术后听力保留的影响因素需扩大样本进一步研究验证。     

Hearing Preservation in Acoustic Neuroma Surgery

Introduction An acoustic neuroma (AN) is a neurinoma arisingfrom the vestibular branch of the VIIIth cranial nerve,thereby also termed “vestibular schawnnomas (VS)”.The histo-pathologically benign nature of this tumorgives the possibility for neuro-otologists to preserve thecochlear nerve and hearing in tumor resection sur-geries. Advances in imaging technology have greatlyimproved early diagnosis of ANs with very small sizesand made tumor removal without significantly insultinghearing. …     

Hearing preservation using combined monitoring of extra-tympanic electrocochleography and auditory brainstem responses during acoustic neuroma surgery

The aim of this study was to evaluate the efficacy of an intraoperative monitoring hearing preservation strategy that includes simultaneous recordings of an auditory brainstem response (ABR) and non-invasive electrocochleography (ECochG). The combined ABR and tympanic membrane (TM) ECochG testing was performed in 74 patients undergoing acoustic neuroma (AN) surgery. In addition, EMG recordings were conducted to monitor the facial nerve function. Hearing was preserved in 19 of the 30 patients with residual hearing prior to surgery (63%), and facial nerve function was maintained in 89% of the patients. In most cases, the presence of both auditory brainstem and TM-ECochG responses at the end of surgery was associated with preservation of postoperative functional hearing; however, eight patients had a TM-ECochG response with a complete loss of the ABR, pointing to deafferentation of the auditory nerve. Tumour size and preoperative hearing thresholds significantly affected the postoperative hearing. The TM-ECochG response yielded large reproducible responses, which, in some patients, was the only way to monitor the auditory function. This auditory monitoring approach offers a valuable auditory tool that helps to improve the hearing preservation during AN surgery.     

Hearing preservation using combined monitoring of extra-tympanic electrocochleography and auditory brainstem responses during acoustic neuroma surgery

The aim of this study was to evaluate the efficacy of an intraoperative monitoring hearing preservation strategy that includes simultaneous recordings of an auditory brainstem response (ABR) and non-invasive electrocochleography (ECochG). The combined ABR and tympanic membrane (TM) ECochG testing was performed in 74 patients undergoing acoustic neuroma (AN) surgery. In addition, EMG recordings were conducted to monitor the facial nerve function. Hearing was preserved in 19 of the 30 patients with residual hearing prior to surgery (63%), and facial nerve function was maintained in 89% of the patients. In most cases, the presence of both auditory brainstem and TM-ECochG responses at the end of surgery was associated with preservation of postoperative functional hearing; however, eight patients had a TM-ECochG response with a complete loss of the ABR, pointing to deafferentation of the auditory nerve. Tumour size and preoperative hearing thresholds significantly affected the postoperative hearing. The TM-ECochG response yielded large reproducible responses, which, in some patients, was the only way to monitor the auditory function. This auditory monitoring approach offers a valuable auditory tool that helps to improve the hearing preservation during AN surgery.     

Intraoperative monitoring of early auditory evoked potentials in hearing acoustic neuroma patients complemented by cochlear nerve action potentials]

Hearing preservation was attempted in eight cases of acoustic neurinomas with good preoperative hearing. This was successful in 3 cases. Brain-stem auditory evoked potentials (BAEP0 were monitored in all cases, and compound nerve action potentials (CNAP) were recorded from the cochlear nerve in the last 3 cases. The BAEP was extremely sensitive to intraoperative manipulation. Intraoperative loss of wave V in BAEP was observed not only in all 5 cases with postoperative hearing loss, but also in 2 out of 3 cases with successful hearing preservation. CNAP correlated better with the hearing outcome than BAEP. In the cases where hearing was preserved, intact CNAP responses were demonstrated at the end of the operation. Conversely, deterioration of CNAP was seen in a case of postoperative hearing loss. CNAP was 10-15 times larger in amplitude than BAEP, so that the new responses were obtainable in shorter intervals. This capability of frequent examination seemed to increase the possibility of avoiding irreversible damage to the hearing by changing surgical tactics. The addition of CNAP monitoring is a good supplement to conventional BAEP monitoring in acoustic neurinoma surgery.     

Evaluation of three intraoperative auditory monitoring techniques in acoustic neuroma surgery

OBJECTIVE: To assess the efficacy of three intraoperative auditory monitoring techniques: auditory brainstem response (ABR), electrocochleography (ECoG), and direct eight nerve monitoring (DENM). STUDY DESIGN: A retrospective review of the intraoperative recordings of ABR, ECoG, and DENM was performed. SETTING: A private, neurotologic practice. PATIENTS: Sixty-six patients with usable preoperative hearing underwent intraoperative auditory monitoring with ABR, ECoG, or DENM. INTERVENTIONS: Intraoperative auditory monitoring. MAIN OUTCOME MEASURES: Postoperative pure-tone hearing threshold and word recognition scores. RESULTS: Of the 66 patients, 16 (24%) had postoperative serviceable hearing. Five (18%) of the 28 with ABR monitoring, 3 (17%) of the 18 with ECoG monitoring, and 8 (40%) of the 20 with DENM monitoring had serviceable hearing after surgery. CONCLUSIONS: This study suggests that DENM may be more effective than ABR or ECoG, although the differences in hearing preservation rates are not statistically significant.     

Transient evoked otoacoustic emissions pattern as a prognostic indicator for hearing preservation in acoustic neuroma surgery.

OBJECTIVE: To determine whether pre-operative transient otoacoustic emission (TEOAE) patterns are predictive of successful hearing preservation in acoustic neuroma surgery. STUDY DESIGN: Retrospective observational study. SETTING: Tertiary referral medical center. PATIENTS: A convenience sample was identified in whom pre-operative TEOAE data were available in patients undergoing acoustic neuroma surgery from 1993-2004. Ninety-three patients were identified who met this inclusion criterion. INTERVENTIONS: Subjects underwent attempted hearing preservation surgery via middle cranial fossa or retrosigmoid approaches. Routine audiometry, ABR, and TEOAE. MAIN OUTCOME MEASURES: Pre- and post-operative pure tone and speech results were categorized into hearing classes A, B, C, and D as described in the American Academy of Otolaryngology guidelines (1995). Hearing preservation was defined by maintenance of the pre-operative hearing class or downgrade to within one hearing class post-op. Pre-operative TEOAE results were divided into five frequency bands and described as positive in each band if there was a response above the noise floor with >50% reproducibility. RESULTS: Hearing was preserved in 51 patients (55%). Of these, 11 (22%) had positive TEOAE response in all five frequency bands measured (1, 1.5, 2, 3, 4 kHz), whereas 40 (78%) had TEOAE responses ranging from 0 to 4 frequency bands. 42 patients failed to preserve their hearing. Of these, only three (7%) had positive TEOAE in all five frequency bands, and 39 (93%) had TEOAE responses ranging from 0 to 4 frequency bands (p<0.05). Other variables of prognostic significance to hearing preservation in our series included smaller tumor size, tumor location within the IAC, better pre-operative hearing, and shorter latencies on ABR. Logistic regression was then used to compare the prognostic value of TEOAE against these variables. In our series, ABR latencies and 5 frequency band response on TEOAE showed the highest significant correlation to hearing preservation (p<0.05). CONCLUSION: A robust pre-operative TEOAE frequency band pattern may be used as a favorable prognostic indicator for potential hearing preservation in acoustic neuroma surgery. The prognostic value may be enhanced when combined with other prognostic factors such as tumor size, tumor location, pre-operative ABR and audiometric results.     

Association between surgical steps and intraoperative auditory brainstem response and electrocochleography waveforms during hearing preservation vestibular schwannoma surgery

Intraoperative monitoring of the auditory pathway by means of either electrocochleography or auditory brainstem response audiometry is valuable during hearing preservation vestibular schwannoma (VS) surgery. A more than 75% intraoperative reduction of the amplitude of these evoked auditory potentials was thought to be related with clear hearing compromise of hearing. We identified 22 patients who satisfied this intraoperative criterion in a cohort of 86 consecutive patients who had attempted hearing preservation VS surgery. The surgical step that temporally coincided with the above event was considered to be the most critical step for hearing monitoring during this kind of surgery. Most frequently, drilling of the internal auditory canal and direct tumor resection were associated with the aforementioned changes, but also drilling of the cortical temporal bone at the very beginning of surgery or the opening of the dura could be implicated. This profound intraoperative amplitude decrease was associated with a profound postoperative hearing impairment in 84% of the cases.     

耳神经外科手术中听觉监护的技术及评价

综述听觉监测在耳神经外科手术中的应用及价值。听觉监测主要是通过对术中听觉通路的监测和预警作用来保护听觉。常见的听觉监测有听性脑干反应、耳蜗电图、听神经直接动作电位和畸变产物耳声发射，其中听神经直接动作电位比其他方法更能体现实时监测的优势。随着监测技术的发展和监测经验的积累，听觉监测能在耳神经外科手术治疗中为听觉的保护起到更大的作用。     

Prevalence of auditory neuropathy/synaptopathy in a population of children with profound hearing loss

OBJECTIVE: To examine the prevalence of auditory neuropathy/synaptopathy (AN/AS) in a cohort of children with profound hearing loss. METHODS: From 1997 until 2004, 5190 children, aged 1-15 years, whose hearing ability was uncertain or who had risk factors for hearing impairment were investigated with subjective and objective hearing tests. Three thousand four hundred and fifteen from these children were screened for AN/AS using pure-tone audiometry, impedance measurement, transient evoked otoacoustic emissions (TEOAE) and click-evoked auditory brainstem responses (ABR). RESULTS: From 3415 patients who participated in an ABR and TEOAE assessment, 379 children showed absent or elevated (> or = 80 dB nHL) ABR thresholds. Within this group we found 32 cases with evidence of AN/AS via visible TEOAE and/or cochlear microphonics (CM) coupled with absent ABR. In the remaining 3036 children, AN/AS, could be ruled out by means of detectable ABR-thresholds and coherent findings in pure-tone audiometry and TEOAE assessment. This results in a prevalence of AN/AS of 0.94% within the group at risk for hearing loss, compared to 8.44% among profoundly hearing impaired children. CONCLUSION: This study shows that AN/AS is a common finding in the population of hearing impaired infants. In the majority of our AN/AS children (50%, n=16), an early audiological diagnosis was made under the age of 12 months. Therefore, clinicians and other health care professionals should generally be sensitised for AN/AS in infants, so that an appropriate treatment can promptly be initiated. Further research on clinical and pathophysiological aspects is necessary to better identify and manage patients suffering from AN/AS.     

听神经瘤术中连续听力监测的初步探讨

目的探讨听神经瘤外科术中连续听力监测的意义。方法采用乙状窦人路，在听性脑干反应（auditory brainstem response，ABR）和耳蜗电图（electrocochleogram，ECochG）监测下完成的听神经瘤切除术10例。对手术过程和术后听力结合术中监测进行分析。结果10例听神经瘤术前听力A级3耳，B级4耳，C级3耳（美国耳鼻咽喉头颈外科学会分级标准）。术前的ABR检查Ⅰ、Ⅲ、Ⅴ波存在者5耳（A级3耳，B级2耳），仅见Ⅰ波者5耳（B级2耳，C级3耳）。麻醉后手术前的监测显示：Ⅰ、Ⅲ、Ⅴ波存在者2耳，仅Ⅰ波存在者6耳，以复合动作电位（compound action potential，CAP）的N1波代替波Ⅰ；无波形者2耳。术后听力保留2耳，肿瘤均〈2cm，术前听力都为A级；连续听力监测显示1耳术中及术毕时Ⅰ、Ⅲ、Ⅴ持续存在，1耳Ⅰ、Ⅲ波存在，Ⅴ波消失；术后听力均为A级。听力未保留8耳，其中6耳术中监测时仅CAP的N1（波Ⅰ）存在，手术过程中夹内听动脉或处理内耳道处肿瘤时，4耳CAP波幅明显下降，甚至下降至0，术毕又恢复至术前的50％～60％或正常；1耳蜗神经与肿瘤一并切除，但CAP始终存在；1耳因牵拉脑干侧的耳蜗神经，CAP波幅降至0，手术结束亦未恢复。2耳为全身麻醉后术前监测中未引出任何波形者，其中1耳术中切除部分肿瘤后，出现CAP波，但波幅低，直至术毕；1耳始终未出现波形。结论联合应用ABR和ECochG术中监测，对提高听力保护率有积极意义，能及时反映术中与保留听力相关的敏感手术步骤，然而外科医师的熟练的解剖和精确的手术技巧是手术成功的最基本因素。     

397例听神经瘤听力特征分析

目的 分析听神经瘤患者听力学特征,为筛查听神经瘤提供参考依据。方法 回顾性分析2019年8月—2022年4月诊治的397例单侧听神经瘤患者临床资料,所有患者均行纯音测听、声导抗测试、言语识别率(SDS)、畸变产物耳声发射(DPOAE)、听性脑干诱发电位(ABR)和颅脑增强MRI。结果 以典型症状就诊者312例,非典型症状就诊者85例。以突发性聋就诊者25例;患耳听力正常者54例,包含大型甚至特大型肿瘤,99例全聋者亦包含内听道和中型肿瘤。5例全聋者言语识别能力未完全消失。DPOAE一致型245例,耳蜗型72例,蜗后型79例。ABR阳性率98.0%(389/397),8例ABR波形正常者中3例为双侧非对称听力损失。结论 非典型症状就诊者占比21.4%,以突发性聋就诊、听力正常或ABR正常者不能排除听神经瘤;DPOAE和ABR可作为筛查听神经瘤的重要检查方法。     

听神经瘤致聋机理——14例(16耳)听神经瘤病人听力测试结果分析

目的 :探讨听神经瘤听力损失的病理生理机制。方法 :对 14例 (16耳 )听神经瘤患者行纯音听阈、阻抗、听性脑干反应 (ABR)、诱发耳声发射测试 (EOAE)及 CT和 (或 ) MRI扫描。 EOAE能引出的 4耳还检测其传出抑制功能 ,ABR不能检测且 EOAE不能引出的重度聋 (听力损失大于 80 d B)有 5耳行鼓岬刺激试验 (PST)。结果 :16耳听神经瘤中2耳 (12 .5 0 % )听力损失源于神经性损害 ;6耳 (37.5 0 % )蜗性损害 ;8耳 (5 0 % )蜗 -神经性损害。能引出 EOAE的 4耳均有传出功能障碍。结论 :EOAE可评价听神经瘤的耳蜗功能状态 ;ABR结合 PST能分析听神经瘤的蜗后神经功能。听神经瘤的听觉病理可同时或单独发生于听外周的耳蜗水平、第 对颅神经 (传入神经 )水平和橄榄核耳蜗传出神经水平。     

Small acoustic neuromas: surgical outcomes versus observation or radiation.

OBJECTIVE: Evaluate factors affecting outcomes of small acoustic neuroma (AN) removal via a middle cranial fossa (MCF) approach, and compare results to published data on observation and radiation therapy. STUDY DESIGN: Retrospective chart review. SETTING: Academic tertiary referral center. METHODS: 162 consecutive patients (ages 19-70) with unilateral AN (0.2-2.5 cm in largest dimension) removed through a MCF approach were reviewed focusing on preservation of hearing, facial nerve function and complications. One hundred thirteen patients had pre-operative word recognition scores (WRS)>70%. RESULTS: Both tumor size and pre-operative WRS were related to post-operative WRS (p<0.01). Overall, at least some hearing was preserved in 94 (60%) of the 156 patients who had hearing before surgery. If the WRS was also >70% (N=113), 56 (50%) maintained WRS>70%. Importantly, WRS for 12 others improved to >70% after surgery. When the patients were stratified by tumor size, the patients with small tumors (2-10 mm) faired better than the overall group. At least some hearing was preserved in 65 (72%) of the 90 patients. If the WRS was also >70% (N=66), 39 (59%) maintained WRS>70%. WRS for eight others improved to >70% after surgery. When the tumor was 1.1-1.4 cm (N=34), the chance of preserving some hearing decreased to 42% (14/33). If the WRS was also >70% (N=23), 9 (39%) maintained WRS>70%. WRS for three others improved to >70% after surgery. When the tumor reached 1.5-2.5 cm (N=35), the hearing preservation rate was 43%. If the WRS was also >70% (N=24), only eight (33%) maintained WRS of 70%, and one other improved to >70%. The addition of intra-operative whole eighth nerve near field monitoring improved results during small tumor (70% WRS in 76% (22/29) of those with >70% pre-operative WRS. Good facial nerve function (HB I-II) was achieved in 97% (86% HB I). When tumor size was 相似文献   

Incidence of vocal cord paralysis with and without recurrent laryngeal nerve monitoring during thyroidectomy

OBJECTIVE: To compare the incidence of postoperative vocal cord paresis or paralysis in a cohort of patients who underwent thyroidectomy with and without continuous recurrent laryngeal nerve (RLN) monitoring by a single senior surgeon. We hypothesize that continuous RLN monitoring reduces the rate of nerve injury during thyroidectomy DESIGN: Retrospective medical chart review. SETTING: Academic tertiary care medical center. PATIENTS: A total of 684 patients (1043 nerves at risk) who underwent thyroid surgery under general anesthesia. MAIN OUTCOME MEASURE: Incidence of vocal cord paresis or paralysis in patients who underwent thyroid surgery with continuous RLN monitoring vs those undergoing surgery without continuous RLN monitoring. RESULTS: The incidence of unexpected unilateral vocal cord paresis based on RLNs at risk was 2.09% (n = 14) in the monitored group and 2.96% (n = 11) in the unmonitored group. This difference was not statistically significant. The incidence of unexpected complete unilateral vocal cord paralysis was 1.6% in each group. Two of the 5 paralyses in the unmonitored group and 7 of the 11 paralyses in the monitored group had complete resolution. CONCLUSIONS: Monitoring of the RLN does not appear to reduce the incidence of postoperative temporary or permanent complete vocal cord paralysis. There appeared to be a slightly lower rate of postoperative paresis with RLN monitoring, but this difference was not statistically significant.     

The evolution of surgical approaches for posterior fossa meningiomas.

OBJECTIVE: To evaluate surgical outcomes for the treatment of posterior fossa meningiomas at the House Ear Clinic from 1987 to 2001. We review our current treatment algorithm and present our postoperative outcomes with attention to facial and auditory neural preservation. STUDY DESIGN: Retrospective review. SETTING: Tertiary care center. PATIENTS: Medical records of 71 patients who underwent posterior fossa meningioma surgery at the House Ear Clinic were reviewed. INTERVENTION: All patients had surgical removal of their meningioma via translabyrinthine, transcochlear, retrosigmoid, extended middle fossa, or combined petrosal approaches by House Ear Clinic neurotologists and neurosurgeons. MAIN OUTCOME MEASURES: Preoperative and postoperative auditory and facial nerve function data were collected. Patient and tumor characteristics including presenting symptoms, completion of tumor resection, and complications secondary to surgery were also recorded. RESULTS: The most common presenting symptoms in this series were otologic, with hearing loss (61%), tinnitus (58%), and imbalance (58%) as the three most common. Gross total resection was achieved in 67 (94%) patients. Hearing-preservation surgery was attempted in 37 (52%) patients (68% via extended middle fossa or combined approach). Twenty-one patients with preoperative Class A hearing had follow-up audiometric data and 18 (86%) had serviceable hearing preserved. Excluding transcochlear craniotomies, 85% of patients had normal facial nerve function postoperatively. Cerebrospinal fluid leak (6%) was the most common complication. CONCLUSIONS: Advances in microsurgical techniques have greatly changed our management of patients with posterior fossa meningiomas. These changes have reduced postoperative morbidity. Specifically, use of the anterior and posterior petrosal approaches has facilitated facial and auditory neural preservation while not compromising the extent of tumor excision.