听神经瘤显微手术治疗和面听神经功能保护的探讨

目的探讨听神经瘤显做于术治疗和面听神经功能保护的疗效。方法分析1999年10月至2002年10月收治经枕下乙状窦后内听道入路手术切除30例听神经瘤的资料，全部病例采用保留面听神经功能的显做外科技术。结果听神经瘤手术全切除29例（96．7％），次全切除1例；面神经解剖保留25例（83．3％），手术后12周面神经功能保留21例（70％）；耳蜗神经解剖保留25例83．3％），手术后2周有效听力保留2例（占术前存在有效听力患者的28．6％），有效听力丧失但可测听力保留15例。结论枕下乙状窦后经内听道入路的听神经显微手术，能够取得较好的肿瘤全切除率和面听神经功能保留率.     

Functional results of preservation of cranial nerves in removal of acoustic neurinoma]

Seventeen patients with acoustic neurinoma were reviewed on the basis of postoperative preservation of facial and acoustic nerve functions. The sizes of tumors were intracanalicular in 5 cases, smaller than 20mm in diameter in 2 cases, smaller than 30mm in 5 cases, and larger than 30mm in 5 cases. In all cases, the facial nerve was anatomically preserved at operation. Functional recoveries of the facial nerve in follow-up were excellent in 7 cases out of 17 (41%), good in 5 (29%) and poor in 5 (29%). Although the functional preservation for the facial nerve was related to the size of the tumor, it was favorable in cases of cystic tumor even with a size larger than 20mm. By pure tone audiogram, hearing was found to be preserved in 12 cases before operation. At operation, the acoustic nerve was anatomically preserved in 4 cases. Postoperative hearing was maintained in two cases, one of which showed a successful preservation of serviceable hearing. In this case, tumor resection was performed with intraoperative monitoring of auditory brain stem reactions (ABRs). Discussion was made concerning a possible surgical candidates for the hearing preservation, and it was proposed that every effort should be made to preserve the cochlear nerve if following conditions were verified in the case: 1) normal or nearly normal hearing (less than 40-50dB hearing loss), 2) the size of tumor is intracanalicular or smaller than 2cm in diameter, 3) there is no deterioration of intraoperative ABR.     

Long-term results of the first 500 cases of acoustic neuroma surgery

OBJECTIVE: This retrospective study focuses on 2 outcome results after surgical intervention for acoustic neuroma: (1) facial nerve status, and (2) hearing preservation. STUDY DESIGN: A total of 484 patients with an acoustic neuroma. RESULTS: Postoperative facial nerve outcomes were significantly different (P < 0.001) according to the size of the tumors. Tumor size had even more influence on the immediate postoperative results. In addition, statistical significance (P < 0.05) was demonstrated in comparing facial nerve outcomes with the surgeon's surgical experience. We also noted that as the patient's age increases, the likelihood for facial dysfunction may increase for all postoperative intervals. The overall success rate of retaining useful hearing was 27% (26 of 95). Class A hearing was retained in 66% (10 of 15) of cases operated on through middle fossa approach in the last 5 years. CONCLUSION: This study demonstrates that tumor size and surgeon's experience are the most significant factors influencing the facial nerve status and hearing outcome after removal of acoustic neuroma.     

Preservation of hearing in surgery of acoustic neuroma

Between 1981 and 1984, 44 patients underwent acoustic neuroma removal by a posterior cranial fossa approach in an attempt to preserve hearing. 7 tumors were small (less than 20 mm), 28 were medium (20 to 40 mm) and 9 large (greater than 40 mm). Of these 44 patients, 4 had normal hearing preoperatively, 15 had serviceable hearing, 10 poor hearing and 15 no hearing. Postoperative hearing was preserved in 11 cases. Of the 19 patients with normal or serviceable hearing, 8 (42%) had serviceable hearing preserved postoperatively. Hearing preservation was achieved in 43% of the cases of small tumors, 25% of those medium tumors and 11% with large tumors. This study confirms the value of the suboccipital approach, which can be used in an attempt to preserve hearing whenever the patient has serviceable hearing preoperatively and whenever the tumor size makes in feasible.     

Transient facial nerve palsy after topical papaverine application during vestibular schwannoma surgery. Case report

Some evidence in the literature supports the topical application of papaverine to the cochlear nerve to prevent internal auditory artery vasospasm and cochlear ischemia as a method of enhancing the ability to preserve hearing during acoustic neuroma surgery. The authors report a case of transient facial nerve palsy that occurred after papaverine was topically applied during a hearing preservation acoustic neuroma removal. A 58-year-old woman presented with tinnitus and serviceable sensorineural hearing loss in her right ear (speech reception threshold 15 dB, speech discrimination score 100%). Magnetic resonance imaging demonstrated a 1.5-cm acoustic neuroma in the right cerebellopontine angle (CPA). A retrosigmoid approach was performed to achieve gross-total resection of the tumor. During tumor removal, a solution of 3% papaverine soaked in a Gelfoam pledget was placed over the cochlear nerve. Shortly thereafter, the quality of the facial nerve stimulation deteriorated markedly. Electrical stimulation of the facial nerve did not elicit a response at the level of the brainstem but was observed to elicit a robust response more peripherally. There were no changes in auditory brainstem responses. Immediately after surgery, the patient had a House-Brackmann Grade V facial palsy on the right side. After several hours, this improved to a Grade I. At the 1-month follow-up examination, the patient exhibited normal facial nerve function and stable hearing. Intracisternal papaverine may cause a transient facial nerve palsy by producing a temporary conduction block of the facial nerve. This adverse effect should be recognized when topical papaverine is used during CPA surgery.     

Operative management of acoustic neuromas: the priority of neurologic function over complete resection

The objective of surgical management of acoustic tumors is to remove them entirely and preserve facial nerve function and hearing when possible. A dilemma arises when it is not possible to remove the entire tumor without incurring additional neurologic deficits. Twenty patients who underwent intentional incomplete surgical removal of an acoustic neuroma to avoid further neurologic deficit were retrospectively reviewed. They were divided into a subtotal group (resection of less than 95% of tumor) and a near-total group (resection of 95% or more of tumor) and were followed yearly with either computed tomography or magnetic resonance imaging. The subtotal group was planned and consisted of elderly patients (mean age, 68.5 years) with large tumors (mean, 3.1 cm). The near-total group consisted of younger patients (mean age, 45.8 years) and smaller tumors (mean, 2.3 cm). The mean length of followup for all patients was 5.0 years. Ninety percent of patients had House grade I or II facial function post-operatively. Radiologically detectable tumor regrowth occurred in only one patient, who was in the subtotal resection group. Near-total resection of acoustic tumor was not associated with radiologic evidence of regrowth of tumor for the period of observation. Within the limits of the follow-up period of this study, subtotal resection of acoustic neuroma in elderly patients was not associated with clinically significant recurrence in most patients and produced highly satisfactory rates of facial preservation with low surgical morbidity.     

Facial nerve neuromas: report of 10 cases and review of the literature

OBJECTIVE: This study reviewed the management and outcomes of facial neuromas during the past decade at our institution. The goal was to analyze differences in presentation on the basis of location of the facial neuroma, review facial nerve function and hearing preservation postoperatively, and understand the characteristics of patients with tumors limited to the cerebellopontine angle or internal auditory canal. We also report an unusual case of a facial neuroma limited to the nervus intermedius. METHODS: Nine patients with facial neuromas and one with Jacobson's nerve neuroma underwent surgery, and total resection was accomplished in nine patients. A chart review for pre- and postoperative data was performed, after which all patients were evaluated on an outpatient basis. RESULTS: The mean age of the patients was 47 years; mean follow-up time was 33.1 months. The most common presenting symptoms were hearing loss (six patients) and facial paresis (five patients). A total of five patients had progressive (four patients) or recurrent (one patient) facial paresis. No patient experienced worsened hearing as a result of surgery, and one experienced improvement in a conductive hearing deficit. Five patients required cable graft repair of the facial nerve; four improved to House-Brackmann Grade 3 facial paresis. Four of five patients with preserved anatomic continuity of the facial nerve regained normal facial function. There were no surgical complications. No tumors have recurred during follow-up. We report the second nerve sheath tumor limited to the nervus intermedius. CONCLUSION: This series documents that facial neuromas can be resected safely with preservation of facial nerve and hearing function. Preservation of anatomic continuity of the facial nerve should be attempted, and it does not seem to lead to frequent recurrence. Tumors limited to the cerebellopontine angle/internal auditory canal are a unique subset of facial neuromas with characteristics that vary greatly from facial neuromas in other locations, and they are indistinguishable clinically from acoustic neuromas.     

Hearing preservation in acoustic neuroma surgery: importance of adhesion between the cochlear nerve and the tumor

OBJECT: To evaluate the possible prognostic factors for hearing preservation, the authors retrospectively reviewed the results of 30 consecutive acoustic neuroma operations in which hearing preservation was attempted, in a total series of 63 acoustic neuromas. METHODS: Intracanalicular tumors or those that extended less than 3 mm outside the porus acusticus (10 cases) were resected via the middle fossa approach. The retrosigmoid approach was used for tumors exceeding the limits for the middle fossa approach (20 cases). Overall, hearing was preserved (pure tone average < or = 50 dB and speech discrimination score > or = 50%) in 21 patients (70%). There were 11 patients with severe adhesion between the cochlear nerve and tumor capsule, and 19 without. Hearing was preserved postoperatively in only two (18.2%) of 11 patients with severe adhesion, whereas all 19 without severe adhesion had hearing preservation. CONCLUSIONS: The presence or absence of severe adhesion in the interface between the cochlear nerve and the tumor might be the most significant prognostic factor for hearing preservation postsurgery.     

Results of acoustic neuroma radiosurgery: an analysis of 5 years' experience using current methods

OBJECT: The goal of this study was to define tumor control and complications of radiosurgery encountered using current treatment methods for the initial management of patients with unilateral acoustic neuroma. METHODS: One hundred ninety patients with previously untreated unilateral acoustic neuromas (vestibular schwannomas) underwent gamma knife radiosurgery between 1992 and 1997. The median follow-up period in these patients was 30 months (maximum 85 months). The marginal radiation doses were 11 to 18 Gy (median 13 Gy), the maximum doses were 22 to 36 Gy (median 26 Gy), and the treatment volumes were 0.1 to 33 cm3 (median 2.7 cm3). The actuarial 5-year clinical tumor-control rate (no requirement for surgical intervention) for the entire series was 97.1+/-1.9%. Five-year actuarial rates for any new facial weakness, facial numbness, hearing-level preservation, and preservation of testable speech discrimination were 1.1+/-0.8%, 2.6+/-1.2%, 71+/-4.7%, and 91+/-2.6%, respectively. Facial weakness did not develop in any patient who received a marginal dose of less than 15 Gy (163 patients). Hearing levels improved in 10 (7%) of 141 patients who exhibited decreased hearing (Gardner-Robertson Classes II-V) before undergoing radiosurgery. According to multivariate analysis, increasing marginal dose correlated with increased development of facial weakness (p = 0.0342) and decreased preservation of testable speech discrimination (p = 0.0122). CONCLUSIONS: Radiosurgery for acoustic neuroma performed using current procedures is associated with a continued high rate of tumor control and lower rates of posttreatment morbidity than those published in earlier reports.     

Early proactive management of vestibular schwannomas in neurofibromatosis type 2

OBJECTIVE: The treatment of patients with neurofibromatosis Type 2 has always been challenging for neurosurgeons and neurotologists. Guidelines for appropriate management of this devastating disease are controversial. METHODS: A retrospective study of 28 patients with neurofibromatosis Type 2 who underwent 40 middle fossa craniotomies for excision of their acoustic tumors is reported. Eleven patients underwent bilateral procedures. The study focused on hearing preservation and facial nerve results for this group of patients. The 16 male patients and 12 female patients ranged in age (at the time of surgery) from 10 to 70 years, with a mean age of 22.6 years. The mean tumor size was 1.1 cm (range, 0.5-3.2 cm), and the majority of tumors were less than 1.5 cm. RESULTS: Measurable hearing was preserved in 28 ears (70%), with 42.5% being within 15 dB pure-tone average and 15% speech discrimination score of preoperative levels. In 55% of cases there was no change in the hearing class, as defined by the American Academy of Otolaryngology-Head and Neck Surgery. Of the 11 patients who underwent bilateral operations, 9 (82%) retained some hearing bilaterally. After 1-year follow-up periods (mean, 12.8 mo), 87.5% of patients exhibited normal facial nerve function (House-Brackmann Grade I). CONCLUSION: Early surgical intervention to treat acoustic tumors among patients with neurofibromatosis Type 2 is a feasible treatment strategy, with high rates of hearing and facial nerve function preservation.     

大型听神经瘤手术面神经功能的保留

目的 评估大型听神经瘤显微手术治疗后远期面神经功能,分析影响术后面神经功能的因素.方法 回顾性分析2002年1月至2009年11月实施的连续176例大型听神经瘤(直径≥30mm)手术的患者资料.采用House-Brackmann(HB)面神经功能分级系统评价术前及术后远期面神经功能.肿瘤大小与面神经功能结果的关系采用线性趋势检验统计学方法进行分析.结果 肿瘤全切除168例(95.5%),术后死亡3例(1.7%).面神经完整解剖保留169例(96.0%).共随访到135例患者,失访41例.随访时间3个月～7年,平均3年.随访＞1年的96例听神经瘤面神经功能HB 1～2级79例(82.3%),其中55例巨大型(直径＞40 mm)听神经瘤患者面神经功能HB 1～2级40例(72.7%).分析显示面神经功能结果与肿瘤直径之间存在线性关系(P＜0.05).结论 经乙状窦后入路切除大型听神经瘤,绝大部分肿瘤切除后可获得优良的远期面神经功能.肿瘤大小是影响术后面神经功能的重要因素.

Abstract：

Objectiyes To evaluate the long-term facial nerve function of patients following microsurgical removal of large and huge acoustic neuroma, and to identify the factors that influence these outcomes. Methods A retrospective review was performed which included 176 consecutive patients with a large acoustic neuroma(≥30 mm)underwent a retrosigmoid craniotomy for tumor resection between January 2002 to November 2009. House-Brackmann(HB)Scale was used preoperatively and in a long-term follow-up after surgery. Test for linear trend was applied for statistic analysis. Results Complete resection was achieved in 168(95. 5%)of these 176 patients with a mortality of 1.7%. Anatomic preservation of the facial nerve was attained in 96. 0% of the patients. In the series of 96 patients who had at least 1-year follow-up(mean 3.0 years)the facial nerve function preservation(HB grade 1-2)was totally attained in 79 patients(82.3 %), and 40 of 55 patients(72. 7 %)who presented huge tumors(diameter ＞ 40 mm)among the 96 patients had facial nerve function preserved. Analysis showed that facial nerve function correlated linearly with tumor sizes(x2 = 14. 114, v, = 1, P ＜ 0. 05). Conclusions Complete removal of large and giant acoustic neuroma may abtained via retrosigmoid approach with facial nerve preservation. Excellent longterm facial function can be expected in the majority of patients who undergo microsurgical removal of vestibular schwannoma via the suboccipital retrosigmoid approach. Tumor size is a significant prognostic parameter for facial nerve function following vestibular schwannoma surgery.     

听神经瘤显微手术面神经损伤的预防

目的总结与分析听神经瘤显微手术中预防面神经损伤的方法。方法经MRI和（或）CT检查确诊的大型听神经瘤（≥4．0cm）180例（72％）及中型听神经瘤（2．4～4．0cm）70例（28％）。均采用经患侧枕下乙状窦后入路保留面神经的显微手术。注意三大解剖关系：骨性解剖、蛛网膜解剖、神经与血管的解剖。肿瘤囊内减压后,确认面神经的起始位置、面神经与肿瘤的关系、面神经变形与扭曲、面神经分离的方法、面神经的断裂端-端吻合。随访6个月～1年。结果肿瘤全切除240例（96．0％）;次全切除10例（4．0％）,其中死亡1例（0．4％）。面神经功能评定：Ⅰ级214例（85．6％）;Ⅱ级25例（10．0％）;Ⅲ级5例（2．1％）;Ⅳ级5例（2．1％）。结论术中注意典型的解剖位置,正确的手术入路和显微手术技术可达到较高的肿瘤全切除率,提高面神经的功能保全率。     

Hearing preservation after acoustic neurinoma operation

Between 1981 and 1984, 44 patients underwent acoustic neurinoma removal by a posterior cranial fossa approach with an attempt to preserve hearing. Seven tumors were small (less than 20 mm), 28 were medium (20 to 40 mm), and 9 were large (greater than 40 mm). Preoperatively, 4 patients had normal hearing, 15 had serviceable hearing, 10 had poor hearing, and 15 had no hearing. Postoperative hearing was preserved in 11 cases. Of the 19 patients with normal or serviceable hearing, 8 (42%) had serviceable hearing preserved postoperatively. Hearing preservation was achieved in 43% of the patients with small tumors, 25% of those with medium tumors, and 11% of those with large tumors. This study confirms the value of the suboccipital approach, which can be used in an attempt to preserve hearing whenever the patient has serviceable hearing preoperatively and whenever the tumor size makes it feasible.     

Radical intracapsular removal of acoustic neurinomas. Long-term follow-up review of 11 patients

Historically, the neurosurgical treatment of large acoustic neurinomas has developed with two principal goals: complete tumor removal and preservation of facial nerve function. A recent goal for small tumors is the preservation of hearing. Out of a personal series of 124 acoustic neurinomas treated over the past 35 years, the senior author has undertaken a radical intracapsular approach in 12 patients with large tumors (greater than 3 cm in diameter). Surgical indications for intracapsular removal included advanced age (five cases), the patient's wish to avoid any risk of facial paralysis (six cases), contralateral facial palsy (one case), and contralateral deafness (one case). Eleven of these 12 patients were available for follow-up review. Tumor recurrence developed in two patients (18%) at 2 and 3 years postoperatively; there were no late recurrences. Four patients died of unrelated causes, 10 to 19 years after surgery. The remaining five patients have survived a mean of 12 years since surgery without recurrence (range 3 to 22 years). Facial function was preserved in nine patients (82%). The results suggest that radical intracapsular removal may be the procedure of choice under certain circumstances and may offer an alternative to focused high-energy radiation.     

Acoustic (loudspeaker) facial EMG monitoring: II. Use of evoked EMG activity during acoustic neuroma resection

Facial electromyographic (EMG) activity was continuously monitored via loudspeaker during eleven translabyrinthine and nine suboccipital consecutive unselected acoustic neuroma resections. Ipsilateral facial EMG activity was synchronously recorded on the audio channels of operative videotapes, which were retrospectively reviewed in order to allow detailed evaluation of the potential benefit of various acoustic EMG patterns in the performance of specific aspects of acoustic neuroma resection. The use of evoked facial EMG activity was classified and described. Direct local mechanical (surgical) stimulation and direct electrical stimulation were of benefit in the localization and/or delineation of the facial nerve contour. Burst and train acoustic patterns of EMG activity appeared to indicate surgical trauma to the facial nerve that would not have been appreciated otherwise. Early results of postoperative facial function of monitored patients are presented, and the possible value of burst and train acoustic EMG activity patterns in the intraoperative assessment of facial nerve function is discussed. Acoustic facial EMG monitoring appears to provide a potentially powerful surgical tool for delineation of the facial nerve contour, the ongoing use of which may lead to continued improvement in facial nerve function preservation through modification of dissection strategy.     

Use of the ultrasonically activated scalpel in acoustic neuroma surgery: preliminary report

Recently, the ultrasonic activated scalpel (the Harmonic Scalpel, HS) has been introduced in laparoscopic surgery. We have applied the HS in debulking the tumor in the posterior fossa and concluded that this is useful in acoustic neuroma surgery. Fifteen patients with a tumor extending more than 20 mm into the posterior fossa were included in this study. The extended middle cranial fossa approach type II was used in 13 patients and type III (hearing preservation surgery) was used in 2 patients. In one of two patients, hearing was preserved. Postroperative facial nerve function according to the House-Brackmann method was grade I in 12 patients, grade II in 2 patients, and grade III in 1 patient. Compating the technique of using HS to a pair of bipolar forceps and/or ultrasonic cavitational aspirator, the former can result in better preservation of the facial nerve function.     

Use of the Ultrasonically Activated Scalpel in Acoustic Neuroma Surgery: Preliminary Report

Recently, the ultrasonic activated scalpel (the Harmonic Scalpel, HS) has been introduced in laparoscopic surgery. We have applied the HS in debulking the tumor in the posterior fossa and concluded that this is useful in acoustic neuroma surgery. Fifteen patients with a tumor extending more than 20 mm into the posterior fossa were included in this study. The extended middle cranial fossa approach type II was used in 13 patients and type III (hearing preservation surgery) was used in 2 patients. In one of two patients, hearing was preserved. Postroperative facial nerve function according to the House-Brackmann method was grade I in 12 patients, grade II in 2 patients, and grade III in 1 patient. Compating the technique of using HS to a pair of bipolar forceps and/or ultrasonic cavitational aspirator, the former can result in better preservation of the facial nerve function.     

Retrosigmoid removal of acoustic neuroma: experience 1978-1988

The need to preserve hearing during acoustic neuroma removal has rekindled interest in labyrinth-sparing procedures. This review of 11 years' experience with the retrosigmoid approach to acoustic neuroma removal includes 335 procedures in 332 patients. There were no intraoperative deaths; two patients died in the postoperative period. The facial nerve was preserved in 86.3% of procedures, and auditory function was preserved in 45 procedures (34% of those tumors were 2 cm or smaller). Postoperative complications occurred in 101 procedures, the most common being cerebrospinal fluid otorhinorrhea in 40 cases; 25 of these required secondary surgery. Meningitis occurred 16 times and aspiration 8 times; all other complications were less frequent. Tumor removal was incomplete in eight procedures; in only one of these cases has tumor recurred. The six recurrences usually were identified 5 or more years postoperatively. This has prompted us to follow patients for 7 years postoperatively. Major changes in our management include the use of the supine position and of electrophysiologic monitoring. Advantages of the approach are: (1) wide access to the tumor, (2) applicability to all tumor sizes, (3) potential to preserve facial and auditory function in all cases, and (4) ability to change procedure without sacrificing labyrinth. This review confirms our confidence in this approach to acoustic neuroma removal.     

神经电生理监测在显微切除听神经瘤术中面听神经保护的意义

目的探讨显微听神经瘤手术中神经电生理监测对面听神经保护的意义。方法1996年1月~2001年12月未行术中神经电生理监测者为非监测组(n=18),2002年1月~2006年12月行术中神经电生理监测者为监测组(n=22),比较手术前后2组面听神经症状改善情况。结果术后24h内未监测组听力障碍好转1例,无变化9例,加重8例,面瘫症状好转1例,无变化2例,加重4例;监测组听力障碍好转9例,无变化12例,加重1例,面瘫症状好转6例,无变化5例。监测组听力障碍和面瘫症状好转优于未监测组(Z=3.389,P=0.001;Z=2.470,P=0.014)。术后6个月随访,未监测组听力障碍减轻或消失4例,无改善8例,加重6例,面瘫症状减轻或消失1例,无改善4例,加重2例;监测组听力障碍减轻或消失15例,无改善6例,加重1例,面瘫症状减轻或消失10例,无改善1例。术后6个月时监测组听力障碍和面瘫症状恢复显著优于非监测组(Z=3.105,P=0.002;Z=3.187,P=0.001)。结论听神经瘤手术中行神经电生理监测可有效保护面听神经。     

The High Rate CIS Auditory Brainstem Implant for Restoration of Hearing in NF-2 Patients.

Aim: Hearing preservation is one of the major goals of acoustic neuroma surgery. In NF-2 patients, bilateral hearing loss is frequently caused by the disease or results from its treatment. Several implant devices for electrical stimulation of the cochlear nucleus have been developed to restore serviceable hearing in these patients. We report our experience and results using a high rate continuous interleaved sampling (CIS) auditory brainstem implant (ABI). Methods: Between June 1997 and May 2004, 24 NF-2 patients were managed by our group. In 20 patients an ABI was implanted successfully. The cochlear nucleus was located using anatomical landmarks and E-ABR recordings after resection of the neuroma via a retrosigmoid approach in the semi-sitting position. The 12-channel stimulating electrode array was inserted and fixed in the lateral recess. There were no surgical complications related to implantation apart from pseudomeningo that were managed by lumbar drainage. Results: In one patient the electrode array became dislocated and this necessitated revision surgery which was successful. One patient failed to gain benefit from the implant. Overall, 70% of electrodes were found to be serviceable for auditory stimulation, 5.3% of electrodes were primarily nonauditory, and in 7.8% side effects during stimulation were observed. Lip reading was improved by more than 100% as a result of the additional auditory input. For many patients, comprehension of open speech was restored to a useful level. Almost all patients were able to perceive environmental sounds and tinnitus was masked. Conclusions: Restoration of hearing using ABIs in NF-2 patients is a safe and promising procedure for those who would otherwise be totally deaf. The high rate CIS speech processing strategy has proven to be very useful and effective in direct cochlear nucleus stimulation.