Effects of Electrode Location on Estimates of Neural Health in Humans with Cochlear Implants.

There are a number of psychophysical and electrophysiological measures that are correlated with SGN density in animal models, and these same measures can be performed in humans with cochlear implants (CIs). Thus, these measures are potentially applicable in humans for estimating the condition of the neural population (so called "neural health" or "cochlear health") at individual sites along the electrode array and possibly adjusting the stimulation strategy in the CI sound processor accordingly. Some measures used to estimate neural health in animals have included the electrically evoked compound potential (ECAP), psychophysical detection thresholds, and multipulse integration (MPI). With regard to ECAP measures, it has been shown that the change in the ECAP response as a function of increasing the stimulus interphase gap ("IPG Effect") also reflects neural density in implanted animals. These animal studies have typically been conducted using preparations in which the electrode was in a fixed position with respect to the neural population, whereas in human cochlear implant users, the position of individual electrodes varies widely within an electrode array and also across subjects. The current study evaluated the effects of electrode location in the implanted cochlea (specifically medial-lateral location) on various electrophysiological and psychophysical measures in eleven human subjects. The results demonstrated that some measures of interest, specifically ECAP thresholds, psychophysical detection thresholds, and ECAP amplitude-growth function (AGF) linear slope, were significantly related to the distances between the electrode and mid-modiolar axis (MMA). These same measures were less strongly related or not significantly related to the electrode to medial wall (MW) distance. In contrast, neither the IPG Effect for the ECAP AGF slope or threshold, nor the MPI slopes were significantly related to MMA or MW distance from the electrodes. These results suggest that "within-channel" estimates of neural health such as the IPG Effect and MPI slope might be more suitable for estimating nerve condition in humans for clinical application since they appear to be relatively independent of electrode position.

Immediate and Long-term Hearing Outcomes With the Middle Cranial Fossa Approach for Vestibular Schwannoma Resection.

OBJECTIVE: To analyze the immediate postoperative and long-term hearing outcome data in patients who have undergone hearing preservation attempts with the middle cranial fossa (MCF) approach for the resection of sporadic vestibular schwannoma. STUDY DESIGN: Retrospective review of a surgical patient cohort. SETTING: Tertiary academic referral center. PATIENTS: Adult patients with unilateral sporadic vestibular schwannoma. INTERVENTION: Surgical treatment with a MCF approach. MAIN OUTCOME MEASURE: Comparison of pre- and postoperative audiometric data in accordance with the 1995 and 2012 American Academy of Otolaryngology/Head and Neck Surgery guidelines on reporting hearing outcomes and with a word recognition score only scale. Long-term hearing outcome data were analyzed in the following postoperative groups: 3 to 5, 6 to 8, 9 to 11, and 12+ years after surgery. RESULTS: From 1999 to 2016, 174 patients underwent the MCF approach and 155 of them met inclusion criteria for analysis of hearing outcome data. Class A or B hearing was preserved in 70% of the entire cohort after recovery. Seventy-one patients with measurable hearing met criteria for long-term data analysis. The rate of American Academy of Otolaryngology/Head and Neck Surgery class A or B hearing preservation was 82% at 3 to 5 years and declined thereafter. The rate of word recognition score class I or II hearing preservation was 98% at 3 to 5 years and declined less rapidly thereafter. Patients with preoperative Class A hearing had significantly higher rates of successful hearing preservation at all postoperative intervals. CONCLUSION: Delayed hearing loss occurs in a progressively increasing fashion but speech understanding remains durable for a majority of patients whose hearing is initially preserved with the MCF approach.

Middle cranial fossa approach to repair tegmen defects assisted by three-dimensionally printed temporal bone models.

OBJECTIVES/HYPOTHESIS: To explore the perioperative utility of three-dimensionally (3D)-printed temporal bone models of patients undergoing repair of lateral skull base defects and spontaneous cerebrospinal fluid leaks with the middle cranial fossa approach. STUDY DESIGN: Case series. METHODS: 3D-printed temporal bone models-based on patient-specific, high-resolution computed tomographic imaging-were constructed using inexpensive polymer materials. Preoperatively, the models demonstrated the extent of temporal lobe retraction necessary to visualize the proposed defects in the lateral skull base. Also preoperatively, Silastic sheeting was arranged across the modeled tegmen, marked, and cut to cover all of the proposed defect sites. The Silastic sheeting was then sterilized and subsequently served as a precise intraoperative template for a synthetic dural replacement graft. Of note, these grafts were customized without needing to retract the temporal lobe. RESULTS: Five patients underwent the middle cranial fossa approach assisted by 3D-printed temporal bone models to repair tegmen defects and spontaneous cerebrospinal fluid leaks. No complications were encountered. The prefabricated dural repair grafts were easily placed and fit precisely onto the middle fossa floor without any additional modifications. All defects were covered as predicted by the 3D temporal bone models. At their postoperative visits, all five patients maintained resolution of their spontaneous cerebrospinal fluid leaks. CONCLUSIONS: Inexpensive 3D-printed temporal bone models of tegmen defects can serve as beneficial adjuncts during lateral skull base repair. The models provide a panoramic preoperative view of all tegmen defects and allow for custom templating of dural grafts without temporal lobe retraction. LEVEL OF EVIDENCE: 4 Laryngoscope, 127:2347-2351, 2017.

Hearing preservation and facial nerve outcomes in vestibular schwannoma surgery: results using the middle cranial fossa approach.

OBJECTIVE: To evaluate surgical results using the middle cranial fossa approach for hearing preservation vestibular schwannoma surgery. STUDY DESIGN: Retrospective case review. SETTING: Tertiary referral academic center. PATIENTS: Seventy-three consecutive patients with vestibular schwannoma operated on using the middle cranial fossa approach between February 1999 and February 2005. INTERVENTIONS: The tumors were removed via the middle cranial fossa approach with modifications to improve exposure. Standard auditory brainstem and facial nerve monitoring were used. MAIN OUTCOME MEASURES: Pre- and postoperative hearing measures and facial function, tumor size, and postoperative complications. Hearing status was categorized into Classes A, B, C, and D as described by the American Academy of Otolaryngology-Head and Heck Surgery "Guidelines for the Evaluation of Hearing Preservation in Acoustic Neuroma, 1995." RESULTS: Thirty-four patients presented with Class A hearing preoperatively. Among patients presenting with Class A hearing, a total of 27 (80%) maintained Class A or B hearing postoperatively. Of these, 21 (62%) remained in Class A, 6 (18%) deteriorated slightly to Class B, and 7 (20%) deteriorated to Class D postoperatively. Twenty-eight patients presented with Class B hearing preoperatively. Of these, 18 (64%) remained in Class B, 3 (11%) deteriorated to Class C, and 7 (25%) deteriorated to Class D. Three patients had Class C hearing preoperatively. Of these, 2 (66%) remained in Class C and 1 (33%) deteriorated to Class D. Eight patients presented in Class D and one of these improved to Class C postoperatively. Overall, 62 patients presented with useful (Class A or B) hearing and 45 (73%) remained in Class A or B. Nineteen patients had tumors larger than 10 mm in greatest dimension and had Class A or B hearing preoperatively. Of these, 11 (58%) retained Class A or B hearing postoperatively. At 4 months or greater follow-up, facial nerve outcome were excellent in 96%: House-Brackmann Grade I in 61 (85%), Grade II in 8 (11%), and Grade III in 3 (4%). There were no Grade IV, V, or VI results on final follow-up. Six (8%) patients developed cerebrospinal fluid leaks. CONCLUSION: By achieving excellent exposure and using meticulous microsurgical technique, it is possible to resect small vestibular schwannomas via the middle fossa approach, with preservation of hearing at excellent or preoperative levels in the majority of patients, with excellent or satisfactory facial nerve outcomes in 96% of patients.

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.

Malignant transformation of a high-grade osteoblastoma of the petrous apex with subcutaneous metastasis.

We describe the clinical presentation, management, and pathologic findings in a case of osteosarcoma of the petrous apex with an atypical metastasis to the lower abdominal wall. We retrospectively reviewed the record of a 49-year-old man who was diagnosed with a right petrous apex lesion, which biopsy identified as a high-grade osteoblastoma. After two attempts at en bloc resection were not curative, radiation and chemotherapy were recommended. The patient subsequently developed a cutaneous lower abdominal mass that was diagnosed as an osteosarcoma. Meanwhile, the petrous apex tumor continued to grow despite treatment until the patient died from the burden of disease. Temporal bone osteoblastomas and osteosarcomas are both extremely rare, and they can be difficult to differentiate histologically. Our case illustrates this difficulty and demonstrates the possibility of a high-grade osteoblastoma's malignant conversion to an osteosarcoma.

Identification and characterization of choline transporter-like protein 2, an inner ear glycoprotein of 68 and 72 kDa that is the target of antibody-induced hearing loss.

The Kresge Hearing Research Institute-3 (KHRI-3) antibody binds to a guinea pig inner ear supporting cell antigen (IESCA) and causes hearing loss. To gain insight into the mechanism of antibody-induced hearing loss, we used antibody immunoaffinity purification to isolate the IESCA, which was then sequenced by mass spectroscopy, revealing 10 guinea pig peptides identical to sequences in human choline transporter-like protein 2 (CTL2). Full-length CTL2 cDNA sequenced from guinea pig inner ear has 85.9% identity with the human cDNA. Consistent with its expression on the surface of supporting cells in the inner ear, CTL2 contains 10 predicted membrane-spanning regions with multiple N-glycosylation sites. The 68 and 72 kDa molecular forms of inner ear CTL2 are distinguished by sialic acid modification of the carbohydrate. The KHRI-3 antibody binds to an N-linked carbohydrate on CTL2 and presumably damages the organ of Corti by blocking the transporter function of this molecule. CTL2 mRNA and protein are abundantly expressed in human inner ear. Sera from patients with autoimmune hearing loss bind to guinea pig inner ear with the same pattern as CTL2 antibodies. Thus, CTL2 is a possible target of autoimmune hearing loss in humans.

Corticosteroid response and supporting cell antibody in autoimmune hearing loss.

OBJECTIVE: To determine whether antibodies to supporting cells are associated with response to corticosteroids in patients with autoimmune sensorineural hearing loss. DESIGN: Prospective analysis of antibody to inner-ear antigens. SETTING: Collaborating otology practices in Pennsylvania, Michigan, and Indiana. PATIENTS: Sixty-three patients with rapidly progressive unilateral or bilateral sensorineural hearing loss of unknown cause suggestive of autoimmune sensorineural hearing loss. INTERVENTIONS: Pretreatment audiometry, serum analysis by Western blot (WB) and immunofluorescence (IF) tests, corticosteroid therapy, and follow-up audiometry. MAIN OUTCOME MEASURES: Antibody reactivity and audiogram changes were analyzed for association with response to treatment. RESULTS: More than half of the patients (37/63) had antibodies to both a 68- to 72-kDa protein and to inner-ear supporting cells, 16 patients had positive results on one assay only, and 10 had negative results on both. Twenty-eight patients improved and 35 did not. The WB findings did not correlate with response. Of the WB-positive patients, 49% (21/43) improved, as did 35% (7/20) of the WB-negative patients (P = .30). In contrast, 53% (25/47) of IF-positive patients improved, compared with only 19% (3/16) in the IF-negative group (P = .02). Of those who improved, 89% (25/28) were IF positive. CONCLUSIONS: Antibody to an inner-ear supporting cell antigen was significantly associated with hearing improvement after corticosteroid therapy (relative rate, 2.8). Patients with IF-positive serum are nearly 3 times more likely to experience improved hearing with corticosteroid treatment than those who are IF negative. Antibodies to inner-ear supporting cell antigen may have value in diagnosis and treatment of patients with autoimmune sensorineural hearing loss.

Hemangiomas of the geniculate ganglion.

OBJECTIVE: To describe the presentation, evaluation, and management of patients with geniculate ganglion hemangioma. STUDY DESIGN: Retrospective case review. SETTING: Tertiary-care academic medical center. PATIENTS: Six patients with hemangiomas of the geniculate ganglion, evaluated and managed at a single institution. INTERVENTION: All patients underwent imaging and follow-up, with five of the patients undergoing operative intervention. MAIN OUTCOME MEASURES: Tumor size and extent, facial nerve and hearing function, histopathologic findings, and complications are discussed as a function of observation versus microsurgical excision. RESULTS: Six patients with ossifying hemangiomas of the geniculate ganglion were evaluated at a single institution over a 10-year period. These patients underwent operative intervention when their facial nerve function began to decline. Hearing was preserved in five of the six cases. Resection and grafting of the facial nerve was required in five of six cases. Two of the six cases were found to have histologic evidence of facial nerve infiltration on pathologic examination. CONCLUSION: The majority of these tumors infiltrated the facial nerve and could not be completely removed without excision of the nerve itself. Based on this experience, it would seem reasonable to defer surgical excision until facial nerve function has declined to grade 3 or worse. Whether earlier subtotal excision would result in better outcomes or not remains unanswered. This study presents several complicated scenarios that illustrate the difficulty of clinical decision-making in this disease. Associated clinical dilemmas and controversies are discussed.

External auditory canal closure in cochlear implant surgery.

OBJECTIVE: To evaluate surgical techniques and complications associated with external auditory canal (EAC) closure in cochlear implant surgery. STUDY DESIGN: Retrospective case review. SETTING: Tertiary referral center with a large cochlear implant program. PATIENTS: Twenty-eight patients (8 adults and 20 children) underwent multichannel cochlear implantation with EAC closure. The follow-up periods ranged between 1 and 10 years. Closure of the EAC was performed in conjunction with implantation of ears with chronic suppurative otitis media or cochlear drill-out procedures for ossification, or for access to the cochlea in patients with abnormal temporal bone anatomy. A modified Rambo technique was used for EAC closure in all but one case. INTERVENTIONS: Cochlear implantation with EAC closure and subsequent clinical and radiologic follow-up. MAIN OUTCOME MEASURES: Postoperative complications or the development of cholesteatoma in the implanted ear. RESULTS: Cholesteatoma developed in the implanted ear in two patients. Breakdown of EAC closure occurred in one of these patients. The details of these patients are reviewed. CONCLUSION: Closure of EAC can be done with relatively low risk. Close and careful follow-up is required for early detection of a developing cholesteatoma.

Cochlear implantation in chronic suppurative otitis media.

OBJECTIVE: To evaluate management options for cochlear implantation in patients with chronic suppurative otitis media. STUDY DESIGN: Retrospective case review. SETTING: Tertiary referral center with a large cochlear implant program. PATIENTS: Ten patients with chronic suppurative otitis media who received cochlear implants were identified. Case history, etiology of hearing loss, and management of the ear with the implant were evaluated. INTERVENTIONS: Cochlear implantation and subsequent rehabilitation. MAIN OUTCOME MEASURES: Early and late complications were evaluated. RESULTS: No early or late complications were identified in this group of patients after an average follow-up period of about 4 years. CONCLUSION: Cochlear implantation can be safely achieved in patients with chronic suppurative otitis media. There are several options for the management of these patients, and the approach chosen should be individualized on the basis of clinical findings.

Cochlear implants in young children.

The past 20 years have seen the cochlear implant evolve from an innovative but radical concept to the standard of care in the management of children with severe to profound hearing loss. All children receiving the cochlear implant achieve substantial benefit; however, performance gains are optimized by a team approach to the evaluation and management of these children. The critical elements of this team include audiologists, speech pathologists, and surgeons with specific interest, expertise, and dedication to the management of children with cochlear implants. Children are not well served by practitioners who delegate follow-up to educational programs not experienced in children with implants. Long-term involvement and dedication on the part of teachers, speech pathologists, audiologists, surgeons, and family are critical to maximizing the benefit the child receives.

Prosthetic stimulation of the auditory system with intraneural electrodes.

Prosthetic electrical stimulation of the auditory system is presently accomplished either via scala tympani electrode arrays or via cochlear nucleus surface electrode arrays. Many of the early cochlear implant studies, however, used electrode arrays placed within the auditory nerve itself--either within the modiolus or within the trunk of the nerve. For many reasons, such intraneural electrode arrays were abandoned in favor of intrascalar arrays. There remain, however, several theoretical and practical reasons why intraneural arrays might be advantageous, and recent developments in electrode technology solve many of the problems posed by early attempts at intraneural stimulation. In this article, we review the history and current status of intraneural auditory stimulation, and present some preliminary results of this mode of stimulation in an animal model.

Lesions of the petrous ridge: metastatic pituitary carcinoma with discussion of differential diagnosis.

OBJECTIVE: To discuss the differential diagnosis of petrous ridge lesions based on a rare case of metastatic pituitary carcinoma. PATIENT: A 41-year-old man with a past medical history of pituitary adenoma and hypopituitarism presented with imbalance and vertigo. Imaging showed a mass eroding the left posterior petrous face. INTERVENTION: Transtemporal, transmastoid approach for complete resection of tumor. MAIN OUTCOME MEASURES: Surgical pathology and imaging studies. RESULTS: Surgical pathology revealed metastatic pituitary carcinoma. The patient has been followed at our institution for 28 months postoperatively without evidence of recurrence. CONCLUSION: Lesions of the petrous ridge are rare. The wide differential diagnosis includes endolympatic sac tumor, meningioma, jugulotympanic paraganglioma, myeloma, and metastasis. The clinician must take into account unique imaging features on CT and MRI, and final diagnosis often requires pathologic analysis.

The clinical phenotype of SDHC-associated hereditary paraganglioma syndrome (PGL3).

CONTEXT: Mutations in the genes encoding subunits of the succinate dehydrogenase complex cause hereditary paraganglioma syndromes. Although the phenotypes associated with the more commonly mutated genes, SDHB and SDHD, are well described, less is known about SDHC-associated paragangliomas. OBJECTIVE: To describe functionality, penetrance, number of primary tumors, biological behavior, and location of paragangliomas associated with SDHC mutations. DESIGN: Families with an SDHC mutation were identified through a large cancer genetics registry. A retrospective chart review was conducted with a focus on patient and tumor characteristics. In addition, clinical reports on SDHC-related paragangliomas were identified in the medical literature to further define the phenotype and compare findings. SETTING: A cancer genetics clinic and registry at a tertiary referral center. PATIENTS: Eight index patients with SDHC-related paraganglioma were identified. RESULTS: Three of the eight index patients had mediastinal paraganglioma and four of the eight patients had more than one paraganglioma. Interestingly, the index patients were the only affected individuals in all families. When combining these index cases with reported cases in the medical literature, the mediastinum is the second most common location for SDHC-related paraganglioma (10% of all tumors), occurring in up to 13% of patients. CONCLUSIONS: Our findings suggest that thoracic paragangliomas are common in patients with SDHC mutations, and imaging of this area should be included in surveillance of mutation carriers. In addition, the absence of paragangliomas among at-risk relatives of SDHC mutation carriers suggests a less penetrant phenotype as compared to SDHB and SDHD mutations.

Durability of hearing preservation after microsurgical treatment of vestibular schwannoma using the middle cranial fossa approach.

OBJECT: The middle cranial fossa (MCF) approach is a microsurgical technique described as a primary option in the treatment of small, intracanalicular schwannomas involving the eighth cranial nerve. Excellent rates of complete tumor resection, hearing preservation, preservation of facial nerve function, and low complication rates have been reproduced using this technique. However, the durability of hearing preservation attained using the various treatment options has not been adequately assessed. The purpose of this study was to evaluate the durability of long-term hearing preservation in patients with vestibular schwannoma (VS) treated via the MCF approach. The authors hypothesize that hearing preservation in these patients will prove to be durable years after treatment in a high percentage of cases. METHODS: Retrospective medical chart review was performed in 103 consecutive patients undergoing resection of VS via a modified MCF approach between 1999 and 2008. Patients in whom surgical goals were gross-total resection and hearing preservation were included. Preoperative and postoperative hearing assessment was performed using standard audiometric testing, and classified according to American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) guidelines as a primary outcome measure. Outcomes and neurological complications initially, and at 1, 3, and 5 years following operation were analyzed. RESULTS: Initial hearing preservation rates were in keeping with the best previously published results. At initial postoperative audiometric follow-up, of the patients presenting with Class A hearing, 67% remained Class A, 17% were Class B, 1% were Class C, and 15% were Class D. Of patients presenting with Class B hearing, 24% were Class A, 53% remained Class B, 6% were Class C, and 18% were Class D. Of patients presenting with Class C hearing, 100% remained Class C. To assess the durability of hearing preservation in our patients, the authors evaluated hearing function at regular intervals after the initial postoperative audiometric follow-up. Audiometric data were available for 56 patients at 5-year follow-up. Of the 20 patients with Class A hearing at initial postoperative follow-up with 5-year follow-up, 13 (65%) remained Class A, 6 (30%) were Class B, and 1 (5%) was Class C. Of the 12 patients with Class B hearing at initial postoperative follow-up with 5-year follow-up, 4 (33%) were Class A, 4 (33%) remained Class B, and 4 (33%) were Class C. Of the 3 patients with Class C hearing at initial postoperative follow-up with 5-year follow-up, all 3 (100%) remained Class C. CONCLUSIONS: A majority of patients with preserved hearing following the MCF approach for treatment of VS experience durability of their preserved hearing at 5-year follow-up. The initial AAO-HNS classification was preserved in 13 (65%) of the 20 patients who had Class A hearing at 5 years, and in 8 (67%) of the 12 who had Class B hearing at 5 years. Overall, a decline in AAO-HNS classification was noted in 15% of patients with preserved Class A hearing, and in 33% of those with preserved Class B hearing. Facial nerve function was preserved in 91% of cases. Superior hearing preservation as well as good outcomes in facial nerve function and few serious complications can be accomplished using the MCF approach for resection of small VSs.

Electrocochleography as a diagnostic and intraoperative adjunct in superior semicircular canal dehiscence syndrome.

OBJECTIVE: To determine the electrocochleographic characteristics of ears with superior semicircular canal dehiscence (SSCD) and to examine its use for intraoperative monitoring in canal occlusion procedures. STUDY DESIGN: Case series. SETTING: Academic medical center. PATIENTS: Thirty-three patients (45 ears) had clinical and computed tomographic evidence of SSCD; 8 patients underwent intraoperative electrocochleography (ECoG) during superior canal occlusion; 9 patients underwent postoperative ECoG after SSCD occlusion. INTERVENTIONS: Diagnostic, intraoperative, and postoperative extratympanic ECoG; middle fossa or transmastoid occlusion of the superior semicircular canal. MAIN OUTCOME MEASURE: Summating potential (SP) to action potential (AP) ratio, as measured by ECoG, and alterations in SP/AP during canal exposure and occlusion. RESULTS: Using computed tomography as the standard, elevation of SP/AP on ECoG demonstrated 89% sensitivity and 70% specificity for SSCD. The mean SP/AP ratio among ears with SSCD was significantly higher than that among unaffected ears (0.62 versus 0.29, p < 0.0001). During occlusion procedures, SP/AP increased on exposure of the canal lumen (mean change ± standard deviation, 0.48 ± 0.30). After occlusion, SP/AP dropped below the intraoperative baseline in most cases (mean change, -0.23 ± 0.52). All patients experienced symptomatic improvement. All patients who underwent postoperative ECoG 1 to 3 months after SSCD repair maintained SP/AP of 0.4 or lesser. CONCLUSION: These findings expand the differential diagnosis of abnormal ECoG. In conjunction with clinical findings, ECoG may support a clinical diagnosis of SSCD. Intraoperative ECoG facilitates dehiscence documentation and allows the surgeon to confirm satisfactory canal occlusion.

Angioleiomyoma of the internal auditory canal: clinical and radiographic features.

OBJECTIVE: Discussion of a rare case of angioleiomyoma of the internal auditory canal. PATIENT: Thirteen-year-old female patient with a 1-year history of progressive hearing loss. INTERVENTION: Middle cranial fossa approach providing complete surgical extirpation. MAIN OUTCOME MEASURE: Surgical pathology. RESULTS: Radiography and history suggestive of vestibular schwannoma; pathology revealed angioleiomyoma. CONCLUSION: Angioleiomyoma is a rare lesion of the internal auditory canal that has many similar clinical and radiographic features of a vestibular schwannoma. There are no previous reports of this tumor occurring within the internal auditory canal in this age group.