Hussam K. El-Kashlan

Evaluation of Clinical Measures of Equilibrium

Objective: Evaluate the clinical utility of several simple measures of static and dynamic equilibrium in human subjects. In particular, one proposed clinical measure, the Clinical Test of Sensory Integration and Balance (CTSIB) was compared with dynamic posturography for the measurement of postural control capabilities.

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.

Pediatric cochlear implant patient performance as a function of age at implantation.

Objective: The objective of this study was to examine the effect that age at implantation has on performance of children who received multichannel cochlear implants. Study Design: This is a retrospective study of 295 children who were broken down into 5 age groups based on age at implantation: 1–3 years, 3–5 years, 5–7 years, 7–9 years, and 9–11 years. Speech perception test scores obtained 12, 24, and 36 months postactivation were compared for the 5 groups using repeated-measures analysis of variance. Setting: This study was carried out at a tertiary academic medical center. Patients: Subjects consisted of 295 children who ranged in age from 12 months to 10 years 11 months at the time they obtained their cochlear implant. Intervention: All patients received their cochlear implant at a single implant facility. Main Outcome Measures: Performance on several speech perception tests was compared 12, 24, and 36 months postactivation. Performance was evaluated as a function of age at implantation. Results: Patients in all 5 groups demonstrated improved scores when compared with scores obtained preoperatively with hearing aids. Repeated-measures analysis of variance (ANOVA) revealed a significant group by time interaction for 3 of the 5 measures. For all three of these measures, children implanted at younger ages demonstrated greater gains in speech perception over time than children implanted at older ages. Conclusions: These results are in agreement with those of previous studies indicating that early implantation facilitates improved development of speech perception skills in profoundly deaf children.

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.

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.

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.

Antibodies to HSP-70 in normal donors and autoimmune hearing loss patients.

Objective: To evaluate serum antibody to heat shock protein (HSP) 70 as a marker for autoimmune sensorineural hearing loss (AISNHL). Design: Sera from 20 patients with rapidly progressive sensorineural HL and 20 control volunteers without HL were tested for antibody reactivity against multiple HSP 70 substrates. Substrates included recombinant human HSP (rHuHSP) 72, purified bovine brain heat shock cognate (HSC) 73 and HSP 72, as well as heat‐shocked and non‐heat‐shocked protein extracts from bovine kidney (MDBK) cells. All serum donors were previously tested for antibody to guinea pig inner ear supporting cells; 17 of 20 patients but none (0 of 20) of the controls were positive. Methods: Sera were tested using Western blots. Results: Reactivity with rHuHSP 70 was observed in 16 patients and 17 controls. Similarly, 15 of 20 patients and 17 of 20 controls stained for both HSP 72 and HSC 73 from the bovine brain. When tested against the heat‐shock‐induced and control MDBK extracts, six patients and nine controls had greater reactivity with the induced HSP 72. Conclusion: The frequency of antibodies to HSP substrates did not differ in patients and controls. Prior studies reported that HSP 72 is the 68 kD antigen commonly detected by AISNHL sera. However, we show that HSP 72 antibodies are no more prevalent in patients than in normal controls. Thus, it is unlikely that the 68 kD protein is HSP 72. Therefore, HSPs are not appropriate substrates for serodiagnosis of AISNHL.

Reconstruction of Complex Parotidectomy Defects Using the Lateral Arm Free Tissue Transfer

OBJECTIVES: The study goal was to show that the lateral arm flap is a viable reconstructive option for complex parotidectomy defects. STUDY DESIGN AND SETTING: We studied a case series at a tertiary care medical center from March 1997 to March 2002. The lateral arm flap was used to reconstruct parotidectomy defects that included a composite resection of adjacent tissue in 30 patients. There were 19 men and 11 women (mean age, 62 years; mean follow-up, 19 months). The mean flap area was 114 cm2, and the mean flap volume was 172 cm3. The posterior cutaneous nerve of the forearm (PCNF) was used as a facial nerve cable graft in 14 patients. Facial disability outcomes were measured using the Facial Clinimetric Evaluation scale. RESULTS: The major and minor complication rates with use of this reconstructive approach were low: 16.7% (5 of 30) and 26.7% (8 of 30), respectively. Donor site morbidity was minimal, with no patient having a major donor site complication and 23.3% (7 of 30) having minor complications. Functional recovery of the facial nerve occurred in 6 of 8 evaluable patients who underwent facial nerve grafting using the PCNF. Controlling for degree of facial nerve paralysis, Facial Clinimetric Evaluation scale scores of our patients were not statistically different than those of a historic population with a facial paralysis and no surgical defect. CONCLUSIONS: The lateral arm free flap effectively restores facial appearance when used for reconstruction of complex parotidectomy defects. The PCNF, a nerve harvested with the lateral arm flap, can be used as a facial nerve cable graft with a high rate of success. SIGNIFICANCE: The lateral arm flap is successful as a single donor site for reconstructing facial contour and the facial nerve after major ablative defects in the parotid region.

Children with cochlear implants who live in monolingual and bilingual homes.

Objective: To determine if exposure to a second language impacts the ability of children with cochlear implants to develop spoken English skills. Study Design: Matched-pairs comparison of postoperative speech perception and speech/language data of children from monolingual and bilingual homes with cochlear implants. Setting: Tertiary medical facility. Subjects: Twelve matched pairs of children with unilateral cochlear implants who reside in monolingual or in bilingual homes. Pairs were matched for age of implantation, cochlear anatomy, educational setting, and device type. All subjects received their implant before the age of 6 years. Intervention: Subjects participated in routine speech perception and speech and language assessments at various postimplantation time intervals. Main Outcome Measures: Matched-pairs t tests and mixed-model analyses were used to evaluate and compare scores obtained by the 2 groups on the Peabody Picture Vocabulary Test, The MacArthur-Bates Communicative Development Inventory: Words and Gestures, The Oral and Written Language Scales, The Infant-Toddler Meaningful Auditory Integration Scale, and the Student Oral Language Observation Matrix. Results: No significant differences were found between the scores of children living in bilingual homes when compared with the scores obtained by children living in monolingual homes at any interval tested. Conclusion: This study supports the belief that exposure to a second language at home does not impair primary language acquisition for some young children with cochlear implants. The study suggests that some children with cochlear implants can learn multiple spoken languages and that parents of such children do not need to avoid using a minority language with their child who has a cochlear implant.

Intraoperative monitoring and facial nerve outcomes after vestibular schwannoma resection.

Objective To determine the predictive value of proximal facial nerve electrical threshold and proximal-to-distal facial muscle compound action potential amplitude ratio on facial nerve outcomes after resection of vestibular schwannomas. Study Design Retrospective case review. Setting Tertiary care hospital. Patients Two hundred twenty-nine patients undergoing resection of vestibular schwannomas with intraoperative facial nerve monitoring at a single institution. Intervention All patients underwent resection of vestibular schwannomas with the use of intraoperative monitoring. Main Outcome Measure Facial nerve function was classified according to the House-Brackmann scale at the patients last office follow-up. Last follow-up was at least 6 months after surgery. Results Good facial nerve function (House-Brackmann Grade I or II) was observed in 87% of the patients at their last office follow-up. Proximal-to-distal amplitude ratio and proximal electric threshold were statistically significant in predicting facial nerve outcome. A mathematical model predicting the probability of good outcome on the basis of the intraoperative parameters is presented. Conclusion Intraoperative monitoring has significantly decreased facial nerve morbidity in vestibular schwannoma surgery. Despite the advances in surgery and monitoring, a group of patients still have poor facial nerve outcomes. The use of intraoperative nerve monitoring may be able to predict poor long-term facial nerve outcomes and thus modify the timing of rehabilitation.