Robert A. Williamson

Coronal Computed Tomography Prevalence of Superior Semicircular Canal Dehiscence

OBJECTIVES The relatively new clinical entity superior canal dehiscence syndrome (SCDS) is diagnosed by clinical symptoms and signs. Coronal computed tomography (CT) has been used to confirm the diagnosis. A consecutive series of temporal bone CT scans was reviewed to define the prevalence of a dehiscent-appearing superior semicircular canal. STUDY DESIGN AND SETTING Temporal bone CT scans performed over a 2-year period at a university-based tertiary referral center were reviewed independently by 3 individuals. Scans were excluded if coronal images were not obtained or reconstructed from axial images. Prevalence figures for dehiscent-appearing superior semicircular canal were determined by consensus. Medical records of selected individuals with a dehiscent-appearing canal were reviewed for study indications and otologic symptoms. RESULTS A dehiscent-appearing superior semicircular canal was seen in 9% of studies. Correlation among examiners was greater than 94%. Medical records indicated symptoms suggestive of or compatible with the diagnosis of SCDS in rare cases. CONCLUSION The prevalence of a dehiscent-appearing superior semicircular canal on coronal CT of the temporal bones performed with 1.0-mm collimation is substantially greater than that predicted by temporal bone histologic study. Clinical symptoms compatible with the diagnosis were seldom recorded, suggesting low specificity. The high sensitivity and low specificity of CT scan create a risk for overdiagnosis of SCDS if the coronal CT scans are not correlated with clinical symptoms.

Facial Nerve Grading System 2.0

Objective: To present an updated version of the original Facial Nerve Grading Scale (FNGS), commonly referred to as the House-Brackmann scale. Study Design: Controlled trial of grading systems using a series of 21 videos of individuals with varying degrees of facial paralysis. Results: The intraobserver and interobserver agreement was high among the original and revised scales. Nominal improvement is seen in percentage of exact agreement of grade and reduction of instances of examiners differing by more then one grade when using FNGS 2.0. FNGS 2.0 also offers improved agreement in differentiating between grades 3 and 4. Conclusion: FNGS 2.0 incorporates regional scoring of facial movement, providing additional information while maintaining agreement comparable to the original scale. Ambiguities regarding use of the grading scale are addressed.

Inflammatory pseudotumor of the temporal bone.

Objective To characterize the clinical presentation, imaging characteristics, intraoperative findings, and key histopathologic features of inflammatory pseudotumors of the temporal bone. Findings from an index case are presented, and the literature is reviewed for comparison. Study Design Retrospective case review. Setting University tertiary referral center. Patients Cases were identified by review of surgical specimens from the temporal bone and lateral skull base with histopathologic confirmation. A single case was identified at our institution. Nine additional cases were identified in the literature; clinical features were reviewed. Intervention Of reported cases, treatment consisted of complete surgical excision in eight cases and subtotal excision in one. The index patient underwent surgical excision with postoperative corticosteroid therapy for adjacent meningeal involvement, after histopathologic interpretation. Corticosteroids were administered to one patient with residual microscopic tumor, and external beam radiotherapy was used for residual/recurrent disease in one case. Results The lesions were typically locally aggressive with extensive bony erosion. Three cases (33%) demonstrated labyrinthine and otic capsule involvement. Four cases (44%) involved the facial nerve. Characteristic histopathologic features included fibroblastic proliferation and a mixed inflammatory cell infiltrate in all cases. Mitotic figures, nuclear pleomorphism, and necrosis were rare or nonexistent. Conclusions Inflammatory pseudotumors of the temporal bone are rare but aggressive lesions. Therapy should consist of surgical excision with steroids reserved for residual or intracranial disease or in patients in whom surgery is not an option. These lesions must be differentiated from other infectious, granulomatous, and neoplastic lesions on the basis of histopathologic and immunohistochemical findings.

Cochlear implant electrode misplacement: Incidence, evaluation, and management†‡

To review the presentation and management of improper electrode array placement, and to help guide clinical decision‐making.

Advanced pediatric mastoiditis with and without intracranial complications

Recently, several groups have noticed an increase in cases of advanced pediatric mastoiditis and intracranial complications. The objective of this study was to review the bacteriology of advanced mastoiditis in pediatric patients, with the hypothesis that a difference in bacteriology might explain the development of an intracranial complication.

Auditory performance after cochlear implantation in late septuagenarians and octogenarians

Objective: Previous studies have demonstrated consistent benefit in older adults undergoing cochlear implantation as compared with younger control groups, with age category thresholds between 60 and 70 years. The objective of this study is to report auditory performance in implant recipients older than 75 years, a cohort for which few data have been reported. Study Design: Retrospective chart review. Setting: Academic cochlear implant program in a tertiary-care hospital. Patients: Twenty-eight cochlear implant recipients were subdivided into implant users older than 80 years (Group 1) and recipients currently older than 75 years (Group 2). Intervention: Cochlear implantation. Main Outcome Measures: Open-set speech perception scores. Methods: Postoperative open-set speech perception scores were compared with preoperative scores in the best-aided condition. Criteria were developed to define situations where the implant was considered to be nonbeneficial or less beneficial than amplification, and those data were then subjected to Kaplan-Meier analysis. Results: Group 1 included 13 patients with mean age of 80.7 years at the time of implantation. Group 2 included 15 patients with a mean age of 71.6 years. Scores were significantly better postoperatively at 6 months (p < 0.01) for Group 2 and at 12 months (p < 0.01) for both Groups 1 and 2. Kaplan-Meier curves were constructed for both groups. Conclusion: Cochlear implantation in patients older than 75 years is beneficial, and Kaplan-Meier analysis demonstrates that the clinical benefit is durable over time. Patients older than 80 years obtain similar benefit, although auditory performance was less robust.

Utility of Stepping, Walking, and Head Impulses for Screening Patients for Vestibular Impairments:

Objective To determine if some common screening tests predict scores on detailed, objective diagnostic tests of the vestibular system. Study Design Sixty patients with vestibular disorders were compared with 60 asymptomatic controls. Setting Vestibular diagnostic laboratory, tertiary care center. Subjects and Methods Subjects were screened with head impulse tests, Fukuda stepping tests while walking and marching in place, and tandem walking tests with eyes open and closed. All subjects underwent bithermal caloric tests and Dix-Hallpike maneuvers; patients underwent low-frequency sinusoidal tests of the vestibulo-ocular reflex in darkness and cervical vestibular evoked myogenic potentials. Results On tandem walking tests, patients differed significantly from controls, but receiver operating characteristic scores were < 0.80. On Fukuda tests, patients turned significantly more than controls for walking but not marching, but receiver operating characteristic values were considerably less than 0.80. On head impulse tests, patients with bithermal caloric weakness (≥20% and <60%) did not differ from controls, but patients with severe bithermal caloric weakness (≥60%) differed significantly from controls. Receiver operating characteristic values were >0.80 only for subjects with severe bithermal caloric weakness and were highest, at 0.88, for subjects with severe weakness and age ≥ 60 years. Conclusions The Fukuda test is a poor screening test because it does not correlate well with objective test findings. Tandem walking is best used for screening older patients for vestibular disorders. Positive findings on a head impulse test are probably consistent with severe peripheral vestibular impairment and may be most useful in older patients. In younger patients with vertigo, negative results on head impulse tests may not be informative.

Endolymphatic sac tumor in von Hippel-Lindau disease.

Von Hippel-Lindau (vHL) disease is a rare genetic disorder characterized by retinal angiomas, cerebellar and central nervous system hemangioblastomas, pheochromocytoma, renal cell carcinoma, pancreatic islet cell tumors, and benign cysts involving other organs. The disease affects from 1 in 35,000 to 40,000 population and displays autosomal dominant inheritance with incomplete penetrance. Mutations affecting a tumor suppressor gene localized to chromosome 3p25 are thought to cause the constellation of neoplastic growth (1). Endolymphatic sac tumors (ELSTs) are also associated with vHL and occur in approximately 15% of cases (2). The origin of these tumors has been a source of controversy, but the work of Heffner (3) and others (4,5) has demonstrated that they are low-grade adenocarcinomas that originate in the proximal or rugose portion of the endolymphatic sac. ELSTs are locally aggressive, vascular tumors that may invade adjacent structures in the temporal bone but have not been known to metastasize. The ELST shown in Figure 1 occurred in the left temporal bone of an 8-year-old boy who presented with profound sensorineural hearing loss, intermittent vertigo, and vHL based on mutation analysis that showed a Gto-C nucleotide 601 mutation in the vHL gene on chromosome 3. High-resolution computed tomographic imaging using a bone-window protocol demonstrates a destructive mass involving the posterior aspect of the left petrous temporal bone centered midway between the internal auditory canal and the sigmoid sinus. Bony erosion extends into the posterior semicircular canal, and there are areas of stippling and central calcification within the mass suggestive of an aggressive, erosive process. Magnetic resonance images of ELSTs may demonstrate enhancement on precontrast T1-weighted images and heterogeneous enhancement on T2-weighted images. Larger lesions may show flow voids. Although the diagnosis in this case was relatively straightforward on the basis of the combination of genetic screening studies and characteristic imaging features on computed tomographic scanning, a differential diagnosis of similar lesions should include meningioma, choroid plexus papilloma, paraganglioma, chondrosarcoma, and metastasis. REFERENCES

Cochlear implantation in pediatric patients with Cockayne Syndrome

Cockayne Syndrome (CS) is a rare, autosomal recessive disorder characterized by a spectrum of phenotypic abnormalities, including progressive sensorineural hearing loss (SNHL) that involves both peripheral and central components. To date, a single series of CS patients undergoing cochlear implant (CI) placement has been reported; this study reports on additional previously unreported pediatric CI recipients. Subjective benefits were noted early after activation in both patients, and speech perception scores improved over time as well, varying from 42 to 70% (versus 0-12% previously). Thus, we report that cochlear implantation in pediatric patients with CS can be effective in the management of progressive SNHL.