The role of cochlear and vestibular afferents in long-latency cervical vestibular evoked myogenic potentials.

OBJECTIVE: To examine the origin of cervical vestibular evoked myogenic potential (cVEMP) late waves (n34-p44) elicited with air-conducted click stimuli. DESIGN: Using a retrospective design, cVEMPs from normal volunteers were compared to those obtained from patients with vestibular and auditory pathologies. STUDY SAMPLE: (1) Normal volunteers (n = 56); (2) severe-to-profound sensorineural hearing loss (SNHL) with normal vestibular function (n = 21); (3) peripheral vestibular impairment with preserved hearing (n = 16); (4) total vestibulocochlear deficit (n = 23). RESULTS: All normal volunteers had ipsilateral-dominant early p13-n23 peaks. Late peaks were present bilaterally in 78%. The p13-n23 response was present in all patients with SNHL but normal vestibular function, and 43% had late waves. Statistical comparison of these patients to a subset of age-matched controls showed no significant difference in the frequencies, amplitudes or latencies of their ipsilateral early and late peaks. cVEMPs were absent in all patients with vestibular impairment. CONCLUSION: The presence of long-latency cVEMP waves was not dependent on the integrity of sensorineural hearing pathways, but instead correlated with intact vestibular function. This finding conflicts with the view that these late waves are cochlear in origin, and suggests that vestibular afferents may assume a more prominent role in their generation.

Post Cochlear Implantation Vertigo: Ictal Nystagmus and Audiovestibular Test Characteristics.

OBJECTIVE: To investigate ictal nystagmus and audiovestibular characteristics in episodic spontaneous vertigo after cochlear implantation (CI). STUDY DESIGN: Retrospective and prospective case series. PATIENTS: Twenty-one CI patients with episodic spontaneous vertigo after implantation were recruited. INTERVENTIONS: Patient-initiated home video-oculography recordings were performed during one or more attacks of vertigo, using miniature portable home video-glasses. To assess canal and otolith function, video head-impulse tests (vHITs) and vestibular-evoked myogenic potential tests were conducted. MAIN OUTCOME MEASURES: Nystagmus slow-phase velocities (SPVs), the presence of horizontal direction-changing nystagmus, and post-CI audiovestibular tests. RESULTS: Main final diagnoses were post-CI secondary endolymphatic hydrops (48%) and exacerbation of existing Ménière's disease (29%). Symptomatic patients demonstrated high-velocity horizontal ictal-nystagmus (SPV, 44.2°/s and 68.2°/s in post-CI secondary endolymphatic hydrop and Ménière's disease). Direction-changing nystagmus was observed in 80 and 75%. Two were diagnosed with presumed autoimmune inner ear disease (SPV, 6.6°/s and 172.9°/s). One patient was diagnosed with probable vestibular migraine (15.1°/s).VHIT gains were 0.80 ± 0.20 (lateral), 0.70 ± 0.17 (anterior), and 0.62 ± 0.27 (posterior) in the implanted ear, with abnormal values in 33, 35, and 35% of each canal. Bone-conducted cervical and ocular vestibular-evoked myogenic potentials were asymmetric in 52 and 29% of patients (all lateralized to the implanted ear) with mean asymmetry ratios of 51.2 and 35.7%. Reversible reduction in vHIT gain was recorded in three acutely symptomatic patients. CONCLUSION: High-velocity, direction-changing nystagmus time-locked with vertigo attacks may be observed in post-CI implant vertigo and may indicate endolymphatic hydrops. Fluctuating vHIT gain may be an additional marker of a recurrent peripheral vestibulopathy.

Subjective visual horizontal correlates better with ocular than with cervical vestibular evoked myogenic potentials.

OBJECTIVE: To examine the relationship between widely used otolith function tests: the Subjective Visual Horizontal (SVH) and Vestibular Evoked Myogenic Potentials (VEMP). METHODS: A retrospective analysis was performed on 301 patients who underwent SVH, ocular and cervical VEMP (oVEMP and cVEMP) tests on the same day. Correlations between the mean SVH tilt and amplitude asymmetry ratios for bone-conducted (BC) oVEMP and air-conducted (AC) cVEMP were examined. Diagnoses included vestibular neuritis, stroke, vestibular migraine, Meniere's disease, sudden sensorineural hearing loss (SSNHL) and vestibular schwannoma. RESULTS: SVH results were concordant with the oVEMP in 64% of cases and the cVEMP in 51%. Across all patients, SVH demonstrated a significant moderate correlation with BC oVEMP amplitude asymmetry ratios (r = 0.55, p < 0.001) and a weak correlation with AC cVEMP amplitude asymmetry ratios (r = 0.35, p < 0.001). A stronger correlation between SVH and oVEMPs was observed in patients with vestibular neuritis (r = 0.67, p < 0.001) and SSNHL (r = 0.76, p = 0.001). CONCLUSIONS: SVH correlates better with oVEMP than cVEMP symmetry. SIGNIFICANCE: This finding reinforces the hypothesis of a common utricular origin for both SVH and oVEMPs which is distinct from the saccular origin of cVEMPs.

Impact of Cochlear Implantation on Canal and Otolith Function.

OBJECTIVE: To quantify the impact of cochlear implantation (CI) on all five vestibular end-organs and on subjective ratings of post-CI dizziness. METHODS: Seventy-two patients undergoing unilateral CI were recruited for the study. All participants completed pre- and post-CI three-dimensional video head-impulse tests (3D vHITs) to assess semicircular-canal (SC) function, air- and bone-conducted (AC and BC) cervical and ocular vestibular-evoked myogenic potentials (cVEMPs and oVEMPs) to assess otolith-function and the dizziness handicap inventory (DHI) to measure self-perceived disability. RESULTS: Nineteen percent of patients reported new or worsened dizziness postsurgery. Post-CI abnormalities (new lesions and significant deteriorations) were seen in the AC cVEMP (48%), AC oVEMP (34%), BC cVEMP (10%), and BC oVEMP (7%); and lateral (L) (17%), posterior (P) (10%), and anterior (A) (13%) SC vHITs. CI surgery was more likely to affect the AC cVEMP compared with the other tests (χ2 test, p < 0.05). Fifty percent of patients reported no dizziness pre- and postsurgery. In the implanted ear, normal pre-CI vHIT gain was preserved in lateral semicircular canal (LSC) (69%), anterior semicircular canal (ASC) (74%), and posterior semicircular canal (PSC) (67%), and normal reflex amplitudes were found in AC cVEMP (25%), AC oVEMP (20%), BC cVEMP (59%), and BC oVEMP (74%). Statistically significant decreases were observed in LSC vHIT gain, AC cVEMP amplitude, and AC oVEMP amplitude postsurgery (p < 0.05). There was a significant moderate positive correlation between change in DHI scores and the summed vestibular deficit postsurgery (r(51) = 0.38, p < 0.05). CONCLUSION: CI can impact tests that assess all five vestibular end-organs and subjective ratings of dizziness. These results support pre and post-surgical vestibular testing and assist preoperative counseling and candidate selection.

Endoscopic Stapedotomy: A Systematic Review.

OBJECTIVES: Stapes surgery has evolved from its origins in 1956. Microscopic assisted stapedotomy remains the most common technique but the introduction of endoscopic ear surgery has led to some units using this new approach. The endoscope delivers a wide angled, contextual view of the stapes, and associated pathology. This systematic review provides a critical analysis of the current published endoscopic data, allowing comparison to the established microscopic technique. DATA SOURCES: Six databases (PubMed, Medline, Cochrane database, AMED, EMBASE, and CINAHL) were searched for studies within the last 10 years. STUDY SELECTION AND DATA EXTRACTION: English language articles including 5 or more cases were included. Primary outcomes included audiological results and reported complications. Data was extracted according to PRISMA guidelines. RESULTS: Thirteen papers were identified comprising 361 endoscopic stapes surgeries. Postoperative temporary facial nerve weakness was reported in 3 patients (0.8%) which all resolved within 4 weeks. Chorda tympani injury occurred in 21 cases (5.8%) and vertigo in 61 (16.9%). The audiometric outcomes of endoscopic stapes surgery were available for 259 patients and showed air bone gap closure rates of 71.4% (0-10 dB), 25.9% (11-20 dB), 2.3% (21-30 dB), and 0.4% (>30 dB). CONCLUSIONS: Endoscopic stapes surgery has similar audiometric outcomes compared to the traditional microscopic approach with air bone gap closure values of <20 dB in 97.3% of cases. However, the complication rates of chorda tympani damage, postoperative dysguesia, and tympanic membrane perforation for endoscopic stapes surgery are high. Caution should therefore be taken before undertaking stapes surgery with the endoscopic technique. Further studies are required to prove superiority over well established existing microsurgical methods.

Endoscopic Management of Early Stage Middle Ear Paragangliomas - An Australian Case Series.

OBJECTIVE: To analyze the outcomes of the endoscopic transcanal approach for removal of early stage middle ear paraganglioma tumors (MEPT). STUDY DESIGN: Cases series with chart review. SETTING: Two tertiary Australian Otology centers. PATIENTS: Adult patients with middle ear paraganglioma tumors treated with transcanal endoscopic approach from 2/2016 to 12/2019. Tumor staging was described using the Modified Fisch-Mattox (MFM). Inclusion criteria included patients with an MFM Class A or B. Exclusion criteria included higher staged or syndromic disease. INTERVENTION: All tumors were managed with transcanal endoscopic approach. MAIN OUTCOME MEASURES: Primary outcome measures included disease clearance and hearing measured according to the AAO-HNS guidelines. Secondary outcomes included complications, duration of surgery, and length of stay. RESULTS: Ten patients underwent totally endoscopic transcanal resection of MEPT (9 female, mean age of 45.5 years, 70% were left sided). Mean tumor size was 6.1 mm (SD 3.4 mm). Five cases (50%) were classified using the MFM system as class A1, two cases were class A2, and three cases were class B1. Three cases required canalplasty for access but were completed entirely endoscopically. Nine of the 10 cases had complete audiometric data. Pre- and postoperative mean air conduction remained stable with a decrease in mean air-bone gap of 2.84 dB. Postoperative complications include one pinhole perforation. There were no facial nerve complications. Mean follow-up period was 10 months (range 4-25 mo) with all cases having resolution of pulsatile tinnitus and no tumor recurrence. CONCLUSION: The transcanal endoscopic approach for early stage MEPT offers excellent visualization and permits safe and effective removal of disease with the advantages of a minimally invasive technique for patient recovery.

Novel Radiologic Approaches for Cholesteatoma Detection: Implications for Endoscopic Ear Surgery.

Technological advancement in computed tomography (CT) and MRI has improved cholesteatoma detection rates considerably in the past decade. Accurately predicting disease location and extension is essential for staging, planning, and preoperative counseling, in particular in the newer approach of endoscopic ear surgery. Improved sensitivity and specificity of these radiological methods may allow the surgeon to confidently monitor patients, therefore avoiding unnecessary surgery. This article outlines recent advances in CT and MRI technology and advantages and disadvantages of the newer techniques. Emphasis on improving the feedback loop between the radiologist and surgeon will increase the accuracy of these new technologies.

Endoscopic Stapedectomy: Collective Experience From a Large Australian Center.

INTRODUCTION: Endoscopic stapes surgery is a technically demanding procedure that is increasing in popularity. Surgical outcomes and complication rates have been demonstrated to be comparable to traditional microscopic techniques. The surgical outcomes for patients undergoing stapes surgery performed by the Sydney Endoscopic Ear Surgery Research Group are presented. STUDY DESIGN: Retrospective review from prospectively gathered database. SETTING: Tertiary referral centers. PATIENTS: A retrospective case review of patients undergoing endoscopic stapes surgery performed by four surgeons between February 2015 and July 2019 was carried out. Sixty nine patients were identified, and assessed for demographics, functional results, and postoperative complications. INTERVENTION: Endoscopic stapedotomy. MAIN OUTCOME MEASURE: Postoperative hearing results. RESULTS: Sixty eight of 69 patients (98.6%) achieved an air-bone gap (ABG) closure of less than 20 dB. Sixty of 69 patients (87%) achieved and ABG closure of less than 10 dB. The average improvement of the ABG over four frequencies achieved was 26.5 dB (range, 0-61). Postoperative complications were infrequent and self-limiting. Six patients experienced dysgeusia without obvious chorda tympani injury, four patients developed short lived vertigo, and two patients experienced tinnitus. CONCLUSIONS: Endoscopically assisted stapes surgery represents a safe alternative to traditional microscopic techniques, with similar morbidity and audiological outcomes.

The Endoscopic Relationship of the Stapedius Muscle to the Facial Nerve: Implications for Retrotympanic Surgery.

OBJECTIVES: The stapedius muscle, tendon, and pyramidal eminence are structures within the retrotympanum. In cholesteatoma surgery, the retrotympanum is a common site of residual disease. The removal of the pyramidal eminence during surgery is sometimes necessary to obtain better visualization of the superior retrotympanum during surgery. Understanding the relational anatomy of structures in the region to the facial nerve allows the surgeon to safely access regional disease. This study aims to better understand the anatomical relationship between the mastoid portion of the facial nerve, the pyramidal eminence, and the stapedius muscle. A secondary aim is to demonstrate that removal of the stapedius muscle in the cadaver model, can increase exposure to the retrotympanic space. STUDY DESIGN: Anatomical cadaveric observation study. METHODS: Endoscopic dissection of cadaveric heads was undertaken. Classification of the superior and inferior retrotympanic area was performed. The anatomy of the stapedius muscle was described including relationships, depth, course, and angle with respect to the facial nerve. The pyramidal eminence and stapedius muscle were removed in all specimens and the exposure of the retrotympanum re-evaluated to determine if exposure of the region was increased. RESULTS: In all cases (11 ears), the stapedius muscle was located medial and anterior to the mastoid portion of the facial nerve, with the second genu superior. The mean antero-posterior distance from the apex of the pyramidal eminence, which the stapedius tendon enters, to the stapes itself was 4.10 mm (range, 2.92-5.73 mm; standard deviation [SD] 0.90 mm). In all cases, irrespective of sinus tympani conformation, removal of the pyramidal eminence and stapedial bony crest in proximity to the facial nerve allowed exposure of the whole retrotympanic region, using a 0-degree endoscope. CONCLUSIONS: The pyramidal eminence and stapedius muscle have a relatively constant relationship to the facial nerve. Removal of the stapedius muscle in the human cadaver model increases the exposure of the sinus tympani and subpyramidal space. Increased visualization in this region, may reduce risk of residual cholesteatoma in patients.

Contralateral recovery of cochlear function after cochlear implantation.

Significant recovery of sensorineural hearing loss in either ear after cochlear implantation (CI) is rare. We present the case of a 57-year-old lady with medically treated depression and a background of chronic suppurative otitis media (CSOM) in the non-implanted ear, who clearly fulfilled audiological criteria for CI. Two years post-implantation her CSOM in the non-implanted ear was addressed with blind sac closure of the ear. Post-operatively the hearing thresholds in this ear had improved to the extent that a bone-anchored hearing aid became a viable option. The literature is carefully reviewed to consider possible explanations of this phenomenon.