Iatrogenic inner ear dehiscence associated with lateral skull base surgery: a systematic analysis of drilling injuries and their causal factors.

PURPOSE: Drilling injuries of the inner ear are an underreported complication of lateral skull base (LSB) surgery. Inner ear breaches can cause hearing loss, vestibular dysfunction, and third window phenomenon. This study aims to elucidate primary factors causing iatrogenic inner ear dehiscences (IED) in 9 patients who presented to a tertiary care center with postoperative symptoms of IED following LSB surgery for vestibular schwannoma, endolymphatic sac tumor, Meniere's disease, paraganglioma jugulare, and vagal schwannoma. METHODS: Utilizing 3D Slicer image processing software, geometric and volumetric analysis was applied to both preoperative and postoperative imaging to identify causal factors iatrogenic inner ear breaches. Segmentation analyses, craniotomy analyses, and drilling trajectory analyses were performed. Cases of retrosigmoid approaches for vestibular schwannoma resection were compared to matched controls. RESULTS: Excessive lateral drilling and breach of a single inner ear structure occurred in 3 cases undergoing transjugular (n=2) and transmastoid (n=1) approaches. Inadequate drilling trajectory breaching ≥1 inner ear structure occurred in 6 cases undergoing retrosigmoid (n=4), transmastoid (n=1), and middle cranial fossa approaches (n=1). In retrosigmoid approaches the 2-cm visualization window and craniotomy limits did not provide drilling angles to the entire tumor without causing IED in comparison to matched controls. CONCLUSIONS: Inappropriate drill depth, errant lateral drilling, inadequate drill trajectory, or a combination of these led to iatrogenic IED. Image-based segmentation, individualized 3D anatomical model generation, and geometric and volumetric analyses can optimize operative plans and possibly reduce inner ear breaches from lateral skull base surgery.

Psychological Status as an Effect Modifier of the Association Between Allergy Symptoms and Allergy Testing.

OBJECTIVE: Patient-reported outcome measures, while valuable, may not correlate with diagnostic test results. To better understand this potential discrepancy, our objective was to determine whether psychological health is an effect modifier of the association between patient-reported allergy outcome scores and allergy test results. STUDY DESIGN: Prospective outcomes study. SETTING: Tertiary care hospital and community-based clinic. METHODS: This study included 600 patients at least 18 years of age who presented for symptoms related to allergic rhinitis and completed the related sinonasal outcome test (SNOT), which includes validated nasal, allergy, and psychological domains. Stratified analyses of odds ratios and Spearman correlation coefficients were utilized to assess for effect modification by psychological status. RESULTS: Worse patient-reported allergic rhinitis symptoms were significantly associated with positive allergy test results (odds ratio [OR] 1.69, 95% confidence interval [CI] 1.22-2.34, P = .002) in patients with better psychological health. In contrast, there was no association in patients with worse psychological health (OR 1.06, 95% CI 0.36-3.10, P = .92). These findings were corroborated by assessments of correlation: allergy domain scores were positively correlated with allergy testing scores (Spearman rho 0.18, 95% CI 0.10-0.25, P < .001) in patients with better psychological health, while there was no correlation in patients with worse psychological health (-0.02, 95% CI -0.16-0.12, P = .77). CONCLUSIONS: Psychological status was an effect modifier of the association between allergy domain and allergy testing data. When assessing the relationship between subjective measures, such as sinonasal validated instruments, and objective measures, such as allergy test results, accounting for effect modifiers such as psychological state can provide clinical and research-related insights.

The Impact of Sinonasal Symptoms in Relation to Potentially Life-Threatening Comorbidities.

OBJECTIVE: While general health may be influenced by sinonasal symptoms, their effects may be overshadowed by comorbid states which may be more serious. To assess the validity of this postulate, we measured the extent to which sinonasal symptoms and concurrent conditions influenced general health. STUDY DESIGN: Observational outcomes study. SETTING: Academic medical center, community care sites. METHODS: Adults with sinonasal symptoms completed the 22-item Sinonasal Outcome Test, along with the Patient-Reported Outcomes Measurement Information System global health short form. Comorbidities were categorized with the Deyo modification of the Charlson comorbidity index. Multivariate regression analyses were utilized to determine the relative impact of sinonasal symptoms and concurrent comorbid conditions on general health. RESULTS: Data from 219 consecutive patients demonstrated that sinonasal symptoms were associated with significantly diminished general physical (ß = -1.431, p < .001), mental (ß = -1.000, p < .001), overall (ß = -1.026, p < .001), and social health (ß = -0.872, p = .003), regardless of the presence of potentially life-threatening comorbid conditions. Comorbid conditions included cardiovascular disease, chronic obstructive pulmonary disease, connective tissue disease, peptic ulcer, diabetes mellitus, and hepatic disease. The effect of sinonasal symptoms was neither subsumed nor overshadowed by the effects of comorbid states. Nasal, ear, sleep, and psychological domain scores were also associated with general physical, mental, and global health while adjusting for the impact of comorbidities. CONCLUSION: Sinonasal symptoms have a substantial effect on general health which is not subsumed by the presence of potentially life-threatening concurrent comorbidities. These data may help support the importance of funding and resource allocation for conditions causing sinonasal symptoms.

Normative Values for the Inner EAR Scale.

OBJECTIVE: To determine normative values for the Inner Effectiveness of Auditory Rehabilitation (Inner EAR) scale, a validated instrument utilized to study the impact of hearing loss and potential treatments. STUDY DESIGN: Observational outcomes study. SETTING: Academic medical center and community care sites. METHODS: We included patients who were at least 18 years of age and completed the Inner EAR scale, pure-tone audiometry, and word recognition score assessment. Based on audiometry results, patients were categorized as having: (1) normal bilateral hearing, (2) unilateral hearing loss, and (3) bilateral hearing loss. The distributions of Inner EAR scale scores were assessed within each category. Fisher's exact test was utilized to determine whether data-driven threshold values could discriminate among the 3 clinical groups. RESULTS: Two hundred and twenty-two consecutive patients with hearing-related complaints met inclusion criteria. Mean Inner EAR scores for patients with bilateral hearing loss (29.2, interquartile range [IQR] 10-41.5), unilateral hearing loss (38.9, IQR 23-49), and normal hearing (46.6, IQR 31-62) were significantly different (analysis of variance F < 0.0001). An Inner EAR score threshold of 50 supported the ability to statistically significantly discriminate between bilateral hearing loss and normal hearing (p = .003), as well as between unilateral hearing loss and normal hearing (p = .015). CONCLUSION: An Inner EAR score normative threshold value of 50 provides significant discriminatory ability between normal hearing and unilateral or bilateral hearing loss on audiometry. Normative values provide useful, frequently referenced data when assessing responses to treatment. Based on these data, this threshold may help distinguish patients with and without perceived functional impact from hearing loss.

The Role of Body Mass Index on Hearing Outcomes After Stapes Surgery.

BACKGROUND: Increased body mass index (BMI) has been associated with postoperative complications in multiple surgical specialties. In otologic surgery involving the stapes, where appropriate patient positioning and surgical dexterity are necessary for proper prosthesis placement, patients with higher BMI could make surgery more challenging. The purpose of this study is to evaluate the impact of BMI on outcomes after stapes surgery. METHODS: Medical records were examined from January 2015 to December 2017 in patients undergoing stapedectomy or stapedotomy at two tertiary care facilities. A retrospective cohort analysis comparing hearing outcomes on postoperative audiogram following procedural intervention with BMI was performed. The primary outcome was postoperative air-bone gap (dB) on audiogram. RESULTS: Two hundred sixty three stapedotomy and stapedectomy patients were included in the study. Six percent had BMI less than 18.5 (underweight), 30% had BMI between 18.6 and 24.9 (normal weight), 38% had BMI between 25 and 29.9 (overweight), 24% had BMI above 30 (obese). The mean preoperative and postoperative air-bone gap (ABG) was 27.0 dB (standard deviation [SD] 15) and 10.4 dB (SD 10.6), respectively, with a postoperative ABG less than or equal to 20 dB in 87% of cases. There were no significant differences in postoperative ABG results when comparing the BMI categories (p = 0.11). CONCLUSIONS: Stapedotomy and stapedectomy are effective surgeries that can be performed by experienced surgeons with successful hearing improvement. While high BMI patients may be a challenge to position appropriately for their surgery, this does not translate to altered otologic outcomes for these patients.

Iatrogenic Inner Ear Dehiscence After Lateral Skull Base Surgery: Therapeutic Dilemma and Treatment Options.

OBJECTIVE: To describe a series of patients with iatrogenic inner ear dehiscence after lateral skull base surgery and discuss treatment options. PATIENTS: Three patients with history of recent lateral skull base surgery, symptoms consistent with inner ear dehiscence, and radiographically proven bony dehiscence on postoperative imaging. INTERVENTIONS: All patients were initially managed conservatively with serial outpatient visits. Two patients with large cochlear and vestibular dehiscences had round window reinforcement procedures. One patient had transmastoid resurfacing for repair of an iatrogenic posterior semicircular canal dehiscence. MAIN OUTCOME MEASURES: Anatomical location of dehiscences; treatment options; subjective auditory and vestibular symptoms pre-dehiscence, post-dehiscence and after dehiscence repair; pre- and post-audiogram when available. RESULTS: Patient ages were 46, 52, and 60 with two of three being women. None of the patients had subjective auditory or vestibular symptoms of inner ear dehiscence before initial skull base surgery, but they all had development of these symptoms afterwards. All patients were initially managed conservatively, but all ultimately required a surgical procedure. The two patients who elected for round window reinforcements, and the one patient who required transmastoid resurfacing, had significant improvement of symptoms. CONCLUSIONS: Iatrogenic inner ear dehiscence after skull base surgery is best dealt with and repaired intraoperatively. Should intraoperative repair not be possible, transcanal round window reinforcement is a minimally invasive option for medial otic capsule dehiscence, although long-term outcomes are unclear. For lateral otic capsule dehiscence, a transmastoid approach is recommended. LEVEL OF EVIDENCE: IV.

Prevalence of Radiographic Cochlear-Facial Nerve Dehiscence.

OBJECTIVE: To determine the prevalence of radiographic cochlear-facial nerve dehiscence (CFD). STUDY DESIGN: Retrospective radiological study. SETTING: Two tertiary-referral centers. PATIENTS: Two hundred six temporal-bone computed tomography (CT) scans (405 total ears) of otology/neurotology patients from two academic institutions between the years 2014 and 2017. INTERVENTION: Diagnostic. MAIN OUTCOME MEASURES: The cochlear-facial nerve partition width (CFPW) was measured on coronal CT sections and defined as the shortest distance between the cochlear basal turn and facial nerve (FN) labyrinthine segment. We used logistics regression analyses to determine positive predictors for radiographic evidence of CFD. RESULTS: The overall prevalence of radiographic CFD was 5.4% (22/406 ears). 9.2% of patients (19/206) had CFD. Of these 19 patients, only one patient had mixed hearing loss that could not be explained by any other vestibular or auditory etiology. Three out of 206 patients had dehiscence in both ears (1.4%). The average CFPW was 0.6 ±â€Š0.2 mm, and fallopian canal width was 1.1 ±â€Š0.02 mm (n = 405). Older age, use of traditional CT scans, and thinner CT slice thickness were significant predictors for radiographic CFD. CONCLUSIONS: The radiographic prevalence of CFD is higher than what is reported in histologic studies, and may over-estimate the true prevalence of CFD. The clinician should keep this in mind when considering this as potential cause for third-window symptoms.

Electrode Array Displacement into the Fallopian Canal in Revisions of Long-standing Cochlear Implants.

OBJECTIVE: To describe extracochlear extension of revision cochlear implant arrays into the Fallopian canal. PATIENTS: Two adult patients with extension of revision cochlear implant arrays into the Fallopian canal. INTERVENTIONS: Computed tomography (CT), selective deactivation of non-functional electrodes. MAIN OUTCOME MEASURES: Facial nerve function, facial nerve stimulation, cochlear implant electrode position, radiography, functional hearing. RESULTS: Two patients presented with failure of their long-standing cochlear implants (CIs). One patient with presumed postviral hearing loss presented with declining function and increasing facial stimulation from an implant placed 30 years previous. A second with postmeningitic hearing loss presented with a draining mastoid fistula from an implant placed 7 years before. Both patients were reimplanted with minimal insertion resistance via the established electrode tract, yet demonstrated facial nerve stimulation during intraoperative telemetry and on device activation. Postoperative CTs of each patient showed exit of the electrode from the cochlea into the tympanic or labyrinthine Fallopian canal. Both patients can use their devices effectively with selective electrode deactivation. CONCLUSIONS: Our cases illustrate the potential association of long-standing electrodes with otic capsule changes, allowing extracochlear malposition of subsequent arrays. This can occur despite apparently uneventful reinsertion of a flexible array without undue force. Previously reported histopathology confirms the potential for a reactive osteitis from arrays that may contribute to this phenomenon. Intraoperative facial stimulation with neural telemetry testing can raise suspicion of a malpositioned array involving the Fallopian canal. Such cases can be effectively managed with selective deactivation of malpositioned electrode contacts.

Iatrogenic Phenol Injury Causing Facial Paralysis With Tympanic Membrane and Ossicular Necrosis.

OBJECTIVE: To describe a serious iatrogenic injury and propose means of reducing the risk of its reoccurrence. PATIENTS: A 21-year-old man who suffered facial paralysis, complete necrosis of the tympanic membrane, and ossicular discontinuity because of chemical burn from accidental application of copious amounts of topical anesthetic phenol into the ear. INTERVENTIONS: Conservative management of facial paralysis and delayed reconstruction of the tympanic membrane and ossicular chain. MAIN OUTCOME MEASURES: Gradual recovery to grade 1/6 facial function, successful repair of the tympanic membrane, but persistent 30-dB conductive hearing loss after partial ossicular replacement prosthesis presumably because of scarring. CONCLUSION: Phenol is a highly toxic chemical, topically to both skin and eyes. Absorbed through the skin it can have lethal cardiotoxicity. It is also potent neurotoxin at concentrations much lower (4-7%) than used for tympanic membrane anesthesia (89%) and has long been used therapeutically to destroy nerves in patients of contractions or intractable pain. Otologists need to have a healthy respect for the dangers of using phenol. As only a minute quantity is needed for tympanic anesthesia, commercially available prepackaged applicators are preferred. Storage of stock bottles of 89% phenol solutions in clinical settings risks injury to both patients and practitioners.

Abducens Nerve Avulsion and Facial Nerve Palsy After Temporal Bone Fracture: A Rare Concomitance of Injuries.

BACKGROUND: Avulsion of the abducens nerve in the setting of geniculate ganglion injury after temporal bone fracture is unreported previously. We discuss clinical assessment and management of a patient with traumatic avulsion of cranial nerve (CN) VI in the setting of an ipsilateral CN VII injury after temporal bone fracture and call attention to this unusual injury. CASE DESCRIPTION: A 26-year-old man suffered a temporal bone fracture after a motor vehicle accident and developed diplopia and right-sided facial droop. Six weeks after the accident, the patient was readmitted with worsening diplopia and ipsilateral facial weakness. He demonstrated absent lateral gaze on the right suggestive of either restrictive movement or right. CN VI DEFICIT: In addition, he had right-sided facial palsy graded as 6/6 House-Brackmann. High-resolution computed tomography demonstrated a right-sided longitudinal otic capsule-sparing temporal bone fracture that propagated into the facial nerve canal and geniculate fossa. Magnetic resonance imaging revealed discontinuity of the right CN VI between the pons and the Dorello canal, as well as injury to the ipsilateral geniculate ganglion. CN VII was intact proximally, from the pons through the internal auditory canal. Consensus was reached to proceed with conservative management. At 13 months after injury, the patient reported 1/6 House-Brackmann with no improvement in CN VI function. CONCLUSIONS: This case illustrates 2 subtle findings on imaging with potential therapeutic implications, notably the role of surgical intervention for facial nerve palsy.

BMP4 induction of sensory neurons from human embryonic stem cells and reinnervation of sensory epithelium.

In mammals, hair cells and auditory neurons lack the capacity to regenerate, and damage to either cell type can result in hearing loss. Replacement cells for regeneration could potentially be made by directed differentiation of human embryonic stem (hES) cells. To generate sensory neurons from hES cells, neural progenitors were first made by suspension culture of hES cells in a defined medium. The cells were positive for nestin, a neural progenitor marker, and Pax2, a marker for cranial placodes, and were negative for alpha-fetoprotein, an endoderm marker. The precursor cells could be expanded in vitro in fibroblast growth factor (FGF)-2. Neurons and glial cells were found after differentiation of the neural progenitors by removal of FGF-2, but evaluation of neuronal markers indicated insignificant production of sensory neurons. Addition of bone morphogenetic protein 4 (BMP4) to neural progenitors upon removal of FGF-2, however, induced significant numbers of neurons that were positive for markers associated with cranial placodes and neural crest, the sources of sensory neurons in the embryo. Neuronal processes from hES cell-derived neurons made contacts with hair cells in denervated ex vivo sensory epithelia and expressed synaptic markers, suggesting the formation of synapses. In a gerbil model with a denervated cochlea, the ES cell-derived neurons engrafted in the auditory nerve trunk and sent out neurites that grew toward the auditory sensory epithelium. These data indicate that hES cells can be induced to form sensory neurons that have the potential to treat neural degeneration associated with sensorineural hearing loss.