Iatrogenic Third Window After Retrosigmoid Approach to a Vestibular Schwannoma Managed with Cochlear Implantation

Inner Ear Breaches from Vestibular Schwannoma Surgery: Revisiting the Incidence of Otologic Injury from Retrosigmoid and Middle Cranial Fossa Approaches

OBJECTIVE

To assess the rate of iatrogenic injury to the inner ear in vestibular schwannoma resections.

STUDY DESIGN

Retrospective case review.

SETTING

Multiple academic tertiary care hospitals.

PATIENTS

Patients who underwent retrosigmoid or middle cranial fossa approaches for vestibular schwannoma resection between 1993 and 2015.

INTERVENTION

Diagnostic with therapeutic implications.

MAIN OUTCOME MEASURE

Drilling breach of the inner ear as confirmed by operative note or postoperative computed tomography (CT).

RESULTS

21.5% of patients undergoing either retrosigmoid or middle fossa approaches to the internal auditory canal were identified with a breach of the vestibulocochlear system. Because of the lack of postoperative CT imaging in this cohort, this is likely an underestimation of the true incidence of inner ear breaches. Of all postoperative CT scans reviewed, 51.8% had an inner ear breach. As there may be bias in patients undergoing postoperative CT, a middle figure based on sensitivity analyses estimates the incidence of inner ear breaches from lateral skull base surgery to be 34.7%.

CONCLUSIONS

A high percentage of vestibular schwannoma surgeries via retrosigmoid and middle cranial fossa approaches result in drilling breaches of the inner ear. This study reinforces the value of preoperative image analysis for determining risk of inner ear breaches during vestibular schwannoma surgery and the importance of acquiring CT studies postoperatively to evaluate the integrity of the inner ear.

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.

Prevalence and associated risk factors of tinnitus among adult Palestinians: a cross-sectional study

Tinnitus is a common complaint with potentially negative impact on quality of life. Prevalence of tinnitus ranges from 5 to 43% worldwide. This variation could be due to the heterogeneity of tinnitus assessment. This has limited the progress in understanding tinnitus. Therefore, we employed a standardized and a validated assessment method to determine the prevalence and related risk factors of tinnitus among Palestinians for the first time. This is a cross-sectional study in which we questioned a representative sample of 618 subjects in one-to-one interviews. The prevalence of any tinnitus was 30.6% among adult Palestinians. Participants from the oldest age group were almost five times more likely to have tinnitus. Moreover, participants with head and neck pain syndrome, severe hearing impairment, sleeping disorders or frequent complaints of vertigo were approximately two times more likely to have tinnitus. Our study provides novel information regarding tinnitus in Palestine and improves our understanding of tinnitus. This will improve the diagnosis and consequently will contribute in reducing the prevalence and perhaps in preventing tinnitus. As tinnitus still has no known cure, further investigations of modifiable risk factors and causes of tinnitus are crucial to prevent it in the future.