Prognostic Significance of Changes in the Internal Acoustic Meatus Caused by Vestibular Schwannoma.

Abstract

The prognostic significance of the variety of changes in the internal auditory meatus (IAM) caused by vestibular schwannoma was retrospectively analyzed in 69 consecutive patients with vestibular schwannoma. Preoperative bone-window computed tomography was used to classify IAM changes into extensive destruction (17%), widening (46%), and normal IAM (36%). Extensive destruction (47 ± 19 years) and widening (48 ± 13) occurred in significantly younger patients than normal IAM (59 ± 9). Preoperative hearing was significantly more severely disturbed in patients with extensive destruction than in those with widening or normal IAM. IAM change was significantly related to the tumor consistency, as normal IAM was more common in patients with cystic tumor than in those with solid tumor. Postoperative hearing and facial function were worse in patients with severe IAM change, although the relationship between the IAM change and the surgical result was not significant. One patient with extensive destruction developed postoperative cerebrospinal fluid (CSF) leakage through the air cells around the IAM, and needed surgical repair. Severe IAM change occurs with solid tumor and causes severely disturbed preoperative hearing in younger patients, which reflects the tumor aggressiveness. Severe IAM change increases the technical difficulty of tumor removal and the risk of postoperative CSF leakage, and is associated with a poorer prognosis for patients with vestibular schwannoma.

The impact of hypotension due to the trigeminocardiac reflex on auditory function in vestibular schwannoma surgery

“…50 Additionally, the extent of IAC widening and tumor growth in the anterior and caudal directions are significant predictors for postoperative auditory function in patients with large tumors. 30 Somers, et al, 46 evaluated magnetic resonance imaging findings and found that low intralabyrinthine signal intensity documented on gradient echo images was associated with a lower rate of hearing preservation.…”

Radiological and Clinical Factors Predicting the Facial Nerve Outcome following Retrosigmoid Approach for Large Vestibular Schwannomas (VSs)

“…[10][11][12] Moreover, the effect on facial nerve outcome of several other factors such as histological features, clinical presentation, extrameatal tumor extension, bony changes in the internal acoustic meatus, and radiological features has been documented. [11][12][13][14][15] However, the majority of these studies lacked uniformity in terms of surgical approaches, operating surgeons, techniques of tumor excision, and methods of facial nerve preservation. The aim of our study was to identify various radiological and clinical factors that correlate with the facial nerve outcome after VS surgery using the retrosigmoid approach.…”

Functional Consequences of the Trigeminocardiac Reflex

“…94,95 Twenty-seven percent of all vestibular schwannoma patients present with deafness preoperatively, and another 44% are deaf postoperatively. 86 In addition, the extent of IAC widening and tumor growth anteriorly and caudally to the IAC are significant predictors of postoperative auditory function in schwannoma surgery for large tumors. 86 In addition, the extent of IAC widening and tumor growth anteriorly and caudally to the IAC are significant predictors of postoperative auditory function in schwannoma surgery for large tumors.…”

“…81 The facial nerve was preserved in 87% of retrosigmoid cases and 50% in middle fossa cases. 83,86 Also, the extent of IAC widening and tumor growth anteriorly and caudally to the IAC are significant predictors of postoperative auditory function in large tumors. Accidental injury of the labyrinth, for example, is followed by hearing loss in the majority of the cases despite the cochlear nerve preservation.…”

“…87,89 Severe changes in the IAC that were verified in preoperative bone-window computed tomography have also been found to be associated with poor preoperative hearing function as well as with an unfavorable postoperative outcome regarding hearing preservation. 86,95 Somers et al 90 evaluated magnetic resonance imaging findings and found that a low intralabyrinthine signal intensity on gradient echo images predicted a lower rate of hearing preservation. 86,95 Somers et al 90 evaluated magnetic resonance imaging findings and found that a low intralabyrinthine signal intensity on gradient echo images predicted a lower rate of hearing preservation.…”