Impact of video-endoscopy on the results of retrosigmoid-transmeatal microsurgery of vestibular schwannoma: prospective study

Abstract

Endoscopy-assisted microsurgery represents modern trend of treatment of the cerebellopontine angle (CPA) pathologies including vestibular schwannoma (VS). Endoscopes are used in adjunct to microscope to achieve better functional results with less morbidity. Angled optics, magnification and illumination enable superior view in the operative field. Consecutive 89 patients with untreated unilateral sporadic vestibular schwannoma undergoing tumor resection via a retrosigmoid approach during 2008-2010 were prospectively analysed. Endoscopy-assisted microsurgical (EA-MS) removal was performed in 39 cases (Grade 1: 2, Grade 2: 5, Grade 3: 9, Grade 4: 22, Grade 5: 1) and microsurgical (MS) removal was performed in 50 cases (Grade 1: 1, Grade 2: 3, Grade 3: 9, Grade 4: 34, Grade 5: 3). Minimally invasive approach with craniotomy ≤ 2.5 cm was employed for small tumors (Grade 1 and 2) in the EA-MS group. Endoscopic technique was used for monitoring of neuro-vascular anatomy in CPA, during dissection of the meatal portion of tumors, assessment of radicality and for identification of potential pathways for CSF leak formation. All cases in MS group were deemed as radically removed. In the EA-MS group, residual tumor tissue in the fundus of internal auditory canal not observable with microscope was identified with endoscope in four cases. Such cases were radicalized. Tumor recurrence was not observed during the follow-up in EA-MS group. There is a suspicious intrameatal tumor recurrence on the repeated MRI scan in one patient in the MS group. Neither mortality nor infection was observed. The most common complication was pseudomeningocele (EA-MS 20 cases; MS 23). It was managed with aspiration with or without tissue-gluing in all cases without the need for any surgical revision. Adjunctive use of endoscope in the EA-MS group identified potential pathways for CSF leak formation, which was not observable with the microscope in five patients. Improved cochlear nerve (EA-MS: 22, MS: 14; p = 0.012), brainstem auditory evoked potentials (EA-MS: 3 of 8, MS: 0 of 4) and hearing (EA-MS: 14 of 36, MS: 4 of 45; p = 0.001) preservation were observed in EA-MS group. Despite the trend for better useful hearing (Gardner-Robertson class 1 and 2) preservation (EA-MS: 8 of 26, MS: 1 of 16) there were no significant differences in the postoperative hearing handicap inventory in both groups. There were no differences in the postoperative tinnitus in both groups. Better facial nerve preservation (EA-MS: 39, MS: 44; p = 0.027) and excellent-very good (House-Brackmann 1 or 2) facial nerve function (EA-MS: 31, MS: 29; p = 0.035) were observed in EA-MS group. Postoperative compensation of vestibular lesion, symptoms typical for VS, patients assessed by dizziness handicap inventory, facial disability index were comparable in both studied groups. Adjunctive use of endoscope during the VS surgery due to its magnification and illumination enable superior view in the operative field. It is valuable for assessment of radicality of resection in the region of i...

Complications of Microsurgery of Vestibular Schwannoma

“…The same is true for the retrosigmoid-transmeatal approach in which the most common pathways of leak formation are perimeatal air cells of petrous bone; therefore, their sealing is crucial for CSF leak prevention. The addition of endoscopic and endoscopy-assisted vestibular schwannoma surgery seems to be beneficial for improved identification of potential pathways of CSF leakage [34]. The material used for petrous bone air cells sealing can also be considered a significant factor.…”

“…Overall incidences of persisting postoperative vertigo and disequilibrium in VS microsurgery have ranged from 1% to as high as 30% [16, 69, 81]. In our previous study [34], the patient's age was identified as the only important factor associated with disordered vestibular compensation following retrosigmoid VS microsurgery. Thus, new methods including prehabituation and biofeedback seem to be a logical step of outcome improvement [72, 77].…”

Comparison of microscopic and endoscopic view of the internal acoustic meatus: A cadaveric study

“…Better exposure encourages for less drilling of the posterior wall of the IAM which consequently will reduce the risk of injury to endolymphatic duct, common crus, vestibule or ampulla of the posterior semicircular canal (Domb and Chole, ). Early endoscopic inspection supports identification of tumor extension, neurovascular structures and relationships, the proximity of the jugular bulb and the fundus of the IAM (Gerganov et al, ; Göksu et al, ; Chovanec et al, ). Accidentally opened mastoid cells can easily be identified and sealed to prevent postoperative CSF fistula (Göksu et al, ).…”

Risk of Posterior Semicircular Canal Trauma When Using a Retrosigmoid Approach for Acoustic Neuroma Surgery and Role of Endoscopy: An Imaging Study

“…1 The most common cause of CSF leakage regardless of approach is unrecognized open air cells during drilling. 1,3,7 Other morbidities that may arise from the retrosigmoid approach include injury to the cerebellum, cranial nerves, and vessels; headache; and hearing loss despite saving the cochlear nerve anatomy. 4 The hearing loss may be the result of an injury to the posterior semicircular canal during the surgeon's attempt to expose the internal acoustic canal (IAC) posteriorly.…”