Morbidity Rate of the Retrosigmoid versus Translabyrinthine Approach for Vestibular Schwannoma Resection

BACKGROUND AND OBJECTIVES: Controversy related to the choice of surgical approach for vestibular schwannoma (VS) resection remains. Whether the retrosigmoid (RS) or translabyrinthine (TL) approach should be performed is a matter of debate. In the context of a lack of clear evidence favoring one approach, we conducted a retrospective study to compare the morbidity rate of both surgical approaches. SUBJECTS AND METHODS: 168 patients underwent surgical treatment (2007-2013) for VS at our tertiary care center. There were no exclusion criteria. Patients were separated into two groups according to the surgical approach: TL group and RS group. Signs and symptoms including ataxia, headache, tinnitus, vertigo and cranial nerve injuries were recorded pre- and postoperatively. Surgical complications were analyzed. Perioperative facial nerve function was measured according to House-Brackmann grading system. RESULTS: Tumor resection was similar in both groups. Facial paresis was significantly greater in RS group patients preoperatively, in the immediate postoperative period and at one year follow-up (p < 0.05). A constant difference was found between both groups at all three periods (p=0.016). The evolution of proportion was not found to be different between both groups (p=0.942), revealing a similar rate of surgically related facial paresis. Higher rate of ataxic gait (p=0.019), tinnitus (p=0.039) and cranial nerve injuries (p=0.016) was found in RS group patients. The incidence of headache, vertigo, vascular complications, cerebrospinal fluid leak and meningitis was similar in both groups. No reported mortality in this series. CONCLUSIONS: Both approaches seem similar in terms of resection efficacy. However, according to our analysis, the TL approach is less morbid. Thus, for VS in which hearing preservation is not considered, TL approach is preferable.

Locacorten Vioform Ototoxicity Upon Guinea Pig Middle Ear Application

BACKGROUND AND OBJECTIVES: Locacorten Vioform (Novartis UK) is frequently prescribed for otomycosis. Its component, Clioquinol, also has anti-bacterial properties. Up to this point, its ototoxic potential has not been evaluated. Our objective aims to evaluate Locacorten Vioform’s potential ototoxicity when applied directly to the middle ear cavity. MATERIALS AND METHODS: We performed an experimental prospective animal study in our animal research center with 20 Hartley guinea pigs divided into 2 groups. The first group (experimental) was treated with Locacorten Vioform in one ear and with a physiologic saline solution in the other. The second group (positive control) was treated with concentrated gentamycin in one ear and physiologic saline in the other. Auditory brainstem response measurements were obtained before and after three sets of injections. Statistics were analyzed using a variance analysis with repeated measures. The histological state of cochlear outer hair cells was compared between the two groups using scanning electron microscopy. RESULTS: Average hearing loss in ears treated with Locacorten Vioform was 32.1 dB, compared with a 2.5 dB average loss in the saline-treated ears. Ears treated with gentamycin lost an average of 33.0 dB. There were clinically and statistically significant differences between the two ears of the guinea pigs in both groups (p < 0.001). Scanning electron microscopy revealed severe pericochlear and cochlear inflammation and ossification in the Locacorten Vioform-treated ears. Gentamycin caused significant destruction of outer hair cell architecture. CONCLUSIONS: Locacorten Vioform induces a hearing loss similar to that caused by gentamycin when applied directly to the middle ear of a guinea pig model. Electron microscopy indicates a pericochlear and cochlear inflammatory reaction with ossification.