Jose Perez

Management of vestibular schwannoma: A pilot case series with postoperative ABR monitoring

OBJECTIVE Auditory brainstem response (ABR) monitoring is regularly used in surgery of vestibular schwannoma to achieve hearing preservation. Despite ABR preservation at the end of surgery, there are cases with postoperative deafness. To date it is unclear whether these are false positive ABR data or cases of secondary hearing loss. In this pilot study, we focused on the early postoperative phase and possible ABR changes in this period. PATIENT AND METHOD In a prospective study from March 2008 to April 2009, eleven patients (5 female and 6 male) with vestibular schwannoma and preoperative residual hearing were investigated by repeated postoperative ABR investigation at seven dates during the first week. ABR results, hearing function and tumor extension were categorized according to Hannover classification system. The postoperative developments of the first week after surgery are described. RESULTS Hearing preservation was achieved in 55% (6 of 11) of the patients. In the early postoperative phase, three patients with an ABR loss at the end of surgery showed some kind of recovery. In one case, a permanent recovery could be reproduced and developed step by step during the early postoperative phase. Three patients showed a postoperative deterioration resulting in a complete ABR loss. In one of these cases, it was probably a technical problem, but in the two other cases it was a real impairment. In 8 of 11 ABR, quality changed considerably during the early postoperative phase. CONCLUSION This pilot study identifies considerable change of ABR formation occurring in a considerable proportion of patients early after vestibular schwannoma resection. Obviously, in some patients, the endoperative state of the ABR is not the final state. Some patients show a postoperative improvement and some a deterioration towards a complete loss of all ABR components. Whether secondary hearing loss could be presented by early detection, will be a matter of further studies.

CXCR4: A new player in vestibular schwannoma pathogenesis

Background CXCR4 is a chemokine receptor that recruits blood stem cells and increases tumor cell growth and invasiveness. We examined CXCR4 expression in vestibular schwannomas (VS) from patients with and without neurofibromatosis type 2 (NF2) and correlated the levels with the patients’ clinical characteristics. The aim was to determine whether CXCR4 can be used as a prognostic marker and as a target for systemic therapy. Results Overall, CXCR4 mRNA levels were 4.6-fold higher in VS versus control; the levels were 4.9-fold higher in NF2 patients and 4.2-fold higher in sporadic VS patients. IHC and WB showed heterogeneous protein expression, and CXCR4 was expressed mainly in S100-positive Schwann cells. There was no correlation between the CXCR4 protein levels and tumor extension. However, there was a trend towards correlation between higher expression levels and greater hearing loss. Materials and Methods CXCR4 mRNA and protein levels were determined in VS samples (n = 60); of these, 30 samples were from patients with NF2. Healthy nerves from autopsies served as controls. CXCR4 mRNA levels were measured by PCR, and protein levels were measured by immunohistochemistry (IHC) and Western blotting (WB). Tumor extension and hearing loss were categorized according to the Hannover Classification as clinical parameters. Conclusions CXCR4 mRNA was overexpressed in VS relative to healthy vestibular nerves, and there was a trend towards higher CXCR4 expression levels being correlated with greater functional impairment. Thus, CXCR4 may be a prognostic marker of VS, and CXCR4 inhibition has potential as a systemic approach for the treatment of VS.

Advantage of a Structured Trainee Program in Surgery of Vestibular Schwannomas: Retrospective Analysis of 615 Cases

Purpose: Most of the literature regarding the outcome in vestibular schwannoma surgery considers results of one senior surgeon. We follow a different strategy. All surgeons pass through a trainee program and all operations are done together with ENT surgeons. We present an analysis of our data and compare the results to the literature. Methods: From 1994 to 2003, 615 patients were operated by 12 surgeons. The mean age was 49.8 ± 13 years (min. 7, max. 78 yrs). Mean tumor size was 20.5 ± 8.6 mm (min. 6, max. 65 mm). The size of tumors was graded with the Hannover Classification Scale. Mean follow-up time was 22.8 ± 27.2 months. Outcome of hearing and facial function was evaluated by a modified Gardner-Robertson scale and the House-Brackmann scale. The rate of complications was also registered. Results: Complete tumor removal was achieved in 86%. Hearing could be preserved in 31% of the patients. Twenty-one percent maintained good functional hearing. One year after surgery facial function was graded H-B 1 to 2 in 86%, H-B 3 to 4 in 9%, and H-B 5 to 6 in 5% of the patients. Statistical differences between senior surgeons and “inexperienced” surgeons were not seen. The rate of complication showed no statistical differences. Conclusion: The results are similar to the results reported in the literature. In our opinion it is possible to achieve a high quality of surgery of vestibular schwannomas within the scope of a trainee program. A precondition is implementation of a long-term and structured program under the unwavering surveillance of a skilled surgeon of vestibular schwannomas.