Facial nerve monitoring parameters as a predictor of postoperative facial nerve outcomes after vestibular schwannoma resection.

OBJECTIVE: To evaluate whether the intraoperative stimulus threshold and response amplitude measurements from facial electromyography can predict facial nerve function at 1 year after vestibular schwannoma resection. STUDY DESIGN: Prospective study. SETTING: Tertiary academic center. PATIENTS: Seventy-four consecutive vestibular schwannoma patients. INTERVENTION: The minimal stimulus intensity (in milliamperes) and electromyographic response amplitude (in microvolts) were recorded during stimulation applied to the proximal facial nerve after vestibular schwannoma removal. MAIN OUTCOME MEASURE: Facial nerve outcomes at 1 year were evaluated using the House-Brackmann scale. Analysis was then performed to evaluate whether these electrophysiologic recordings and tumor size could predict facial nerve functional outcomes. RESULTS: Of the 74 patients, 66 of 74 (89%) had House-Brackmann Grade I or II facial nerve function and 8 of 74 (11%) had House-Brackmann Grade III-VI function at 1 year after surgery. If standards were set for intraoperative minimal stimulus intensity of 0.05 mA or less and response amplitude of 240 microV or greater, the authors were able to predict a House-Brackmann Grade I or II outcome in 56 of 66 (85%) patients at 1 year after surgery. With these same electrophysiologic parameters, only 1 of 8 (12%) House-Brackmann Grade III-VI patients also met this standard and thus gave a false-positive result. Logistic regression analysis of the data showed that both a stimulus threshold of 0.05 mA or less and a response amplitude of 240 microV or greater predicted a House-Brackmann Grade I or II outcome with a 98% probability. However, stimulus threshold or response amplitude alone had a much lower probability of the same result. In addition, although tumor size was found to independently predict facial nerve outcomes at 1 year, it did not improve the ability to predict facial nerve function over a model using stimulus intensity and amplitude alone. CONCLUSION: Individually, minimal stimulus intensity or response amplitude was less successful in predicting long-term postoperative facial nerve function. However, if both parameters are considered together, the study demonstrates that they are good prognostic indicators for facial nerve function at 1 year after surgery.     

Grafting assay distinguishes promotion sensitive from promotion resistant JB6 cells

The JB6 mouse epidermal cell system has been used extensively as an in vitro transformation model for the study of tumor promotion. The standard JB6 cell assay for promotion of transformation is carried out in soft agar or other anchorage independent conditions. The present study was directed to the development of an in vivo model to distinguish the promotion resistant (P-) and promotion sensitive (P+) progression phenotypes. Results indicate that the grafting assay distinguishes P- and P+ cells in vivo with P+ but not P- cells forming tumors within 7-9 weeks. Expression of dominant negative mutant jun TAM67 blocks both anchorage independent transformation response and graft bed tumor formation by P+ cells, suggesting that the requirement for AP-1 activation in transformation now applies in vivo. Expression of mutated p53 produced a gain of P+ phenotype in P- cells in vitro, but not in vivo. Histochemical and Northern blot analysis for expression of various keratinocyte markers revealed no evidence for expression, suggesting a loss of keratinocyte markers following establishment in culture. In summary, the skin-grafting assay described in this study appears to be a valid in vivo assay for distinguishing the preneoplastic progression phenotypes represented by JB6 P- and P+ cells.      

Evaluation of MR-angiography for pre-operative assessment of living kidney donors

INTRODUCTION: Pre-operative magnetic resonance tomography (MR) and MR-angiography (MRA) have rendered favorable results for the assessment of renal anatomy preceding living-related kidney transplantation. However, limited value of MRA in the detection of accessory renal vasculature is reported. METHODS: We compared the results of pre-operative contrast-medium-enhanced MRA of the last 30 consecutively performed nephrectomies in living kidney donors with the intraoperative findings of vascular, parenchymal, and ureteral anatomy. RESULTS: Pre-operative MRA diagnosed a solitary renal artery in 24 cases (80%) and a normal venous, ureteral and parenchymal anatomy in all cases. Intraoperatively, the surgeon confirmed the normal pre-operative MRA findings of ureter and parenchyma. Yet, in 6 out of 30 patients (20%) vascular architecture differed from the pre-operative imaging: four of them, who had a radiologically regular anatomy, were found to have accessory vessels upon surgical preparation. In the fifth patient, MRA revealed an accessory lower polar artery, which was confirmed during surgery. An undiagnosed third arterial vessel, located behind the renal vein, led to an aortic bleeding. In the sixth case, the adrenal gland artery was misinterpreted as an accessory superior polar artery of the kidney in MRA. Additionally, a radiologically undetected inferior polar artery was dissected during nephrectomy and led to partial hypoperfusion of the graft. Subsequent retrospective reevaluation of the MRA by experienced radiologists was unable to identify the intraoperative anatomical discrepancies. Hence, sensitivity of MRA was 60% (6 out of 10 cases) for accessory renal vessel detection and 80% (24 out of 30 cases) for overall sensitivity in determining renal vessel number. DISCUSSION: MRA is a reliable method for the non-invasive investigation of living kidney donors and provides valuable information required by the surgeon. But, as the technique misses small diameter vessels, it cannot be recommended as sole diagnostic tool in unclear cases.     

C-erb-B2 (HER2/neu) expression in synovial sarcoma of the head and neck

BACKGROUND: Synovial sarcoma is a malignant mesenchymal tumor composed of varying proportions of spindle and epithelial cell components. Because of the histologic and immunohistochemical similarity of synovial sarcoma to epithelial carcinomas, we hypothesized that the human epithelial growth factor receptor 2 (C-erb-B2, also termed HER2/neu) may contribute to the tumor phenotype and provide a new therapeutic target for this soft tissue tumor. METHODS: Three head and neck, one chest wall, and seven extremity synovial sarcomas were evaluated for C-erb-B2 (HER2/neu) expression by immunohistochemistry, Western immunoblotting, and fluorescence in situ hybridization (FISH). RESULTS: The head and neck cases demonstrated immunohistochemically strong positive staining, whereas tumors from other anatomic locations showed neither positive nor cytoplasmic restricted staining. Antigen-targeted antibody therapy (trastuzumab) was initiated in two patients. CONCLUSIONS: These results demonstrate that C-erb-B2 (HER2/neu) may play a role in the tumorigenesis of synovial sarcoma; and, therefore, antigrowth factor therapies may provide a previously unrecognized pharmaceutical approach to soft tissue tumors. The data also suggest that although synovial sarcoma of the head and neck and synovial sarcoma of the extremities have similar morphologic features, they may be clinically and mechanistically distinct entities.