Seth J. Kanowitz

Auditory Brainstem Implantation in Patients with Neurofibromatosis Type 2

Objectives: Multichannel auditory brainstem implants (ABI) are currently indicated for patients with neurofibromatosis type II (NF2) and schwannomas involving the internal auditory canal (IAC) or cerebellopontine angle (CPA), regardless of hearing loss (HL). The implant is usually placed in the lateral recess of the fourth ventricle at the time of tumor resection to stimulate the cochlear nucleus. This study aims to review the surgical and audiologic outcomes in 18 patients implanted by our Skull Base Surgery Team from 1994 through 2003.

Outcomes of minimally invasive endoscopic resection of anterior skull base neoplasms.

The objective of this study was to review clinical outcomes of minimally invasive endoscopic resection (MIER) for anterior skull base (ASB) neoplasms.

Clinical utility of intraoperative volume computed tomography scanner for endoscopic sinonasal and skull base procedures.

Background Intraoperative surgical navigation has become widely accepted as an important tool for improvement of surgical outcomes and reduction of complication in endoscopic sinus surgery (ESS). The purpose of this study was to assess the clinical utility of intraoperative volume computed tomography (CT) scanning in endoscopic sinonasal and skull base procedures. Methods Retrospective review of patients who underwent intraoperative volume CT imaging (xCAT; XoranTechnologies, Ann Arbor, MI) during endoscopic sinonasal and skull base surgery during a 3-month period was performed. Intraoperative, computer-enabled triplanar review of reformatted 0.4-mm images was performed in all cases. Results Intraoperative volume CT scanning was completed in 25 patients. Surgical procedures included revision/primary ESS for chronic rhinosinusitis (CRS) with or without polyposis (12 cases) and mucoceles (6 cases) as well as endoscopic neoplasm resection (5 cases), endoscopic fibro-osseous lesion resection (1 case), and endoscopic meningoencephalocele repair (1 case). The indications for intraoperative CT scanning included assessment of surgical dissection (23 cases), extent of tumor resection (6 cases), and frontal stent placement (6 cases). Based on the intraoperative volume CT information, additional interventions, including additional tumor resection (2 cases), dissection of ethmoid partitions (2 cases), frontal bone drilling during Draf IIB (1 case), and repositioning of a frontal stent (1 case) were performed in 6 (24%) cases. Conclusion Intraoperative volume CT scanning was successfully performed in 25 patients undergoing ESS. Because additional surgical intervention was performed in 24% of cases, this technology may have an important role in endoscopic sinonasal and skull base procedures.

Total tympanic membrane reconstruction: AlloDerm versus temporalis fascia.

BACKGROUND AND OBJECTIVE: Patients who require surgery for chronic otitis media with perforation and cholesteatoma frequently provide no residual tympanic membrane that is usable in grafting procedures. A novel technique of total tympanic membrane reconstruction (TTMR) is described that maximizes perforation closure rate in these situations while minimizing mucosalization, incomplete healing, and anterior blunting. The specific aim of this report is to assess the safety and efficacy of TTMR and to compare the results obtained with AlloDerm compared with temporalis fascia as a grafting material. METHODS : The records of 50 patients operated within the years 1999 and the 2004 were reviewed. TTMR with intact canal wall was performed in all cases. Both clinical and audiometric data were analyzed. RESULTS : Overall perforation closure rate was 92%. There was no statistical significance in closure rate when grafting with AlloDerm versus temporalis fascia. A statistically significant shortened healing time was observed with AlloDerm grafting. CONCLUSIONS : TTMR is a highly effective and safe technique.

Topical budesonide via mucosal atomization device in refractory postoperative chronic rhinosinusitis.

Background Nebulized budesonide (Pulmicort Respules, AstraZeneca, Wilmington, DE) provides control of respiratory tract inflammation in asthmatic patients. The Mucosal Atomization Device (MAD; Wolfe-Tory Medical, Salt Lake City, UT) is a novel sinonasal atomization device. Methods Uncontrolled case series of postoperative patients with chronic rhinosinusitis (CRS) who received budesonide via MAD was performed. Results A total of 44 patients with a mean age of 53.5 years met inclusion criteria. The average follow-up was 31.5 weeks (SD 17.55; range, 8 to 80 weeks). Overall, patient and physician global assessments demonstrated moderate to significant improvement. Average daily oral prednisone usage among patients who took systemic steroids (n = 27) was reduced from 7.96 to 1.94 mg/day without relapse of polyps, mucosal edema, and nasal discharge. Prednisone use was reduced to zero in 16 patients and reduced or stabilized in 10 other patients. Conclusion Topical budesonide via MAD may reduce the need for systemic prednisone and improve both physician and patient global assessment scores in postoperative CRS patients. Additional investigation is warranted to exclude placebo effect, spontaneous resolution, and regression to the mean as responsible factors for the reported findings.

A cadaveric model for balloon-assisted endoscopic paranasal sinus dissection without fluoroscopy

Background Recently, balloon catheter (BC) dilatation of paranasal sinus ostia has been introduced. In this procedure, a balloon-tipped catheter is placed across a sinus ostium over a flexible wire under fluoroscopic guidance, and inflation of the balloon enlarges the ostium. Some rhinologists have criticized this procedure for its failure to remove tissue and bone, especially in the setting of sinonasal polyposis. This project seeks to develop strategies for incorporating BC technology into standard functional endoscopic sinus surgery procedures. Methods Endoscopic sinus dissection of three human cadaveric heads was performed with conventional instruments supplemented by lacrimal duct BCs (LacriCATH; Quest Medical, Allen, TX). No fluoroscopy was used. Each dissection was videotaped for later review. Results For frontal recess dissection, these steps were performed under endoscopic visualization: (1) passage of the BC between frontal recess partitions, (2) BC inflation, and (3) removal of fractured frontal recess partitions with conventional instruments. This approach was used successfully in each frontal recess. Under endoscopic visualization, a BC was passed into the sphenoid ostium and inflated; this maneuver successfully dilated each sphenoid ostium. It was not feasible to reliably pass the BC through the natural maxillary ostium. Each BC was inflated to 8 atm for 30 seconds. No evidence of orbital or skull base injury was noted. No fluoroscopy was used. Conclusion BCs may be used as adjunctive instrumentation for endoscopic sinus dissection without fluoroscopy. This strategy warrants additional technical and clinical development.

Comprehensive management of failed frontal sinus obliteration

Background Treatment of patients with failed frontal sinus (FS) obliteration (FSO) remains an important challenge in the endoscopic era. Advances in endoscopic techniques have facilitated the application of minimally invasive approaches for clinical scenarios that previously required open procedures. Methods A retrospective chart review of patients presenting with failed FSO from January 1, 2001 to June 30, 2007 was performed. Results Seventeen patients (mean age, 52.8 years; 10 men and 7 women) presented at an average of 9.7 years from initial FSO. The most common primary presenting symptoms included headache (41.2%) and forehead swelling (23.5%). Seven patients had prior craniotomies and 10 patients had prior endoscopic sinus surgery. All patients underwent surgical exploration; revision procedures were required in 5 patients. Definitive procedures included endoscopic frontal sinusotomy (EFS; 10 patients), endoscopic frontal drill-out (3 patients), revision osteoplastic frontal sinusotomy with obliteration reversal (2 patients), and repeat FSO (2 patients). One patient required revision EFS twice. Initial intraoperative findings included mucocele (13 cases), bone wax (3 cases), fibrous tissue (2 cases), and polypoid mucosa (1 case). All patients had resolution or improvement of their primary presenting signs/symptoms. All FSO reversal patients achieved functional FS patency documented by endoscopy and/or CT scan with mean follow-up of 9.5 months (range, 1.5-30.8 months). Conclusion Operative exploration should be considered in all patients with persistent or recurrent symptoms and/or signs of failed FSO. In most instances, repeat FSO can be avoided, and a minimally invasive endoscopic strategy can be used successfully.

Anatomical and technical correlates in endoscopic anterior skull base surgery: A cadaveric analysis

Objective: The objectives of this study were to 1) evaluate anatomical relationships and 2) develop technical correlates for endoscopic anterior skull base (ASB) surgery. Study Design: Cadaver study. Setting: Minimally invasive surgery laboratory. Subjects and Methods: Ten adult fresh-frozen cadaver heads were dissected from December 2006 to December 2007. The endoscopic trans-cribriform, trans-ethmoid approach to the anterior cranial base was refined over these consecutive dissections. Endoscopic orientation along the ventral axis was assessed with 0°, 30°, and 70° rigid telescopes. Anatomical dimensions of the ASB window were measured in the anteroposterior (posterior table of frontal sinus to planum sphenoidale) and transverse (orbit-to-orbit) dimensions at the anterior ethmoid artery (AEA) and posterior ethmoid artery (PEA). Results: Endoscopic cadaveric dissections confirmed technical feasibility of ASB surgery and greatly enhanced understanding of ASB anatomical concepts. The 30° rigid endoscope provided the most optimal view from the frontal sinus to the planum sphenoidale with the least distortion, relative to 0° and 70° scopes. Careful identification of the AEA and PEA was requisite for proper orientation at the ASB. The posterior one third of the ASB was thickest and always required drilling for resection. The mean boundaries of the ASB window were 33.7 mm (anterior to posterior) and 23.5 and 19.1 mm at the AEA and PEA (orbit to orbit), respectively. Conclusion: This prospective cadaveric study outlined key correlates for endoscopic ASB surgery. It serves to highlight the requisite technical steps and anatomical dimensions when the trans-nasal endoscopic route is employed for ASB pathology.

Utility of sagittal reformatted computerized tomographic images in the evaluation of the frontal sinus outflow tract.

Background Anatomic and mucosal obstruction of the frontal sinus outflow tract (FSOT) can result in frontal sinusitis often associated with frontal headache. Thorough evaluation of symptomatic patients requires axial and coronal computerized tomographic (CT) scans of the paranasal sinuses (PNS). With the advent of multichannel multidetector CT scanning, the availability of high-quality sagittal images has become increasingly widespread. However, the utility of these images in the assessment of FSOT patency has not yet been established. Methods A retrospective review of coronal and sagittal images from 25 PNS CT scans (50 sides) were randomized, blinded, and independently evaluated by two neuroradiologists. FSOT obstruction by agger nasi cells, the ethmoid bulla, and mucosal disease was assessed. A degree of confidence was rendered for each of these findings. The results were then compared against a consensus diagnosis, which was rendered based upon simultaneous reading of the coronal and sagittal images. Generalized estimating equations were used to assess the difference between sagittal and coronal images in terms of reader confidence and diagnostic concordance with the consensus. Results Review of sagittal images had a higher degree of concordance with the consensus than did coronal images, and was highest for mucosal disease. Both readers were more confident in rendering a diagnosis based upon the sagittal images. Conclusion Sagittal reformatted CT images of the PNS are helpful in the radiologic evaluation of the FSOT. Experienced neuroradiologists had a higher degree of confidence in the diagnosis of the obstruction of the FSOT using sagittal reformatted images.

Endoscopic management of sphenoclival neoplasms: Anatomical correlates and patient outcomes

Objective: To characterize the endoscopic anatomy of the sphenoid sinus and the adjacent clivus and cavernous sinus, and to review patient outcomes for neoplasms in this region. Study Design: Cadaver dissection and chart review. Setting: Cadaver laboratory and tertiary care center. Subjects and Methods: Fresh-frozen cadaver heads were dissected to study the endoscopic anatomy of the sphenoclival region. Retrospective chart review of patients undergoing endoscopic resection of sphenoclival neoplasms between 2000 and 2008 was performed. Results: Transnasal endoscopic access to the sphenoid sinus was obtained in 10 cadaver heads. A clival window with mean dimensions of 1.4 cm × 1.7 cm was created. Through the clival window, identification and dissection of the basilar and vertebral arteries, mamillary bodies, third ventricle, cranial nerves III through VI, and cervical rootlets were possible. Nineteen patients with mean age of 56.2 years were treated. The most common pathologies were inverted papilloma (5), chordoma (4), squamous cell carcinoma (2), and adenoid cystic carcinoma (2). None of the patients required adjunct craniotomies. Nine patients received adjuvant therapies. Thirteen (68.4%) patients had no evidence of disease, five (26.3%) patients were alive with disease, and one (5.3%) patient died of disease at mean follow-up of 32.6 months. Conclusion: The sphenoclival region poses a significant surgical challenge given its central location at the skull base and proximity to critical structures. This study demonstrates that transnasal endoscopic access to the sphenoclival region is technically feasible and allows successful surgical extirpation of tumors with a low complication rate and acceptable patient outcomes.