Ryan G. Porter

Effects of electrical stimulation and gonadal steroids on rat facial nerve regenerative properties

PURPOSE The neurotherapeutic effects of nerve electrical stimulation and gonadal steroids have independently been demonstrated. The purpose of this study was to investigate the therapeutic potential of a combinatorial treatment strategy of electrical stimulation and gonadal steroids on peripheral nerve regeneration. METHODS Following a facial nerve crush axotomy in gonadectomized adult male rats, testosterone propionate (TP), dihydrotestosterone (DHT), or estradiol (E(2)) was systemically administered with/without daily electrical stimulation of the proximal nerve stump. Facial nerve outgrowth was assessed at 4 and 7 days post-axotomy using radioactive labeling. RESULTS Administration of electrical stimulation alone reduced the estimated delay in sprout formation but failed to accelerate the overall regeneration rate. Conversely, TP treatment alone accelerated the regeneration rate by approximately 10% but had no effect on the sprouting delay. Combining TP with electrical stimulation, however, maintained the enhanced rate and reduced the sprouting delay. DHT treatment alone failed to alter the regeneration rate but combining it with electrical stimulation increased the rate by 10%. E(2) treatment alone increased the regeneration rate by approximately 5% but with electrical stimulation, there was no additional effect. CONCLUSIONS Electrical stimulation and gonadal steroids differentially enhanced regenerative properties. TP, an aromatizable androgen, augmented regeneration most, suggesting a synergism between androgenic and estrogenic effects. Therapeutically, combining electrical stimulation with gonadal steroids may boost regenerative properties more than the use of either treatment alone.

Temporal bone osteoradionecrosis after surgery and radiotherapy for malignant parotid tumors.

Objective: To assess the incidence of osteoradionecrosis (ORN) of the temporal bone after surgery with radiotherapy for malignant parotid tumors. Setting: A tertiary care, academic medical center. Patients: All patients who underwent surgical resection with postoperative radiotherapy (RT) for a malignant parotid tumor between July 1988 and July 2007. Interventions: A retrospective chart analysis to determine the extent of surgery, the RT parameters, and the incidence of ORN of the temporal bone. Main Outcome Measures: The incidence of ORN in 3 subgroups of patients. Results: The 221 patients with malignant parotid tumors who underwent surgical resection with postoperative RT were divided into groups 1, parotidectomy only; 2, parotidectomy with mastoidectomy; and 3, parotidectomy with subtotal petrosectomy. The overall incidence of temporal bone ORN in group 1 was 2 (2%) of 106; in group 2, 8 (13%) of 64; and in group 3, 0 (0%) of 51. Conclusion: The incidence of temporal bone ORN is higher after mastoidectomy for facial nerve identification or resection in patients undergoing parotidectomy with postoperative radiotherapy. Oversew of the ear canal with mastoid obliteration should be considered in this subgroup of patients to avoid this long-term complication of radiotherapy used in the treatment of malignant parotid tumors.

Comparison of Extratemporal and Intratemporal Facial Nerve Injury Models

The purpose of this study was to compare functional recovery and motor nerve conduction following a distal extratemporal crush injury of the facial nerve to a more proximal intratemporal crush injury.

Association between adipose graft usage and postoperative headache after retrosigmoid craniotomy.

Objective: To evaluate the association between extradural abdominal fat graft placement for the closure of retrosigmoid craniotomy defects and postoperative headache. Study Design: Retrospective chart review and analysis of patient questionnaires. Setting: Tertiary care academic medical center. Patients: One hundred twenty-seven patients who underwent retrosigmoid craniotomy between March 1999 and December 2006. Intervention(s): All patients underwent retrosigmoid craniotomy for removal of cerebellopontine angle tumors and received either an abdominal fat graft closure or a standard wound closure. Main Outcome Measure(s): Using a written patient questionnaire, the presence or absence of both overall postoperative headache and specific postcraniotomy headache according to International Headache Society criteria was assessed. Of those patients who had postoperative headaches, the evaluation of headache severity was assessed using a standardized 5-point scale. Results: Eighty-five patients returned completed questionnaires. Fifty-two respondents received adipose grafts; 33 did not. The adipose group demonstrated significantly less chronic postcraniotomy headaches (11.9% versus 30.3%; p < 0.05). Additionally, the adipose group described less severe headaches at all time frames studied with significant differences at 1 month (1.59 versus 2.29; p < 0.05) and 3 months (1.37 versus 2.06; p < 0.05) using the modified headache severity scale. Conclusion: When compared with standard wound closure without adipose grafting, use of an abdominal fat graft during retrosigmoid craniotomy wound closure is associated with both decreased incidence of chronic postoperative headache and decreased severity of postoperative headaches at all time intervals studied.

Improved facial nerve outcomes using an evolving treatment method for large acoustic neuromas.

Objective To describe a successful paradigm for the treatment of large acoustic neuromas (vestibular schwannomas). Study Design Retrospective case review. Setting Tertiary referral center. Patients The charts of 2,875 acoustic neuroma patients at Michigan Ear Institute were reviewed to identify 153 patients who underwent surgical resection for large acoustic neuromas (≥3 cm) between 2000 and 2009. Intervention(s) Staged surgical resection or single stage surgery with or without adjuvant stereotactic radiosurgery. Main Outcome Measure(s) Postoperative facial nerve outcomes are reported using the House-Brackmann (HB) facial nerve grading scale and compared with historical controls from a literature review. Rates of adverse outcomes are also reported. Results Seventy-five patients underwent staged surgical resection of their tumors, whereas 78 patients underwent either single stage surgery or surgery with subsequent stereotactic radiosurgery. Eighty-one percent of patients in the staged surgical resection group had a postoperative HB Grade I or II facial nerve function compared with 75% in the single stage surgical group. Overall, 78% of patients in the current study had HB Grade I or II after treatment compared with a mean of 53% in the literature for similar sized tumors. Our methods including the decision to use staged surgery when necessary, dissection of tumor with stimulating dissector-directed intraoperative monitoring, and use of adjuvant stereotactic radiosurgery are described. Conclusion Using the described paradigm, large acoustic neuromas can be successfully treated with either staged or single-stage surgical resection with or without adjuvant radiosurgery to obtain more favorable facial nerve outcomes than historically reported controls while minimizing morbidity for the patient.

Lower Cranial Nerve Function Following Jugular Foramen Tumor Resection

Objective: Describe the presentation, tumor characteristics, and postoperative lower cranial nerve function following surgery for jugular foramen tumors. Method: Thirty jugular foramen tumor resections performed between 1989 and 2009 were reviewed. The mean age was 48.2 years (range, 18.6-77.7 years) at time of presentation. Surgical approaches included infratemporal fossa (70%), retrosigmoid (23%), transtemporal (20%), transcondylar (17%), and transcervical (17%). The mean follow-up was 4.6 years. Results: Combined surgical approaches were used in over 50% of the cases, and 60% underwent preoperative tumor embolization. Tinnitus was the most common presenting symptom, and middle ear or neck mass was the most common presenting sign. The most common diagnosis was paraganglioma. Six patients required tracheotomy, and 8 had feeding tubes at discharge. Fifty-seven percent of patients underwent speech or swallow therapy, 43% were treated with vocal cord injections, and 17% underwent medialization thyroplasty. Cerebrospinal fluid leak was uncommon (13%), and meningitis occurred in 1 patient. Normal or near-normal facial nerve function was maintained in 89% of patients. Conclusion: Resection of jugular foramen tumors carries a significant risk of lower cranial nerve dysfunction; however, long-term speech, airway, and swallowing morbidity can be minimized with contemporary ancillary surgical procedures.

P094: Ruptured Carotid Artery Pseudoaneurysm in the Middle Ear

Objectives: 1. To describe our experience managing a pseudoaneurysm of the petrous internal carotid artery that was violated during middle ear surgery. 2. To discuss a review of the literature relating to petrous internal carotid artery pseudoaneurysm. Methods: The following is a case report describing our experience managing a 3 centimeter pseudoaneurysm of the petrous portion of the internal carotid artery that was encountered in January 2007 during a tympanoplasty and revision mastoidectomy in a 47-year-old female undergoing a tympanoplasty and revision mastoidectomy at a tertiary care university medical center. A brief review of the literature relating to petrous carotid artery pseudoaneurysms follows. Results: The patient was taken to the interventional neuroradiology suite and underwent transarterial occlusion of the affected internal carotid artery. The patient was then escorted to the operating room for a postauricular infratemporal transpetrosal approach to the pseudoaneurysm and definitive over-sewing of the external ear canal. Conclusions: Iatrogenic pseudoaneurysms resulting from violation of an aberrant carotid artery during middle ear surgery are rare occurrences that have been documented in the otolaryngology literature. Pre-existing pseudoaneurysms are also an important phenomenon to consider when preparing a patient for a middle ear procedure. Although injury to a preexisting pseudoaneurysm is a serious event, the situation can be successfully managed using a multidisciplinary approach involving interventional radiology techniques coupled with definitive otologic repair in the operating room. Ryan G. Porter, Sr., MD1, John P. Leonetti, MD1, Lotfi Hacein-Bey, MD2, Sam J. Marzo, MD1 Departments of OtolaryngologyHead & Neck Surgery1 and Radiology2 Loyola University Medical Center Maywood, Illinois