Preservation Of Cranial Nerves Research Articles

Anti-P0 Antibody-Conjugated Nanoscale Contrast Agent Targeting the Myelin Sheath for Intraoperative Visible Delineation of Cranial Nerves.

The preservation of cranial nerves is a major problem that surgeons encounter when resecting a tumor in the posterior cranial fossa. Most cranial nerve injuries occur because the tight adhesion between the tumor capsule and cranial nerves renders the nerves indistinguishable. In this study, a nerve-specific nanoscale contrast agent was developed for visually distinguishing cranial nerves from the tumor surface in real time. To enable the contrast agent to specifically bind peripheral nerves, a previously reported biodegradable multiblock polyurethane nanoparticle (BMPU NP) was conjugated with an antibody against myelin protein zero (MPZ, P0), which is expressed on myelin sheaths in peripheral nerve fibers. Coomassie brilliant blue G (CB) was encapsulated into the BMPU NP for visual contrast. The CB-BMPU NP specifically stained mouse peripheral nerve fibers blue when directly applied to the nerve surface ex vivo and in vivo. The CB-BMPU NP also achieved satisfactory visual contrast of the trigeminal nerve in a mouse nerve-tissue adhesion model. This study offers new insights for the development of intraoperatively applied nerve-specific contrast agents for delineating cranial nerves adhered to tumors.

Radiomics-Based Prediction of Long-Term Treatment Response of Vestibular Schwannomas Following Stereotactic Radiosurgery.

Stereotactic radiosurgery (SRS) is one of the treatment modalities for vestibular schwannomas (VSs). However, tumor progression can still occur after treatment. Currently, it remains unknown how to predict long-term SRS treatment outcome. This study investigates possible magnetic resonance imaging (MRI)-based predictors of long-term tumor control following SRS. Retrospective cohort study. Tertiary referral center. Analysis was performed on a database containing 735 patients with unilateral VS, treated with SRS between June 2002 and December 2014. Using strict volumetric criteria for long-term tumor control and tumor progression, a total of 85 patients were included for tumor texture analysis. All patients underwent SRS and had at least 2 years of follow-up. Quantitative tumor texture features were extracted from conventional MRI scans. These features were supplied to a machine learning stage to train prediction models. Prediction accuracy, sensitivity, specificity, and area under the receiver operating curve (AUC) are evaluated. Gray-level co-occurrence matrices, which capture statistics from specific MRI tumor texture features, obtained the best prediction scores: 0.77 accuracy, 0.71 sensitivity, 0.83 specificity, and 0.93 AUC. These prediction scores further improved to 0.83, 0.83, 0.82, and 0.99, respectively, for tumors larger than 5 cm. Results of this study show the feasibility of predicting the long-term SRS treatment response of VS tumors on an individual basis, using MRI-based tumor texture features. These results can be exploited for further research into creating a clinical decision support system, facilitating physicians, and patients to select a personalized optimal treatment strategy.

Predicting hearing outcomes before primary radiosurgery for vestibular schwannomas.

Optimizing outcomes in the management of patients with vestibular schwannomas (VSs) requires consideration of the patient's goals. Earlier recognition of VS by imaging has led to an evolution in management. Stereotactic radiosurgery (SRS) has emerged as a frequently used strategy designed to reduce management risks, obtain long-term tumor control, and preserve current neurological function. The authors analyzed features that impact hearing preservation rates in patients with serviceable hearing prior to SRS. The study included 307 patients who had serviceable hearing (Gardner-Robertson hearing scale [GR] grade 1 or 2, speech discrimination score ≥ 50%, pure tone average ≤ 50 dB) at the time of SRS. The authors evaluated parameters that included age, tumor volume, hearing status, disequilibrium, tinnitus, Koos class, sex, and tumor margin dose. The Pittsburgh Hearing Prediction Score (PHPS) was evaluated as a method to predict long-term hearing outcomes in these cases. At a median of 7.6 years after SRS (range 1-23 years), tumor control was achieved in 95% of patients. The overall serviceable hearing preservation rate was 77.8% at 3 years, 68.8% at 5 years, and 51.8% at 10 years. The PHPS assigns a total of 5 points based on patient age (1 point if < 45 years, 2 points if 45-59 years, and 3 points if ≥ 60 years), tumor volume (0 points if < 1.2 cm3, 1 point if ≥ 1.2 cm3), and GR grade (0 points if grade 1 hearing, 1 point if grade 2 hearing) The serviceable hearing preservation rate was 92.3% at 10 years in patients whose score total was 1. In contrast, none of the patients whose PHPS was 5 maintained serviceable hearing at 10 years (p < 0.001). SRS resulted in a high rate of long-term tumor control and cranial nerve preservation. The PHPS helped to predict long-term hearing preservation rates in patients who underwent SRS when they still had serviceable hearing. The best long-term hearing preservation rates were found in younger patients with smaller tumor volumes.

Infratemporal approach with anterior transposition of facial nerve in paraganglioma surgery

Abstract Introduction The treatment of glomus jugulare tumors can be extremely challenging. In certain patients, residual tumor is left at surgery to prevent devastating lower cranial nerve deficits or to reduce potential morbidity associated with carotid artery injury. The interest of this article is to demonstrate the importance of anterior transposition of the facial nerve in the approach of the jugular paraganglioma and to analyze the surgical technique, complications, and outcomes. Methods We retrospectively studied 07 patients with jugular paragangliomas treated between January 2010 and December 2016 at Ali Ait Idir University Hospital in Algiers, Algeria. All patients were operated by the infratemporal fossa approaches type A (Fisch) [13]. We have developed for better exposed jugular golf the anterior transposition of the facial nerve. Preoperative embolization was performed for all patients. Results Total removal was possible in 04 patients. The most frequent and also the most dangerous surgical complication was lower cranial nerve deficit. This deficit occurred in 02 patients, but it was transient in one cases. Cerebrospinal fluid leakage remains a potentially fatal complication. In our study two patients developed CSF leaks and were treated conservatively with iterative lumbar punctures. Transposition of a normal facial nerve usually causes moderate postoperative paresis that may improve partially within 3 to 6 months. Conclusion Radical resection of jugular paragangliomas is difficult, and infratemporale approach (Fisch type A) with anterior transposition of facial nerve offer the best chance of total removal with preservation of facial and lower cranial nerves.

Retrosigmoid Craniotomy for Resection of an Epidermoid Cyst of the Posterior Fossa.

This video illustrates the case of a 51-year-old woman who presented with sudden-onset headache, vertigo, and nausea. Imaging revealed an epidermoid cyst of the posterior fossa with mass effect upon the brainstem and displacement of the basilar artery. This lesion was approached using a left-sided keyhole retrosigmoid craniotomy with monitoring of the cranial nerves. This video illustrates the technique of internal debulking of the cyst contents with minimal manipulation of the cyst capsule, which is often densely adherent to the brainstem, cranial nerves, and vessels in the posterior fossa. Resection of the capsule is often associated with a higher rate of cranial nerve deficits. The tumor was removed completely, but the cyst capsule was left in place. The patient had House–Brackmann grade II facial paralysis postoperatively and complained of some diminished hearing in the left ear. Epidermoid cysts are benign tumors, but the patient may experience much morbidity from their overly aggressive resection, especially when the capsule is densely adhering to critical structures. An alternate strategy is to decompress the contents of the epidermoid cyst, thereby decompressing the brainstem and converting this disease process into a chronic disease that may require reoperation in the long term. Given the tight confines of the posterior fossa, aggressive internal decompression of tumors and mobilization from the brainstem and adjacent nerves are key to avoiding injury to the brainstem and cranial neuropathies. In patients with benign tumors, the goal of the operation should be decompression of the brainstem and preservation of cranial nerve function. The link to the video can be found at: https://youtu.be/nk8-VztB0OI .

Novel method of intraoperative ocular movement monitoring using a piezoelectric device: experimental study of ocular motor nerve activating piezoelectric potentials (OMNAPP) and clinical application for skull base surgeries.

Intraoperative monitoring systems that utilize various evoked potentials for the detection and/or preservation of cranial nerves have become increasingly common due to recent technical and commercial developments, particularly during skull base surgeries. We established a novel system for the intraoperative monitoring of the extraocular motor nerves (eOMNs) using a piezoelectric device capable of detecting imperceptible vibrations induced by ocular movement, with sensors placed on the eyelids alone. We first evaluated the efficacy and reliability of this device for the intraoperative monitoring of eOMNs in two Beagle dogs. Based on the results, we then determined the appropriate stimulation parameters for use in human surgical cases involving removal of various skull base tumors. Animal experiments revealed that a 0.4mA monopolar electrical stimulation was required to elicit significant responses and that these responses were not inferior to those obtained via the electrooculogram/electromyogram. Significant responses were also detected in preliminary clinical investigations in human patients, following both direct and indirect monopolar electrical stimulation of the oculomotor and abducens nerves, although obtaining responses from the trochlear nerve was difficult. Intraoperative monitoring using a piezoelectric device provides a simple and reliable method for detecting eOMNs, especially the oculomotor and abducens nerves. This monitoring system can be adapted to various surgeries for skull base tumor.

Stereotactic irradiation for treatment of acoustic neuromas

Stereotactic cerebral irradiation is a radiotherapeutic technique for precise delivery of ionizing irradiation to an intracranial target with simultaneous sparing of adjacent parenchyma. Treatment can be administered by a multi-source cobalt-60 device (gamma knife) or a dedicated linear accelerator.The target dose can be delivered in a large, single fraction (stereotactic radiosurgery SRS) or in multiple, daily increments (stereotactic radiotherapy SRT). The latter approach combines the physical dose localization advantages of SRS with the radiobiologic benefits of dose fractionation. This literature review will present the rationale and clinical results of SRS and SRT for the treatment of acoustic neuromas. Emphasis will be placed on tumor control, imaging outcome and cranial nerve preservation. The findings demonstrate that SRS and SRT represent reasonable therapeutic options for patients with acoustic neuromas.

Surgical treatment of large vestibular schwannomas in patients with neurofibromatosis type 2: outcomes on facial nerve function and hearing preservation.

Surgical treatment of vestibular schwannoma (VS) in patients with neurofibromatosis type 2 (NF2) along with functional preservation of cranial nerves is challenging. The aim of this study was to analyze the outcomes of hearing and facial nerve function in patients with NF2 who underwent large-size VS (> 2cm) surgery. From 2006 to 2016, one hundred and forty NF2 patients were included with 149 large-size VS resections using retrosigmoid approach. Hearing function was classified according to the American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) criteria. Preoperative and one-year postoperative facial nerve function were both assessed using the House-Brackmann (H-B) grading scale. A multivariate logistic regression was performed to identify preoperative predictors for facial function outcomes. No operative death we noted. Total tumor removal was achieved in 82.6% of the operated VSs. The anatomical integrity of the facial nerve was preserved in 67.8% of surgeries. Good facial nerve function (H-B Grades I-III) was maintained in 49.6% of patients at 12months after surgery. Tumor size larger than 3cm and preoperative facial weakness related with worse outcome of facial nerve function (P < 0.001; for both). Hearing preservation surgeries were attempted in 31 ears. Class B or C hearing according to the AAO-HNS criteria was maintained in 7 ears (22.5%), and measurable hearing was maintained 11 ears (35.5%). It is challenging to maintain hearing and facial nerve function in NF2 patients with large VSs. Early surgical intervention is an appropriate choice to decrease the risk of neurological functions deficit.

Cranial Nerve Preservation Following Surgical Treatment for Epidermoid Cysts of the Posterior and Middle Fossae.

Epidermoid cysts are rare lesions, accounting for 0.2 to 1.8% of all intracranial tumors. They most commonly occur in the cerebellopontine angle where they may cause a breadth of neurologic complications due to mass effect on the nearby cranial nerves (CN), vascular structures, and the brain stem. Treatment of epidermoid cysts is surgical, with the goal of complete resection using microsurgical technique and even more importantly preservation of the involved CNs, vasculature, and brain parenchyma. Successful surgery can result in total resolution of symptoms, but, in certain situations, may not be advisable due to adherence, scarring, or inflammation making dissection of CN fascicles difficult and possibly hazardous. We conducted a retrospective review from 1998 to 2016 and compiled a series of 28 skull base epidermoid cysts operated on at our institution. Cases were evaluated for presenting symptoms, history of prior resection, and postoperative results including CN function, extent of resection, residual tumor, and need for reoperations. The average tumor size (largest diameter) was 3.9 cm with a range of 1 to 7cm. Eighteen of twenty-eight (64%) patients underwent a gross total resection and ten underwent subtotal resection. No patients, whether presenting with CN deficits or not, experienced permanent worsening of CN function following surgery. Complete resection of epidermoid cysts should remain a high priority of therapy, but, in our opinion, preservation of CN function should be a primary goal, determining the extent of resection to provide patients with the highest quality of life possible following surgery.

Cranial Nerve Preservation following Surgical Treatment for Epidermoid Cysts of the Posterior and Middle Fossae

Cranial Nerve Preservation following Surgical Treatment for Epidermoid Cysts of the Posterior and Middle Fossae

Low-Dose Gamma Knife Radiosurgery for Vestibular Schwannomas: Tumor Control and Cranial Nerve Function Preservation After 11 Gy.

This study aims to report tumor control rates and cranial nerve function after low dose (11.0 Gy) Gamma knife radiosurgery (GKRS) in patients with vestibular schwannomas. A retrospective chart review was performed on 30 consecutive patients with vestibular schwannomas treated from March 2004 to August 2010 with GKRS at the Robert H. Lurie Comprehensive Cancer Center of Northwestern University. The marginal dose for all patients was 11.0 Gy prescribed to the 50% isodose line. Median follow-up time was 42 months. The median treatment volume was 0.53 cm3. Hearing data were obtained from audiometry reports before and after radiosurgery. The actuarial progression free survival (PFS) based on freedom from surgery was 100% at 5 years. PFS based on freedom from persistent growth was 91% at 5 years. One patient experienced tumor progression requiring resection at 87 months. Serviceable hearing, defined as Gardner-Robertson score of I-II, was preserved in 50% of patients. On univariate and multivariate analyses, only higher mean and maximum dose to the cochlea significantly decreased the proportion of patients with serviceable hearing. Vestibular schwannomas can be treated with low doses (11.0 Gy) of GKRS with good tumor control and cranial nerve preservation.

Surgery for Benign Salivary Neoplasms.

Salivary neoplasms are relatively infrequent entities that account for only 4% of tumors of the head and neck. Although slow-growing lesions of the preauricular area and submandibular space are often confused with sebaceous cysts, lymph nodes, or lipomas by the non-otolaryngologist, otolaryngologists-head and neck surgeons recognize that all preauricular and submandibular masses should be considered a salivary neoplasm until proven otherwise. Surgery remains the treatment of choice for benign salivary gland neoplasms; however, techniques continue to evolve in order to preserve salivary function and reduce surgical morbidity. The goals of management of benign salivary neoplasms include accurate diagnosis of the lesion, complete surgical extirpation, and functional preservation of adjacent cranial nerves. Accurate diagnosis is aided by appropriate preoperative physical examination, imaging, and fine needle aspiration biopsy. Benign neoplasms typically present as slow-growing, painless, mobile masses without adverse features, such as tissue fixation, ulceration, a cranial nerve deficit, or regional lymphadenopathy. Preoperative imaging with ultrasonography, computed tomography, or magnetic resonance imaging reveals well-circumscribed lesions without an infiltrative growth pattern or associated adenopathy. Fine needle aspiration biopsy may favor a benign neoplasm, supporting the clinical presentation. Surgery for a benign or malignant salivary neoplasm is in essence a false dichotomy since the surgeon can never be completely confident of the diagnosis until the specimen is removed. The surgeon must recognize the significant overlap between benign and malignant salivary masses in terms of clinical presentation, imaging, and cytology, which requires the surgeon to remain vigilant and flexible at the time of surgery should tissue characteristics or frozen section analysis suggest a malignant process.

Improved Postoperative Facial Nerve and Hearing Function in Retrosigmoid Vestibular Schwannoma Surgery Significantly Associated with Semisitting Position

The pros and cons of semisitting positioning (SSP) versus lateral, horizontal positioning (LP) during retrosigmoid vestibular schwannoma (VS) surgery, especially concerning postoperative cranial nerve and brain stem preservation, are under continuous discussion. In a single-center retrospective cohort study, 30 VSs operated on in SSP compared with 30 operated on in LP with comparable demography were analyzed. During SSP surgery, transesophageal echocardiographic monitoring for venous air embolism was used continuously. Electrophysiologic cranial nerve monitoring was used in both groups. Length of surgery was significantly different between both groups: 183 minutes mean in SSP surgery versus 365 minutes mean in LP surgery (P = 0.0001). Postoperative rates of facial palsy and hearing loss were also significantly different. Six months postoperatively, 63% had normal facial nerve function after SSP surgery, whereas in LP surgery, 40% had no facial palsy (P = 0.02). Hearing preservation rate was also significantly different: 44% in SSP surgery compared with 14% in LP surgery who had preserved hearing (P = 0.006). Because of cerebrospinal fluid leaks, there were 3 operative revisions in the LP group (10%) and 1 (3.3%) in the SSP group. A clinically insignificant venous air embolism rate was found in 3.3% of patients (1/30) during SSP surgery. The neurologic outcome after 6 months was 1.2 on the Rankin Scale in the LP group and 1.0 in the SSP group, with zero mortality. SSP compared with LP surgery was associated with significantly shorter operation time and better facial and cochlear nerve function in VS surgery postoperatively, without differences in complication rates.

PP10.13 – 2944: An unusual case of infantile botulism: Clostridium botulinum Bf (C. botulinum Bf) infection in UK

Objective We discuss a rare case of infantile Clostridium botulinum Bf infection, the associated diagnostic pitfalls and paediatric-specific management strategies. Methods A retrospective review of the patient's medical notes was undertaken. Results A previously well, weaned infant presented at 6 months with two days of reduced feeding and salivary pooling. There was no history of honey exposure. Initially, gag-reflex was absent, with preservation of other cranial nerves. Antigravity movements of limbs, reflexes, and respiratory effort, were maintained. Symptoms progressed within a week to reveal hypotonia, absent antigravity movements, with preservation of reflexes, within upper limbs. Lower limb examination was normal. Eye-movements were preserved, however pupils were slowly and asymmetrically reactive. Respiratory decompensation led to intubation and subsequent tracheostomy. Lumbar puncture, metabolic screens, and MRI brain were normal. Neurophysiology showed diffuse, severely attenuated motor nerve amplitude consistent with axonal variant Guillian-Barre Syndrome, thus IVIG was commenced. Due to the atypical presentation of descending paralysis, infantile botulism was considered. Stool specimens were positive for C. botulinum Bf. Botulinum antitoxin therapy (Baby BIG) was initiated, leading to rapid recovery. Public health investigation did not show a reservoir for this infection. Conclusion C. botulinum Bf is rare, with eight previous international cases. Our case is only the second recent presentation in UK. The case confirms that dual C.botulinum neurotoxins should be considered in diagnoses for infants presenting with isolated cranial nerve palsies, including bulbar signs. Furthermore, rapidly descending paralysis involving pupillary mydriasis and poorly reactive pupils are consistent features of infantile botulism. Additionally this case highlights that neurophysiology interpretation in infants is unreliable, with clinical suspicion of botulism guiding investigation. Treatment for infantile botulism centres on Baby BIG therapy. This immunoglobulin is specifically selected for high titres of type A and B “neutralising antibodies”, which combat the most common strains of infantile botulism.

Unilateral Vestibular Schwannomas in Childhood without Evidence of Neurofibromatosis: Experience of 10 Patients at a Single Institute.

We investigated the clinical presentation and management issues of unilateral vestibular schwannomas in childhood without evidence of neurofibromatosis. Ten pediatric patients with unilateral vestibular schwannoma and no evidence of neurofibromatosis were treated by the senior author at Tiantan Hospital from January 1994 to December 2014. The clinical manifestations, neuroimaging findings, treatment methods, and therapeutic results were retrospectively reviewed. The study included 6 male and 4 female patients. The mean age of the patients was 13.9 years (range, 11-15 years). Common clinical features included increased intracranial pressure, hearing loss, and ataxia. The median diameter of the tumors was 5.15 cm. Gross total resection was achieved in 9 of 10 patients via a suboccipital retrosigmoid approach, and the perioperative mortality rate was 10%. The follow-up period ranged from 1 to 12 years. One patient with facial nerve injury recovered to House? Brackmann grade I postoperatively, 5 to grade II-III, and 2 to grade IV-V. Only 1 patient had preserved hearing. The clinical features of pediatric vestibular schwannomas are different from those of adult vestibular schwannomas, and cranial nerve preservation in children is more difficult. When a child presents with hearing loss as well as cognitive disability, a vestibular schwannoma should be highly suspected. Hypervascular vestibular schwannomas in childhood should be managed by multistaged surgeries.

Subtotal resection for management of large jugular paragangliomas with functional lower cranial nerves.

To evaluate tumor control following subtotal resection of advanced jugular paragangliomas in patients with functional lower cranial nerves and to investigate the utility of salvage radiotherapy for residual progressive disease. Case series with planned chart review. Tertiary academic referral center. Patients who presented with advanced jugular paragangliomas and functional lower cranial nerves were analyzed. Primary outcome measures included extent of resection, long-term tumor control, need for additional treatment, and postoperative lower cranial nerve function. Twelve patients (mean age, 46.2 years; 7 women, 58.3%) who met inclusion criteria were evaluated between 1999 and 2013. The mean postoperative residual tumor volume was 27.7% (range, 3.5%-75.0%) of the preoperative volume. When the residual tumor volume was less than 20% of the preoperative volume, no tumor growth occurred over an average of 44.6 months of follow-up (P < .01). Four tumors (33.3%) demonstrated serial growth at a mean of 23.5 months following resection, 2 of which were treated with salvage stereotactic radiotherapy providing control through the last recorded follow-up. No patient experienced permanent postoperative lower cranial neuropathy as a result of surgery. Subtotal resection of jugular paragangliomas with preservation of the lower cranial nerves is a viable management strategy. If more than 80% of the preoperative tumor volume is resected, the residual tumor seems less likely to grow.

Modern approaches to vestibular schwannomas treatment in patients with neurofibromatosis type 2 using stereotactic radiosurgery

Introduction. The results and efficacy of stereotactic radiosurgery (SRS) in treatment of patients with vestibular shwannomas (VS) associated with neurofibromatosis type 2 (NF2) are analyzed.Materials and methods. In 12 patients with NF2 (in total 17 VS) 15 VS-NF2 were irradiated using linear accelerator Trilogy. The prescribed doze (PD) for VS-NF2 was 12.0 – 13.0 Gy (median 12.5 Gy, in average 12.5 Gy); maximal doze — from 13.01 to 15.0 Gy (median 14.31 Gy, in average 14.19 Gy); targets volume — from 0.226 to 8.258 cm3 (median 3.564 cm3, in average 3.61 cm3).Results. In 15 VS-NF2, treated with SRS, local control was achieved in 93%. In 7 patients after SRS there were no negative changes in neurological state, in 4 of them positive clinical dynamics was observed. Hearing preservation rate was 57%. After SRS occlusive hydrocephalus, resistant trigeminal pain, aggravation of facial nerve dysfunction were not identified.Conclusions. SRS is non-invasive method of VS-NF2 treatment, it provides local control and preservation of cranial nerves function adjacent to the tumor.

Subtotal Resection for Management of Large Jugular Paragangliomas with Intact Lower Cranial Nerves

Objectives: (1) Evaluate the use of subtotal resection as the primary treatment modality for large jugular paragangliomas in patients with intact lower cranial nerves. (2) Evaluate functional outcomes and tumor control following subtotal resection. (3) Identify the utility of salvage radiotherapy for residual progressive disease. Methods: Retrospective series from a tertiary academic referral center evaluating patients who presented with advanced (Glasscock-Jackson grade 3 to 4) jugular paragangliomas (JP) and normal lower cranial nerve function. Primary outcome measures included extent of resection, long-term tumor control, need for additional treatment, and postoperative lower cranial nerve function. Results: Fourteen patients seen between 1999 and 2013 (mean age 48.6 years; range, 26-70) met inclusion criteria. The average maximum preoperative tumor dimension was 3.1 cm. The mean postoperative residual tumor volume was 29.3% (range, 3.5%-58.4%). When the residual tumor volume was less than 20% of the preoperative volume, no tumor growth occurred through an average of 35.4 months of follow-up ( P &lt; .01). Four tumors (28.6%) demonstrated serial growth at an average of 22.5 months following resection, 3 of which were treated with salvage stereotactic radiotherapy providing durable control at an average of 12 months of follow-up. No patient experienced permanent postoperative lower cranial neuropathy. Conclusions: Subtotal resection of JP with preservation of the lower cranial nerves is a viable management strategy. If &gt;80% of the preoperative tumor volume is resected, the residual tumor is less likely to grow. Radiotherapy offers effective treatment for recurrent tumor following subtotal resection.

Small Vestibular Schwannomas Presenting with Facial Nerve Palsy

To describe the surgical management and convalescence of two patients presenting with severe facial nerve weakness associated with small intracanalicular vestibular schwannomas (VS). Retrospective review. Two adult female patients presenting with audiovestibular symptoms and subacute facial nerve paralysis (House-Brackmann Grade IV and V). In both cases, post-contrast T1-weighted magnetic resonance imaging revealed an enhancing lesion within the internal auditory canal without lateral extension beyond the fundus. Translabyrinthine exploration demonstrated vestibular nerve origin of tumor, extrinsic to the facial nerve, and frozen section pathology confirmed schwannoma. Gross total tumor resection with VIIth cranial nerve preservation and decompression of the labyrinthine segment of the facial nerve was performed. Both patients recovered full motor function between 6 and 8 months after surgery. Although rare, small VS may cause severe facial neuropathy, mimicking the presentation of facial nerve schwannomas and other less common pathologies. In the absence of labyrinthine extension on MRI, surgical exploration is the only reliable means of establishing a diagnosis. In the case of confirmed VS, early gross total resection with facial nerve preservation and labyrinthine segment decompression may afford full motor recovery-an outcome that cannot be achieved with facial nerve grafting.

Preservation of cranial nerves during removal of the brain for an enhanced student experience in neuroanatomy classes

Neuroanatomy teaching at the University of Leeds includes the examination of isolated brains by students working in small groups. This requires the prosected brains to exhibit all 12 pairs of cranial nerves. Traditional methods of removing the brain from the skull involve elevating the frontal lobes and cutting each cranial nerve as the brain is reflected posteriorly. This can leave a substantial length of each nerve attached to the skull base rather than to the removed brain. We have found a posterior approach more successful. In this study, five adult heads were disarticulated at the level of the thyroid cartilage and placed, prone, in a head stand. A wedge of bone from the occipital region was removed before the cerebellum and brainstem were elevated to visualize the cranial nerves associated with the medulla oblongata, cerebellopontine angle and mesencephalic-pontine junction prior to cutting them as close to the skull as possible. Five brains were successfully removed from the skull, each having a full complement of cranial nerves of good length attached to them. This approach significantly increases the length and number of cranial nerves remaining attached to the brain, which supports student education. For integration into head and neck dissection courses, careful consideration will be required to ensure the necks are suitably dissected and to decide whether the cranial nerves are best left attached to the skull base or brain.