Cervical and ocular vestibular evoked myogenic potentials in determining nerve division involvement in patients with a tumor located in the internal auditory canal

OBJECTIVES

The study aimed at the analysis of the parameters of acoustic cervical and ocular vestibular evoked myogenic potentials (AC-cVEMP and AC-oVEMP) response in patients with a confirmed tumor located in the internal auditory canal. It also aimed to assess to what degree a combination of these tests may be of benefit in the preoperative indication of the affected nerve division via preoperative determination whether the tumor originated from the superior or inferior division of the vestibular nerve, both divisions, or if it originated from a different nerve in the internal auditory canal.

METHODS

The study group included 50 patients. Preoperative MRI scans were used to measure tumor diameter. AC-cVEMP and AC-oVEMP testing were performed before tumor resection. The surgeon was asked for a detailed description of the tumor origin.

RESULTS

The corrected amplitude of cVEMP was significantly lower on the tumor side than on the non-affected side and in the control group. The corrected Asymmetry Ratio (AR) of cVEMPs in patients with the tumor was significantly elevated above the reference values with the mean being 58.29% and the mean AR of oVEMPs in patients the tumor was 71.78% which made both results significantly higher than in the control group. Neither cVEMP nor oVEMP latency was significantly correlated with tumor size. Data obtained from cVEMP and oVEMP tests was an effective indicator of tumor origin in 74% of patients showing which division (or both divisions) of the VIII^th nerve was affected in comparison with information obtained from the surgeon.

CONCLUSIONS

The combined use of AC-cVEMP and AC-oVEMP tests may be useful in surgical planning in patients the tumor located in the internal auditory canal, providing a highly probable determination of the division of the affected nerve. Such information is valuable for the surgeon as it offers additional knowledge about the tumor before the procedure. cVEMP and oVEMP results may not be used as the basis for the calculation of tumor size in patients.

Quality of life related to symptomatic outcomes in patients with vestibular schwannomas: A Canadian Centre perspective

Patients with vestibular schwannomas (VS) typically present with hearing loss and tinnitus as well as variable cranial nerve dysfunctions. Surgical resection, stereotactic radiotherapy and/or conservative management employing serial magnetic resonance or computed tomography imaging serve as the main treatment options. Quality of life (QoL) may be impacted by the extent of tumour burden and exacerbated or relieved by treatment. Subjective assessment and quality of life inventories provide valuable information in client centered approaches with important implications for treatment. The intention of QoL measurements affecting VS patients within a clinical setting is to facilitate discussions regarding treatment options and objectively evaluate patient- centered clinical outcomes in a naturalistic setting.

Prognostic Factors and Results of Radiation Therapy in Optic Pathway Tumors

Aims and Background

The role of radiotherapy in the management of patients with optic pathway tumors remains controversial. This study analyzes the outcome of patients treated with radiotherapy and attempts to identify the groups of patients that may require early therapy.

Methods

We retrospectively reviewed 36 patients with optic pathway tumors treated with radiotherapy alone (26 patients) or with postoperative radiotherapy (10 patients). Seven patients had optic nerve tumors and 29 patients had chiasmal tumors. The actuarial progression free survival and observed survival probabilities were calculated using the Kaplan-Meier method and differences between curves were evaluated by the Mantel-Cox test. The obtained significant variables in the univariate analysis were analyzed using the Cox proportional hazards model.

Results

The 10-year actuarial progression-free survival (10-y PFS) rate was 86% for patients with optic nerve gliomas and 47% for patients with chiasmal tumors. The 10-year actuarial observed survival (10-y OS) rate was 75% for patients with optic nerve gliomas and 53% for patients with chiasmal gliomas. In the group of patients with chiasmal tumors, progression-free survival and observed survival rates were significantly lower in infants (10-y PFS: 30%; 10-y OS: 37%), in patients with neurological deficits (10-y PFS and 10-y OS: 23%), in patients with signs of elevated intracranial pressure (10-y PFS and 10-y OS: 9%), with hydrocephalus (10-y PFS and 10-y OS: 0%), or with impairment of consciousness (10-y PFS and 10-y OS: 17%). Evaluation by computed tomography scanning was associated with a significantly higher probability of PFS. Radiation doses lower than 50 Gy were associated with significantly lower PFS and OS rates. In the Cox multivariate analysis, presence of neurological deficits and radiation dose significantly influenced observed survival. Presence of hydrocephalus significantly influenced progression-free survival.

Conclusions

The prognosis of patients with chiasmal gliomas presenting with neurologic deficits is poor and should be treated at diagnosis. A minimum tumor dose of 50 Gy is recommended.

Absent stapedial reflex: otosclerosis or middle ear tumor?

We present an unusual case in which a patient diagnosed as having otosclerosis on the basis of clinical and audiologic findings actually had a middle ear facial nerve schwannoma. To the best of our knowledge, this is the first reported case in English literature in which a facial nerve schwannoma presented with conductive deafness of gradual onset and absent stapedial reflex with a normally functioning facial nerve. We also include a review of the literature.

Intraparotid facial nerve schwannoma: clinician beware

Intraparotid facial nerve schwannomas are rare neoplasms that are challenging to diagnose and manage. Many patients present with a painless, palpable facial mass. The presence of facial paralysis is variable. Imaging studies and fine-needle aspiration cytology are not always helpful in preoperative diagnosis. With early diagnosis of facial nerve schwannoma, management of the patient can be planned and, ultimately, facial nerve function optimized. By reviewing the literature and 2 cases from a series of patients seen in our practice, we provide insight into the current diagnosis and treatment of a rare pathology.

Immunohistochemical analysis of the purinoceptor P2X7 in human lingual nerve neuromas

AIMS

Recent evidence suggests that the purinoceptor P2X7 may be involved in the development of dysesthesia following nerve injury, therefore, the aim of the present study was to investigate whether a correlation exists between the level of P2X7 receptor expression in damaged human lingual nerves and the severity of the patients' symptoms.

METHODS

Neuroma-in-continuity specimens were obtained from patients undergoing surgical repair of the damaged lingual nerve. Specimens were categorized preoperatively according to the presence or absence of dysesthesia, and visual analog scales scores were used to record the degree of pain, tingling, and discomfort. Indirect immunofluorescence using antibodies raised against S-100 (a Schwann cell marker) and P2X7 was employed to quantify the percentage area of S-100 positive cells that also expressed P2X7.

RESULTS

P2X7 was found to be expressed in Schwann cells of lingual nerve neuromas. No significant difference was found between the level of P2X7 expression in patients with or without symptoms of dysesthesia, and no relationship was observed between P2X7 expression and VAS scores for pain, tingling, or discomfort. No correlation was found between P2X7 expression and the time between initial injury and nerve repair.

CONCLUSION

These data show that P2X7 is expressed in human lingual nerve neuromas from patients with and without dysesthesia. It therefore appears that the level of P2X7 expression at the injury site may not be linked to the maintenance of neuropathic pain after lingual nerve injury.

Malignant orbital schwannoma with massive intracranial recurrence

BACKGROUND

A 62 year old male presented with progressive diplopia, left orbital pain and impairment of visual acuity.

METHOD AND FINDINGS

Neuroradiological investigation disclosed an orbital tumour. The lesion was totally excised. Histopathology examination revealed a malignant peripheral nerve sheath tumour (MPNST). The tumour recurred with intracranial extension. The patient died 13 months after the initial diagnosis.

CONCLUSIONS

To our knowledge, this is the first reported example of a massive intracranial recurrence of an orbital MPNST. The epidemiological features, clinical course and treatment of these lesions are discussed.

Isolated intraorbital schwannoma arising from the abducens nerve

CASE REPORT

A case of isolated schwannoma of the orbit, arising from the terminal branches of the abducens nerve to the lateral rectus muscle, is reported. The patient presented with a painless proptosis of the left eye.

DISCUSSION

Preoperative diagnosis of benign intraorbital neoplasm was made by means of CT and MR scans; the mass was radically excised through a microsurgical lateral orbitotomy and the pathological examination revealed a schwannoma. Features of orbital schwannoma are described, together with some details concerning the surgical strategy and the history of the evolution of the lateral orbitotomy.

Microsurgery for vestibular schwannoma after gamma knife radiosurgery

BACKGROUND

We evaluated the clinical characteristics of microsurgery for vestibular schwannoma (VS) after failed gamma knife radiosurgery (GKS).

METHOD

Twelve patients, 5 men and 7 women aged 19 to 70 years (mean 54.5 years), who underwent microsurgery after failed GKS for VS were studied retrospectively.

FINDINGS

The median interval between GKS and microsurgery was 28.8 months (range, 6.6-120 months) and 4 patients had undergone previous microsurgery. The mean volume of tumour at GKS was 6.9 cm(3) (range, 0.5-19.7 cm(3)) and the mean prescription dose to the tumour margin was 12.3 Gy. Microsurgery involved the lateral suboccipital approach in all patients. Tumour expansion involved solid enlargement in 7 patients, cystic enlargement in 3, and central necrosis in 2. Bleeding was slight in all patients except in one, probably because of the previous irradiation. Adhesion to the brain stem was severe in 7 patients. Identification of the facial nerve was easy in 5 operations and difficult in 7. Dissection of the tumour from the facial nerve was difficult in most interventions because of severe adhesions or colour change. Severe adhesions between the trigeminal nerve and the tumour was observed in 2 patients. The tumour was subtotally removed except around the internal auditory canal in most patients. Only one residual tumour increased in size and needed second GKS. The function of the facial nerve deteriorated in 3 patients, was unchanged in 7, and improved in 2. All patients had lost hearing on the affected side at the time of microsurgery.

CONCLUSIONS

Microsurgery for VS after failed GKS presents some technical difficulties. Dissection of the tumour from the facial nerve or brain stem is likely to be difficult. We recommend subtotal resection without dissection of the facial nerve and tumour, because growth of the residual tumour was rare in our series.

Retro-tympanic pulsatile mass originating from dumb-bell jugular foramen schwannoma

BACKGROUND

Jugular foramen (JF) tumours are uncommon with paraganglioma, schwannoma and meningioma occurring most commonly in this location. JF schwannoma with extension to the retro-tympanic area has been described only once.

METHODS

20-year-old man presented with headache, blurred vision, vomiting and diplopia.

FINDINGS

A left pulsatile retro-tympanic mass was seen at otoscopy. A jugular foramen tumour was found on CT and MR images. The intracranial portion of the tumour later diagnosed as schwannoma was removed. Control ENT examination confirmed that the residual retro-tympanic mass was no-longer pulsatile.

CONCLUSIONS

Jugular foramen schwannomas may also extend into the retro-tympanic area.

Management strategies for bilateral vestibular schwannomas

BACKGROUND

Bilateral vestibular schwannomas (VS) are rare. Most patients in India present late in the course of illness with large tumors and disabling deafness. Clinical presentation and management goals are different from that of unilateral VS.

AIMS

To highlight the differences in clinical presentations and surgical results of bilateral VS compared to unilateral VS; and, to propose a management strategy for these tumors with reference to tumor size, extent of growth and the presence or absence of hearing impairment.

METHOD

This is a retrospective study of 16 patients with bilateral VS treated over 10 years in a tertiary referral hospital. Assessment of VIIth and VIIIth cranial nerve function, tumor size, volume and extent of growth was performed in all patients. The management strategy was based on Samii's classification of tumor extent. All patients were operated using a retromastoid suboccipital approach. Postoperative results were analyzed and compared with those of unilateral VS.

RESULTS

The mean age of presentation was 25.7 years. Hearing impairment was the commonest symptom. Headache with features of raised intracranial pressure were present in 10 (62.5%) patients. Giant tumors were present in seven (43.7%) patients; large tumors in eight (50%) and a medium-sized tumor in one (6.3%). Total tumor resection was achieved in 13 patients and subtotal resection in two. One patient was managed conservatively and followed up with serial CT scans. On the contralateral side, one large tumor required total excision. One medium sized tumor underwent sub-capsular excision in an attempt to preserve hearing. The facial nerve was anatomically preserved in seven (46.7%) patients and in one, the cochlear nerve was anatomically preserved. There was no peri-operative mortality.

CONCLUSIONS

Patients with bilateral schwannomas are younger, have larger lesions, poorer preoperative hearing and are more likely to lose either auditory and/or facial nerve function during attempted total resection of the tumor. Classifying the tumors into two groups by extent, that is, tumors extending to the cerebellopontine angle cistern (T1-T3a) and, tumors extending to or compressing the brainstem (T3b to T4b), allows the surgical strategy to be defined.

Characterizing the auditory changes in tumor metastasis to the bilateral internal auditory canals

We report the changes in auditory function in a patient with tumor metastasis to the bilateral internal auditory canals (IAC). The hearing gradually deteriorated at frequencies below 1 kHz and above 4 kHz, with the auditory brainstem response (ABR) eventually becoming absent in both ears. However, distortion product otoacoustic emissions (DPOAE) were present at low frequencies, which suggests that the organ of Corti in its upper turn remained unaffected by tumor invasion. Metastatic tumors in the bilateral IAC have been reported to mimic neurofibromatosis type 2, and radiological differentiation from acoustic schwannoma is difficult. We characterize the hearing deterioration caused by metastasis of malignant tumors in the IAC.

Ocular neuromyotonia with spastic lid closure

Ocular neuromyotonia is characterized by tonic spasms of extraocular muscles evoked by eccentric gaze that induces transient strabismus and diplopia. We report the case of a 70-year-old woman who initially presented with unilateral deficits in fifth and sixth cranial nerve functions attributed to a fifth cranial nerve schwannoma. After radiation treatment, she developed neuromyotonia and synkinesis of the ipsilateral third cranial nerve. During the attacks of neuromyotonia, the left eyelids were often spastically closed, a phenomenon not previously reported. The ocular neuromyotonia regressed spontaneously within 3 years, but components of the synkinesis persisted. Ephaptic transmission in a damaged third cranial nerve may be responsible for the neuromyotonia and synkinesis. Synkinesis is a more enduring manifestation.

Dura-Based Giant Intracranial Schwannoma in the Middle Fossa -Case Report-

A 49-year-old female presented with a rare giant schwannoma arising from the dura mater of the middle fossa manifesting as loss of left visual acuity. Magnetic resonance imaging revealed a heterogeneously enhanced giant mass in the left middle fossa. Surgery via the transsylvian approach confirmed the origin of the tumor between the left internal carotid artery and the trigeminal nerve in the lateral wall of the cavernous sinus. Elongated abducens nerve was confirmed, but no tumor adhesion to the abducens nerve was found. The tumor was closely attached to the dura mater of the middle fossa and the lateral wall of the cavernous sinus. The histological diagnosis was schwannoma. Both left oculomotor and abducens nerve pareses occurred immediately after the operation but gradually resolved over 3 months. The operative findings indicated that this schwannoma may have arisen from the meningeal branch of the trigeminal nerve in the dura mater of the middle fossa.

Surgical Management of Jugular Foramen Schwannomas With Hearing and Facial Nerve Function Preservation: A Series of 23 Cases and Review of the Literature

OBJECTIVE

Schwannomas of the jugular foramen are rare lesions and controversy regarding their management still exists. The objective of this retrospective study was to analyze the management and outcome in a series of 23 cases collected at a single center.

SETTING

This study was conducted at a quaternary private otology and skull base center.

METHODS

Charts belonging to patients with a diagnosis of jugular foramen schwannoma attending our center between May 1988 and April 2006 were examined retrospectively.

RESULTS

The study group consisted of 23 patients. One patient (a 73-year-old woman) with normal lower cranial nerves function was managed with watchful expectancy and regular clinical and radiologic follow ups. The infratemporal fossa approach-type A (IFTA-A) was performed in 3 cases. One patient underwent a transcochlear-transjugular approach. Of the 22 patients surgically treated, 12 patients were operated on by the petrooccipital transsigmoid approach (POTS). In one patient with a preoperative dead ear, a combined POTS-translabyrinthine approach was adopted. Two patients were operated on through the POTS approach combined with the transotic approach. In another case (a 67-year-old woman), a subtotal tumor removal through a transcervical approach was planned to resect a 10-cm mass in the neck. One patient underwent a first-stage combined transcervical-subtotal petrosectomy approach to remove a huge tumor in the neck; the second-stage intradural removal of the tumor was accomplished through a translabyrinthine-transsigmoid-transjugular approach. The last patient underwent a first-stage combined transcervical-subtotal petrosectomy approach to remove the neck tumor component; this patient is now waiting for the second-stage intradural removal of the tumor. Complete tumor removal was accomplished in 21 cases and in one case, a residual schwannoma was left in place in the area of the jugular foramen. The 3 patients who were operated on by IFTA-A underwent permanent anterior transposition of the facial nerve. At 1-year follow up, 2 of these patients had House-Brackmann grade I and 1 reached grade IV. The patient who underwent a transcochlear-transjugular approach had a permanent posterior transposition of the facial nerve. At 1-year follow up, he had grade III facial nerve function. Postoperative facial nerve function was normal (House-Brackmann grade I) in all patients operated on by the POTS approach. Twelve patients had hearing-preserving surgery using the POTS approach. Good hearing was preserved in 10 cases (83.3%), the majority of whom (58.3%) maintained their preoperative hearing level. There was no perioperative mortality. One patient (4.5%) experienced a postoperative cerebrospinal fluid leak. After surgery, all patients did not recover the function of the preoperatively paralyzed lower cranial nerves. A new deficit of one or more of the lower cranial nerves was recorded in 50% of cases. So far, no patient has experienced recurrence during the follow-up period as ascertained by computed tomography or magnetic resonance imaging.

CONCLUSIONS

Surgical resection is the treatment of choice for jugular foramen schwannomas. The POTS approach allowed single-stage, total tumor removal with preservation of the facial nerve and of the middle and inner ear functions in the majority of cases. Despite the advances in skull base surgery, new postoperative lower cranial nerve deficits still represent a challenge.

Percutaneous radio-frequency mandibular nerve rhizotomy guided by CT fluoroscopy

We describe a new method for radio-frequency mandibular nerve rhizotomy under CT fluoroscopy. A patient with cancer had severe intractable and drug-resistant pain in his left mandibular region. Because he had an anatomic deformity due to cancer invasion and radiation therapy, we planned a mandibular nerve rhizotomy under CT fluoroscopic imaging. The needle was advanced to the mandibular nerve just caudal to the foramen ovale under real-time CT fluoroscopy, avoiding the cancer region. Pain scores of the patient were reduced after the nerve rhizotomy, without any complications.

Compression of the Rostral Ventrolateral Medulla by a Vagal Schwannoma of the Cerebellomedullary Cistern Presenting with Refractory Neurogenic Hypertension: Case Report

OBJECTIVE:

The rostral ventrolateral medulla is thought to serve as a final common pathway for the integration of central cardiovascular information and to be important for the mediation of central pressor responses. An association between essential hypertension and neurovascular compression of the rostral ventrolateral medulla has been reported. This may be mediated by an increase in sympathetic tone.

CLINICAL PRESENTATION:

Schwannomas arising from the lower cranial nerves (Cranial Nerves IX-XI) are rare, constituting only 3% of all intracranial schwannomas unassociated with neurofibromatosis. The majority of these tumors present as jugular foramen lesions and, less commonly, they occur along the extracranial course of these nerves. An intracisternal location is extremely rare. Fewer than 15 cases of pathologically proven intracisternal vagal schwannomas in the absence of neurofibromatosis have been reported.

INTERVENTION:

We report a case of vagal schwannoma in the cerebellomedullary cistern causing distortion of the vagal root entry zone and presenting with refractory neurogenic hypertension. Total microsurgical excision of this tumor, arising from one of the rootlets of the vagus nerve, was achieved. Immediately postoperatively, blood pressure decreased markedly, and despite our effort to maintain the blood pressure with fluids, the patient developed a cerebral infarction in the watershed zone.

CONCLUSION:

We discuss the proposed mechanism of hypertension, and the perioperative management, stressing blood pressure control. A review of the literature regarding vagal schwannomas is also presented. To the best of our knowledge, this is the first case report of a cerebellomedullary cistern vagal schwannoma presenting with neurogenic hypertension.

April 2002: 35-year-old healthy man with enlarging right parotid mass

The April 2002 Case of the Month (COM). 35-year-old healthy man developed a mass in the right parotid gland. A superifical parotidectomy was performed for a 4.5 x 1.5 x 1.5 cm mass involving the intraparotid facial nerve. Grossly the tumor was multinodular, smooth and yellow with normal surrounding salivary gland. Microscopically, the tumor showed expanding nodules composed of proliferating fibroblasts, Schwann cells, and perineural-like cells in a myxoid stroma. Normal peripheral nerve twigs were identified in the periphery of the tumor. There was no increased mitotic activity, cellularity or nuclear pleomorphism. S-100 immunohistochemical stain was positive. The tumor was diagnosed as a solitary plexiform neurofibroma. Plexiform neurofibromas in this area have been described in children with von Recklinghausen's disease or neurofibromatosis 1 (NF 1). Plexiform neurofibromas typically involve deep seated nerve trunks and is considered pathognomonic for NF 1. This unusual case represents a solitary variant of plexiform neurofibroma presenting as a parotid mass in an adult patient without a personal stigmata or family history of NF 1.

Usefulness of transcervical approach for surgical treatment of hypoglossal schwannoma with paraspinal extension: case report

BACKGROUND

Usefulness of transcervical approach to hypoglossal schwannoma with paraspinal extension is described herein.

CASE DESCRIPTION

A 54-year-old woman presented with gradually worsening left hypoglossal nerve palsy. The findings were of a tumor lying in the left hypoglossal canal and paraspinal region and were consistent with hypoglossal schwannoma. Subtotal intracapsular removal of the tumor was performed via transcervical approach. The symptoms improved, and no additional symptoms were noted.

CONCLUSION

The transcervical approach and intracapsular removal of the tumor under electrophysiological monitoring provided for successful minimally invasive surgery in this case of hypoglossal schwannoma.

Stereotactic Radiosurgery for Vestibular Schwannomas: Analysis of 317 Patients Followed More Than 5 Years

OBJECTIVE:

Many investigators have reported successful treatment of vestibular schwannomas with gamma knife radiosurgery (GKRS). However, long-term outcomes should be evaluated before concluding that GKRS is truly safe and effective for the treatment of vestibular schwannomas.

METHODS:

Between May 1991 and December 1998, 346 consecutive patients (excluding those presenting with neurofibromatosis Type 2) were treated with GKRS. Of these, 317 patients were assessed. Twenty-nine patients were lost to follow-up within 5 years.

RESULTS:

The median follow-up period was 7.8 years. Of 301 patients who underwent serial follow-up imaging, two (1%) experienced complete remission, 184 (61%) experienced partial remission, 93 (31%) had stable tumors, and 22 (7%) experienced treatment failure. The actuarial 5- or 10-year progression-free survival (PFS) rate was 93 and 92%, respectively. Tumors less than 15 cm3 in volume (10-yr PFS, 96%; P < 0.001) or which did not compress the brainstem and deviate the fourth ventricle (10-yr PFS, 97%; P = 0.008) resulted in significantly better PFS rates. Failure of treatment usually occurred within 3 years. When the tumor was treated with a marginal dose of 13 Gy or less, the hearing preservation rate was 68%, transient facial palsy developed at a rate of 1%, and facial numbness developed at a rate of 2%.

CONCLUSION:

GKRS proved to be a safe and effective treatment for patients followed longer than 5 years who presented with tumors with a volume of less than 15 cm3 and who did not have significant fourth ventricle deviation. Good functional outcomes were observed in this group of patients.

Localized Transcranial Electrical Motor Evoked Potentials for Monitoring Cranial Nerves in Cranial Base Surgery

OBJECTIVE:

To describe a novel monitoring technique that allows “functional” assessment of cranial nerve continuity during cranial base surgery.

METHODS:

Facial motor evoked potentials (MEP) in 71 consecutive patients were obtained by localized transcranial electrical stimulation in all patients requiring facial nerve monitoring during the period from November 2002 to August 2004. With transcranial electrical stimulation localized to the contralateral cortex, facial nerve MEPs are obtained through stimulation of more proximal intracranial structures.

RESULTS:

Logistic regression revealed that the final-to-baseline facial MEP ratio predicted satisfactory (House-Brackmann Grade 1 and 2 function) immediate postoperative facial function (0.005 > P > 0.0005). Contingency table analysis showed high correlation (χ2, P ≤ 2 × 108) and acceptable test characteristics using a 50% final-to-baseline MEP ratio.

CONCLUSION:

Facial nerve MEPs recorded intraoperatively during cranial base surgery using the proposed technique predicts immediate postoperative facial nerve outcome. This technique can also be used to monitor other motor cranial nerves in cranial base surgery.

Management of vagal paraganglioma: Is operative resection really the best option?

BACKGROUND

Vagal paragangliomas cannot be resected without sacrifice of the vagal nerve. The risk of bilateral vocal cord palsy has been reason to postpone treatment of this benign and slow growing neoplasm in hereditary cases. Postponement could be considered for solitary cases as well.

METHODS

An institute-based review of 48 patients with vagal paragangliomas over the past 30 years was performed.

RESULTS

Forty-eight patients with 58 vagal paragangliomas were studied. All but 4 patients had multiple paragangliomas and should be considered hereditary cases. The 10 patients that underwent an operation lost the vagal nerve; 60% of them had additional cranial nerve palsy postoperatively. In the group of patients who were followed for an average period of 8.5 years, 3 patients (8%) developed cranial nerve palsy.

CONCLUSIONS

Aggressive treatment of vagal paragangliomas leads to unnecessary early loss of vagal nerve function. A period of clinical and radiologic follow-up preceding an operation may lead to prolonged preservation of voice and swallowing functions in these patients, without grave consequences for other lower cranial nerves.

Respuesta evocada auditiva de tronco en el schwannoma del VIII par: correlación anatomofisiológica y funcional. Nuestra experiencia

INTRODUCTION

Schwannomas are tumors charasteristically originated from the nerve sheath. They expande eccentrically from the nerve promoting a disturbance in the neural function either due to vascular compresion or to the effect of the tumor itself on the nerve, disturbance that can be evidenced with the Auditory-evoked Brainstem Response (ABR), fact that constituted the base for their diagnosis in the past. The new radiological techniques developed over the last decades have made possible an earlier diagnosis, and therefore changed their prognosis in terms of nerve function. Diagnosis is more certain today with these techniques so it could seem that ABR may not have any longer a role in the management of this condition.

OBJECTIVE

To describe the most frequent ABR patterns in those patients suffering from acoustic schwannoma related to the size of the tumour and the remanent audition thresholds, and to determine the value of this test in our practice.

MATERIAL AND METHODS

We describe the ABR features found in our series of 72 patients. Whose diagnosis was done between 1997 and 2003 in relation to the size of the tumour and the residual auditory function.

RESULTS AND CONCLUSIONS

ABR has a good sensibility for detection of acoustic schwannoma. This sensibility decreases in small-sized tumours, specially in intracanalicular ones. ABR patterns do not relate to the size of the tumour but they do to the auditory function. The authors defend ABR to be a very valuable test due to the information and accesibility they provide.

[Facial nerve tumours]

INTRODUCTION

Tumours originating in the facial nerve are extremely rare and their therapeutic approach requires the aid of specialists from a number of disciplines.

AIMS

Our aim was to analyse the cases treated in our centre over a five-year period.

PATIENTS AND METHODS

All the subjects submitted to surgical interventions to treat facial nerve tumours between January 1992 and December 1996 were evaluated retrospectively. Data recorded from all patients included age, sex, side affected, time prior to diagnosis, presenting symptom and symptoms observed at the time of diagnosis, previous history of disorders affecting the facial nerve and associated neurological symptoms. We also noted the location of the lesion, the surgical technique used, pathology findings, post-operative complications, length of post-operative stay in hospital, facial sequelae and surgical repair procedures used on the facial nerves involved in the intervention.

RESULTS

Six cases, with a mean age of 29 years (range: 16-46 years), were treated. Three of the patients were males (50%). Symptoms of the disease included facial palsy (4), neurosensory hypoacusis (1) and tinnitus (1). All six individuals (100%) had alterations affecting facial functioning in the course of the disease. The pathological diagnosis was schwannoma in four cases and hemangioma in the other two. Neural grafts were carried out in three patients and some kind of deficit was observed at the end of the follow-up in all the cases.

CONCLUSIONS

Facial nerve tumours are very infrequent. An early diagnosis is needed to diminish the facial sequelae following surgery performed to treat this clinical entity.

A rare case of cellular schwannoma involving the trigeminal ganglion

Cellular schwannomas rarely involve the cranial nerves, being more common in the spinal and peripheral nerves. A rare case of cellular schwannoma involving the gasserian ganglion, a hitherto unreported site, that extended infratentorially to present as a cerebellopontine angle tumor is reported. It is important to recognize that cellular schwannomas can histologically mimic malignant peripheral nerve sheath tumors because of their high cellularity and mitotic activity, but they are relatively benign tumors with a tendency to recur but not metastasize.

Subfrontal Schwannoma Without Hyposmia-Case Report-

A 44-year-old man presented with a rare subfrontal schwannoma with headache. He had undergone radiation therapy for a pineal lesion 30 years previously, but the histology was not verified. On admission, neurological examination revealed no focal deficits including hyposmia. Computed tomography demonstrated a mass measuring 5 x 3 cm in the right anterior cranial fossa. Magnetic resonance imaging revealed a heterogeneously enhanced mass with multiple cysts. The tumor, which was clearly separable from the surrounding normal brain, was totally resected through a right frontal craniotomy. There was no adhesion between the tumor and the olfactory groove or cribriform plate. The frontal base dura was suspected to be the tumor attachment. The patient was discharged without hyposmia. Histological examination revealed a typical pattern of schwannoma consisting of Antoni type A and type B. Immunohistochemical staining was positive for S-100 protein but negative for epithelial membrane antigen. Subfrontal schwannoma not associated with the olfactory groove or cribriform plate is extremely rare. The operative findings and absence of hyposmia suggest that the meningeal branch of the trigeminal nerve was the origin of the tumor. However, the possibility of radiation-induced reactive Schwann cells cannot be excluded.

Facial Nerve Tumors

OBJECTIVE

To evaluate the surgical results in primary facial nerve (FN) tumors.

STUDY DESIGN

Retrospective case review.

SETTING

Private neuro-otological and skull-base tertiary referral center.

PATIENTS

Twenty eight consecutive patients affected by primary FN tumors that underwent surgery between December 1990 and February 2001.

INTERVENTIONS

The lesions were removed through a variety of surgical approaches, depending on tumor location and extension, as well as preoperative hearing. In one case, partial removal was performed.

MAIN OUTCOME MEASURES

Preoperative and postoperative FN function; preoperative and postoperative hearing level; and postoperative complications.

RESULTS

Based on histologic examination, tumors were distributed as follows: 18 schwannomas, six hemangiomas, two meningiomas, and two neurofibromas. Tumor location varied, with lesions distributed along the entire length of the nerve. Facial dysfunction was the most frequently recorded symptom, followed by hearing loss. Only five patients presented a preoperative grade 1 facial function. In the remaining patients of the group, the facial deficit lasted from 2 to 120 months, with a mean of 31.2 months. Anatomic integrity of the nerve was preserved in 4 cases; all others required a nerve interruption followed by reconstruction using a sural nerve graft. The complications recorded were: one cerebrospinal fluid leak, one postoperative retraction pocket, and one external auditory canal wall resorption requiring a surgical revision. Preoperative hearing remained unchanged in 8 out of the 15 patients in whom a hearing preservation procedure was attempted. In 25 cases, a follow-up of equal to or longer than 1 year was available, with the FN functions: two grade 1, eight grade 3, nine grade 4, three grade 5, and three grade 6. Patients with a preoperative deficit lasting more than 1 year demonstrated the worst recovery.

CONCLUSIONS

Primary FN tumors are rare lesions that include different histologic types. FN deficit represents the most common symptom, but it is not present in all cases. A conservative strategy is often adopted in presence of a normal preoperative facial function. When surgical management is selected, the decision on surgical approach to use depends on tumor size and location, as well as on preoperative hearing. FN integrity may be spared in rare occasions, but more frequently nerve reconstruction is required. Final facial function recovery is mainly dependent on the preoperative presence of FN deficit and its duration.

[Gamma knife radiosurgery for trigeminal schwannomas]

OBJECTIVE

To evaluate the role of gamma knife (GK) in the treatment of trigeminal schwannomas.

METHODS

From June 1994 to June 2000, 38 patients with trigeminal schwannoma treated with GK radiosurgery were reviewed. GK was the primary treatment modality in 30 cases and followed microsurgery in 8 cases. Of the 38 tumors, 12 had small cysts within the tumors, the rest were solid. The mean diameter of the 38 tumors was 32 mm (range: 16 approximately 48 mm) and the tumors ranged in volume from 2 to 33 cm(3) (with a mean mean volume of 9 cm(3)). The maximum dose irradiated to tumor was 20 to 33 Gy (mean: 26 Gy), the tumor margin dose ranged from 11 to 15 Gy (mean: 13 Gy).

RESULTS

35 patients had been followed for 26 to 98 months (mean: 65 months). 20 had been followed more than 60 months. Mild numbness or diplopia relieved completely in 12 patients after GK treatment. Improvement of neurological deficits was seen in 11, unchanged dysfunction or slightly worsening of trigeminal nerve deficits in 9. Three patients had mild worsened symptoms at different time because of tumor progression. Tumor growth control: tumor disappeared after GK treatment was observed in 5 cases from 18 to 36 months after, a marked decrease in volume was observed in 24 cases, unchange in 2 cases and increase in 3 cases at 5, 26, and 60 months after respectively. One patient with resolved symptom refused to have MRI examination for more than 6 years. Of the three increased tumors, one recurrent malignant schwannoma elapsed 26 months after GK treatment. The second was a small tumor and started to progress 5 years after, but after second GK treatment, the tumor decreased again. The third was large tumor and was subtotally removed through surgery because of tumor swelling 5 months after. At last follow-up, the residual tumor remained stable. The control rate of the 35 tumors was 91% (32/35).

CONCLUSION

Small and middle-size trigeminal schwannomas are the best candidates for GK radiosurgery. The control dose is 13 to 14 Gy.

Neurofibromatosis 2: two case reports

Our study presents two cases of neurofibromatosis 2 (NF2) that have been diagnosed at the Ear, Nose, and Throat Department of Hradec Králové (Czech Republic). The first case involved a young man with a history of sudden hearing loss accompanied by tinnitus on the left side. The diagnosis of NF2 was made, and an operation for left acoustic neuroma was performed. Looking toward the future, the acoustic neuroma on the right side should be resolved as well. The second case concerned a woman (the mother of our patient 1) examined at the same Ear, Nose, and Throat Department in 1980, after 4 years of gait instability and progressive loss of hearing and tinnitus on the right side. Computed tomography scan detected a bilateral expansion in the pontocerebellar angles, and a large tumor on the right side was removed. The patient is deaf and has facial palsy without progression of symptomatology during long-term follow-up. These two cases document the rare but serious hereditary disease of NF2. Its most frequent first presentation is acoustic neuroma; further, benign tumors of the nervous system and juvenile cortical cataract also are often detected. The variability of number, location, and biological behavior of tumors associated with NF2 require an individual patient treatment approach, long-term follow-up, and insertion of appropriate hearing aids. Important also is a genetic examination to exclude pathological NF2 genes in the first-degree relatives of the affected individuals.

Pathological laughter in a patient with trigeminal neurinoma

We present a 47-year-old woman with a long history of anxiety and a more recent history of shock-like facial pain and episodes of laughter without any motivation. She could not explain the laughing bursts and did not have a sense of mirth preceding it. On neurological examination she presented a VI nerve palsy and trigeminal hypoesthesia (V2 and V3) on the right side. Magnetic resonance imaging exhibited a large cystic lesion on the right middle fossa causing significant compression on the brain stem. A frontoorbitozygomatic and pretemporal combined approach was performed. During intra and extradural exploration a large tumor was found on the trigeminal nerve. The whole lesion was resected, revealing to be a neurinoma on pathological exhamination. She maintained a VI nerve palsy but had complete remission of the unmotivated laughing episodes during the one year follow up.

[Diagnostic image (86). A man with thirst and diplopia]

A 71-year-old man was thirsty, had bone pains and a double vision. Multiple myeloma with hypercalcemia was diagnosed. One tumour in the clivus turned out to be compressing the left N. abducens.

Abducens nerve schwannoma: a case report and review of the literature

BACKGROUND

Schwannomas of the abducens nerve are extremely rare tumors; only 10 cases have been reported so far. The tumor may be located within the cavernous sinus (CS) or more commonly at the prepontine region. Patients usually present with VIth cranial nerve paresis.

CASE DESCRIPTION

We report a case of a 42-year-old male patient who presented with headache, vertigo, and hearing deficit, but no symptoms or signs related to a VIth cranial nerve impairment. Computed tomography and magnetic resonance imaging showed a large mass with a ring-like contrast enhancement in the prepontine area. Surgical treatment, via a simple retrosigmoid suboccipital approach, revealed a schwannoma originating from the VIth cranial nerve at its prepontine portion. Postoperative histological examination confirmed the diagnosis of schwannoma, and the patient had only a VIth cranial nerve palsy, which resolved during long-term follow-up.

CONCLUSIONS

Abducens schwannomas are rare tumors, representing less than 1% of all intracranial schwannomas in our clinic and about 13% of oculomotor nerve schwannomas reported in the literature. These lesions can be mainly divided into tumors originating from the intracavernous portion of the VIth cranial nerve or more commonly from the cisternal part of the nerve, leading to a lesion in the prepontine region. In such cases, with no invasion of the cavernous sinus, radical tumor resection with preservation of the abducens nerve can be performed via a simple suboccipital retrosigmoid approach.

Trigeminal schwannomas: removal of dumbbell-shaped tumors through the expanded Meckel cave and outcomes of cranial nerve function

OBJECT

As in patients with vestibular schwannomas, advances in surgical procedures have markedly improved outcomes in patients with trigeminal schwannomas. In this article the authors address the function of cranial nerves in a series of patients with trigeminal schwannomas that were treated with gross-total surgical removal. The authors emphasize a technique they use to remove a dumbbell-shaped tumor through the expanded Meckel cave, and discuss the advantage of the extradural zygomatic middle fossa approach for total removal of tumor and preservation or improvement of cranial nerve function.

METHODS

Within an 11-year period (1989-2000), 25 patients (14 female and 11 male patients with a mean age of 44.4 years) with benign trigeminal schwannomas were surgically treated by the senior author (O.A.) with the aim of total removal of the tumor. Three patients had undergone previous surgery elsewhere. Trigeminal nerve dysfunction was present in all but two patients. Abducent nerve paresis was present in 40%. The approach in each patient was selected according to the location and size of the lesion. Nineteen tumors were dumbbell shaped and extended into both middle and posterior fossae. All 25 tumors involved the cavernous sinus. The zygomatic middle fossa approach was particularly useful and was used in 14 patients. The mean follow-up period was 33.12 months. In patients who had not undergone previous surgery, the preoperative trigeminal sensory deficit improved in 44%, facial pain decreased in 73%, and trigeminal motor deficit improved in 80%. Among patients with preoperative abducent nerve paresis, recovery was attained in 63%. Three patients (12%) experienced a persistent new or worse cranial nerve function postoperatively. Fifth nerve sensory deficit persisted in one of these patients, sensory and motor dysfunction in another, and motor trigeminal weakness in the third patient. In all patients a good surgical outcome was achieved. One patient died 2 years after treatment from an unrelated cause. In three patients the tumors recurred after an average of 22.3 months.

CONCLUSIONS

Preservation or improvement of cranial nerve function can be achieved through total removal of a trigeminal schwannoma, and skull base approaches are better suited to achieving this goal. The zygomatic middle fossa approach is particularly helpful and safe. It allows extradural tumor removal from the cavernous sinus, the infratemporal fossa, and the posterior fossa through the expanded Meckel cave.

Transtemporal facial nerve schwannoma without facial nerve paralysis

Facial schwannoma is a relatively rare but well documented lesion, presenting either as a mass or with facial nerve symptoms. In this report, an extensive facial schwannoma, extending from the brain stem to the periphery with minimal facial nerve symptoms and normal facial function is presented.

Visual pathway tumors and hydrocephalus

The authors evaluated the impact of hydrocephalus on the clinical picture of children with visual pathway tumor (VPT) with or without neurofibromatosis (NF). Charts of children with VPT treated in the authors' center since 1985 were retrospectively reviewed, and those with hydrocephalus were selected and summarized. Thirty-five children with VPT were found, of whom 20 had NF. Hydrocephalus was found in 4 children with NF (20%) and in 5 without NF (33.3%). In 6 of the children, ventricular dilatation with signs of acute increased intracranial pressure already existed at the time of diagnosis and the hydrocephalus was shunted at this time. In the other 3 children, all with NF, the hydrocephalus resulted from slowly developing aqueductal stenosis, leading in 2 to severe visual acuity deterioration. The results suggest that in children with VPT and NF, hydrocephalus, and especially hydrocephalus resulting from aqueductal stenosis, is more frequent than in the general population of NF patients, and less frequent than in VPT patients without NF. The possibility of the indolent development of hydrocephalus should be borne in mind while following children with NF. The optic nerve, when already involved with a glioma, is more vulnerable to increased pressure. Thus, in children with VPT and NF, any ventricular dilatation should lead to a consideration of early shunting.

Pathological laughter as a presenting symptom of massive trigeminal neuromas: report of four cases

OBJECTIVE AND IMPORTANCE

This is a report of four cases of huge trigeminal neuromas that presented with the principle symptom of pathological laughter (PL).

CLINICAL PRESENTATION

All four patients were male and were in either the third or fourth decade of life. In addition to PL, there were neurological deficits related to trigeminal nerve, brainstem, and cerebellar dysfunctions.

INTERVENTION

All tumors were radically excised via a lateral basal temporal approach. The PL was cured immediately after surgery.

CONCLUSION

PL sometimes precedes other neurological manifestations and may be a useful localizing sign. The clinical and radiological features in our cases suggest that PL is a result of extra-axial compression of the pons and adjoining neural structures.

[Monitoring of the auditory stem evoked potentials in removal of tumors of the posterior cranial fossa]

The material of intraoperative monitoring of the acoustic stem evoked potentials (ASEP) in 9 patients with tumors of the stem and in 28 patients with the parastem localization was analyzed. It was shown that changes in the amplitude of ASEP rather than latency were the decisive factor in the assessment of the functional state of the brain stem. It was found that even the pronounced changes of the bioelectrical activity recorded during the excision of the tumor could be reversible after a change of the strategy of the operative intervention and/or after performing the necessary therapeutic measures. An important test of favorable prognosis of the postoperative course is considered to be the normalization of brain activity, ASEP included, at the final stages of the operation.

Audiovestibular findings prior to and after acoustic neuroma surgery

We performed a retrospective study of 131 patients who underwent microsurgical removal of statoacoustic neuroma at the University of Wuerzburg. Our goal was to evaluate objective audiovestibular findings prior to and after surgery. Our analysis focused on the evaluation of quantitative parameters in speech and pure-tone audiometry and on the reactivity of the vestibular system.

Surgical findings in idiopathic trigeminal neuropathy mimicking a trigeminal neurinoma

Idiopathic trigeminal neuropathy is a benign disorder where the main clinical feature is facial numbness limited to the territory of one or more divisions of the trigeminal nerve, persisting for a few weeks to several years and in which no underlying disease can be identified. The case of a 37-year-old man with a brief history of sensory and motor trigeminal symptoms who showed magnetic resonance imaging (MRI) findings consistent with a small trigeminal neurinoma is reported. The patient was operated on but no tumour could be found during surgery and a biopsy was taken from the portio major. Pathological diagnosis was chronic non granulomatous inflammatory reaction with areas of coagulation necrosis. Control MRI showed complete resolution of the trigeminal abnormalities. It is concluded that in patients with MRI findings suggestive of a small trigeminal schwannoma, benign idiopathic trigeminal neuropathy should also be considered in the differential diagnosis. A conservative approach with sequential MRI studies may avoid an unnecessary surgical exploration.

Sympathectomy does not affect the early ectopic discharge from myelinated fibres in ferret inferior alveolar nerve neuromas

Ectopic neural activity from damaged axons is thought to contribute to the development of sensory disorders following nerve injury. Here we have studied the role of sympathetic fibres in the generation or potentiation of this abnormal activity by determining the effect of predegenerating these fibres. Twelve adult ferrets were used in the study and six of them underwent sympathectomy by removal of the left superior cervical ganglion. Electrophysiological recordings were made from myelinated axons in fine filaments dissected from the inferior alveolar nerve, 3 days after it had been ligated further distally, and the level of spontaneous activity and mechanical sensitivity was determined. There was no significant difference between the level or characteristics of spontaneous activity, or the level of mechanical sensitivity, in the two groups of animals. We conclude that, in this animal model, the absence of sympathetic nerve fibres does not affect the development or characteristics of ectopic neural activity in the early period following nerve injury.

Prognostic value of the pattern electroretinogram in cases of tumors affecting the optic pathway

BACKGROUND

Tumors compressing the optic pathway may lead to irreversible loss of vision which may be detected by the pattern electroretinogram (PERG) because of its relation to ganglion cell function.

METHODS

Eyes of 19 patients were tested shortly before and 5-10 days after tumor surgery. Visual acuity, the 30-deg visual field and the transient and steady-state pattern reversal ERG were measured.

RESULTS

Using patterns of 1.5 x 1.2 deg there was a good correlation between the change of pre- and post-surgical visual performance and most of the pattern ERG amplitudes. For all variables tested--P50, N95- and steady-state amplitude--there was a critical value beyond which the visual outcome could be bad or favorable, whereas patients showing higher amplitudes always remained stable or improved after surgery.

CONCLUSION

The positive correlation between pattern ERG amplitudes and the post-surgical outcome in the case of tumors affecting the optic pathway may be helpful in predicting the outcome for these patients.

Preoperative electroneurography (ENoG) in parotid surgery: assessment of facial nerve outcome and involvement by tumor--a preliminary study

BACKGROUND

Facial electroneurography (ENoG) is an established and reliable method for assessing neural degeneration in various conditions affecting the facial nerve. The facial nerve may be subclinically involved by parotid tumors, but estimating such involvement preoperatively may be difficult when facial function is normal. The hypothesis that preoperative ENoG: (1) can detect subclinical facial nerve degeneration as a measure of involvement by parotid tumors and (2) can predict facial nerve function following parotidectomy was prospectively evaluated in the present study.

METHODS

Twenty-two patients undergoing parotidectomy for tumors were tested preoperatively with ENoG, and their facial nerve function was graded pre- and postoperatively (House-Brackmann system). Eight patients had malignant tumors and 14 benign tumors.

RESULTS

In patients with malignant tumors, lower percentage of preoperative ENoG response indicated nerve involvement that was not evident on clinical examination and correlated significantly (p = .035) with postoperative facial nerve dysfunction. Preoperative ENoG reduction of greater than 80% was found in all patients whose facial nerve was infiltrated by tumor. In 14 patients with benign tumors, preoperative ENoG results had no correlation with postoperative facial function.

CONCLUSIONS

In malignant tumors, even when facial function is clinically intact, a low preoperative ENoG response may predict facial nerve involvement by the tumor. The lower the preoperative ENoG response, the poorer is the expected postoperative facial nerve function. There was no such correlation in benign parotid tumors.

Hemifacial spasm caused by a hemangioma at the geniculate ganglion: case report

OBJECTIVE AND IMPORTANCE

Hemifacial spasm is rarely caused by facial nerve lesions in the temporal bone. Intratemporal facial nerve hemangiomas may initially present as facial spasm.

CLINICAL PRESENTATION

A 30-year-old woman developed right hemifacial spasm. Physicians observed slight weakness on the right side of her face, in addition to the hemifacial spasm, but routine radiological examinations did not detect any abnormal findings along the course of the facial nerve. Although the patient underwent neurovascular decompression, the spasm persisted postoperatively. Two years after surgery, the right facial palsy progressed. Concurrently, the hemifacial spasm diminished. High-resolution computed tomography demonstrated a small mass lesion expanding the cortex of the right petrosal bone involving the geniculate ganglion of the facial nerve.

INTERVENTION

The patient underwent a second craniotomy through a subtemporal extradural route, and the tumor was completely removed. A pathological examination demonstrated a cavernous hemangioma.

CONCLUSION

Routine radiological examinations may fail to detect small intratemporal facial nerve hemangiomas, particularly at the geniculate ganglion. Therefore, when physicians encounter atypical facial spasm, the intratemporal portion of the facial nerve should be carefully examined using high-resolution computed tomography.

Management of vestibular schwannomas (acoustic neuromas): auditory and facial nerve function after resection of 120 vestibular schwannomas in patients with neurofibromatosis 2

OBJECTIVE

Vestibular schwannomas (VSs) affect young patients with Neurofibromatosis 2 (NF-2) and cause very serious problems for hearing, facial expression, and brain stem function. Our objective was to determine a therapy concept for the right timing and indication of neurosurgical therapy.

METHODS

In 1000 consecutive VS resections, 120 tumors in 82 patients with NF-2 were surgically treated by the same surgeon (MS) at the Department of Neurosurgery at Nordstadt Hospital from 1978 to 1993. The mean age of the patients was 27.5 years. Sixty tumors were surgically treated in 41 male patients, and 60 tumors were surgically treated in 41 female patients. Bilateral tumor resection was performed in 38 patients (76 operations, after previous partial surgery in 15 cases elsewhere), and unilateral operations were performed in 44 patients, 5 of whom had undergone ipsi- or contralateral surgery that was performed elsewhere. The operative and clinical findings are evaluated and compared with the data of patients without NF-2.

RESULTS

In 105 cases, complete tumor resections were achieved. In 15 cases, deliberate subtotal resections were performed. These were for brain stem decompression in 4 cases and for hearing preservation in the last hearing ear in 11 cases, with successful preservation in 8 of the 11. Pre- and postoperative hearing rates were higher in male than in female patients (70% in male versus 65% in female patients before surgery and 40.5 versus 31%, respectively, after surgery). Hearing was preserved in 29 of 81 ears (36%). The rate of preservation was 24% in cases of large tumors and 57% in cases of small tumors (<30 mm). Twenty-one of 82 patients (26%) were bilaterally deaf before surgery. Twenty-five patients had uni- or bilateral hearing after surgery (i.e., 41 % of those with preoperative hearing or 30.5% of the whole group). Anatomic facial nerve preservation was achieved in 85%. The facial nerve was reconstructed intracranially at the cerebellopontine angle by sural grafting in 17 cases and by hypoglossal-facial reanimation in 5. Two deaths occurred 1 and 3 months postsurgically as a result of malignant tumor growth with brain stem dysfunction and respiratory problems. In summary, for patients with NF-2, the presentation ages are lower, tumor progression is faster, the chances of anatomic and functional nerve preservation are lower, the chances of good outcomes are best when surgery is performed early and when there is good preoperative hearing function, and the danger of sudden hearing loss is higher. The chances and danger often differ from side to side among individual patients.

CONCLUSION

The indication and the timing of tumor resections are in some respects different from normal VS handling and are dependent on the tumor extension and related necessity of brain stem decompression and on the auditory function. As an optimal goal, completeness of resection with functional cochlear nerve preservation is formulated, and as an acceptable compromise, subtotal microsurgical resection with functional cochlear nerve preservation in the last hearing ear is suggested.

Improvement in visual function in an eye with a presumed optic nerve sheath meningioma after treatment with three-dimensional conformal radiation therapy

The treatment of optic nerve sheath meningiomas (ONSM) is controversial. Radiation therapy has been used with some success in patients with progressive visual loss. We report a case of visual improvement in a patient with an optic nerve sheath meningioma and progressive visual field loss, treated with conformal radiotherapy.

[The role of cervical input in vestibular compensation]

The role of proprioceptive input from cervical receptors in vestibular compensation was investigated. Vibratory stimulation to the dorsal neck muscle was given to patients with unilateral vestibular lesions. The length of the displacement of the center of gravity, maximum sway length, and sway area increased markedly during vibratory stimulation to the dorsal neck. In patients in whom compensation had been achieved, a position vector to the side of the lesion increased and the center of gravity moved to the side of the lesion. From these results, it can be speculated that cervical input plays an important role in the process of vestibular compensation.

Twelfth-nerve palsy. Analysis of 100 cases

OBJECTIVE

To describe the causes and characteristics of hypoglossal nerve palsy.

DESIGN

A review of 26 years of personal experience in a large public hospital.

RESULTS

Twelfth-nerve palsies usually appear as signs rather than symptoms. Tumors, predominantly malignant, produced nearly half of the palsies (49 cases), while gunshot wounds made trauma (12) the second most common cause. Stroke (6), hysteria (6), multiple sclerosis (6), surgery (5), Guillain-Barré neuropathy (4), and infection (4) together accounted for about one third of the patients.

CONCLUSION

Twelfth-nerve palsy proved to be an ominous sign, with only 15% of patients experiencing complete or nearly complete recovery.