Gamma Knife surgery for schwannomas originating from cranial nerves III, IV, and VI

Successful surgical treatment of oculomotor palsy due to schwannoma of the cavernous sinus in a 7-year-old girl: a case report

Oculomotor nerve schwannoma in children not associated with neurofibromatosis is a rare disease, with 26 pediatric cases reported so far. There is no established treatment plan. A 7-year-old girl presented with oculomotor nerve palsy. Surgical reduction of the tumor combined with postoperative gamma knife surgery preserved the oculomotor nerve, improved oculomotor nerve function, and achieved tumor control during the observation period of 20 months. The combination of partial surgical resection and gamma knife surgery as a treatment strategy for oculomotor nerve schwannoma resulted in a good outcome.

Imaging of trochlear nerve schwannomas: a case series and systematic review of the literature

Purpose Trochlear nerve schwannomas are rare tumors. So far, only 121 cases have been published. We present four new cases, discuss the imaging characteristics and summarize all previously published cases through a systematic review.Methods Four cases, all treated in AZ Sint-Jan Hospital Brugge-Oostende (Belgium), were collected, including their demographic, clinical and radiological data. All MR imaging was performed with the three-dimensional fluid-attenuated inversion recovery (3D-FLAIR), turbo spin echo T1 high-resolution (TSE T1 HR), three-dimensional balanced fast-field echo (3D b-FFE) and three-dimensional T1 black blood (3D T1 black blood) sequence. We compared our findings with the present literature through a systematic literature review in accordance with the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines.Results Screening with routine unenhanced 3D-FLAIR imaging could identify all schwannomas as hyperintense lesions on the course of the trochlear nerve. The use of 3D T1 black blood sequences was superior in depicting the lesions, while high-resolution 3D b-FFE images enabled us to visualize the anatomic boundaries of the lesions in detail. Most trochlear schwannomas are located in the ambient cistern, at or just below the free edge of the tentorium.Conclusion The majority of trochlear nerve schwannomas are located cisternal and display variable enhancement on contrast administration. 3D-FLAIR imaging is superior in detecting these lesions. Comparison with data collected from previous cases demonstrates the importance of early diagnosis and treatment. Generally, patients with trochlear nerve schwannomas have a good prognosis.

Diagnostic and Therapeutic Strategy for Vagal Schwannoma: Case Series and Literature Review

Background and Objectives: Clinical management of vagal schwannoma is a real diagnostic and therapeutic challenge because the medical history and clinical examination are often non-specific and vagal nerve injury following surgical resection still represents an unsolved problem. The aim of this paper is to provide a case series along with a diagnostic and therapeutic algorithm for vagal schwannoma of the head and neck, combining our experience with clinical evidence available in the literature. Materials and Methods: We retrospectively analyzed a series of patients affected by vagal schwannoma who were treated between 2000 and 2020. In addition, a review of the literature on vagal schwannoma management was conducted. Based on the cases described and the literature review, we made a diagnostic and therapeutic algorithm for the management of vagal schwannoma. Results: We were able to identify 10 patients affected by vagal schwannoma and treated between 2000 and 2020. All patients presented with a painless, mobile, slow-growing lateral neck mass with onset varying from a few months to years. The preoperative diagnostic workup included ultrasound (US) in nine cases, computed tomography (CT) with contrast in six patients and magnetic resonance imaging (MRI) of the neck in seven cases. All patients included in this study were surgically treated. Conclusions: Vagal schwannoma management represents a true challenge for clinicians and surgery is currently the most effective therapeutic strategy. A multidisciplinary approach through the collaboration of otolaryngologist with other specialists is desirable to develop a tailored treatment plan for the patient.

A Sporadic Cisternal Cystic Oculomotor Schwannoma-Case Report and Review of Literature

Schwannoma arising from a pure motor cranial nerve in sporadic cases is a rare finding. We report adult female patient presented with a seizure without oculomotor palsy. On evaluation, she was diagnosed with cystic oculomotor schwannoma and underwent surgery. She developed oculomotor palsy postoperatively. Here, we describe a rare sporadic cystic oculomotor schwannoma.

Schwannoma-associated third nerve palsy: A pediatric case report

Acquired third nerve palsies are infrequently seen in children, but are often associated with serious pathologies. This article presents a pediatric case of tumor-associated, isolated third nerve palsy, which took two years to diagnose. The patient initially presented with an isolated, dilated pupil and progressed over several months to a complete third nerve palsy. In this case, high-resolution neuroimaging eventually led to the diagnosis of a presumed schwannoma as the cause of her third nerve palsy. We review her case, the importance of high-resolution imaging, and management options.

Cisternal oculomotor schwannoma: a rare cause of anisocoria with ptosis in a child

Background

Primary nerve sheath tumor of cranial nerve is a rare intracranial space occupying lesion that most commonly involves vestibular nerve. Oculomotor nerve schwannoma, without neurofibromatosis, is an extremely uncommon entity especially in children. Though any cranial nerve can be involved by schwannoma except I and II nerve as these cranial nerves lack a Schwann cell sheath.

Case presentation

We herein report a 14-year-old boy presenting with an oculomotor schwannoma in the absence of features of neurofibromatosis, manifesting as progressive diplopia, ptosis, and blurring of vision.

Conclusions

Most similar previous case reports in literature reported oculomotor schwannoma in adults, unlike our case. The detection rate of such rare lesions has, however, increased in the last two decades due to neuroimaging advances.

Management of non-vestibular schwannomas in adult patients: a systematic review and consensus statement on behalf of the EANS skull base section. Part I: oculomotor and other rare non-vestibular schwannomas (I, II, III, IV, VI)

BACKGROUND

Non-vestibular schwannomas are relatively rare, with trigeminal and jugular foramen schwannomas being the most common. This is a heterogeneous group which requires detailed investigation and careful consideration to management strategy. The optimal management for these tumours remains unclear, and there are several controversies. The aim of this paper is to provide insight into the main principles defining management and surgical strategy, in order to formulate a series of recommendations.

METHODS

A task force was created by the EANS skull base section along with its members and other renowned experts in the field to generate recommendations for the surgical management of these tumours on a European perspective. To achieve this, the task force performed an extensive systematic review in this field and had discussions within the group. This article is the first of a three-part series describing non-vestibular schwannomas (I, II, III, IV, VI).

RESULTS

A summary of literature evidence was proposed after discussion within the EANS skull base section. The constituted task force dealt with the practice patterns that exist with respect to pre-operative radiological investigations, ophthalmological assessments, optimal surgical and radiotherapy strategies and follow-up management.

CONCLUSION

This article represents the consensually derived opinion of the task force with respect to the treatment of non-vestibular schwannomas. For each of these tumours, the management of these patients is complex, and for those which are symptomatic tumours, the paradigm is shifting towards the compromise between function preservation and progression-free survival.

Less common extracerebral tumors

This chapter examines the results of GKNS on a variety of extraparenchymal skull base tumors some benign and some malignant. For the benign tumors there is good evidence on the effectiveness of the method for pretty much all diagnoses. For malignant extraparenchymal tumors the results are more limited and GKNS only has a supportive role in these lesions.

Oculomotor nerve schwannoma: case series and literature review

Oculomotor nerve schwannomas are rare benign cranial nerve tumors. There are only a limited number of reports on this pathology in the literature, and there are currently no established management guidelines that aid providers in deciding on surgical versus nonsurgical management. We assess the published literature on the topic to identify indications for treatment as well as outcome measures (e.g., local control rates, survival rates, and complication rates) that have been reported as associated with the various treatment modalities. We attempt to develop an algorithm for evaluation and treatment of oculomotor nerve schwannomas in order to establish consensus on how these tumors should be treated.

Ice Pack Test Eased Ptosis in a Patient Presenting with a Possible Oculomotor Nerve Schwannoma: A Case Report

A 32-year-old man presented with complete third nerve palsy. Brain magnetic resonance imaging revealed a possible sporadic oculomotor nerve schwannoma in the left cavernous sinus. Interestingly, the patient’s ptosis was fluctuating and eased immediately after application of ice over his eyelid. The ice pack test (IPT) is a simple and fast method that can help diagnose myasthenia gravis (MG) in patients with ptosis. Additional diagnostic investigations (antibody assays and repetitive stimulation) excluded associated MG in the patient. Tumor treatment with Gamma Knife radiosurgery was planned. This case highlights the finding that IPT can also be positive in neurogenic (non-myasthenic) ptosis, but its usefulness in other disorders associated with muscle weakness and fatigability remains questionable.

Outcomes after stereotactic radiosurgery for schwannomas of the oculomotor, trochlear, and abducens nerves

OBJECTIVE

Cranial nerve (CN) schwannomas are intracranial tumors that are commonly managed by stereotactic radiosurgery (SRS). There is a large body of literature supporting the use of SRS for vestibular schwannomas. Schwannomas of the oculomotor nerves (CNs III, IV, and VI) are rare skull base tumors, occurring close to the brainstem and often involving the cavernous sinus. Resection can cause significant morbidity, including loss of nerve function. As for other schwannomas, SRS can be used to manage these tumors, but only a handful of cases have been published so far, often among reports of other uncommon schwannoma locations.

METHODS

The goal of this study was to collect retrospective multicenter data on tumor control, clinical evolution, and morbidity after SRS. This study was performed through the International Radiosurgery Research Foundation. Patients managed with single-session SRS for an oculomotor cranial nerve schwannoma (CN III, IV, or VI) were included. The diagnosis was based on diplopia or ptosis as the main presenting symptom and anatomical location on the trajectory of the presumed cranial nerve of origin, or prior resection confirming diagnosis. Demographic, SRS dose planning, clinical, and imaging data were collected from chart review of the treated patients. Chi-square and Kaplan-Meier analyses were performed.

RESULTS

Seven institutions submitted data for a total of 25 patients. The median follow-up time was 41 months. The median age at the time of treatment was 52 years. There were 11 CN III schwannomas, 11 CN IV schwannomas, and 3 CN VI schwannomas. The median target volume was 0.74 cm3, and the median marginal dose delivered was 12.5 Gy. After SRS, only 2 patients (including the only patient with neurofibromatosis type 2) had continued tumor growth. Crude local control was 92% (23/25), and the 10-year actuarial control was 86%. Diplopia improved in the majority of patients (11/21), and only 3 had worsening following SRS, 2 of whom also had worsened ptosis, both in the context of tumor progression.

CONCLUSIONS

SRS for schwannomas of the oculomotor, trochlear, and abducens nerves is effective and provides tumor control rates similar to those for other cranial nerve schwannomas. SRS allows improvement of diplopia in the majority of patients. SRS should therefore be considered as a first-line treatment option for oculomotor nerve schwannomas.

Abducens nerve schwannoma of the cavernous sinus: A case report and literature review

Background:

Schwannomas of the abducens nerve are a rare pathology and are encountered less within the cavernous sinus. We describe a case of sixth cranial nerve schwannoma, in the cavernous sinus.

Case Description:

A 50-year-old lady, presented with 2 years history of double vision and left facial numbness that started 6 months before presentation, found to have hyperintense lobulated mass at the left cavernous sinus extending into Meckel’s cave with bony remodeling on magnetic resonance imaging. She underwent left frontotemporal craniotomy, combined extra-intradural approach, gross total resection. She had a gradual recovery of the sixth cranial nerve function.

Conclusion:

Abducens nerve schwannoma of the cavernous sinus is a rare and challenging tumor. However amenable to surgical intervention with favorable neurological outcome.

Parasellar Schwannomas: Extradural vs Extra-Intradural Surgical Approach

BACKGROUND

Schwannomas of the parasellar region may arise from the trigeminal, oculomotor, trochlear, and abducens nerves.

OBJECTIVE

To define the tumor origin, location, and dural relationship (extradural vs extra-intradural vs cisternal) on preoperative magnetic resonance imaging (MRI), in order to plan the best surgical approach (purely extradural vs extra-intradural).

METHODS

Twenty-four patients with parasellar schwannomas who underwent surgery were retrospectively analyzed. Twenty arose from the trigeminal nerve (7 intracavernous and 13 within the Meckel's cave), 3 from the oculomotor nerve, and 1 from the abducens nerve. The preoperative identification of the tumor location (extradural vs extra-intradural vs cisternal) and the nerve of origin was defined on MR sequences. All patients were operated on through a pterional approach (extradural or extra-intradural route).

RESULTS

The tumor location was correctly defined on MRI in 22 out of 24 cases (92%) and the nerve of origin in 22 (92%). An extradural approach without intradural exploration was performed in all 5 intracavernous trigeminal schwannomas, in 11 out of 13 of the Meckel's cave, and in 2 schwannomas of the oculomotor nerve. Two schwannomas of the Meckel's cave with transgression of the medial dural wall, 1 of the oculomotor nerve, and the abducens nerve schwannoma required an extra-intradural approach. Complete tumor resection was obtained in 19 out of 24 cases (80%).

CONCLUSION

The pterional extradural approach is sufficient for Dolenc type I and II trigeminal schwannomas, excepting for those transgressing the inner dural layer. Schwannomas of the oculomotor and abducens nerves with cisternal location require an extradural-intradural approach.

Management of oculomotor nerve schwannoma: Systematic review of literature and illustrative case

Background:

Oculomotor nerve schwannoma (ONS) is an extremely rare intracranial benign tumor. Till date, there is no standard treatment of oculomotor schwannoma. Here, we present an illustrative case report of ONS, perform a systematic review of literature on surgically and radiosurgically treated cases and morbidity related to both treatment modalities.

Methods:

We performed a systematic review of literature for cases with ONS treated with surgery or radiosurgery using PubMed/Ovid Medline.

Results:

Till date, there are 60 reported cases of ONS (45 treated surgically and seven radiosurgically) with the dominance of female gender (53%) and mean age of 35.2 years (Range 1–66). In 8% of the cases, there was no involvement of cranial nerve (CN) III and 92% of the cases CN III alone or together with CN II, IV, V, and VI. In 67% of the cases a complete resection and 33% a partial resection performed. In 73% of the cases, postoperative third nerve palsy was documented, 22% improved after surgery and in around 5% of cases, the outcome was not described. In the radiosurgically treated cases of nonvestibular schwannoma including ONS, the progression-free interval of approximately 2 years was above 90%.

Conclusion:

Due to the high rate of postoperative complete oculomotor nerve palsy, a subtotal resection avoiding the nerve injury seems to be a feasible option. Radiosurgery is another option to treat small size schwannoma. A combined treatment with microsurgery followed by radiosurgery may allow effective treatment for large size oculomotor schwannoma.

Sporadic Cisternal Oculomotor Nerve Schwannoma: A Rare Case with Review of Literature

Cranial nerve schwannomas usually arise from sensory nerve and the occurrence of schwannoma in a motor nerve is rare, especially in sporadic cases. Oculomotor nerve schwannomas (ONS) are rare and they are unique as they arise from motor nerve. ONS palsy may or may not be the presenting feature of oculomotor schwannoma. We present the case of a young male with ONS, presenting with oculomotor nerve palsy along with features of raised intracranial pressure. Oculomotor schwannoma is described in literature only as case reports, and oculomotor nerve is also a rare site for schwannoma as being a motor nerve. In this article, we describe a case of cisternal ONS with review of pertinent literature.

Recurrent isolated oculomotor nerve palsy caused by schwannoma in a pediatric patient

Isolated schwannomas of motor nerves to extraocular muscles are uncommon. In addition, most previous studies on oculomotor nerve schwannoma discuss adult patients, and pediatric cases are rare. We report a 10-year-old girl who developed recurrent oculomotor nerve palsy caused by schwannoma without any vascular malformation. Although the incidence is rare in pediatric patient, the recurrent isolated oculomotor nerve palsy due to schwannoma can develop, and it should be considered in the differential diagnosis of ocular motility disorders in pediatric patients. Careful imaging evaluation is needed to identify schwannoma due to its small size, deep location in the brain, and rarity.

Radiosurgery in trochlear and abducens nerve schwannomas: case series and systematic review

INTRODUCTION

Schwannomas involving the occulomotor cranial nerves  (CNs; III, IV and VI), can be disabling, due to the associated diplopia and decreased quality of life and are extremely rare. We evaluated the role of Gamma Knife surgery (GKS) in these cases.

METHODS

Five patients with CN IV and VI schwannomas (three and two, respectively) were treated in Lausanne University Hospital between 2010 and 2015. Four benefitted from upfront GKS and one from a combined approach (planned subtotal resection followed by GKS), due to a large preoperative tumour volume (size, 3 × 2 × 2.5 cm; volume, 7.9 ml), with symptomatic mass effect and oedema, as well as an entrapement cyst at the brainstem interface, in a young patient. Neuro-ophtalmological evaluation was performed at baseline and during each follow-up time-point. A systematic literature review is presented and compared to the present report.

RESULTS

The mean follow-up was 44.4 months (12-54). Initial clinical presentation was diplopia in four cases and cavernous sinus syndrome in one. The marginal dose was 12 Gy in all cases. The mean target volume was 1.51 cm³ (0.086-5.8). The mean prescription isodose volume (PIV) was 1.71 cm³ (0.131-6.7). At last follow-up, all patients presented with disappearance of the baseline symptoms. Tumour control was achieved in 100%, with decrease in volume in all cases. The systematic review analysed 11 peer-reviewed studies, with a total of 35 patients. For uniformly reported CN VI, the mean marginal radiation dose ranged between 12 and 12.5 Gy, with disappearance of symptoms in 12.5%, improvement in 31.25%, stabilisation in 6.25%, worsening in 12.5%. Tumour volume decreased in all cases.

CONCLUSIONS

Our data suggest that first intention GKS is a safe and effective option for patients with small to medium size oculomotor schwannomas, providing a high rate of clinical alleviation and tumour control. When the initial tumour volume is too large for first intention GKS, a combined approach with planned subtotal resection followed by GKS can be performed, with favourable and comparable outcomes as in upfront GKS.

Schwannoma of the trochlear nerve-an illustrated case series and a systematic review of management

Schwannomas of cranial nerves in the absence of systemic neurofibromatosis are relatively rare. Among these, schwannomas of the trochlear nerve are even less common. They can be found incidentally or when they cause diplopia or other significant neurological deficits. Treatment options include observation only, neuro-ophthalmological intervention, and/or neurosurgical management via resection or sterotactic radiosurgery (SRS). In recent years, the latter has become an attractive therapeutic tool for a number of benign skull base neoplasm including a small number of reports on its successful use for trochlear Schwannomas. However, no treatment algorithm for the management of these tumors has been proposed so far. The goal of this manuscript is to illustrate a case series of this rare entity and to suggest a rational treatment algorithm for trochlear schwannomas, based on our institutional experience of recent cases, and a pertinent review of the literature. Including our series of 5 cases, a total of 85 cases reporting on the management of trochlear schwannomas have been published. Of those reported, less than half (40 %) of patients underwent surgical resection, whereas the remainder were managed conservatively or with SRS. Seventy-six percent (65/85) of the entire cohort presented with diplopia, which was the solitary symptom in over half of the cases (n = 39). All patients who presented with symptoms other than diplopia or headaches as solitary symptoms underwent surgical resection. Patients in the non-surgical group were mostly male (M/F = 3.5:1), presented at an older age and had shorter mean diameter (4.6 vs. 30.4 mm, p < 0.0001) when compared to the surgical group. Twelve patients in the entire cohort were treated with SRS, none of whom had undergone surgical resection before or after radiation treatment. Trochlear schwannoma patients without systemic neurofibromatosis are rare and infrequently reported in the literature. Of those, patients harboring symptomatic trochlear Schwannomas do not form a single homogenous group, but fall into two rather distinct subgroups regarding demographics and clinical characteristics. Among those patients in need of intervention, open microsurgical resection as well as less invasive treatment options exist, which all aim at safe relief of symptoms and prevention of progression. Both open microsurgical removal as well as SRS can achieve good long-term local control. Consequently, a tailored multidisciplinary treatment algorithm, based on the individual presentation and tumor configuration, is proposed.

Gamma Knife radiosurgery in the treatment of abducens nerve schwannomas: a retrospective study

OBJECTIVE Of the intracranial schwannomas, those arising from the vestibular nerves are the most common. Abducens nerve (AN) schwannomas are very rare, and there is limited literature on their optimal management. Therapeutic options include surgery and/or stereotactic radiosurgery. The aim of this study was to evaluate the role of Gamma Knife radiosurgery (GKRS) in these sixth cranial nerve (CN) schwannomas. METHODS The authors performed a retrospective analysis of patients who had undergone GKRS for intracranial tumors at their institute in the period from 2003 to 2010. Inclusion criteria were as follows: isolated AN paresis on presentation, a lesion along the course of the sixth CN, and imaging features characteristic of a schwannoma. Patients with other CN deficits and neurofibromatosis Type 2 were excluded. Symptomatic improvement was defined as the resolution of or an improvement in diplopia noted on a subjective basis or as an improvement in lateral eyeball excursion noted objectively on follow-up. A reduction in tumor volume by at least 20%, as noted by comparing the pre- and post-GKRS images, was deemed significant. RESULTS Six patients with a mean age of 37.1 years (range 17-55 years) underwent primary GKRS. There were 2 prepontine cistern, 3 cavernous sinus, and 1 cisterno-cavernous tumor. The mean duration of symptoms was 6.1 months (range 3-12 months). The mean tumor volume was 3.3 cm³ (range 1.5-4.8 cm³). The mean tumor margin radiation dose was 12.5 Gy (range 12-14 Gy), while the median margin dose was 12 Gy (50% isodose line). The median number of isocenters used was 5 (range 4-8). The brainstem received an average 8.35-Gy radiation dosage (range 5.5-11 Gy). The mean follow-up duration was 44.3 months (range 24-78 months). Symptoms remained stable in 1 patient, improved in 3, and resolved in 2 (total improvement 83%). Magnetic resonance imaging at the last follow-up showed a stable tumor size in 3 patients (50%) and a reduction in the other 3. Thus, the tumor control rate achieved was 100%. No new CN deficits were noted. CONCLUSIONS Abducens nerve schwannomas are rare intracranial tumors. They can be cavernous, cisternal, or cisterno-cavernous in location. Excellent tumor control rates and symptomatic improvement can be achieved with GKRS, which appears to be a safe and effective, minimally invasive modality for the treatment of such lesions. Therefore, it is reasonable to consider GKRS as the initial treatment of choice for this rare pathology. Long-term follow-up will be essential for further recommendations.

Trochlear Nerve Schwannoma Treated with Gamma Knife after Excision: A Case Report and Review of the Literature

Trochlear nerve schwannomas are extremely rare. We present a surgically excised case of trochlear nerve schwannoma followed by Gamma Knife (ELEKTA, Stockholm, Sweden) after histologic confirmation. A 52-year-old man presented with diplopia, gait disturbance, and sensory disturbance. Magnetic resonance imaging demonstrated a large cystic mass at ambient cistern on the right side. Subtotal excision followed by Gamma Knife surgery was undertaken. His neurologic symptoms disappeared with radiologic reduction in size at 15-month follow-up. Because Gamma Knife can manage trochlear nerve schwannomas well, surgical excision should be reserved for large ones and limited to subcapsular or subtotal removal with the expectation of possible recovery of neurologic dysfunction.

Oculomotor nerve schwannoma: a case report

Schwannomas account for about 8% of intracranial tumors and 90% are vestibular schwannomas. Oculomotor schwannoma without neurofibromatosis is extremely rare. A 41-year-old female presented with complaints of blurred vision, and the neurologic examination revealed afferent pupillary defect and decreased visual acuity of the left side. Brain magnetic resonance image showed an extra axial mass in the left superior orbital fissure. The patient underwent major surgery via the fronto-temporal approach. The tumor originated from the oculomotor nerve and was subtotally removed under microscopic surgery. The pathological findings confirmed the tumor as a schwannoma. After surgery, ptosis and medial gaze limitation of the left eye was detected, but the symptoms improved gradually.

Management of oculomotor nerve schwannomas in two different locations: surgical nuances and comprehensive review

Rare tumors with anecdotal reportage, oculomotor schwannomas are most often seen in the oculomotor cistern close to the anterior clinoidal region. Adding to the small series of reported cases of this unusual lesion, we report two male patients in their second decade who presented with different degrees of oculomotor palsy. The location of the lesion was caverno-cisternal in one case and orbito-cavernous in the other. Intricate neurovascular relationships of this lesion, especially in non-cavernous locations, are discussed. The risk of damage to nerve rootlets enmeshed within the lesion is high with attempts at near-total excision, rendering the anatomical preservation of the nerve an arduous exercise. The authors review literature pertaining to this unusual lesion and elucidate surgical nuances which may have a bearing on outcome.

Long-term control of petroclival meningiomas through radiosurgery

OBJECT

Because of their critical location adjacent to brain, cranial nerve, and vascular structures, petroclival meningiomas remain a clinical challenge. The authors evaluated outcomes in 168 patients with petroclival meningiomas who underwent Gamma Knife surgery (GKS) during a 21-year interval.

METHODS

Gamma Knife surgery was used as either primary or adjuvant treatment of 168 petroclival meningiomas involving the region between the petrous apex and the upper two-thirds of the clivus. The most common presenting symptoms were trigeminal nerve dysfunction, balance problems, diplopia, and hearing loss. The median tumor volume was 6.1 cm3 (range 0.3-32.5 cm3), and the median radiation dose to the tumor margin was 13 Gy (range 9-18 Gy).

RESULTS

During a median follow-up of 72 months, neurological status improved in 44 patients (26%), remained stable in 98 (58%), and worsened in 26 (15%). Tumor volume decreased in 78 patients (46%), remained stable in 74 (44%), and increased in 16 (10%), all of whom were subjected to additional management strategies. Overall 5- and 10-year progression-free survival rates were 91 and 86%, respectively. Patients followed up for at least 10 years (31 patients) had tumor and symptom control rates of 97 and 94%, respectively. Eight patients had repeat radiosurgery, 4 underwent delayed resection, and 4 had fractionated radiation therapy. Cerebrospinal fluid diversion was performed in 7 patients (4%). Significant risk factors for tumor progression were a tumor volume > or = 8 cm3 (p = 0.001) and male sex (p = 0.02).

CONCLUSIONS

In this 21-year experience, GKS for petroclival meningiomas obviated initial or further resection in 98% of patients and was associated with a low risk of adverse radiation effects. The authors believe that radiosurgery should be considered as an initial option for patients with smaller-volume, symptomatic petroclival meningiomas.