Trigeminal neuroma: analysis of surgical experience with 73 cases

Multimodality Management of Trigeminal Schwannomas

Patients presenting with trigeminal schwannomas require multimodality management by a skull base surgical team that can offer expertise in both transcranial and transnasal approaches as well as radiosurgical and microsurgical strategies. Improvement in neurologic symptoms, preservation of cranial nerve function, and control of mass effect are the primary goals of management for trigeminal schwannomas. Complete surgical resection is the treatment of choice but may not be possible in all cases. Radiosurgery is an option as primary management for small- to moderate-sized tumors and can be used for postoperative residuals or recurrences. Planned surgical resection followed by SRS for residual tumor is an effective option for larger trigeminal schwannomas. The endoscopic resection is an excellent approach for patients with an extradural tumor or tumors isolated to the Meckel cave. A detailed analysis of a tumor and its surroundings based on high-quality imaging can help better estimate the expected outcome from each treatment. An expert skull base team should be able to provide precise counseling for each patient's situation for selecting the best option.

Rare case of radiation-induced trigeminal schwannoma occurring in a long-term glioblastoma multiforme survivor

Glioblastoma multiforme (GBM) is a high-grade primary brain tumour with a notably poor prognosis. Research demonstrates a median survival of just over 1 year following aggressive treatment. Long-term survival is notably rare. Cranial radiotherapy and postexcisional prophylactic treatment is associated with the development of second, histologically distinct tumours in rare cases. Radiation-induced intracranial schwannomas are uncommon, with only a small number of cranial nerve schwannoma cases reported in recent decades. To our knowledge, this is the first reported case of a radiation-induced benign trigeminal schwannoma occurring following long-term survival from glioblastoma. Here we present (1) a rare case of 14-year survival following treatment of a right parietal glioblastoma and the development of a radiation-induced benign trigeminal schwannoma in a 35-year-old man, and (2) a review of radiation-induced schwannoma cases reported in the existing literature.

Identification of cranial nerves around trigeminal schwannomas using diffusion tensor tractography: a technical note and report of 3 cases

BACKGROUND

There are no large series studies identifying the locations of cranial nerves (CNs) around trigeminal schwannomas (TSs); however, surgically induced cranial neuropathies are commonly observed after surgeries to remove TSs. In this study, we preoperatively identified the location of CNs near TSs using diffusion tensor tractography (DTT).

METHODS

An observational study of the DTT results and intraoperative findings was performed. We preoperatively completed tractography from images of patients with TSs who received surgical therapy. The result was later validated during tumorectomy.

RESULTS

A total of three consecutive patients were involved in this study. The locations of CNs V-VIII in relation to the tumor was clearly revealed in all cases, except for CN VI in case 3.The predicted fiber tracts were in agreement with intraoperative observations.

CONCLUSIONS

In this study, preoperative DTT accurately predicted the location of the majority of the nerves of interest. This technique can be applied by surgeons to preoperatively visualize nerve arrangements.

Surgical management of trigeminal schwannomas: defining the role for endoscopic endonasal approaches

OBJECT

Because multiple anatomical compartments are involved, the surgical management of trigeminal schwannomas requires a spectrum of cranial base approaches. The endoscopic endonasal approach to Meckel's cave provides a minimal access corridor for surgery, but few reports have assessed outcomes of the procedure or provided guidelines for case selection.

METHODS

A prospectively acquired database of 680 endoscopic endonasal cases was queried for trigeminal schwannoma cases. Clinical charts, radiographic images, and long-term outcomes were reviewed to determine outcome and success in removing tumor from each compartment traversed by the trigeminal nerve.

RESULTS

Four patients had undergone endoscopic resection of trigeminal schwannomas via the transpterygoid approach (mean follow-up 37 months). All patients had disease within Meckel's cave, and 1 patient had extension into the posterior fossa. Gross-total resection was achieved in 3 patients whose tumors were purely extracranial. One patient with combined Meckel's cave and posterior fossa tumor had complete resection of the extracranial disease and 52% resection of the posterior fossa disease. One patient with posterior fossa disease experienced a sixth cranial nerve palsy in addition to a corneal keratopathy from worsened trigeminal neuropathy. There were no CSF leaks. Over the course of the study, 1 patient with subtotal resection required subsequent stereotactic radiosurgery for disease progression within the posterior fossa.

CONCLUSIONS

Endoscopic endonasal approaches appear to be well suited for trigeminal schwannomas restricted to Meckel's cave and/or extracranial segments of the nerve. Lateral transcranial skull base approaches should be considered for patients with posterior fossa disease. Further multiinstitutional studies will be necessary for adequate power to help determine relative indications between endoscopic and transcranial skull base approaches.

Endoscopic Endonasal Resection of Trigeminal Schwannomas

The surgical management of trigeminal schwannomas (TNs) entails the use of a variety of cranial base approaches for their effective surgical management. Although an extended middle fossa or posterior petrosal approach may be more appropriate for disease with primarily posterior fossa involvement, the expanded endoscopic approaches are suited for tumors with predominately middle fossa and/or extracranial involvement along the V2 and V3 divisions and limited posterior fossa extension. The endoscopic endonasal resection of TNs within the middle fossa, pterygopalatine fossa, and infratemporal fossa is reviewed in this article with a brief discussion of reported outcomes.

Orbital extension of trigeminal schwannoma

Schwannomas, also known as neurilemmomas, are benign peripheral nerve sheath tumors. Trigeminal schwannomas are rare intracranial tumors. Here, we report a 35-year-old female presenting with an axial proptosis of right eyeball with right-sided III, IV and VI cranial nerve palsy. Her best corrected visual acuity in the right eye was perception of light absent and in the left eye was 20/20. MRI scan revealed a large right-sided heterogeneous, extra-axial middle cranial fossa mass that extended to the intraconal space of right orbit. A diagnosis of intracranial trigeminal nerve schwannoma with right orbital extension was made. Successful surgical excision of the mass with preservation of the surrounding tissues and orbital exenteration was done. Post-operative period was uneventful.

A suggestion of modified classification of trigeminal schwannomas according to location, shape, and extension

Background

Comprehensive knowledge of the anatomical features of trigeminal schwannomas (TSs) is essential in planning surgery to achieve complete tumor resection. In the current report, we propose a modified classification of TSs according to their location of origin, shape, and extension into the adjacent compartment, and discuss appropriate surgical strategies with this classification.

Methods

We retrospectively analyzed 49 patients with TS who were treated surgically by a single neurosurgeon at the Asan Medical Center between 1993 and 2013.

Results

There were 22 males and 27 females, with the median age of 40 years (range, 21-75 years). Median tumor size was 4.0 cm in diameter (2.0-7.0 cm). Tumors were classified as follows: Type M (confined to the middle fossa; 8 cases, 19.0%), P (confined to the posterior fossa; 2 cases, 4.8%), MP (involving equally both middle and posterior fossae; 5 cases, 11.9%), Mp (predominantly middle fossa with posterior fossa extension; 6 cases, 14.3%), Pm (predominantly posterior fossa with middle fossa extension; 16 cases, 38.1%), Me (predominantly middle fossa with extracranial extension; 4 cases, 9.5%). Surgical approach was chosen depending on the tumor classification. More specifically, a frontotemporal craniotomy and extradural approach with or without zygomatic or orbitozygomatic osteotomy was applied to M- or Mp-type tumors; a lateral suboccipital craniotomy with or without suprameatal approach was applied to the majority of P- or Pm-type tumors; and a posterior transpetrosal approach was used in four tumors (three Pm and one MP). Gross total resection was achieved in 95.9% of patients, and the overall recurrence rate was 4.1% (2 patients). Postoperatively, trigeminal symptoms were improved or unchanged in 51.0% of cases (25 patients). Surgical complications included meningitis (5 patients) and cerebrospinal fluid leakage (3 patients). There was no mortality.

Conclusion

TSs are well to be classified with our modified classification and able to be removed effectively and safely by selecting appropriate surgical approaches.

Intracranial nonvestibular neurinomas: Young neurosurgeons' experience

BACKGROUND AND OBJECTIVES

Neurinoma arising from other than nonvestibular cranial nerves is less prevalent. Here we present our experiences regarding the clinical profile, investigations, microneurosurgical management, and the outcome of nonvestibular cranial nerve neurinomas.

MATERIALS AND METHODS

From January 2005 to December 2011, the recorded documents of operated nonvestibular intracranial neurinomas were retrospectively studied for clinical profile, investigations, microneurosurgical management, complications, follow-up, and outcomes.

RESULTS

The average follow-up was 24.5 months. Total number of cases was 30, with age ranging from 9 to 60 years. Sixteen cases were males and 14 were females. Nonvestibular cranial nerve schwannomas most commonly originated from trigeminal nerve followed by glossopharyngeal+/vagus nerve. There were three abducent nerve schwannomas that are very rare. There was no trochlear nerve schwannoma. Two glossopharyngeal+/vagus nerve schwannomas extended into the neck through jugular foramen and one extended into the upper cervical spinal canal. Involved nerve dysfunction was a common clinical feature except in trigeminal neurinomas where facial pain was a common feature. Aiming for no new neurodeficit, total resection of the tumor was done in 24 cases, and near-total resection or gross total resection or subtotal resection was done in 6 cases. Preoperative symptoms improved or disappeared in 25 cases. New persistent deficit occurred in 3 cases. Two patients died postoperatively. There was no recurrence of tumor till the last follow-up.

CONCLUSION

Nonvestibular schwannomas are far less common, but curable benign lesions. Surgical approach to the skull base and craniovertebral junction is a often complex and lengthy procedure associated with chances of significant morbidity. But early diagnosis, proper investigations, and evaluation, along with appropriate decision making and surgical planning with microsurgical techniques are the essential factors that can result in optimum outcome.

Endoscope-Assisted Retrosigmoid Intradural Suprameatal Approach for Surgical Treatment of Trigeminal Schwannomas

BACKGROUND:

Trigeminal schwannomas are the most common intracranial nonvestibular schwannomas, and the dumbbell-shaped subtype is the most challenging.

OBJECTIVE:

To evaluate the efficiency and safety of the endoscope-assisted retrosigmoid intradural suprameatal approach (EA-RISA) for dumbbell trigeminal schwannomas and to compare EA-RISA with classic RISA.

METHODS:

A retrospective study of all patients with trigeminal schwannomas was performed with a focus on dumbbell tumors. Tumors were classified according to a modified Samii classification. Extent of tumor removal, outcome, and morbidity rates in the 2 subgroups were compared.

RESULTS:

Twenty patients were enrolled: 8 had dumbbell-shaped tumors (type C1), 8 had middle fossa tumors (A1-3), 3 had extracranial extension (D2), and 1 had posterior fossa tumor. Gross total resection was achieved in 15 and near-total resection in 5 patients. In 4 patients with dumbbell tumors, the classic RISA (Samii approach) was used; EA-RISA was used in the other 4 patients. The extent of petrous apex drilling was determined individually on the basis of the anatomic variability of suprameatal tubercle and degree of tumor-induced petrous apex erosion; in 2 patients, only minimal drilling was needed. The endoscope was applied after microsurgical tumor removal and in 3 of 4 patients revealed a significant unrecognized tumor remnant in the anterolateral and superolateral aspects of the Meckel cave. Thus, the EA-RISA technique allowed gross total resection of the tumor.

CONCLUSION:

The EA-RISA enlarges the exposure obtained with the classic RISA. Its judicious use can help achieve safe and radical removal of dumbbell-shaped trigeminal schwannomas (C1 type).

Trigeminal schwannoma extending into the parapharyngeal space

Parapharyngeal space tumors are very rarely seen, and surgical approach to these tumors has not been well established. Most of these tumors are benign and originated from salivary glands and neurogenic in nature. In this case, we report a patient who has a trigeminal schwannoma extending into the deep parapharyngeal space and explain our surgical approach.

Operative management of trigeminal neuromas: an analysis of a surgical experience with 55 cases

BACKGROUND

The trigeminal schwannoma is the second most common intracranial schwannoma. Their proximity to the critical skull base neural and vascular structures increases the complexity of surgical treatment. The aim of this study was to better understand the surgical approaches and the prognosis, as well as to assess the optimum therapeutic schedule.

METHODS

This was a retrospective study of 55 patients with trigeminal schwannomas who visited our department between Jan 2007 and Jan 2012. We analyzed the clinical and radiological presentation, tumor characteristics, surgical approaches, the prognosis.

RESULTS

The patients were 30 women and 25 men of mean age 36 years (range, 6-66 years) who received postoperative neurological and neuroradiological follow-up. The tumor was located in the middle fossa (type A) in 13 cases, in the posterior fossa (type B) in ten cases, in the middle and posterior fossae (type C) in 21 cases, and in the branches of the trigeminal nerve (type D) in 11 cases. The most common symptom was facial hypesthesia or numbness in 36 patients (65 %) . Total and nearly total tumor resection was achieved in 51 cases (93 %). Three patients (5 %) had worsening of preexisting deficits and there was no perioperative mortality. With an average follow-up period of 35 months, facial hypesthesia persisted in 26 patients (72 %),and improved in ten patients (28 %). Facial pain was relieved in 11 patients (100 %). There has been a recurrence in one case (2 %) and all patients resumed independent and social reintegration.

CONCLUSION

This study demonstrates radical surgery with excellent neurological outcomes is the primary treatment of trigeminal schwannomas. Appropriate selection of surgical approach according to tumor types is highly important and necessary. The preoperative facial pain could be relieved, hypesthesia frequently remains or could even be worsened after surgery.

Anatomical study on Meckel cave with endoscopic endonasal, endo-maxillary sinus, and endo-pterygoid process approaches

Objective

To study anatomical structures related to Meckel cave with endonasal endoscopic approach and to provide an anatomical basis for endoscopic surgery in Meckel cave.

Methods

Meckel cave of 5 adult skulls (10 sides) were fixed with 10% formalin. The anatomical structures of Meckel cave and the related zones adjacent to Meckel cave were observed and measured with endoscopic endonasal approach.

Results

Endoscopic endonasal, endo-maxillary sinus, and endo-pterygoid process approaches were successfully applied in observation of the anatomical structures of meckel cave and the rerated zones adjacent to Meckel cave and in measurement of distances between related anatomical structures for each case of samples. The relevant data were obtained. The distance between the front mouth of palatovaginal canal and vidian canal was 21.4±7 mm, the distance between opening of sphenoid sinus to the upper margin of the choana was 22.3±2.8 mm, the distance between the opening of vidian and foramen rotundum was 7.57±0.7 mm and the length of the pterygoid canal was 13.3±1.2 mm. Based on these data, the positions of the related important structures can be roughly located during surgical operation and various important structures in Meckel cave and its adjacent zones can be found out in a convenient and safe way.

Conclusion

1) It is feasible to use endonasal endoscopic approach to perform surgical operation in Meckel cave; 2) Use of endonasal endoscopic approach can protect and fully take the advantage of the vidian nerve to locate the position of foramina lacerum of the internal carotid artery during surgical operation; and 3) the observational and experimental data obtained with this approach can provide the rational basis for clinical operation procedures.

Long-term results for trigeminal schwannomas treated with gamma knife surgery

PURPOSE

Surgical resection is considered the desirable curative treatment for trigeminal schwannomas. However, complete resection without any complications remains challenging. During the last several decades, stereotactic radiosurgery (SRS) has emerged as a minimally invasive treatment modality. Information regarding long-term outcomes of SRS for patients harboring trigeminal schwannomas is limited because of the rarity of this tumor. The aim of this study was to evaluate long-term tumor control and functional outcomes in patients harboring trigeminal schwannomas treated with SRS, specifically with gamma knife surgery (GKS).

METHODS AND MATERIALS

Fifty-three patients harboring trigeminal schwannomas treated with GKS were evaluated. Of these, 2 patients (4%) had partial irradiation of the tumor, and 34 patients (64%) underwent GKS as the initial treatment. The median tumor volume was 6.0 cm(3). The median maximum and marginal doses were 28 Gy and 14 Gy, respectively.

RESULTS

The median follow-up period was 98 months. On the last follow-up image, 7 patients (13%) had tumor enlargement, including the 2 patients who had partial treatment. Excluding the 2 patients who had partial treatment, the actuarial 5- and 10-year progression-free survival (PFS) rates were 90% and 82%, respectively. Patients with tumors compressing the brainstem with deviation of the fourth ventricle had significantly lower PFS rates. If those patients with tumors compressing the brainstem with deviation of the fourth ventricle are excluded, the actuarial 5- and 10-year PFS rates increased to 95% and 90%, respectively. Ten percent of patients had worsened facial numbness or pain in spite of no tumor progression, indicating adverse radiation effect.

CONCLUSIONS

GKS can be an acceptable alternative to surgical resection in patients with trigeminal schwannomas. However, large tumors that compress the brainstem with deviation of the fourth ventricle should be surgically removed first and then treated with GKS when necessary.

Endoscopic approach to the trigeminal nerve: an anatomic study

OBJECTIVE

To describe an endoscopic perspective of the surgical anatomy of the trigeminal nerve.

METHODS

Nine adult cadaveric heads were dissected endoscopically.

RESULTS

Opening the pterygopalatine fossa is important because many key anatomical structures (V2, pterygopalatine ganglion, vidian nerve) can be identified and traced to other areas of the trigeminal nerve. From the pterygopalatine ganglion, the maxillary nerve and vidian nerve can be identified, and they can be traced to the gasserian ganglion and internal carotid artery. An anteromedial maxillectomy increases the angle of approach from the contralateral nares due to an increase in diameter of the piriform aperture, and provides excellent access to the mandibular nerve, the petrous carotid, and the cochlea.

CONCLUSIONS

Identification of key anatomical structures in the pterygopalatine fossa can be used to identify other areas of the trigeminal nerve, and an anteromedial maxillectomy is necessary to expose the ipsilateral mandibular nerve and contralateral cranial level of the trigeminal nerve.

Stereotactic radiosurgery for trigeminal schwannoma: a clinical retrospective study in 52 cases

OBJECTIVE

To evaluate the radiological and clinical outcomes in a series of patients in whom stereotactic radiosurgery (SRS) was used to treat trigeminal schwannomas.

METHODS

The records of 52 patients who underwent SRS for trigeminal schwannoma were reviewed using a retrospective study. The median patient age was 47.1 years (range, 18-77); 20 patients (38.5%) had undergone prior tumor resection and 32 (61.5%) underwent radiosurgery on the basis of imaging diagnosis only. The most frequent presenting symptoms were facial numbness (29 patients), jaw weakness (11 patients), facial pain (10 patients) and diplopia (4 patients). Fifty-two cases with solid tumors were mainly solid in 44 cases (84.6%), mostly cystic in 2 cases (3.8%), and cystic and solid mixed in 6 cases (11.5%). Two cases of mostly cystic tumor first underwent stereotactic cystic fluid aspiration and intracavitary irradiation, and then had MRI localization scan again for gamma knife treatment. The mean tumor volume was 7.2 ml (range, 0.5-38.2). The mean prescription radiation dose was 13.9 Gy (range, 11-17), and the mean prescription isodose configuration was 47.9%.

RESULTS

At a mean follow-up of 61 months (range, 12-156), neurological symptoms or signs improved in 35 patients (67.3%), 14 patients (26.9%) had a stable lesion, and worsening of the disease occurred in 2 patients (3.8%). On imaging, the schwannomas almost disappeared in 8 (15.4%), shrank in 32 (61.5%), remained stable in 5 (9.6%), and increased in size in 7 patients (13.5%). Tumor growth control was achieved in 45 (86.5%) of the 52 patients.

CONCLUSIONS

SRS is an effective and minimally invasive management option for patients with residual or newly diagnosed trigeminal schwannomas. The use of SRS to treat trigeminal schwannomas resulted in good tumor control and functional improvement.

Endoscopic approaches to the trigeminal nerve and clinical consideration for trigeminal schwannomas: a cadaveric study

Object

The course of the trigeminal nerve straddles multiple fossae and is known to be very complex. Comprehensive anatomical knowledge and skull base techniques are required for surgical management of trigeminal schwannomas. The aims of this study were to become familiar with the endoscopic anatomy of the trigeminal nerve and to develop a minimally invasive surgical strategy for the treatment of trigeminal schwannomas.

Methods

Ten fresh cadavers were studied using 5 endoscopic approaches with the aid of 4-mm 0° and 30° endoscopes to identify surgical landmarks associated with the trigeminal nerve. The endoscopic approaches included 3 transcranial keyhole approaches (the extradural supraorbital, extradural subtemporal, and retrosigmoid approaches), and 2 endonasal approaches (the transpterygoid and the transmaxillary transpterygoid approaches).

Results

The trajectories of the extradural supraorbital, transpterygoid, and extradural subtemporal approaches corresponded with the course of the first, second, and third divisions of the trigeminal nerve, respectively. The 3 approaches demonstrated each division in intra- and extracranial spaces, as well as the Meckel cave in the middle cranial fossa. The interdural space at the lateral wall of the cavernous sinus was exposed by the extradural supraorbital and subtemporal approaches. The extradural subtemporal approach with anterior petrosectomy and the retrosigmoid approach visualized the trigeminal sensory root and its neighboring neurovascular structures in the posterior cranial fossa. The transmaxillary transpterygoid approach revealed the course of the third division in the infratemporal fossa.

Conclusions

The 5 endoscopic approaches effectively followed the course of the trigeminal nerve with minimal invasiveness. These approaches could provide alternative options for the management of trigeminal schwannoma.

Multicompartmental trigeminal schwannomas: management strategies and outcome

Trigeminal schwannomas (TS), though the second most common intracranial schwannomas, represent only 0.8 to 8% of all Schwannomas. Advancement in imaging and microsurgical techniques has led to a remarkable improvement in the outcome of these benign tumors. Multicompartmental TS, though extensive, have an excellent outcome after surgery. In this article, we present our experience in the management of multicompartmental TS (types middle/posterior [MP], middle/extracranial [ME], and middle/posterior and extracranial [MPE]) and outcome in this rather uncommon group of tumors. This retrospective study included all the cases of multicompartmental TS operated at our institute from 1999 to 2009. The medical data were analyzed retrospectively. The demographic profile, clinical features, radiological findings, management strategies, postoperative complications, length of hospitalization, and outcome were noted. Follow-up data were collected from outpatient department records. The range and average duration of follow-up were noted. There were a total of 43 patients with TS operated over this period. Among them, 4 were type B, 5 type C, 11 type D, 18 type E, and 5 type F. The study included 26 patients (4 type B, 18 type E, and 4 type B). A variety of approaches were used to approach the tumor. Of 26, 23 patients had a gross total or near-total excision while 2 patients were lost to follow-up. Among the three patients who had a near-total excision and follow-up magnetic resonance imaging showed a small residual tumor, two are on close follow-up with no increase in the size of the tumor over a follow-up period of 3 years, the other patient is a 5-year-old boy who is too young for radiosurgery and is on follow-up. There was no mortality while four patients have had fresh permanent postoperative deficits. Multicompartmental TS are a rare, complex but eminently treatable group of tumors. A variety of surgical approaches can be used to excise the tumor. The choice of approach needs to be individualized with total excision providing excellent results.

Endoscopic endonasal approach for nonvestibular schwannomas

BACKGROUND

Nonvestibular schwannomas of the skull base often represent a challenge owing to their anatomic location. With improved techniques in endoscopic endonasal skull base surgery, resection of various ventral skull base tumors, including schwannomas, has become possible.

OBJECTIVE

To assess the outcomes of using endoscopic endonasal approach (EEA) for nonvestibular schwannomas of the skull base.

METHODS

Seventeen patients operated on for skull base schwannomas by EEA at the University of Pittsburgh Medical Center from 2003 to 2009 were reviewed.

RESULTS

Three patients underwent combined approaches with retromastoid craniectomy (n = 2) and orbitopterional craniotomy (n = 1). Three patients underwent multistage EEA. The rest received a single EEA operation. Data on degree of resection were found for 15 patients. Gross total resection (n = 9) and near-total (>90%) resection (n = 3) were achieved in 12 patients (80%). There were no tumor recurrences or postoperative cerebrospinal fluid leaks. In 3 of 7 patients with preoperative sensory deficits of trigeminal nerve distribution, there were partial improvements. Patients with preoperative reduced vision (n = 1) and cranial nerve VI or III palsies (n = 3) also showed improvement. Five patients had new postoperative trigeminal nerve deficits: 2 had sensory deficits only, 1 had motor deficit only, and 2 had both motor and sensory deficits. Three of these patients had partial improvement, but 3 developed corneal neurotrophic keratopathy.

CONCLUSION

An EEA provides adequate access for nonvestibular schwannomas invading the skull base, allowing a high degree of resection with a low rate of complications.

Gamma Knife surgery for nonvestibular schwannomas: radiological and clinical outcomes

OBJECT

Most intracranial schwannomas arise from cranial nerve (CN) VIII. Stereotactic radiosurgery is a mainstay of treatment for vestibular schwannomas. Intracranial schwannomas arising from other CNs are much less common. We evaluate the efficacy of Gamma Knife surgery on nonvestibular schwannomas including trigeminal, hypoglossal, abducent, facial, trochlear, oculomotor, glossopharyngeal, and jugular foramen tumors.

METHODS

Thirty-six patients with nonvestibular schwannomas were treated at the University of Virginia Gamma Knife center from 1989 to 2008. The median patient age was 48 years (mean 45.6 years, range 10-72 years). Schwannomas arose from the following CNs: CN III (in 1 patient), CN IV (in 1), CN V (in 25), CN VI (in 2), CN VII (in 1), CN IX (in 1), and CN XII (in 3). In 2 patients, tumors arose from the jugular foramen. The median tumor volume was 2.9 cm(3) (mean 3.3 cm(3), range 0.07-8.8 cm(3)). The median margin dose was 13.5 Gy (range 9.3-20 Gy); the median maximum dose was 30 Gy (range 21.7-50.0 Gy).

RESULTS

The mean and median follow-up times of 36 patients were 54 and 37 months, respectively (range 2-180 months). At the last radiological follow-up, the tumor size had decreased in 20 patients, remained stable in 9 patients, and increased in 7 patients. The 2-year actuarial progression-free survival was 91%. Higher maximum dose was statistically related to tumor control (p = 0.027). Thirty-three patients had adequate clinical follow-up. Among them, 21 patients had improvement in their presenting symptoms, 8 patients were stable after treatment with no worsening of their presenting symptoms, 2 patients developed new symptoms, and 1 patient experienced symptom deterioration. Notably, 1 patient with neurofibromatosis Type 2 developed new symptoms that were unrelated to the tumor treated with Gamma Knife surgery.

CONCLUSIONS

Gamma Knife surgery is a reasonably effective treatment option for patients with nonvestibular schwannomas. Patients require careful follow-up for tumor progression and signs of neurological deterioration.

Combined craniofacial approach for the removal of a large trigeminal schwannoma invading the infratemporal fossa

BACKGROUND

Trigeminal schwannomas are rare tumours accounting for 0.07-0.36% of all intracranial tumours and 0.8-8% of intracranial schwannomas. Symptoms and signs of these lesions depend on the site of the tumour, which may compress the nerve of origin or adjacent nerves.

CASE REPORT

We describe a case of a 69-year-old woman with a history of progressively worsening hypoesthesia involving the third division of the trigeminal nerve. A tumour of 5-cm diameter was revealed within the right cranial middle fossa, extending to the lateral wall of the cavernous sinus, the infratemporal fossa and the posterior wall of the maxillary sinus. A combined craniofacial approach was undertaken. A right extended subtemporal craniotomy was performed. The intracranial component of the tumour, originating from the third division of the trigeminal nerve and compressing the cavernous sinus, was removed in total. We proceeded with a Weber-Ferguson approach through which the extracranial component of the tumour was also totally resected. The postoperative computed tomography of the head has shown complete tumour removal. The histopathologic examination revealed a cellular neurinoma. Postoperatively, the patient expressed a transitory palsy of the oculomotor nerve, which resolved within a few weeks. The patient remains free of recurrence with mild hypoesthesia of the third trigeminal branch 5 years after treatment.

DISCUSSION

Surgery of trigeminal schwannomas may be a very challenging task. Various surgical approaches for trigeminal schwannomas excision have been described. With this combined approach, the tumour was freed from the surrounding tissues and was easily and totally removed.

Trigeminal Schwannomas: Skull Base Approaches and Operative Results in 105 Patients

BACKGROUND:

Trigeminal schwannomas make up 0.8% to 8% of all intracranial schwannomas.

OBJECTIVE:

To analyze our surgical experience with trigeminal schwannomas.

METHODS:

We performed 107 operations on 105 patients harboring trigeminal schwannomas over the past 30 years. We classified the tumors as peripheral, ganglion cavernous, posterior fossa root, and dumbbell types according to the portion of the nerve that gave rise to the tumor.

RESULTS:

Fourteen were peripheral-type tumors (13.1%), 39 (36.4%) were ganglion cavernous type, 22 (20.6%) were posterior fossa root type, and 32 (30.0%) were dumbbell type. Sixty-five tumors were solid, 35 were mixed, and only 7 were cystic. Among solid tumors, 14 were vascular, fibrous, and adherent to adjacent structures. Total or near-total removal was performed in 86 cases (81.9%), and subtotal removal was achieved in 18 (17.1%). The most common symptom was facial hypesthesia, occurring in 69 patients. This symptom improved in 11 patients, persisted in 50 patients, and worsened in 8 patients after surgery. New postoperative hypesthesia was observed in 8 patients. The second most common symptom was facial pain, observed in 24 patients. Facial pain subsided in 22 and persisted in 2 patients after surgery. Diplopia was observed in 21 patients. This symptom improved postoperatively in 14 patients, persisted in 6 patients, and worsened in 1 patient.

CONCLUSION:

The present series demonstrates acceptable results using microsurgical treatment to remove trigeminal schwannomas. Pain and diplopia may be relieved after surgery; however, hypesthesia frequently remains or may be worsened by surgery.

Stereotactic Radiosurgery of Cranial Nonvestibular Schwannomas: Results of Single- and Multisession Radiosurgery

BACKGROUND:

Surgical resection of nonvestibular cranial schwannomas carries a considerable risk of postoperative complications. Stereotactic radiosurgery (SRS) offers a non-invasive treatment alternative. The efficacy and safety of multi-session SRS of nonvestibular cranial schwannomas has not been well studied.

OBJECTIVE:

To analyze the results of single- and multi-session SRS of nonvestibular cranial schwannomas.

METHODS:

From 2001 to 2007, 42 lesions in 40 patients were treated with SRS at Stanford University Medical Center, targeting schwannomas of cranial nerves IV (n = 1), V (n = 18), VII (n = 6), X (n = 5), XII (n = 2), jugular foramen (n = 8), and cavernous sinus (n = 2). SRS was delivered to a median marginal dose of 18 Gy (range, 15-33 Gy) in 1 to 3 sessions, targeting a median tumor volume of 3.2 cm3 (range, 0.1-23.7 cm3). The median doses for treatments in 1 (n = 18), 2 (n = 9), and 3 (n = 15) sessions were 17.5, 20, and 18 Gy, respectively.

RESULTS:

With a median follow-up of 29 months (range, 6-84 months), tumor control was achieved in 41 of the 42 lesions. Eighteen of 42 lesions (43%) decreased in size; 23 tumors (55%) remained stable. There were 2 cases of new or worsening cranial nerve deficits in patients treated in single session; no patient treated with multi-session SRS experienced any cranial nerve toxicity (P = 0.18).

CONCLUSION:

SRS of nonvestibular cranial schwannomas provides excellent tumor control with minimal risk of complications. There was a trend towards decreased complications with multi-session SRS.

Linear Accelerator Radiosurgery for Nonvestibular Schwannomas

BACKGROUND:

Nonvestibular schwannomas are uncommon tumors of the brain often treated by surgical resection. Surgery may be associated with high morbidity.

OBJECTIVE:

We present a series of nonvestibular schwannomas treated with linear accelerator radiosurgery during a 19-year period.

METHODS:

This is a retrospective analysis of patients who underwent treatment of nonvestibular schwannomas at the University of Florida with linear accelerator radiosurgery between August 1989 and February 2008. Forty-nine patients underwent treatment during the study period, and 6 were lost to follow up. The mean age was 51 years (range, 17-82 years), 39% had previous surgical resection, and 67% presented with preradiosurgery cranial nerve deficits. There were 25 trigeminal, 18 jugular foramen, 2 facial, 2 oculomotor, 1 hypoglossal, and 1 high cervical schwannomas. The median tumor volume was 5.3 mL (range, 0.3-24.5 mL), treated with a median dose of 1250 cGy (range, 1000-1500 cGy). Study endpoints were actuarial local tumor control and neurological outcome.

RESULTS:

Forty-three patients were available for a median follow-up of 37 months (range, 6-210 months). Actuarial local tumor control was 97% at 1 year, 91% at 4.5 years, and 83% at 5 years. There were 4 new cranial nerve deficits (9%) including facial numbness (2 patients), anesthesia dolorosa (1 patient), and facial weakness (1 patient). Thirty-nine percent had documented clinical and/or symptomatic improvement. There were no other morbidity and no mortality with treatment.

CONCLUSION:

Radiosurgery for nonvestibular schwannomas offers good actuarial local tumor control and has superior morbidity compared with surgical resection. This is the largest linear accelerator radiosurgical series, and the second largest radiosurgical series reported to date.

Endoscopic assistance in the epidural subtemporal approach and Kawase approach: anatomic study

BACKGROUND

Few reports exist in the literature about the use of endoscope assistance in the identification of structures in the posterior fossa.

OBJECTIVE

To asses the advantage of endoscopic assistance in the epidural subtemporal and Kawase approaches by studying anatomic exposure and surgical freedom in the posterior cranial fossa.

METHODS

Twelve epidural subtemporal approaches were performed on 6 adult cadaveric heads. On the same specimens, 6 endoscope-assisted subtemporal approaches and 6 Kawase approaches were then performed. At the end of each Kawase approach, endoscope assistance was used. The microsurgical observations were performed with a surgical microscope with magnification ranging from 4 x to 40 x. Endoscopic observations were made with a 0 degrees , 4-mm rod-lens endoscope. Anatomic exposure and surgical freedom were analyzed.

RESULTS

Endoscopic assistance during the epidural subtemporal approach increased the anatomic exposure 3 mm superiorly, 20 mm inferiorly, and 10 mm medially from the trigeminal nerve. Surgical freedom was limited in the temporal lobe, the petrous apex, and the trigeminal nerve. The amount of increased anatomic exposure obtained with endoscopic assistance during the Kawase approach was 26 mm inferiorly and medially from the trigeminal nerve. Surgical freedom was limited by the brainstem and the depth of the posterior cranial fossa.

CONCLUSION

The endoscope-assisted subtemporal approach can be useful in visualizing tumor in the posterior fossa. It can help the surgeon in planning further surgical steps through consideration of the size, extension, and adherence of the tumor to surrounding structures. The endoscope-assisted Kawase approach permits maximum anatomic exposure of the posterior cranial fossa, although the deepest neurovascular structures could be better addressed with more direct approaches.

Trigeminal neurinomas with extracranial extension: analysis of 28 surgically treated cases

Object

The object of this paper was to review the authors' experience with 28 cases of trigeminal neurinomas having an extracranial extension.

Methods

The authors analyzed 28 cases of trigeminal neurinoma in which there was an extracranial extension of the tumor. All patients were treated in their department between the years 1989 and 2009.

Results

There was tumor extension along the ophthalmic division of the nerve in 4 cases, along the maxillary division in 5, and along the mandibular division in 13. In 6 tumors there was diffuse extracranial extension and the exact extracranial division of nerve involvement could not be ascertained. In 10 cases, the tumor had a multicompartmental location—in the posterior fossa, the middle fossa, and the extracranial compartment. Tingling paraesthesiae, numbness, and diffuse pain in the distribution of the trigeminal nerve were common symptoms and were present in 90% of patients. The extracranial component had a well-defined perineural/meningeal membrane cover that was continuous with the middle fossa dura mater and isolated the tumor tissue from the adjoining critical structures. In 7 out of 10 cases, even the posterior fossa component of the tumor was entirely “interdural” (within the confines of the dura). The maximum dimension of the tumor was > 4 cm in 22 cases. A limited “transcranial” approach with (12 cases) or without (16 cases) zygomatic osteotomy was found suitable for resection of these tumors. In 4 cases a lateral orbitotomy was performed. Total tumor resection was performed in 20 cases and partial resection in 8. The duration of follow-up ranged from 6 months to 19 years. Two patients required additional surgery for symptomatic recurrence.

Conclusions

Extracranial extensions of trigeminal neurinomas have a well-defined meningeal covering. In most cases resection was performed via a minimally invasive cranial avenue (a “reverse skull base approach”). Radical resection was associated with an excellent long-term outcome.

Surgery for a case of three-compartment trigeminal schwannoma : technical aspects

Complete removal of three-compartment trigeminal schwannomas is a challenge to neurosurgeons. To expand exposure of each compartment, the combination and modification of skull base approaches are necessary. The 61-year-old woman was admitted with chronic headache. Preoperative magnetic resonance imaging showed 47×50×40 mm-sized tumor originating primarily in the middle cranial fossa extended to the posterior and the infratemporal fossa. We performed operation in five stage; 1. Zygomatic osteotomy, 2. Inferior temporal fossa plate removal and foramen ovale opening, 3. Cavernous sinus opening, 4. Tailored anterior petrosectomy, 5. Meckel's cave opening. Combination of skull base surgery should be concerned according to the patient. In this study, extradural basal extension with zygomatic osteotomy, interdural posterior extension with tailored anterior petrosectomy, and intracavernous exploration are reasonable options for remodeling three-compartment lesion into a single compartment. Tailoring of bone resection and exploring through natural pathway between meningeal layers accomplish single-stage operation for complete removal of tumors.

Trigeminal schwannomas: experience with 57 cases and a review of the literature

Trigeminal schwannoma is a mostly benign tumor that can be cured by complete resection. Over the last few decades, several pioneers have developed surgical approaches enabling the total removal of such tumors. We analyzed 57 patients who underwent radical surgery, including 45 patients who underwent skull base surgery as their initial treatment, for removal of trigeminal schwannomas. Here, we report the surgical management of these cases. Since 1990, all such patients have been treated using three main types of middle fossa skull base approaches, which minimize the exposure of the brain: the anterior transpetrosal approach, subtemporal interdural approach (Dolenc), or a combination of these approaches. Before 1990, total tumor removal was achieved in only three of eight patients (38%). After 1990, the tumors were totally removed in 43 patients (90%) and were nearly completely removed in an additional three patients (6%). Among the patients who underwent skull base surgery as their initial treatment, a complete resection was achieved in 93% (42/45 patients) of the cases. However, total surgical removal after surgery and Gamma knife surgery was very difficult because of dense adhesions to the brain stem and cranial nerves. No surgery-related mortalities occurred in this series, and the individual KPS scores were more than 90% among the patients who underwent skull base surgery. No recurrences requiring additional surgery have occurred after an average follow-up period of 4.9 years. Most of the trigeminal schwannomas could be removed totally and safely during a single operation after the introduction of skull base surgery. Therefore, radiosurgery should not be applied as the treatment of first choice for younger patients. A correct anatomical knowledge is critical for minimizing brain exposure and avoiding surgical complications.

"Interdural" oculomotor neurinoma: report of two surgically treated cases

BACKGROUND

Dural relationships and their possible implications on surgical treatment of oculomotor nerve neurinomas are discussed on the basis of surgical experience with two cases.

MATERIALS AND METHODS

We describe two cases with large oculomotor neurinomas that probably arose from the precavernous sinus segment of the nerve. Both tumors were located entirely within the confines of dura or were "interdural." Operating within the limits set and protection afforded by the dura, the tumors could be excised relatively easily and safely. While the third nerve function recovered completely in one patient, the other continued to have complete third nerve palsy. The duration of follow-up in two cases was 52 and 24 months.

RESULTS AND CONCLUSIONS

Even the intracranial component of large oculomotor neurinoma can be covered entirely by dura. Understanding of the dural relationship can assist in planning and conduct of surgery.

Nonvestibulocochlear cranial nerve schwannomas

OPINION STATEMENT

Nonvestibulocochlear cranial nerve schwannomas traditionally have been managed by surgical excision. Although debulking surgery is still considered the first treatment option for larger tumors, stereotactic radiosurgery is now preferred for smaller tumors because of its high tumor control rate and low treatment-related morbidity. Furthermore, an initial period of radiologic and clinical observation following the diagnosis should be strongly considered for smaller tumors because some may not grow or may grow at a slow rate. Medical management of tumor-associated symptoms (when present) should not be ignored. Most importantly, the time has come to embark on the first randomized controlled trials comparing clinical and radiologic observation, surgery, and radiosurgery in the management of cranial nerve schwannomas.

Direct and remote outcome after treatment of tumours involving the subtemporal fossa and related structures with the extended subtemporal approach

BACKGROUND AND PURPOSE

The aim of the study was to present our results of the surgical treatment of subtemporal fossa tumours and surrounding regions using the extended subtemporal approach.

MATERIAL AND METHODS

Twenty-five patients (10 women, 15 men) with subtemporal fossa tumours were included in the study. The neurological and performance status of the patients were assessed before and after surgery as well as at the conclu-sion of treatment. The approximate volume of the operated tumour, its relation to large blood vessels and cranial nerves, as well as consistency and vascularisation were assessed.

RESULTS

The symptom duration ranged from 2 to 80 months (mean: 14 months). In 44% of patients, headache was the predominant symptom. Less frequent symptoms were: paralysis of the abducent nerve and disturbances of the trigeminal nerve. Approximate volume of the tumours ranged from 13 to 169 cm3 (mean: 66 cm3). The most frequent histological diagnosis was meningioma (16%), followed by angiofibroma, neurinoma and adenocystic carcinoma (12%). Total or subtotal resection was achieved in 80% of patients.

CONCLUSIONS

The extended subtemporal approach allows for the removal of tumours of the subtemporal fossa and surrounding regions. This approach also allows one to remove tumours expanding in the regions surrounding the subtemporal fossa only. In such cases the subtemporal fossa constitutes the way of the surgical approach.

Nonvestibular schwannomas: an evaluation of functional outcome after radiosurgical and microsurgical management

PURPOSE

Nonvestibular cranial nerve schwannomas (NVCNS) are relatively rare tumors. We evaluated our experience with radiosurgical and microsurgical treatment alone and in combination for the management of NVCNS.

METHODS

The charts of 62 patients with NVCNS who were treated between 1993 and 2005 at our institution were reviewed. Patients diagnosed with neurofibromatosis type 2 were excluded. The patients underwent microsurgery and/or radiosurgery treatment.

RESULTS

Trigeminal and jugular foramen schwannomas were the most common NVCNS tumors (n = 47), and the only two groups with sufficient numbers of patients to allow comparison of the three treatment approaches. In these two groups, the mean tumor volume was significantly higher in those who received combined therapy (8.59 +/- 2.29 cc), compared with radiosurgery (4.94 +/- 3.02 cc; p = 0.05) or microsurgery alone (5.38 +/- 3.23; p = 0.027). Patients who underwent radiosurgery alone were significantly older (67.7 +/- 13.3 years; p = 0.019) than those treated with microsurgery (55.3 +/- 13.7 years) or with both modalities (48.7 +/- 12.8 years). The Karnofsky Performance Scale scores were significantly higher (p < or = 0.05) at follow-up compared with baseline for all three treatment approaches. There was no significant change in the Glasgow Outcome scores before and after treatment.

CONCLUSIONS

Microsurgery and radiosurgery can both be used to manage NVCNS tumors with excellent results. When treatment with either modality alone is not reasonable, tumors can be managed effectively with combined micro- and radiosurgery treatment.

Surgical management of trigeminal schwannomas

OBJECT

The authors provide a detailed review of the surgical management of trigeminal schwannomas (TSs) and also discuss the best surgical approach based on the surgical anatomy and tumor extension.

METHODS

A series of 17 patients with TSs who were surgically treated between 1987 and 2008 at the authors' institution is reported. The lesions were small (< 3 cm) in 2, medium (between 3 and 4 cm) in 5, large (> 4 cm) in 6, and giant (> 5 cm) in 4 cases. Preoperative symptoms included trigeminal hypesthesia (53%), facial pain (53%), headaches (35.3%), hearing impairment (17.6%), seizures (17.6%), diplopia (11.8%), ataxia (11.8%), and hemiparesis and increased intracranial pressure with papilledema (5.9%). The mean follow-up duration was 10.5 years (121.6 months), with an average of 0.8 patients per year.

RESULTS

Total tumor excision was possible in 16 patients, with no surgery-related deaths. Postoperative trigeminal anesthesia was observed in 7; trigeminal motor function was preserved in 7. Two developed cerebrospinal fluid leakage, 2 presented with mild facial palsy, and 1 patient with neurofibromatosis Type 2 had recurrence of the tumor, which was uneventfully removed. Of the 9 who reported facial pain, only 1 remained symptomatic postoperatively.

CONCLUSIONS

The best treatment for TSs is complete microsurgical removal. Postoperative preservation of trigeminal nerve function is possible when resection of the lesion is performed at well-established skull base neurosurgical centers. Although good results have been reported with radiosurgery, no cure can be obtained with this therapeutic modality. Instead, this treatment should be reserved only for nonresectable and residual tumors within the cavernous sinus.

Stereotactic radiosurgery for trigeminal schwannoma: tumor control and functional preservation Clinical article

OBJECT

To evaluate outcome predictors after stereotactic radiosurgery (SRS) in patients with trigeminal schwannomas, the authors compared tumor control, functional preservation, and complications with tumor grade, tumor volume, patient age, and tumor imaging characteristics.

METHODS

The records of 33 consecutive patients with trigeminal schwannoma treated via Gamma Knife surgery were retrospectively reviewed. The median patient age was 49.5 years (range 15.1-82.5 years). Eleven patients had undergone prior tumor resection. Two patients had neurofibromatosis Type 2. Lesions were classified as root type (6 tumors), ganglion type (17 tumors), and dumbbell type (10 tumors) based on their location. The median radiosurgery target volume was 4.2 cm3 (range 0.5-18.0 cm3), and the median dose to the tumor margin was 15.0 Gy (range 12-20 Gy).

RESULTS

At an average of 6 years (range 7.2-147.9 months), the rate of progression-free survival (PFS) at 1, 5, and 10 years after SRS was 97.0, 82.0, and 82.0%, respectively. Factors associated with improved PFS included female sex, smaller tumor volume, and a root or ganglion tumor type. Neurological symptoms or signs improved in 11 (33.3%) of 33 patients and were unchanged in 19 (57.6%). Three patients (9.1%) had symptomatic disease progression. Patients who had not undergone a prior tumor resection were significantly more likely to show improvement in neurological symptoms or signs.

CONCLUSIONS

Stereotactic radiosurgery is an effective and minimally invasive management option in patients with residual or newly diagnosed trigeminal schwannomas. Predictors of a better treatment response included female sex, smaller tumor volume, root or ganglion tumor type, and the application of SRS as the primary treatment.

Surgical management of giant trigeminal schwannomas extending into the parapharyngeal space

PURPOSE

Trigeminal schwannomas extending into the deep parapharyngeal space are relatively rare, and a surgical approach to such tumors has not been well established. We report four cases in which the tumors were completely removed by using a combination of three approaches.

METHODS

Four patients with trigeminal schwannomas extending into the extracranial space were surgically treated using a combination of the transcervical approach, anterolateral retromaxillar pathway via gingivobuccal sulcus, and epi and interdural middle fossa approach.

RESULTS

The maximum diameters of the tumors ranged from 4 to 7 cm. Three tumors extended beyond the lower end of the maxillary sinus. All tumors were completely excised. The Karnofsky performance scales after surgery were more than 90% in all patients.

CONCLUSION

Although the tumors extending to the deep parapharyngeal space are difficult to completely remove via a single approach, a combined approach is useful in these huge extracranial extensions.

CYBERKNIFE RADIOSURGERY FOR TRIGEMINAL SCHWANNOMAS

OBJECTIVE

Trigeminal schwannomas (TS) are benign tumors that are managed by surgical resection and/or stereotactic radiosurgery. Most radiosurgical series report results using the gamma knife. The CyberKnife (Accuray, Inc., Sunnyvale, CA) is a frameless, robotic stereotactic radiosurgical system. In this series, we report our experience using the CyberKnife in the treatment of TS.

METHODS

We retrospectively reviewed the medical records and diagnostic imaging in 13 consecutive patients with TS who were treated with the CyberKnife from 2003 to 2007. Seven patients had a previous surgical resection. The mean tumor volume was 6.3 mL (range, 0.39–19.98 mL), and the mean marginal dose was 18.5 Gy. Six of the tumors were treated in a single session. The mean clinical follow-up period was 21.8 months (range, 7–53 months).

RESULTS

In this series, the tumor control rate was 100%. The average reduction in tumor volume was 45% (range, 14–98%). A modest improvement in facial pain was noted in 4 of the 6 patients who presented with this symptom. One patient had improvement in facial numbness, and another had improvement in pretreatment headaches. One patient developed jaw weakness and facial dysesthesia, and another patient developed asymptomatic radiation necrosis.

CONCLUSION

Although the length of follow-up is limited, we report our initial experience with CyberKnife treatment of TS. Our results demonstrate tumor control rates and clinical outcomes that parallel those of previous reports using gamma knife radiosurgery; however, long-term follow-up studies are needed.

Multicompartmental trigeminal schwannoma--a clinical report

Trigeminal schwannomas are rare, benign tumors. The unique course of the trigeminal nerve allows these tumors to grow into various intracranial compartments. Multicompartmental tumors are infrequent and may present a formidable challenge to the surgeon. Liaison between a neurosurgeon and a craniofacial surgeon ensures optimal surgical outcome. We report one such patient. The tumor was approached via a modified frontotemporal craniotomy with orbitozygomatic osteotomy. It was completely extradural and could be totally excised with minimal morbidity.

Trigeminal schwannomas: experience with 68 cases

Trigeminal schwannomas (TS) are rare. Only a couple of series involving a large number of cases have been reported. In the present study we aimed to analyse the clinical characteristics of TS, the surgical approaches used to treat TS, and the outcomes for patients undergoing surgical treatment for TS via retrospective analysis of departmental records. Data for 68 patients treated for TS in the Department of Neurosurgery at the All India Institute of Medical Sciences between January 1993 and December 2005 were analysed. Most patients were in the fourth decade of life, with the duration of symptoms ranging from 1 month to 13 years. Twenty-nine TSs were classified as type A, 13 as type B and 26 as type C, depending upon size. A skull base approach was used in every surgically treated case. Of the 46 patients for whom radiological follow-up data were available, complete tumour excision was achieved in 35 cases (76%). Follow-up ranged from 3 months to 12 years (mean 62 months). One patient died and nine (15%) had permanent morbidity in the form of corneal opacity (5) or facial (2) or trochlear (2) nerve palsy. We conclude that trigeminal neuromas are best treated by total surgical resection, which yields acceptable results with low rates of mortality and permanent morbidity.

Evolution in the assessment and management of trigeminal schwannoma

EDUCATIONAL OBJECTIVE

At the conclusion of this presentation, the participants should be able to understand the contemporary assessment and management algorithm used in the evaluation and care of patients with trigeminal schwannomas.

OBJECTIVES

1) Describe the contemporary neuroradiographic studies for the assessment of trigeminal schwannoma; 2) review the complex skull base osteology involved with these lesions; and 3) describe a contemporary management algorithm.

STUDY DESIGN

Retrospective review of 23 cases.

METHODS

Chart review.

RESULTS

From 1984 to 2006, of 23 patients with trigeminal schwannoma (10 males and 13 females, ages 14-77 years), 15 patients underwent combined transpetrosal extirpation, 5 patients underwent stereotactic radiation, and 3 were followed without intervention. Of the 15 who underwent surgery, total tumor removal was achieved in 9 patients. Cytoreductive surgery was performed in six patients; of these, four received postoperative radiation. One patient who underwent primary radiation therapy required subsequent surgery. There were no deaths in this series. Cranial neuropathies were present in 14 patients pretreatment and observed in 17 patients posttreatment. Major complications included meningitis (1), cerebrospinal fluid leakage (2), major venous occlusion (1), and temporal lobe infarction (1).

CONCLUSIONS

Trigeminal schwannomas are uncommon lesions of the skull base that may occur in the middle fossa, posterior fossa, or both. Moreover, caudal extension results in their presentation in the infratemporal fossa. Contemporary diagnostic imaging, coupled with selective use of both surgery and radiation will limit morbidity and allow for the safe and prudent management of this uncommon lesion.

Retrospective analysis of peripheral nerve sheath tumors of the second cervical nerve root in 60 surgically treated patients

Object

This study is a retrospective analysis of 60 surgically treated patients with 64 peripheral nerve sheath tumors (PNSTs) at the second cervical (C-2) nerve root. The anatomical subtleties of these tumors and their implications for surgical strategy when compared with other spinal PNSTs and other tumors in the foramen magnum region are reviewed.

Methods

Sixty patients with C-2 PNSTs treated surgically in the Department of Neurosurgery at King Edward VII Memorial Hospital and Seth Gordhandas Sunderdas Medical College between 1992 and 2006 were studied. All patients underwent magnetic resonance imaging. Tumors were divided into 3 groups depending on their anatomical location identified during surgery. Those tumors located within or extending into the spinal dural tube were called Type A, those located within the dural tube of the C-2 ganglion were labeled as Type B, and tumors extending laterally into the paraspinal region were labeled as Type C. Follow-up durations ranged from 6 months to 15 years (mean 64 months).

Results

There were 38 male and 22 female patients in the study, who ranged in age from 6 to 62 years (mean 28 years). Nine patients had clinical features indicative of neurofibromatosis (NF). The mean duration of symptoms at the time of presentation was 27 months (range 4 days–5 years). Two patients had no specific symptoms related to the C-2 PNST, 6 patients had only local symptoms such as neck pain or stiffness, and 52 patients had symptoms of varying degrees of myelopathy. There were 5 solely Type A tumors, 7 Type A + B tumors, 31 Type B tumors, and 21 Type B + C tumors. All Type A, A + B, and B tumors were totally resected. Seven of 21 Type B + C tumors were partially resected, and the remainder were completely resected. All patients postoperatively reported varying improvement in their preoperative symptoms. Except for patients with NF who were disabled by other tumors, the rest of the patients resumed their normal life style. There have been no cases of symptomatic tumor recurrence.

Conclusions

The majority of PNSTs located at the C-2 level in these patients probably arose from the large C-2 ganglion and are limited within the dural confines or are interdural in location. In contrast to other spinal PNSTs, the location of C-2 PNSTs is in most cases posterior to the lateral mass of the atlas and axis and the atlantoaxial joint and is exposed to the posterior without any bone cover. Radical tumor resection is safe, resolution of clinical symptoms is rapid, and recurrence rates are extremely low. In a selected number of cases, bone work for tumor exposure and resection can be entirely avoided.

Gamma-knife radiosurgery in the treatment of trigeminal schwannomas

BACKGROUND

Trigeminal nerve schwannomas account for 0.07%-0.28% of all intracranial tumours. Advances in skull base surgery have led to more aggressive resection of these tumours, but surgery may associated with development of new neurological deficits.

METHODS

In this report, we analyse the long-term results 15 patients with newly diagnosed or residual/recurrent trigeminal schwannoma who underwent gamma-knife treatment.

FINDINGS

During a mean 61 months of follow-up, MRI revealed reduction of tumour size in 13 and no size change in 2 patients. The tumour growth control rate was 100% and only 1 patient had transient facial numbness and diplopia.

CONCLUSIONS

For patients with small to moderate size trigeminal schwannomas, gamma-knife radiosurgery is associated with good tumour control and a minimal risk of adverse radiation effects.

Gamma Knife surgery and trigeminal schwannoma: is it possible to preserve cranial nerve function?

Object

The current study was undertaken to evaluate the tumor control rate and functional outcome after Gamma Knife surgery (GKS) in patients with a trigeminal schwannoma. The conditions associated with the development of cranial neuropathies after radiosurgery were scrutinized.

Methods

The authors reviewed the clinical records and radiological data in 22 consecutive patients who received GKS for a trigeminal schwannoma. The median tumor volume was 4.1 ml (0.2–12.0 ml), and the mean tumor margin dose was 13.3 ± 1.3 Gy at an isodose line of 49.9 ± 0.6% (mean ± standard deviation). The median clinical follow-up period was 46 months (range 24–89 months), and the median length of imaging follow-up was 37 months (range 24–79 months).

Results

Tumor growth control was achieved in 21 (95%) of the 22 patients. Facial pain responded best to radio-surgery, with two thirds of patients showing improvement. However, only one third of patients with facial hypesthesia improved. Six patients (27%) experienced new or worsening cranial neuropathies after GKS. Ten patients (46%) showed tumor expansion after radiosurgery, and nine of these also showed central enhancement loss. Loss of central enhancement, tumor expansion, and a tumor in a cavernous sinus were found to be significantly related to the emergence of cranial neuropathies.

Conclusions

The use of GKS to treat trigeminal schwannoma resulted in a high rate of tumor control and functional improvement. Cranial neuropathies are bothersome complications of radiosurgery, and tumor expansion in a cavernous sinus after radiosurgery appears to be the proximate cause of the complication. Loss of central enhancement could be used as a warning sign of cranial neuropathies, and for this vigilant patient monitoring is required.

Surgical treatment of trigeminal schwannomas

Schwannomas that arise from the trigeminal nerve are rare, but this nerve is the second most frequent intracranial site of schwannoma occurrence next to the vestibular nerve. The advent of microsurgical techniques and skull-base approaches has greatly enhanced the surgical management of these tumors, and outcomes have improved markedly. This report documents 18 cases of histologically verified schwannomas that arose from the trigeminal nerve and were treated surgically in our clinic between January 1992 and July 2005. The patients were ten women and eight men of age 39.7 years (range, 22-62 years). The tumor was located in the middle fossa (type A) in five cases, in the middle and posterior fossae (type C) in nine cases, in the posterior fossa (type B) in two cases, and in the branches of the trigeminal nerve (type D) in two cases. Total excision was achieved in 17 cases, and there was no mortality in the series. Our results indicate that trigeminal schwannomas, regardless of type, can be removed via skull-base approaches. We present an algorithm for surgical management of trigeminal schwannomas based on our experience and information from the literature.