Trigeminal neuroma: analysis of surgical experience with 73 cases

Giant dumbbell-shaped middle cranial fossa trigeminal schwannoma with extension to the infratemporal and posterior fossae

We present a 38-year-old female with a giant dumbbell-shaped trigeminal neurinoma originating primarily in the middle cranial fossa, extending to the infratemporal and posterior fossae through the foramen ovale and Meckel's cave, respectively. Because of the large tumour extension into the Infratemporal Fossa, a combined skull base approach (zygomatic infratemporal - transmandibular) was utilised for tumour removal, with a subsequent excellent outcome. An extensive literature review since 1935, revealed 580 cases of surgically treated trigeminal neurinomas. Among these, only three were located in three distinct compartments, making this the rarest developmental pattern for trigeminal neurinomas.

Gamma Knife surgery for trigeminal schwannoma

Object

Trigeminal schwannomas are rare intracranial tumors. In the past, resection and radiation therapy were the mainstays of their treatment. More recently, neurosurgeons have begun to use radiosurgery in the treatment of trigeminal schwannomas because of its successful use in the treatment of vestibular schwannomas. In this article the authors evaluate the radiological and clinical outcomes in a series of patients in whom Gamma Knife surgery (GKS) was used to treat trigeminal schwannomas.

Methods

Twenty-six patients with trigeminal schwannomas underwent GKS at the University of Virginia Lars Lek-sell Gamma Knife Center between 1989 and 2005. Five of these patients had neurofibromatosis and one patient was lost to follow up. The median tumor volume was 3.96 cm3, and the mean follow-up period was 48.5 months. The median prescription radiation dose was 15 Gy, and the median prescription isodose configuration was 50%. There was clinical improvement in 18 patients (72%), a stable lesion in four patients (16%), and worsening of the disease in three patients (12%). On imaging, the schwannomas shrank in 12 patients (48%), remained stable in 10 patients (40%), and increased in size in three patients (12%). These results were comparable for primary and adjuvant GKSs. No tumor growth following GKS was observed in the patients with neurofibromatosis.

Conclusions

Gamma Knife surgery affords a favorable risk-to-benefit profile for patients harboring trigeminal schwannomas. Larger studies with open-ended follow-up review will be necessary to determine the long-term results and complications of GKS in the treatment of trigeminal schwannomas.

Trigeminal schwannomas: results of Gamma Knife surgery in 37 cases

Object

Information on outcomes of Gamma Knife surgery (GKS) for patients harboring trigeminal schwannomas is limited because these tumors are rare. The authors evaluated tumor control and functional outcomes in patients who underwent GKS for trigeminal schwannomas to clarify the efficacy of this treatment.

Methods

Forty-two patients with trigeminal schwannomas but no evidence of neurofibromatosis Type 2 were treated with GKS at Komaki City Hospital between November 1991 and December 2003. Of these, 37 patients were assessed. The mean tumor volume in these patients was 10 cm3. The mean maximum radiation dose directed to the tumor was 27.9 Gy and the mean dose directed to the tumor margin was 14.2 Gy. The mean follow-up period was 54 months. In four patients (11%) there was complete tumor remission; in 20 (54%) there was partial tumor remission; in eight (22%) the disease remained stable; and in five (14%) the tumor enlarged or uncontrollable facial pain developed with radiation-induced edema requiring resection. The actuarial 5- and 10-year tumor control rates were both 84%. With respect to functional outcomes, 40% of patients noted an improvement in their symptoms, and one patient experienced new symptoms despite good tumor control.

Conclusions

Gamma Knife surgery was a safe and effective treatment for a select group of patients harboring trigeminal schwannomas. Large tumors that compress the brainstem and cause deviation of the fourth ventricle should first be removed surgically and any remnant should be treated by GKS.

Clinical analysis of Gamma Knife surgery for trigeminal schwannomas

Object

The authors sought to assess the clinical effect of Gamma Knife surgery (GKS) for trigeminal schwannomas.

Methods

Between December 1994 and December 2003, 69 patients with trigeminal schwannomas underwent GKS, and 58 patients were followed up and reviewed at the Beijing Neurosurgical Institute. The mean target volume was 4.6 cm3. The mean peripheral dose was 13.1 Gy, and the mean central dose was 28.3 Gy. The mean radiological follow-up period was 42.5 months.

Radiological follow-up demonstrated near-complete disappearance of the tumors in four patients (6.9%), in 34 patients (58.6%) a reduction was seen, in 16 patients (27.6%) no change was observed, and in four patients (6.9%) an enlargement was revealed. The overall tumor control rate was 93.1%. Improvement of presenting neurological symptoms was observed in 28 patients (48.3%), stabilization of presenting neurological symptoms was observed in 23 patients (39.6%), continued progression of presenting neurological symptoms was observed in seven patients (12.1%), and transient cranial nerve dysfunction was observed in six patients (10.4%). Among 13 patients with secondary trigeminal neuralgia, 10 patients had significant improvement or disappearance of trigeminal neuralgia after GKS.

Conclusions

Gamma Knife surgery provides an effective and safe primary and/or adjunct treatment for patients with small- to moderate-sized trigeminal schwannomas, with a low risk of iatrogenic cranial neuropathy and great improvement of clinical symptoms.

The Subtemporal Interdural Approach to Dumbbell-Shaped Trigeminal Schwannomas: Cadaveric Prosection

OBJECTIVE:

Successful resection of dumbbell-shaped trigeminal schwannomas via a subtemporal interdural approach requires an understanding of both the anatomy related to the bone dissection of the petrous apex (Kawase's triangle or quadrilateral) and meningeal anatomy. We studied the meningeal anatomy related to this approach and describe the dural incisions and stepwise mobilization.

METHODS:

Meningeal anatomy around Meckel's cave and porus trigeminus was examined during the subtemporal interdural anterior transpetrosal approach in both sides of 15 cadaveric heads. Histological study of the Meckel's cave region was performed in two cadaveric heads.

RESULTS:

The Gasserian ganglion and trigeminal roots have two layers of dura propria on their dorsolateral surface: an inner layer from the posterior fossa dura propria that constitutes the dorsolateral wall of Meckel's cave and an outer layer from the dura propria of the middle fossa. The cleavage plane between these two layers continues distally as the cleavage plane between the epineural sheaths of the trigeminal divisions and the dura propria of the middle fossa. This cleavage plane serves as the anatomic landmark for the interdural exposure of the contents of Meckel's cave. The superior petrosal sinus is sectioned at the medial aspect of Kawase's triangle and reflected along with the porus trigeminus roof.

CONCLUSION:

Understanding the critical meningeal architecture in and around Meckel's cave allows experienced cranial neurosurgeons to develop a subtemporal interdural approach to dumbbell-shaped trigeminal schwannomas that effectively converts a multiple-compartment tumor into a single-compartment tumor. Dural incisions and stepwise mobilization complements our previous description of the bony dissection for this approach.

Dumbbell trigeminal schwannoma in a child: complete removal by a one-stage pterional surgical approach

OBJECTIVE

The objective was to describe a rare case of a trigeminal schwannoma in a child and the surgical procedure performed for therapy.

PATIENT AND METHODS

A 6-year-old girl presented with tiredness, dysarthric speech and cerebellar symptoms. Imaging studies revealed a unilateral dumbbell-shaped tumour, extending into both the middle and posterior fossa, centred over Meckel's cave. One-stage surgery was performed by pterional craniotomy. The tumour was first debulked in the middle fossa, then peeled from the wall of the cavernous sinus, followed by extirpation of the tumour from the posterior fossa. The tumour extended to the caudal cranial nerves and was completely removed. Trigeminal fascicles were distributed throughout the tumour. Histopathological examination revealed a schwannoma.

CONCLUSION

Trigeminal schwannoma is a tumour that occurs rarely in childhood. Although several, often multistaged surgical strategies have been reported in the literature, this tumour was eradicated by a one-stage pterional approach.

Trigeminal neurinoma associated with Chiari malformation and syringomyelia

We report a 36 year-old woman who presented with headaches and hypoesthesia of the face. MRI revealed a large dumbbell shaped trigeminal neurinoma extending into both the middle and the posterior cranial fossae. In addition, there was a Chiari I malformation and syringomyelia. Within two months of tumor resection, both the Chiari malformation and the syringomyelia resolved. The association of an intracranial space-occupying lesion with Chiari malformation and syringomyelia is reviewed.

Gamma knife radiosurgery for trigeminal schwannomas

BACKGROUND

Trigeminal schwannomas are uncommon tumors that may be microsurgically removed in selected cases, albeit with significant risk for new neurological morbidity. We evaluated the role of stereotactic radiosurgery as an alternative for patients with newly diagnosed or residual trigeminal schwannomas.

METHODS

The records of 23 patients who underwent radiosurgery for trigeminal schwannoma were reviewed. The most frequent presenting symptoms were facial numbness (11 patients), diplopia (6 patients), and facial pain (3 patients). One patient presented with partial complex seizures as the first symptom. Twelve patients had undergone one or more prior resections. Eleven underwent radiosurgery on the basis of imaging diagnosis only. The mean tumor volume was 4.5 mL (range 0.46-11.2 cc). Radiosurgery was performed using a median marginal dose of 15 Gy (range, 13-20 Gy).

RESULTS

At a median imaging follow-up of 40 months (range, 12-146), 20 of 22 evaluable patients (91%) had tumor growth control (regression in 15 and no further tumor growth in 5). One 80-year-old patient died of unrelated cause 4 months after radiosurgery. Two patients with enlarged tumors were treated effectively with repeat radiosurgery. Twelve of 23 patients (52%) reported improvement and 9 (39%) had no change in their symptoms. Two patients noted new neurological complaints (transient facial weakness in 1 patient and worsening of the preradiosurgery facial numbness in another patient).

CONCLUSIONS

Radiosurgery is an effective minimally invasive management option for patients with residual or newly diagnosed trigeminal schwannomas.

Surgical treatment of intracavernous trigeminal schwannomas via a fronto-temporal epidural approach

The purpose of this study is to evaluate the efficacy of the fronto-temporal epidural approach in managing intracavernous trigeminal schwannomas. Five unselected patients harboring an intracavernous trigeminal schwannoma were operated on. Each of them was cured by a single craniotomy. In all cases the skull base approach described by Dolenc [Acta Neurochir. (Wien) 130 (1994) 55] was performed. The complete resection of the tumor and its capsule was gained in all five cases. There was no surgical mortality. No patient developed postoperative major complications. The fronto-temporal epidural approach can be applied for parasellar type trigeminal schwannomas, thus avoiding the exposure of the temporal lobe, and resulting in good chance for total excision of the tumor together with minimal surgical complications.