Update: Trigeminal schwannoma radiosurgery

Stereotactic radiosurgery (SRS) is an effective and minimally invasive management option for patients with residual or newly diagnosed trigeminal schwannomas. The use resulted in good tumor control and functional improvement 1).

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 2).

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 3).

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 4).

It is a promising alternative to conventional microsurgery in cases of neurinomas of the trigeminal nerve including neurotrophic keratopathy, to keep or restore vision 5).

Case series

2013

The records of 52 patients who underwent stereotactic radiosurgery (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%.

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.

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 6).

2009

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).

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.

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 7).

2007

Phi et al. 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).

Tumor growth control was achieved in 21 (95%) of the 22 patients. Facial pain responded best to radiosurgery, 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.

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 8).


Twenty-six patients with trigeminal schwannomas underwent GKS at the University of Virginia Lars Leksell 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 cm(3), 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.

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 9).

2001

A patient developed severe corneal neovascularization within four weeks and the contact lens had to be removed. Three months later an MRI scan was performed, which showed an intracranial tumor originating from the first branch of the trigeminal nerve. Neurinoma of the trigeminal nerve was suspected, and this presumed diagnosis was confirmed by fine needle biopsy. The patient underwent radiosurgery seven weeks later. The epithelium closed, the cornea recovered and stayed stable until the last examination 18 months after radiosurgery.

Radiosurgery is a promising alternative to conventional microsurgery in cases of neurinomas of the trigeminal nerve including neurotrophic keratopathy, to keep or restore vision 10).

References

1) , 6)

Sun J, Zhang J, Yu X, Qi S, Du Y, Ni W, Hu Y, Tian Z. Stereotactic radiosurgery for trigeminal schwannoma: a clinical retrospective study in 52 cases. Stereotact Funct Neurosurg. 2013;91(4):236-42. doi: 10.1159/000345258. Epub 2013 Mar 26. PubMed PMID: 23548989.
2) , 7)

Kano H, Niranjan A, Kondziolka D, Flickinger JC, Dade Lunsford L. Stereotactic radiosurgery for trigeminal schwannoma: tumor control and functional preservation Clinical article. J Neurosurg. 2009 Mar;110(3):553-8. PubMed PMID: 19301456.
3) , 8)

Phi JH, Paek SH, Chung HT, Jeong SS, Park CK, Jung HW, Kim DG. Gamma Knife surgery and trigeminal schwannoma: is it possible to preserve cranial nerve function? J Neurosurg. 2007 Oct;107(4):727-32. PubMed PMID: 17937215.
4) , 9)

Sheehan J, Yen CP, Arkha Y, Schlesinger D, Steiner L. Gamma knife surgery for trigeminal schwannoma. J Neurosurg. 2007 May;106(5):839-45. PubMed PMID: 17542528.
5) , 10)

Ardjomand N, Can B, Schaffler G, Eustacchio S, Scarpatetti M, Pendl G. [Therapy of neurotrophic keratopathy in trigeminal schwannoma with radiosurgery]. Wien Klin Wochenschr. 2001 Aug 16;113(15-16):605-9. German. PubMed PMID: 11571839.

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