Recurrent trigeminal neuralgia: long term outcome of repeat gamma knife radiosurgery.

OBJECTIVE: To date, the efficacy and safety of repeat radiosurgery (RS) for trigeminal neuralgia (TN) is based mainly on short term results. METHODS: Between 1994 and 2006, 93 patients were treated by RS for TN at the Department of Neurosurgery, Graz, Austria. 22 patients underwent repeat gamma knife radiosurgery (GKRS) a mean of 18.8 months after the initial treatment. The mean dose for repeat treatment was 74.3 Gy. Pain outcome was rated using the Barrow Neurological Institute (BNI) Pain Intensity Scale and facial numbness according to the BNI Facial Numbness Scale. RESULTS: Mean follow-up after repeat RS was 5.4 years. Pain relief was noted in 72.7% (16/22) of patients; six patients had a second pain recurrence after a mean of 9.3 months and underwent medical, alternative and/or further RS. One patient was lost to follow-up. BNI pain scale evaluation for 21 patients indicated improvement in 76.2% (16/21) of cases without medication (BNI I and II). Facial numbness was recorded in 73.7% (14/19) but in only one was it classified as bothersome. CONCLUSIONS: Long term observation of repeat GKRS for TN showed good pain relief in more than two-thirds of patients. Despite a high percentage of facial numbness, most likely attributable to the higher delivered dose, repeat RS can still be regarded as safe. However, further studies are needed to determine an optimised treatment protocol.

Long term experience of gamma knife radiosurgery for benign skull base meningiomas.

OBJECTIVES: As most reports on the gamma knife have related only to short or mid-term results, we decided to evaluate the effectiveness and toxicity of radiosurgical treatment for benign skull base meningiomas in 200 patients with a follow up of 5-12 years to define the role of gamma knife radiosurgery (GKRS) for basal meningiomas and to provide further data for comparison with other treatment options. METHODS: In total, 99 patients were treated with a combination of microsurgical resection and GKRS. In 101 patients, GKRS was performed as the sole treatment option. Tumour volumes ranged from 0.38 to 89.8 cm3 (median 6.5 cm3), and doses of 7-25 Gy (median 12 Gy) were given to the tumour borders at covering isodose volume curves (range 20-80%, median 45%). RESULTS: The actuarial progression free survival rate was 98.5% at 5 years and 97.2% at 10 years. Passing radiation induced oedema occurred in two patients (1%). The neurological status improved in 83 cases (41.5%), remained unaltered in 108 (54%), and deteriorated in 9 (4.5%). Worsening was transient in seven patients (3.5%) and unrelated to tumour or treatment in one (0.5%). Repeated microsurgical resection was performed in five patients following GKRS (2.5%). CONCLUSIONS: GKRS has proved to be an effective alternative to microsurgical resection, radiotherapy, and Linac based radiosurgery for adjunctive and primary treatment of selected patients with basal meningiomas. Because of the excellent long term tumour control rate and low morbidity associated with GKRS, this treatment option should be used more frequently in the therapeutic management of benign skull base meningiomas.

Gamma Knife radiosurgery of brainstem gliomas.

From August 1992 until December 1999 Gamma Knife radiosurgery (GKRS) was applied to 21 patients (male to female ratio 14:7) with brainstem gliomas. Patient's median age was 23 years (8-56 years). All tumours were histologically confirmed by biopsy or open surgery: 12 low-grade gliomas and 9 malignant growths. Two lesions were located primarily in the medulla, 12 in the pons and 7 in the midbrain. A median dose of 12 Gy (9-20 Gy) was applied to the tumour margin by the median isodose of 45%. Prior to radiosurgery 4 patients were treated by conventional radiotherapy, 1 had radiotherapy and chemotherapy, 1 patient underwent chemotherapy, and 1 patient was shunted due to hydrocephalus. Neuroimaging controls (MR, CT) were obtained from 19 patients. The median interval between radiosurgery and the last neuroimaging control was 11.8 months (1-74 months). Neuroimaging depicted tumour progression in 2 patients, stable disease in 10 patients and regression in 3 cases. Follow-up periods ranged between 3 and 99 months (median 29 months). The neurological state improved in 5 patients. Microsurgical cyst fenestration was performed in 1 patient after GKRS, shunting procedure was necessary for 2 patients. Nine patients died unrelated to radiosurgery within 3 to 45 months (median 20.7 months). GKRS is an effective treatment modality for brainstem gliomas with satisfying tumour control and functional outcome.