Outcome of Gamma Knife Thalamotomy in Patients with an Intractable Tremor

OBJECTIVE: Tremor is a common movement disorder that interferes with daily living. Since the medication for tremor has some limitations, surgical intervention is needed in many patients. In certain patients who cannot undergo aggressive surgical intervention, Gamma Knife thalamotomy (GKT) is a safe and effective alternative. METHODS: From June 2012 to August 2013, 7 patients with an intractable tremor underwent GKT. Four of these 7 patients had medical comorbidities, and 3 patients refused to undergo traditional surgery. Each patient was evaluated with the modified Fahn-Tolosa-Marin tremor rating scale (TRS) along with analysis of handwriting samples. All of the patients underwent GKT with a maximal dose of 130 Gy to the left ventralis intermedius (VIM) nucleus of the thalamus. Follow-up brain MRI was performed after 3 to 8 months of GKT, and evaluation with the TRS was also performed. RESULTS: Six patients showed objective improvement in the TRS score. Excluding one patient who demonstrated tremor progression, there was 28.9% improvement in the TRS score. However, five patients showed subjective improvement in their symptoms. On comparing the TRS scores between follow-up periods of more and less than 4 months, the follow-up TRS score at more than 4 months of GKT was significantly improved compared to that at less than 4 months of GKT. Follow-up MRI showed radiosurgical changes in 5 patients. CONCLUSION: GKT with a maximal dose of 130 Gy to the VIM is a safe procedure that can replace other surgical procedures.

Fractionated Gamma Knife Radiosurgery for Benign Perioptic Tumors: Outcomes of 38 Patients in a Single Institute

BACKGROUND: This study was performed to evaluate the efficacy and safety of fractionated Gamma Knife radiosurgery (GKRS) for perioptic lesions. METHODS: Thirty-eight patients with perioptic tumors were treated at our institute from May 2004 to December 2008. All patients had a lesion in close contact with the optic apparatus. Twenty-four of these patients had undergone surgical resection before fractionated GKRS. Radiation was delivered in four sessions with 12 hours intervals between sessions. The mean target volume was 3,851 mm3 and the median cumulative marginal dose was 20 Gy. The median follow-up was 38.2 months. Visual acuity and visual fields were analyzed according to visual impairment score using the German Ophthalmological Society guidelines. RESULTS: Tumor control was achieved in 35 (94.6%) of the 37 patients with available follow-up images. Progressive tumor growth was observed in two craniopharyngioma patients (5.4%). Favorable visual outcomes in the postoperative period were achieved in 94.7% of cases (36/38). Sixteen patients showed visual function after fractionated GKRS, twenty cases were stationary, and two patients showed visual function deterioration after GKRS. CONCLUSION: GKRS is a safe and effective alternative to either surgery or fractionated radiotherapy for selected benign lesions that are adjacent to the optic apparatus.

Gamma Knife Radiosurgery for Ten or More Brain Metastases

OBJECTIVE: This study was performed to assess the efficacy of GKS in patients with ten or more brain metastases. METHODS: From Aug 2002 to Dec 2007, twenty-six patients (13 men and 13 women) with ten or more cerebral metastatic lesions underwent GKS. The mean age was 55 years (32-80). All patients had Karnofsky performance status (KPS) score of 70 or better. According to recursive partitioning analysis (RPA) classification, 3 patients belonged to class I and 23 to class II. The location of primary tumor was lung (21), breast (3) and unknown (2). The mean number of the lesions per patient was 16.6 (10-37). The mean cumulated volume was 10.9 cc (1.0-42.2). The median marginal dose was 15 Gy (9-23). Overall survival and the prognostic factors for the survival were retrospectively analyzed by using Kaplan Meier method and univariate analysis. RESULTS: Overall median survival from GKS was 34 weeks (8-199). Local control was possible for 79.5% of the lesions and control of all the lesions was possible in at least 14 patients (53.8%) until 6 months after GKS. New lesions appeared in 7 (26.9%) patients during the same period. At the last follow-up, 18 patients died; 6 (33.3%) from systemic causes, 10 (55.6%) from neurological causes, and 2 (11.1%) from unknown causes. Synchronous onset in non-small cell lung cancer (p=0.007), high KPS score (> or =80, p=0.029), and controlled primary disease (p=0.020) were favorable prognostic factors in univariate analysis. CONCLUSION: In carefully selected patients, GKS may be a treatment option for ten or more brain metastases.

Gamma Knife Radiosurgery of The Brain Stem Cavernous Angioma / 대한뇌혈관외과학회지

From December 2001 to December 2007, twenty one patients with symptomatic brainstem cavernous angioma were treated using the Leksell gamma knife. The median marginal dose was 15 Gy (range 13~18 Gy) at 50% isodose (range 45~80%). Mean follow up period was 33 months (range 4~67 months). Symptomatic improvement was achieved in 14 (66.6%) patients. There were 5 (23.8%) patients with neurological deterioration during follow-up period. Among them one patient aggravated due to overt bleeding and radiation effect was thought be the cause of deterioration in the others. Two patients needed surgical treatment subsequently and the other three patients improved with conservative management. Digital volumetry was performed before and after GKS with mean interval of 17 months (range 5~51 months). Mean volume of the lesions was 1155.6 mm3 (range 130.7~3800 mm3) before GKS and 724.8mm3 (range 36.8~1322 mm3) at the last follow-up. Volume of the lesion decreased in 17 patients (81.0%). GKS is an effective treatment modality for brainstem cavernous angioma in surgically unfavorable location. However, neurological deterioration after GKS was not rare (23%), particularly within 1 yr after GKS. It is necessary to be cautious in dose prescription.

Preliminary Report of Multisession Gamma Knife Radiosurgery for Benign Perioptic Lesions: Visual Outcome in 22 Patients

Objective: Radiosurgery may be contraindicated for lesions adjacent to the optic pathways because of the substantial risk of visual complication. Multisession radiosurgery has been tried as a compromise between single session radiosurgery and fractionated radiotherapy. The purpose of this study is to evaluate the outcomes of multisession gamma knife radiosurgery (GKRS) in 22 patients with perioptic lesions of benign pathology. Methods: In all 22 cases, the lesions were within 1 mm of the optic apparatus and were therefore not considered suitable for single session radiosurgery. Radiation was delivered in 3 to 4 fractions with a median cumulated marginal dose of 20 Gy (range, 15-20 Gy). Results: During a mean follow-up of 29 months (range, 14-44 months), tumor control was achieved in 21 patients. Visual function improved in 7 patients, remained unchanged in 14 patients, and deteriorated in 1 patient with tumor progression. No other complication was observed. Conclusion: This preliminary result supports the idea that multisession GKRS may be an effective and safe alternative for treatment in perioptic lesions that are unsuitable for single session radiosurgery.

Retrospective Analysis on 76 Cases of Cerebral Arteriovenous Malformations Treated by Gamma Knife Radiosurgery

OBJECTIVE: Outcome of gamma knife radiosurgery (GKS) in the consecutive 100 cases with cerebral arteriovenous malformations (AVMs) was analyzed. METHODS: Data from initial 100 patients treated with GKS in the authors' institute were reviewed retrospectively. Spetzler-Martin grade at diagnosis were I in 18 patients, II in 27, III in 36, IV in 11, and V in 8. Thirty-five patients had experienced previous bleeding, 27 patients presented with seizure, and 31 patients presented with headache. The mean volume of the lesion was 4.3 cm3 (0.1-29.3 cm3). The median radiation dose delivered to the margin was 20.0 Gy (13-32 Gy). Mean follow-up period was 37.5 months (5-63 months). RESULTS: Angiographic follow-up was performed in 48 patients at least 2 years after GKS. Sixteen patients were lost in follow up following 2 years from GKS. Twenty-eight of 48 patients (58%) showed complete obliteration and 20 patients (42%) showed partial obliteration. Seven patients presented with post-GKS hemorrhage. Adverse radiation effect (ARE) was observed at follow-up MRI in 25 of 76 patients, and it was symptomatic in 5 patients. Complete obliteration was confirmed in 24 of 31 (77%) patients with volume less than 4 cm3, meanwhile only 4 of 17 (24%) patients with volume of 4 cm3 or more showed complete obliteration. Complete obliteration rate was 67% with 20 Gy or higher marginal dose, 63% with 15-20 Gy, and 17% with less than 15 Gy. CONCLUSION: GKS can provide high rates of obliteration with acceptable risk of morbidity in a subgroup of small AVMs. However, overall outcome in whole spectrum of AVMs, in which large proportion of cases have unfavorable characteristics for radiosurgery, is much worse. More effective therapeutic strategy needs to be developed for large AVMs that are difficult to be managed with current available treatment modalities.

Pituitary Irradiation by Gamma Knife in Intractable Cancer Pain

OBJECTIVE: Cancer pain has been treated by gamma knife radiosurgery(GKS), targeted to the pituitary gland-stalk, as an alternative new pain control method. The purpose of this study is to prove the efficacy and the safety of this treatment. METHODS: Seven patients with intractable cancer pain underwent pituitary gland-stalk irradiation by gamma knife. Selections for patient inclusion in this treatment protocol were no other effective pain treatment options, general condition rated as greater than 40 on Karnofsky Performance Scale, and pain relief by morphine though not satisfactory. The target was the junction between the pituitary stalk and the neurohypophysis. The maximum dose was 150~160Gy with one isocenter in 8mm collimator or two isocenters in 4mm collimator keeping the radiation dose to the optic nerve less than 8Gy. RESULTS: In all seven cases, the significant pain reduction was obtained during immediate post-GKS period without serious complications except one patient who developed transient hypopituitarism and diabetes insipidus. Pain relief was observed within several days, and this effect was prolonged for a quite long time. At a follow up of 1.5 to 13 months, pain recurred in two patients and no hormonal and visual dysfunctions were observed. CONCLUSION: Despite insufficient experience, the efficacy and the safety of GKS for intractable cancer pain were demonstrated in seven patients. This treatment has the potential to ameliorate cancer pain, and GKS will play a more important role in the treatment of intractable pain.