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Dusan Urgosik and Roman Liscak


Ablative procedures are still useful in the treatment of intractable pain despite the proliferation of neuromodulation techniques. In the paper the authors present the results of Gamma Knife thalamotomy (GKT) in various pain syndromes.


Between 1996 and 2016, unilateral GKT was performed in 30 patients suffering from various severe pain syndromes in whom conservative treatment had failed. There were 20 women and 10 men in the study population, with a median age of 80 years (range 53–89 years). The pain syndromes consisted of 8 patients with classic treatment-resistant trigeminal neuralgia (TN), 6 with postherpetic TN, 5 with TN and constant pain, 1 with TN related to multiple sclerosis, 3 with trigeminal neuropathic pain, 4 with thalamic pain, 1 with phantom pain, 1 with causalgic pain, and 1 with facial pain. The median follow-up period was 24 months (range 12–180 months). Invasive procedures for pain release preceded GKT in 20 patients (microvascular decompression, glycerol rhizotomy, balloon microcompression, Gamma Knife irradiation of the trigeminal root, and radiofrequency thermolesion). The Leksell stereotactic frame, GammaPlan software, and T1- and T2-weighted sequences acquired at 1.5 T were used for localization of the targeted medial thalamus, namely the centromedian (CM) and parafascicularis (Pf) nucleus. The CM/Pf complex was localized 4–6 mm lateral to the wall of the third ventricle, 8 mm posterior to the midpoint, and 2–3 mm superior to the intercommissural line. GKT was performed using the Leksell Gamma Knife with an applied dose ranging from 145 to 150 Gy, with a single shot, 4-mm collimator. Pain relief after radiation treatment was evaluated. Decreased pain intensity to less than 50% of the previous level was considered successful.


Initial successful results were achieved in 13 (43.3%) of the patients, with complete pain relief in 1 of these patients. Relief was achieved after a median latency of 3 months (range 2–12 months). Pain recurred in 4 (31%) of 13 patients after a median latent interval of 24 months (range 22–30 months). No neurological deficits were observed.


These results suggest that GKT in patients suffering from severe pain syndromes is a relatively successful and safe method that can be used even in severely affected patients. The only risk of GT for the patients in this study was failure of treatment, as no clinical side effects were observed.

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Hana Malikova, Roman Liscak, and Zdeněk Vojtěch

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Dušan Urgošík, Josef Vymazal, Vilibald Vladyka, and Roman Liščák

Object. Postherpetic neuralgia is a syndrome characterized by intractable pain. Treatment of this pain has not yet been successful. Patients with postherpetic neuralgia will therefore benefit from any progress in the treatment strategy. The authors performed gamma knife radiosurgery (GKS) as a noninvasive treatment for postherpetic trigeminal neuralgia (TN) and evaluated the success rate for pain relief.

Methods. Between 1995 and February 1999, six men and 10 women were treated for postherpetic TN; conservative treatment failed in all of them. The median follow up was 33 months (range 8–34 months). The radiation was focused on the root of the trigeminal nerve in the vicinity of the brainstem (maximal dose 70–80 Gy in one fraction, 4-mm collimator). The patients were divided into five groups according to degree of pain relief after treatment.

A successful result (excellent, very good, and good) was reached in seven (44%) patients and radiosurgery failed in nine (56%). Pain relief occurred after a median interval of 1 month (range 10 days–6 months). No radiation-related side effects have been observed in these patients.

Conclusions. These results suggest that GKS for postherpetic TN is a relatively successful and safe method that can be used in patients even if they are in poor condition. In case this method fails, other treatment options including other neurosurgical procedures are not excluded.

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Josef Novotný Jr., Aurelia Kollová, and Roman Liščák


This study was focused on the development of models with which to predict the occurrence of intracranial edema after Gamma Knife surgery (GKS) of meningiomas, based on clinical and imaging data collected in a large group of patients.


Data in 368 patients with 381 meningiomas treated using the Leksell Gamma Knife unit were analyzed. Follow up of more than 24 months was available in 331 patients (90%); this time period ranged from 24 to 120 months (median 51 months). The actuarial tumor control rate was 97.9% at 5 years. Perilesional edema after GKS was radiologically confirmed in 51 patients (15.4%) and 32 of them (9.7%) were symptomatic; symptoms were temporary in 23 (6.9%) and permanent in nine (2.7%). Ten different factors were proposed as potential predictors for the occurrence of the intracranial edema after GKS: patient's sex, patient's age, previous surgery, edema before GKS treatment, lobulated margin of meningioma, heterogeneous appearance of the tumor, tumor volume, tumor location, maximum dose to the tumor, and dose to the tumor margin. To identify factors having influence on edema occurrence, univariate and multivariate statistical analyses were performed.

There was a significant difference in the incidence of edema for different patient age groups and a significantly higher incidence of edema occurrence in patients in whom no surgical procedure was performed before GKS, those with edema present before GKS, those with a tumor volume larger than 10 cm3, those in whom the tumor was located in the anterior fossa, those in whom the maximum dose to the tumor was higher than 30 Gy, and for different tumor margin doses. A binary logistic regression multifactorial prediction model was used to identify the following significant factors to predict of edema occurrence after GKS: previous surgery, edema before the treatment, tumor volume, tumor location, and tumor margin dose.


Based on these models estimates of the occurrence of edema after the GKS can be made, and consequently treatment parameters can be adjusted to reduce the occurrence of edema. These results may provide grounds for additional patient care such as more frequent follow up or possibly administration of steroids.

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Gabriela Simonová, Josef Novotny Jr., and Roman Liscák

Object. The authors sought to evaluate local tumor control, complications, and progression-free survival in patients harboring low-grade gliomas who were treated with Leksell gamma knife surgery (GKS).

Methods. During a 6-year period 70 patients were treated for verified low-grade gliomas (Grade I or II) by GKS. Statistical analysis was based on 68 patients; two patients were lost to follow up. The median patient age was 17 years. The median target volume was 4200 mm. The median prescription dose was 25 Gy. The median number of fractions was five. Ninety-five percent of patients were treated in five daily fractions.

Partial or complete tumor regression was achieved in 83% of patients with a median time to response of 18 months. There was moderate acute or late toxicity in not more than 5% of patients. In this series the progression-free survival was 92% at 3 years and 88% at 5 years.

Conclusions. Relatively high local tumor control with minimal complications was achieved.

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Gabriela s˘imonová, Josef Novotný, Roman Lis˘c˘ák, and Jir˘í Pilbauer

Object. The purpose of this study was to analyze treatment results, radiation-induced side effects, and prognostic survival factors for patients with uveal melanoma.

Methods. Eighty-one patients with uveal melanoma were treated using the Leksell gamma knife during a period of 6 years (1996–2001). There were 45 men and 36 women with a median age of 59 years (range 22–85 years). Seventyfive of these patients underwent minimal follow up 10 months after treatment. After patient eye immobilization, magnetic resonance (MR) imaging was performed to enable stereotactic localization. A scoring system was used to measure radiation side effects. The median target volume was 640 mm3, and the median applied minimal dose was 31.4 Gy. All patients were examined by an ophthalmologist and with MR imaging at regular intervals. Factors influencing posttreatment survival and side effects were statistically analyzed.

Conclusions. Local tumor control in the 75 patients who underwent minimal follow up after 10 months was achieved in 63 patients (84%), whereas progression was observed in 12 patients (16%). The most frequent side effect was secondary glaucoma, which was detected in 18 patients (25%). The incidence of this side effect was significantly higher when the total volume of peripheral isodose was greater than 1000 mm3 (p = 0.015). Toxicity in the optic nerve here was also significantly higher when the maximum dose to this structure was higher than 9 Gy (p = 0.011), in the cornea when the maximum dose was higher than 15 Gy (p = 0.010), and in the lens when the maximum dose was higher than 10 Gy (p = 0.035). Altogether three pretreatment variables (patient age, tumor location, and dissemination of the disease) and one treatment variable (the minimum dose applied) were identified as having a significant influence on a patient's survival.

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Veronika Paštyková, Josef Novotný Jr., Tomáš Veselský, Dušan Urgošík, Roman Liščák, and Josef Vymazal


The aim of this study was to compare 3 different methods to assess the geometrical distortion of two 1.5-T and one 3-T magnetic resonance (MR) scanners and to evaluate co-registration accuracy. The overall uncertainty of each particular method was also evaluated.


Three different MR phantoms were used: 2 commercial CIRS skull phantoms and PTGR known target phantom and 1 custom cylindrical Perspex phantom made in-house. All phantoms were fixed in the Leksell stereotactic frame and examined by a Siemens Somatom CT unit, two 1.5-T Siemens (Avanto and Symphony) MRI systems, and one 3-T Siemens (Skyra) MRI system. The images were evaluated using Leksell GammaPlan software, and geometrical deviation of the selected points from the reference values were determined. The deviations were further investigated for both definitions including fiducial-based and co-registration–based in the case of the CIRS phantom images. The same co-registration accuracy assessment was also performed for a clinical case. Patient stereotactic imaging was done on 3-T Skyra, 1.5-T Avanto, and CT scanners.


The accuracy of the CT scanner was determined as 0.10, 0.30, and 0.30 mm for X, Y, and Z coordinates, respectively. The total estimated uncertainty in distortion measurement in one coordinate was determined to be 0.32 mm and 0.14 mm, respectively, for methods using and not using CT as reference imaging. Slightly more significant distortions were observed when using the 3-T than either 1.5-T MR units. However, all scanners were comparable within the estimated measurement error. Observed deviation/distortion for individual X, Y, and Z stereotactic coordinates was typically within 0.50 mm for all 3 scanners and all 3 measurement methods employed. The total radial deviation/distortion was typically within 1.00 mm. Maximum total radial distortion was observed when the CIRS phantom was used; 1.08 ± 0.49 mm, 1.15 ± 0.48 mm, and 1.35 ± 0.49 mm for Symphony, Avanto, and Skyra, respectively. The co-registration process improved image stereotactic definition in a clinical case in which fiducial-based stereotactic definition was not accurate; this was demonstrated for 3-T stereotactic imaging in this study. The best results were shown for 3-T MR image co-registration with CT images improving image stereotactic definition by about 0.50 mm. The results obtained with patient data provided a similar trend of improvement in stereotactic definition by co-registration.


All 3 methods/phantoms used were evaluated as satisfactory for the image distortion measurement. The method using the PTGR phantom had the lowest uncertainty as no reference CT imaging was needed. Image co-registration can improve stereotactic image definition when fiducial-based definition is not accurate.

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Gabriela Simonova, Petra Kozubikova, Roman Liscak, and Josef Novotny Jr.


The purpose of this study was to evaluate long-term treatment results, radiation-related toxicity, and prognostic factors for the progression-free survival (PFS) of patients with pilocytic astrocytomas treated by means of stereotactic radiosurgery with a Leksell Gamma Knife.


A total of 25 patients with pilocytic astrocytomas underwent Gamma Knife surgery during the period 1992–2002. The median target volume was 2700 mm3 (range 205–25,000 mm3). The 18 patients treated with 5 daily fractions received a median minimum target dose of 25 Gy. Doses for the 2 patients treated with 10 fractions over 5 days (2 fractions delivered on the same day at least 6 hours apart) were 23 and 28 Gy. For the 5 patients treated with a single fraction, the minimum target dose ranged from 13 to 20 Gy (median 16 Gy).


Complete regression occurred in 10 patients (40%) and partial regression in 10 patients (40%). The 10-year overall survival rate was 96% and the 10-year PFS rate was 80%. Target volume appeared to be a significant prognostic factor for PFS (p = 0.037). Temporary Grade 3 toxicity appeared in 2 patients (8%), and these patients were treated with corticosteroids for 2 months. Permanent Grade 4 toxicity appeared in 2 patients (8%) and was associated with neurocognitive dysfunction. In these 2 individuals, the neurocognitive dysfunction was also felt to be in part the result of the additional therapeutic interventions (4 in one case and 6 in the other) required to achieve durable control of their tumors.


Radiosurgery represents an alternative treatment modality for small residual or recurrent volumes of pilocytic astrocytomas and provides long-term local control. Target volume appears to be the most important factor affecting PFS.

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Roman Liscák, Vilibald Vladyka, Gabriela Simonová, Josef Vymazal, and Josef Novotny Jr.

Object. The authors conducted a study to record more detailed information about the natural course and factors predictive of outcome following gamma knife surgery (GKS) for cavernous hemangiomas.

Methods. One hundred twelve patients with brain cavernous hemangiomas underwent GKS between 1993 and 2000. The median prescription dose was 16 Gy. One hundred seven patients were followed for a median of 48 months (range 6–114 months). The rebleeding rate was 1.6%, which is not significantly different with that prior to radiosurgery (2%). An increase in volume was observed in 1.8% of cases and a decrease in 45%. Perilesional edema was detected in 27% of patients, which, together with the rebleeding, caused a transient morbidity rate of 20.5% and permanent morbidity rate of 4.5%. Before radiosurgery 39% of patients suffered from epilepsy and this improved in 45% of them. Two patients with brainstem cavernous hemangiomas died due to rebleeding. Rebleeding was more frequent in female middle-aged patients with a history of bleeding, a larger lesion volume, and a prescription dose below 13 Gy. Edema after GKS occurred more frequently in patients who had surgery, a larger lesion volume, and in those in whom the prescription dose was more than 13 Gy.

Conclusions. Gamma knife surgery of cavernous hemangiomas can produce an acceptable rate of morbidity, which can be reduced by using a lower margin dose. Lesion regression was observed in many patients. Radiosurgery seems to remain a suitable treatment modality in carefully selected patients.

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Daniela Tlachacova, Michal Schmitt, Josef Novotny Jr., Josef Novotny, Mustafa Majali, and Roman Liscak

Object. The authors sought to compare the quality of treatment planning, radiation protection, and the time taken for treatment in the Leksell gamma knife model B with that using the model C Automatic Positioning System (APS).

Methods. Data were obtained in 463 patients treated with the B model and 518 patients treated with the C model. Data were analyzed in patients in whom the following diagnoses had been made: vestibular schwannoma, pituitary adenoma, meningioma, solitary metastasis, and other benign and malignant solitary tumors. Patients with arteriovenous malformations, ocular lesions, and functional diagnoses were excluded from this study.

Conclusions. With the C model there was a better conformity for most treated targets, such as vestibular schwannomas (p = 0.005) and meningiomas (p = 0.015). The level of radiation exposures to personnel was significantly decreased when using the model C (p < 0.001). There was no significant difference in radiation exposure of extracranial structures for the same number of shots in patients treated by both models. The mean time saved using the C model with the APS was 41 minutes per treatment. It would seem that the gamma knife model C permits better dose conformity, shorter treatment times, and less radiation exposure to personnel.