Gerhard Pendl

Gamma knife surgery in mesial temporal lobe epilepsy: a prospective multicenter study.

Summary:u2003 Purpose: This article is the first prospective documentation of the efficacy and safety of gamma knife surgery (GKS) in the treatment of drug‐resistant epilepsies of mesial temporal lobe origin.

Gamma knife for glioma: Selection factors and survival

PURPOSEnTo determine factors associated with survival differences in patients treated with radiosurgery for glioma.nnnMETHODS AND MATERIALSnWe analyzed 189 patients treated with Gamma Knife radiosurgery for primary or recurrent glioma World Health Organization (WHO) Grades 1-4.nnnRESULTSnnnnCONCLUSIONnThe median minimum tumor dose was 16 Gy (8-30 Gy) and the median tumor volume was 5.9 cc (1.3-52 cc). Brachytherapy selection criteria were satisfied in 65% of patients. Median follow-up of all surviving patients was 65 weeks after radiosurgery. For primary glioblastoma patients, median survival from the date of pathologic diagnosis was 86 weeks if brachytherapy criteria were satisfied and 40 weeks if they were not (p = 0.01), indicating that selection factors strongly influence survival. Multivariate analysis showed that increased survival was associated with five variables: lower pathologic grade, younger age, increased Karnofsky performance status (KPS), smaller tumor volume, and unifocal tumor. Survival was not found to be significantly related to radiosurgical technical parameters (dose, number of isocenters, prescription isodose percent, inhomogeneity) or extent of preradiosurgery surgery. We developed a hazard ratio model that is independent of the technical details of radiosurgery and applied it to reported radiosurgery and brachytherapy series, demonstrating a significant correlation between survival and hazard ratio.nnnCONCLUSIONSnSurvival after radiosurgery for glioma is strongly related to five selection variables. Much of the variation in survival reported in previous series can be attributed to differences in distributions of these variables. These variables should be considered in selecting patients for radiosurgery and in the design of future studies.

A Six Year Experience with the Postoperative Radiosurgical Management of Pituitary Adenomas

Since April 1992, 73 consecutive patients with pituitary adenomas were treated with radiosurgery. There were 31 hormonally inactive adenomas and 42 hormonally active adenomas. All but three patients had been subjected to one or more surgical procedures prior to radiosurgery. Three patients had received fractionated radiotherapy. In the inactive adenoma group, the mean target volume was 4.4 ¿ 3 cm3 and the mean prescription dose was 13.8¿1.5 Gy. In the prolactinoma patients, the mean target volume was 6.7 ¿ 9 cm3 and the mean prescription dose was 14.2 ¿4 Gy. In the acromegalic patients, the mean target volume was 2.9¿2.5 cm3 and the mean prescription dose was 16¿4 Gy. ACTH secreting adenomas had a mean target volume of 3.6 ¿ 5.5 cm3 with a mean prescription dose of 17 ¿4.8 Gy. The mean follow-up time was 28.9 ¿ 21.5 months. Follow-up data was available in 83.6% of the patients. Tumor control was achieved in 98.3% and the endocrinological cure rate was 57%. Pituitary function deteriorated in 19.2%. No patient suffered from radiation induced visual damage. It would seem that postoperative radiosurgery for residual or recurrent pituitary adenomas may be a safe technique that can increase the frequency of therapeutic success.

Gamma Knife radiosurgery of the glomus jugulare tumour - early multicentre experience.

Summary¶u2003Leksell Gamma Knife was used to treat 66 patients with glomus jugulare tumour at 6 European sites between 1992–1998. The age of the patients ranged between 18–80 years (median 54 years). Gamma Knife radiosurgery was a primary treatment in 30 patients (45.5%). Open surgery preceded radiosurgery in 24 patients (36.4%), embolisation in 14 patients (21.2%) and fractionated radiotherapy in 5 patients (7.6%). The volume of the tumour ranged 0.5–27 cm3 (median 5,7 cm3). The minimal dose to the tumour margin ranged between 10–30 Gy (median 16.5 Gy).u2003After radiosurgery 52 patients were followed, the follow up period was 3–70 months (median 24 months). Neurological deficit improved in 15 patients (29%) and deteriorated in 3 patients (5,8%), one transient and two persistant. Neuroradiological follow up using MRI or CT was performed in 47 patients 4–70 months (median 24 months) after radiosurgery. Tumour size decreased in 19 patients (40%) while in the remaining 28 patients (60%) no change in the tumour volume was observed. None of the tumours increased in volume during the observation period. Control angiography was performed in 6 patients. Pathological vascularisation completely disappeared in one patient, reduced in two and there was no change in the remaining three.u2003Radiosurgery proves to be a safe treatment for glomus jugulare tumour with no mortality and no acute morbidity. Because of its naturally slow growth rate, up to 10 years of follow up will be necessary to establish a cure rate after radiosurgery for these lesions.

Radiosurgery for Epilepsy Associated with Cavernous Malformation: Retrospective Study in 49 Patients

OBJECTIVEMicrosurgical resection of a cavernous malformation (CM) with or without associated cortical resection can provide efficient treatment of drug-resistant associated epilepsy. To explore the potential alternative role of radiosurgery and to evaluate its safety and efficacy for this indication, we conducted a retrospective multicenter study. METHODSWe retrospectively reviewed the files of patients with long-lasting drug-resistant epilepsy, presumably caused by CM, who were treated by gamma knife (GK) surgery for the control of their epilepsy in five centers (Marseilles, Komaki City, Prague, Graz, and Sheffield). A satisfactory follow-up was available for 49 patients (mean follow-up period, 23.66 ± 13 mo). The mean duration of epilepsy before the GK procedure was 7.5 (±9.3) years. The mean frequency of seizures was 6.9/month (±14). The mean marginal radiation dose was 19.17 Gy ± 4.4 (range, 11.25–36). Among the 49 patients, 17 (35%) had a CM located in or involving a highly functional area. RESULTSAt the last follow-up examination, 26 patients (53%) were seizure-free (Engel’s Class I), including 24 in Class IA (49%) and 2 patients with occasional auras (Class IB, 4%). A highly significant decrease in the number of seizures was achieved in 10 patients (Class IIB, 20%). The remaining 13 patients (26%) showed little or no improvement. The mediotemporal site was associated with a higher risk of failure. One patient bled during the observation period, and another experienced radiation-induced edema with transient aphasia. Postradiosurgery excision was performed in five patients, and a second radiosurgical treatment was carried out in one patient. CONCLUSIONThis series is the first to specifically evaluate the capability of GK surgery to safely and efficiently treat epilepsy associated with CM. Seizure control can be reached when a good electroclinical correlation exists between CM location and epileptogenic zone. Although we do not recommend GK surgery for prevention of bleeding for a CM that has not bled previously, our findings suggest that GK surgery can be proposed for the treatment of epilepsy when the CM is located in a highly functional area.

Gamma knife radiosurgery for uveal melanomas: an 8-year experience

The purpose of this paper was to note a potential source of error in magnetic resonance (MR) imaging. Magnetic resonance images were acquired for stereotactic planning for GKS of a vestibular schwannoma in a female patient. The images were acquired using three-dimensional sequence, which has been shown to produce minimal distortion effects. The images were transferred to the planning workstation, but the coronal images were rejected. By examination of the raw data and reconstruction of sagittal images through the localizer side plate, it was clearly seen that the image of the square localizer system was grossly distorted. The patient was returned to the MR imager for further studies and a metal clasp on her brassiere was identified as the cause of the distortion.A-60-year-old man with medically intractable left-sided maxillary division trigeminal neuralgia had severe cardiac disease, was dependent on an internal defibrillator and could not undergo magnetic resonance imaging. The patient was successfully treated using computerized tomography (CT) cisternography and gamma knife radiosurgery. The patient was pain free 2 months after GKS. Contrast cisternography with CT scanning is an excellent alternative imaging modality for the treatment of patients with intractable trigeminal neuralgia who are unable to undergo MR imaging.The authors describe acute deterioration in facial and acoustic neuropathies following radiosurgery for acoustic neuromas. In May 1995, a 26-year-old man, who had no evidence of neurofibromatosis Type 2, was treated with gamma knife radiosurgery (GKS; maximum dose 20 Gy and margin dose 14 Gy) for a right-sided intracanalicular acoustic tumor. Two days after the treatment, he developed headache, vomiting, right-sided facial weakness, tinnitus, and right hearing loss. There was a deterioration of facial nerve function and hearing function from pretreatment values. The facial function worsened from House-Brackmann Grade 1 to 3. Hearing deteriorated from Grade 1 to 5. Magnetic resonance (MR) images, obtained at the same time revealed an obvious decrease in contrast enhancement of the tumor without any change in tumor size or peritumoral edema. Facial nerve function improved gradually and increased to House-Brackmann Grade 2 by 8 months post-GKS. The tumor has been unchanged in size for 5 years, and facial nerve function has also been maintained at Grade 2 with unchanged deafness. This is the first detailed report of immediate facial neuropathy after GKS for acoustic neuroma and MR imaging revealing early possibly toxic changes. Potential explanations for this phenomenon are presented.In clinical follow-up studies after radiosurgery, imaging modalities such as computerized tomography (CT) and magnetic resonance (MR) imaging are used. Accurate determination of the residual lesion volume is necessary for realistic assessment of the effects of treatment. Usually, the diameters rather than the volume of the lesion are measured. To determine the lesion volume without using stereotactically defined images, the software program VOLUMESERIES has been developed. VOLUMESERIES is a personal computer-based image analysis tool. Acquired DICOM CT scans and MR image series can be visualized. The region of interest is contoured with the help of the mouse, and then the system calculates the volume of the contoured region and the total volume is given in cubic centimeters. The defined volume is also displayed in reconstructed sagittal and coronal slices. In addition, distance measurements can be performed to measure tumor extent. The accuracy of VOLUMESERIES was checked against stereotactically defined images in the Leksell GammaPlan treatment planning program. A discrepancy in target volumes of approximately 8% was observed between the two methods. This discrepancy is of lesser interest because the method is used to determine the course of the target volume over time, rather than the absolute volume. Moreover, it could be shown that the method was more sensitive than the tumor diameter measurements currently in use. VOLUMESERIES appears to be a valuable tool for assessing residual lesion volume on follow-up images after gamma knife radiosurgery while avoiding the need for stereotactic definition.This study was conducted to evaluate the geometric distortion of angiographic images created from a commonly used digital x-ray imaging system and the performance of a commercially available distortion-correction computer program. A 12 x 12 x 12-cm wood phantom was constructed. Lead shots, 2 mm in diameter, were attached to the surfaces of the phantom. The phantom was then placed inside the angiographic localizer. Cut films (frontal and lateral analog films) of the phantom were obtained. The films were analyzed using GammaPlan target series 4.12. The same procedure was repeated with a digital x-ray imaging system equipped with a computer program to correct the geometric distortion. The distortion of the two sets of digital images was evaluated using the coordinates of the lead shots from the cut films as references. The coordinates of all lead shots obtained from digital images and corrected by the computer program coincided within 0.5 mm of those obtained from cut films. The average difference is 0.28 mm with a standard deviation of 0.01 mm. On the other hand, the coordinates obtained from digital images with and without correction can differ by as much as 3.4 mm. The average difference is 1.53 mm, with a standard deviation of 0.67 mm. The investigated computer program can reduce the geometric distortion of digital images from a commonly used x-ray imaging system to less than 0.5 mm. Therefore, they are suitable for the localization of arteriovenous malformations and other vascular targets in gamma knife radiosurgery.

Treatment of cerebral radionecrosis by hyperbaric oxygen therapy

Clinically observed adverse radiation effects (ARE) are rather uncommon, but modern imaging reveals that they are more common after radiosurgery than previously believed. Little is known about the pathogenesis, and current treatment is mostly empirical. The benefit of hyperbaric oxygen therapy (HBO) on radiation-induced bone and soft tissue necrosis is known in lesions in the maxillofacial area, the mouth and in the head and neck. HBO raises the tissue pO2 and initiates a cellular and vascular repair mechanism. This forms the basis for the hypothesis that it might also help alleviate the results of cerebral radionecrosis. This study is a preliminary attempt to test this hypothesis. Two patients with arteriovenous malformations (AVMs) were chosen for the study. They had been treated with Gamma Knife radiosurgery (GKRS) and had developed imaging signs consistent with ARE. They were treated by breathing 100% oxygen at 2.5 atmospheres absolute (250 kPa) in sessions of 60 minutes per day. This treatment was repeated 40 times in cycles of ten sessions. Both responded well to HBO, one lesion disappeared and the other was reduced significantly in size. No adjuvant steroids were given. These results give evidence that HBO has a potential value in treating ARE but further experience will be needed to confirm its definite benefit.

Incidence of radiation retinopathy after high-dosage single-fraction gamma knife radiosurgery for choroidal melanoma

OBJECTIVEnTo investigate the incidence and clinical findings of radiation retinopathy after single-fraction high-dose gamma knife radiosurgery for choroidal melanoma.nnnDESIGNnRetrospective noncomparative interventional case series.nnnPARTICIPANTSnThirty-two patients with choroidal melanoma.nnnMETHODSnReview of charts, color fundus photographs, and fluorescein angiograms of 32 choroidal melanoma patients after radiosurgery. All patients were treated with the Leksell gamma knife in one fraction with a marginal dose between 40 and 80 Gy (median, 50 Gy) and were followed for at least 24 months (or until enucleation because of complications secondary to radiation).nnnMAIN OUTCOME MEASURESnAny clinical feature of radiation retinopathy and neovascular glaucoma.nnnRESULTSnDuring a mean follow-up of 38 months (range, 6-81 months) we found radiation retinopathy in 84% of our patients. The most common findings in these patients were intraretinal hemorrhages with an incidence of 70%, macular edema and capillary nonperfusion in 63%, and hard exudates in 52% of the patients. Less common were microaneurysms in 30% and retinal neovascularization in 22%. The time of onset of the various radiation-associated retinal findings ranged between 1 and 22 months. Forty-seven percent of all patients developed neovascular glaucoma. In our study there was no correlation between radiation dosage applied and clinical findings.nnnCONCLUSIONSnSingle-fraction high-dose Leksell gamma knife radiosurgery of choroidal melanomas with a median marginal dose of 50 Gy is highly associated with early radiation retinopathy and with neovascular glaucoma.

Gamma knife radiosurgery for glomus jugulare tumours.

Summaryu2003The aim of this clinical study was to determine the tumour control rate, clinical outcome and complication rate following gamma knife treatment for glomus jugulare tumours. Between May 1992 and May 1998, 13 patients with glomus tumours underwent stereotactic radiosurgical treatment in our department. The age of these patients ranged from 21 to 80 years. The male : female ratio was 2 : 11. Six patients had primary open surgery for partial removal or recurrent growth and subsequent radiosurgical therapy. Radiosurgery was performed as primary treatment in 7 cases. The median tumour volume was 6,4 cm3 (range: 4,6–13,7 cm3). The median marginal dose applied to an average isodose volume of 50% (30–50%) was 13,5 Gy (12–20 Gy). In 10 patients, a total of 48 MRI and CT follow-up scans were available. The remaining three patients have been excluded from the postradiosurgical evaluation since the observation time (t<12 months) was too short or patients were lost to follow up. The median interval from Gamma Knife treatment to the last radiological follow-up was 37,6 months (5–68 months). In 4 patients (40%) decreased tumour volumes were observed and in 6 cases (60%) the tumour size remained unchanged. Neurological follow-up examinations revealed improved clinical status in 5 patients (50%), a stable neurological status in 5 patients (50%) and no complications occurred. According to our preliminary experience Gamma Knife radiosurgery represents an effective treatment option for glomus jugulare tumours.

Cavernous Sinus Meningiomas – What Is the Strategy: Upfront or Adjuvant Gamma Knife Surgery?

43 patients with meningiomas of the cavernous sinus form the basis of this study. Two patients were treated with microsurgery alone, 17 patients were treated by Gamma Knife radiosurgery (GKRS) as a primary treatment modality, and 24 patients underwent a combined treatment of microsurgery followed by GKRS. Therefore, in 17 patients the diagnosis rested on clinical and radiological criteria alone. Cranial nerve disorders (CND) related to open surgical treatment were infrequent in this material (3 of 13 patients) due to deliberate strategies of partial or subtotal resection aimed at sparing cranial nerves from surgical maneuvers. In contrast, 6 of 11 patients, admitted for GKRS from other institutions suffered from considerable CND after open surgery and showed only partial improvement after GKRS. In all GKRS cases, no radiation-related complications were seen after a follow-up of 18–62 months (mean 39 months). Moreover, in all cases tumor control was obtained with a stable tumor volume in 63%, reduction of volume in 34.5% and a disappearance of tumor in 2.5%. GKRS is not only an additional treatment for meningiomas involving the cavernous sinus, but may be offered to the patient as an alternative primary treatment.