Roman Liscak

Development of a model to predict permanent symptomatic postradiosurgery injury for arteriovenous malformation patients

PURPOSE To better predict permanent complications from arteriovenous malformation (AVM) radiosurgery. METHODS AND MATERIALS Data from 85 AVM patients who developed symptomatic complications following gamma knife radiosurgery and 337 control patients with no complications were evaluated as part of a multi-institutional study. Of the 85 patients with complications, 38 patients were classified as having permanent symptomatic sequelae (necrosis). AVM marginal doses varied from 10-35 Gy and treatment volumes from 0.26-47.9 cc. Median follow-up for patients without complications was 45 months (range: 24-92). RESULTS Multivariate analysis of the effects of AVM location and the volume of tissue receiving 12 Gy or more (12-Gy-Volume) allowed construction of a significant postradiosurgery injury expression (SPIE) score. AVM locations in order of increasing risk and SPIE score (from 0-10) were: frontal, temporal, intraventricular, parietal, cerebellar, corpus callosum, occipital, medulla, thalamus, basal ganglia, and pons/midbrain. The final statistical model predicts risks of permanent symptomatic sequelae from SPIE scores and 12-Gy-Volumes. Prior hemorrhage, marginal dose, and Marginal-12-Gy-Volume (target volume excluded) did not significantly improve the risk-prediction model for permanent sequelae (p >/= 0.39). CONCLUSION The risks of developing permanent symptomatic sequelae from AVM radiosurgery vary dramatically with location and, to a lesser extent, volume. These risks can be predicted according to the SPIE location-risk score and the 12-Gy-Volume.

A multi-institutional analysis of complication outcomes after arteriovenous malformation radiosurgery

PURPOSE To better understand radiation complications of arteriovenous malformation (AVM) radiosurgery and factors affecting their resolution. METHODS AND MATERIALS AVM patients (102/1255) who developed neurological sequelae after radiosurgery were studied. The median AVM marginal dose (Dmin) was 19 Gy (range: 10-35). The median volume was 5.7 cc (range: 0.26-143). Median follow-up was 34 months (range: 9-140). RESULTS Complications consisted of 80/102 patients with evidence of radiation injury to the brain parenchyma (7 also with cranial nerve deficits, 12 also with seizures, 5 with cyst formation), 12/102 patients with isolated cranial neuropathies, and 10/102 patients with only new or worsened seizures. Severity was classified as minimal in 39 patients, mild in 40, disabling in 21, and fatal in 2 patients. Symptoms resolved completely in 42 patients for an actuarial resolution rate of 54% +/- 7% at 3 years post-onset. Multivariate analysis identified significantly greater symptom resolution in patients with no prior history of hemorrhage (p = 0.01, 66% vs. 41%), and in patients with symptoms of minimal severity: headache or seizure as the only sequelae of radiosurgery (p < 0.0001, 88% vs. 34%). CONCLUSION Late sequelae of radiosurgery manifest in varied ways. Further long-term studies of these problems are needed that take into account symptom severity and prior hemorrhage history.

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

Summary:  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.

Functional magnetic resonance imaging during deep brain stimulation: a pilot study in four patients with Parkinson's disease.

Functional magnetic resonance imaging (fMRI) was performed in patients with Parkinsons disease during deep brain stimulation of the subthalamic nucleus (three patients) and during deep brain stimulation of the ventral intermedius nucleus of the thalamus (one patient). All showed an increase in blood oxygenation level‐dependent signal in the subcortical regions ipsilateral to the stimulated nucleus. This effect cannot be simply explained by a mechanism of depolarization blockade; rather, it is caused by overstimulation of the target nucleus, resulting in the suppression of its spontaneous activity. We confirm that fMRI during deep brain stimulation is a safe method with considerable potential for elucidating the functional connectivity of the stimulated nuclei.

Arteriovenous malformations after Leksell gamma knife radiosurgery: Rate of obliteration and complications - Commentary

OBJECTIVEAlthough relevant information exists regarding the chance of obliterating arteriovenous malformations (AVMs) using radiosurgery, the overall chance of cure after gamma knife radiosurgery is usually only extrapolated from a portion of all monitored patients. This chance and the risks involved in radiosurgery, including repeat treatment when necessary in a defined population of treated patients, were analyzed in our study. METHODSBetween October 1992 and June 2000, gamma knife radiosurgery was performed on 330 patients with AVMs. The volume of the AVM nidus ranged from 0.15 to 28.6 cm3 (median, 3.9 cm3). When complete obliteration was not achieved within 3 years, repeat radiosurgery was performed on 76 patients. The volume of the nidus for the second treatment ranged from 0.09 to 16.8 cm3 (median 2.9 cm3). The result was reviewed in 300 (91%) patients after the first round of treatment and in 68 (89.5%) after the second round of treatment. RESULTSAVM obliteration was achieved in 222 (74%) patients after the first round of radiosurgery and in 47 (69%) after the second. The overall chance of cure was 92% (269 patients). Final angiography verified complete obliteration by 12 to 96 months (median, 25 mo) after initial radiosurgery. Smaller volume AVMs and the application of a higher radiation dose resulted in a higher chance of obliteration. The risk of rebleeding after radiosurgery was 2.1% annually until full obliteration, and the overall mortality from rebleeding was 1%. The risk of permanent morbidity after the first and second radiosurgery treatments were 2.7 and 2.9%, respectively. The cumulative risk of morbidity in both groups of patients was 3.4%. CONCLUSIONAlthough one-quarter of the patients required that the treatment be repeated, gamma knife radiosurgery can offer a high cure rate for patients treated for AVMs with a low risk of morbidity and mortality from rebleeding during the latent period.

Gamma Knife surgery for benign meningioma.

OBJECT Meningioma is the most frequent benign tumor treated with Gamma Knife surgery (GKS); however, the assessment of its efficacy and safety in slow-growing tumors is an ongoing process, requiring analysis of long-term results. METHODS Three hundred sixty-eight patients harboring 400 meningiomas treated between 1992 and 1999 at Na Homolce Hospital were evaluated. The median patient age was 57 years (range 18-84 years). The median tumor volume was 4.4 cm3 (range 0.11-44.9 cm3). The median tumor margin dose to the 50% isodose line was 12.55 Gy (range 6.5-24 Gy). Descriptive analysis was performed in 331 patients (90%); 325 patients had a follow-up longer than 24 months (median 60 months), and six patients were included because of posttreatment complications. The volume of treated tumors decreased in 248 cases (69.7%), remained the same in 99 (27.8%), and increased in nine (2.5%). The actuarial tumor control rate was 97.9% at 5 years post-GKS. Perilesional edema after radiosurgery was confirmed on neuroimaging in 51 patients (15.4%). The temporary and permanent morbidity rates after radiosurgery were 10.2 and 5.7%, respectively. RESULTS A significantly higher incidence of tumor volume increase was observed in men compared with women and in tumors treated with a margin dose lower than 12 Gy. Significant risk factors for edema included an age greater than 60 years, no previous surgery, perilesional edema before radiosurgery, a tumor volume greater than 10 cm3, a tumor location in the anterior fossa, and a margin dose greater than 16 Gy. CONCLUSIONS Stereotactic radiosurgery is a safe method of treatment for meningiomas. A minimum margin dose of 12 to 16 Gy seems to represent the therapeutic window for benign meningiomas with a high tumor control rate in a mid-term follow-up period.

Gamma Knife Radiosurgery of Meningiomas in the Cavernous Sinus Region

Summary For 6 years (1992–1998) we have treated 67 patients with cavernous sinus meningioma using the Leksell gamma knife in the Hospital Na Homolce, Prague. The age of the patients ranged between 19–82 years, median 57 years. Radiosurgery was the primary treatment in 64,2% of the patients, in the rest a microsurgical resection preceded. The volume of the tumour ranged from 0,9–31,4 cm3, median 7,8 cm3. The meningioma was distant from the optic tract in 58% of the cases, in 12% of the cases there was a contact with the tumour and the optic tract without its compression and in 30% of the cases there was a compression of the optic tract caused by the meningioma. The dose to the tumour margin ranged from 10–14 Gy, median 12 Gy. The follow up was available in 53 patients, in intervals of 2–60 months, median 19 months. There was no change in the tumour volume in 48% of the cases, in 52% of the cases a decrease of the tumour volume occurred. No increase of the tumour volume was observed. Clinical symptoms and signs improved in 35,8% of the patients, temporary morbidity was 3,8%. The mortality of the treatment was zero. Hitherto, the results of gamma knife radiosurgery of cavernous sinus meningioma have proved its safety and efficiency, although long term experience with a large group of patients is missing. Advances in neuroradiology and radiosurgical technique have allowed us to treat tumours with a closer contact to the optic tract and nerves compared with the past.

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.

Treatment of essential trigeminal neuralgia with gamma knife surgery

OBJECT The authors present the long-term follow-up results (minimum 5 years) of patients with essential trigeminal neuralgia (TN) who were treated with gamma knife surgery (GKS). METHODS One hundred seven patients (61 females and 46 males) underwent GKS. The median follow up was time was 60 months (range 12-96 months). The target was the trigeminal root, and the maximum dose was 70 to 80 Gy. Repeated GKS was performed in 19 patients for recurrent pain, and the same dose was used. Initial successful results were achieved in 96% of patients, with complete pain relief in 80.4%. Relief was achieved after a median latency of 3 months (range 1 day-13 months). Gamma knife surgery failed in 4% of patients. Pain recurred in 25% of patients after a median latent interval of 36 months (6-94 months). The initial success rate after a second GKS was 89% and 58% of patients were pain free. Pain relapse occurred in only one patient in this group. Hypesthesia was observed in 20% of patients after the first GKS and in 32% after the second GKS. The median interval to hypaesthesia was 35 months (range 3-94 months) after one treatment and 21 months (range 1-72 months) after a second treatment. CONCLUSIONS The initial success rate of pain relief was high and comparable to that reported in other studies. A higher than usual incidence of sensory impairment after GKS could be the long duration of follow-up study and due to the detailed neurological examination.

Long-term Tumor Control of Benign Intracranial Meningiomas After Radiosurgery in a Series of 4565 Patients

BACKGROUND Radiosurgery is the main alternative to microsurgical resection for benign meningiomas. OBJECTIVE To assess the long-term efficacy and safety of radiosurgery for meningiomas with respect to tumor growth and prevention of associated neurological deterioration. Medium- to long-term outcomes have been widely reported, but no large multicenter series with long-term follow-up have been published. METHODS From 15 participating centers, we performed a retrospective observational analysis of 4565 consecutive patients harboring 5300 benign meningiomas. All were treated with Gamma Knife radiosurgery at least 5 years before assessment for this study. Clinical and imaging data were retrieved from each center and uniformly entered into a database by 1 author (A.S.). RESULTS Median tumor volume was 4.8 cm3, and median dose to tumor margin was 14 Gy. All tumors with imaging follow-up < 24 months were excluded. Detailed results from 3768 meningiomas (71%) were analyzed. Median imaging follow-up was 63 months. The volume of treated tumors decreased in 2187 lesions (58%), remained unchanged in 1300 lesions (34.5%), and increased in 281 lesions (7.5%), giving a control rate of 92.5%. Only 84 (2.2%) enlarging tumors required further treatment. Five- and 10-year progression-free survival rates were 95.2% and 88.6%, respectively. Tumor control was higher for imaging defined tumors vs grade I meningiomas (P < .001), for female vs male patients (P < .001), for sporadic vs multiple meningiomas (P < .001), and for skull base vs convexity tumors (P < .001). Permanent morbidity rate was 6.6% at the last follow-up. CONCLUSION Radiosurgery is a safe and effective method for treating benign meningiomas even in the medium to long term.