Repeat Stereotactic Radiosurgery for Progressive or Recurrent Vestibular Schwannomas.

BACKGROUND: Stereotactic radiosurgery (SRS) is a highly effective management approach for patients with vestibular schwannomas (VS), with 10-yr control rates up 98%. When it fails, however, few data are available to guide management. OBJECTIVE: To perform a retrospective analysis of patients who underwent 2 SRS procedures on the same VS to assess the safety and efficacy of this practice. METHODS: This study was opened to centers of the International Gamma Knife Research Foundation (IGKRF). Data collected included patient characteristics, clinical symptoms at the time of SRS, radiosurgery dosimetric data, imaging response, clinical evolution, and survival. Actuarial analyses of tumor responses were performed. RESULTS: Seventy-six patients from 8 IGKRF centers were identified. Median follow-up from the second SRS was 51.7 mo. Progression after the first SRS occurred at a median of 43 mo. Repeat SRS was performed using a median dose of 12 Gy. Actuarial tumor control rates at 2, 5, and 10 yr following the second SRS were 98.6%, 92.2%, and 92.2%, respectively. Useful hearing was present in 30%, 8%, and 5% of patients at first SRS, second SRS, and last follow-up, respectively. Seventy-five percent of patients reported stable or improved symptoms following the second SRS. Worsening of facial nerve function attributable to SRS occurred in 7% of cases. There were no reports of radionecrosis, radiation-associated edema requiring corticosteroids, radiation-related neoplasia, or death attributable to the repeat SRS procedure. CONCLUSION: Patients with progressing VS after radiosurgery can be safely and effectively managed using a second SRS procedure.

Morphological changes after radiosurgery for mesial temporal lobe epilepsy.

BACKGROUND: To review our experience with morphological developments during the long-term follow-up of patients treated by Gamma Knife radiosurgery for mesial temporal lobe epilepsy. METHOD: Between 1995 and 1999, we treated 14 patients with marginal doses of 24 Gy (n = 6) and 18-20 Gy (n = 8). Nine of these were operated on for insufficient seizure control. We reviewed seizure outcome and magnetic resonance images in both operated and unoperated patients and also re-examined histopathology specimens. RESULTS: Of the nine operated patients, two were Engel IIIA, one was IVA, five were IVB, and one was Engel IVC prior to surgery. At their final visit, five cases had become Engel class IA, one patient was ID, and two were IIC. In one patient the follow-up was not long enough for classification. Of the five unoperated patients, one was Engel class IB, one was IIIA, one IIB and one IVB at their final visit. Radionecrosis developed in 11 patients, occurring more often and earlier in those treated with higher doses. Collateral edema reached outside the temporal lobe in six patients, caused uncal herniation in two and intracranial hypertension in three. During longer follow-up, postnecrotic pseudocysts developed in 9 patients, and postcontrast enhancement persisted for 2.5-16 years after GKRS in all 14 patients. In five of them we detected its progression between 2 and 16 years after treatment. Signs of neoangiogenesis were found in two patients and microbleeds could be seen in five. Histopathology revealed blood vessel proliferation and macrophage infiltration. CONCLUSIONS: Early delayed complications and morphological signs suggesting a risk of development of late delayed complications are frequent after radiosurgery for mesial temporal lobe epilepsy. Together with its unproven antiseizure efficacy, these issues should be taken into account when planning future studies of this method.

MRI-guided stereotactic amygdalohippocampectomy: a single center experience.

BACKGROUND: This paper presents our experience of stereotactic radiofrequency amygdalohippocampectomy performed for intractable mesial temporal lobe epilepsy. METHODS: The article describes the cases of 61 patients who were treated during the period from 2004 to 2010. Mean postoperative follow-up was 5.3 years. Neuropsychological results were obtained for a subset of 31 patients. RESULTS: At their last postsurgical visit, 43 (70.5%) patients were Engel class I, six (9.8%) class II, nine (14.8%) class III, and three (4.9%) class IV. The surgery was complicated by four intracranial hematomas. One of them caused acute hydrocephalus and was treated by shunting and resolved without sequelae, while another caused transitory aphasia. The remaining hematomas were asymptomatic. There were two cases of meningitis which required antibiotic treatment. One patient committed suicide due to postoperative depression. After the procedure, we performed open epilepsy surgery and rethermolesions in three and two patients, respectively (8.2%). Patients showed increases in their mean full scale, verbal, and performance intelligence quotient (IQ) scores of 4, 3, and 4 IQ points, respectively (P<0.05). Five (17.2%), four (13.8%), and four (13.3%) patients improved their full scale, verbal, and performance IQ scores, respectively. No significant changes were found in memory performance, with a mean increase of 1, 3, and 0 memory quotient points in global, verbal, and visual memory, respectively (P<0.05). Global memory improved in three (10.3%) patients, verbal memory in one (3.4%), and one patient (3.3%) showed deterioration in visual memory. CONCLUSION: Stereotactic radiofrequency amygdalohippocampectomy offers a safe, effective, and less aggressive treatment modality in cases of well-defined mesial temporal lobe epilepsy. Seizure outcome is comparable with the results of conventional epilepsy surgery and cognitive results could be even better.

Gamma knife radiosurgery for Cushing's disease and Nelson's syndrome.

PURPOSE: This paper presents our 18 years of experience in treating ACTH secreting adenomas (Cushing's disease and Nelson's syndrome) using the Leksell gamma knife (LGK) irradiation. METHODS: Twenty-six patients with Cushing's disease were followed-up after LGK irradiation for 48-216 months (median 78 months). Seventeen patients had undergone previous surgery, in nine patients LGK irradiation was the primary therapy. Furthermore, 14 patients with Nelson's syndrome were followed-up for 30-204 months (median 144 months). RESULTS: LGK treatment resulted in hormonal normalization in 80.7 % of patients with Cushing's disease. Time to normalization was 6-54 months (median 30 months). The volume of the adenoma decreased in 92.3% (in 30.7% disappeared completely). There was no recurrence of the disease. In all 14 patients with Nelson's syndrome ACTH levels decreased (in two patients fully normalized) their ACTH levels. When checked up 5-10 years after irradiation regrowth of the adenoma was only detected in one patient (9.1%), in 27.3% adenoma volume remained unchanged, in 45.4% adenoma volume decreased and in 18.2% adenoma completely disappeared. Hypopituitarism did not develop in any patient where the critical dose to the pituitary and distal infundibulum was respected. CONCLUSION: LGK radiation represents an effective and well-tolerated option for the treatment of patients with Cushing's disease after unsuccessful surgery and may be valuable even as a primary treatment in patients who are not suitable for, or refuse, surgery. In the case of Nelson's syndrome it is possible to impede tumorous growth and control the size of the adenoma in almost all patients.

Leksell Gamma Knife radiosurgery of the jugulotympanic glomus tumor: long-term results.

OBJECT: Glomus tumors usually display indolent behavior, and the effectiveness of radiation in stopping their growth can be assessed after long-term follow-up. Currently only midterm results of radiosurgery are available, so the authors included patients treated by Gamma Knife at least 10 years ago in this study to obtain a perspective of long-term results. METHODS: During the period from 1992 to 2003, the Gamma Knife was used to treat 46 patients with glomus tumors. The age of the patients ranged from 21 to 79 years (median 56 years). Gamma Knife radiosurgery was the primary treatment in 17 patients (37%). Open surgery preceded radiosurgery in 46% of cases, embolization in 17%, and fractionated radiotherapy in 4%. The volume of the tumor ranged from 0.2 to 24.3 cm(3) (median 3.6 cm(3)). The minimal dose to the tumor margin ranged between 10 and 30 Gy (median 20 Gy). RESULTS: One patient was lost for follow-up after radiosurgery. Clinical follow-up was available in 45 patients and 44 patients were followed with MRI in a follow-up period that ranged from 12 to 217 months (median 118 months). Neurological deficits improved in 19 (42%) of 45 patients and deteriorated in 2 patients (4%). Tumor size decreased in 34 (77%) of 44 patients with imaging follow-up, while an increase in volume was observed in 1 patient (2%) 182 months after radiosurgery and Gamma Knife treatment was repeated. One patient underwent another Gamma Knife treatment for secondary induced meningioma close to the glomus tumor 98 months after initial radiosurgical treatment. Seven patients died 22-96 months after radiosurgery (median 48 months), all for unrelated reasons. CONCLUSIONS: Radiosurgery has proved to be a safe treatment with a low morbidity rate and a reliable long-term antiproliferative effect.

Long-term seizure outcome after stereotactic amygdalohippocampectomy.

BACKGROUND: The aim of the study was to evaluate the long-term seizure outcome and complications after stereotactic radiofrequency amygdalohippocampectomy (SAHE) performed for mesial temporal lobe epilepsy (MTLE). METHODS: The article describes the cases of 61 patients who were treated at our institution during the period 2004-2010. Mean post-operative follow-up was 5.3 years. RESULTS: At the last postsurgical visit, 43 (70.5 %) patients were Engel Class I, six (9.8 %) Class II, nine (14.8 %) Class III and three (4.9 %) Class IV. The surgery was complicated by four intracranial haematomas. One of them caused acute hydrocephalus and was treated by shunting and resolved without sequelae. After SAHE, we performed open epilepsy surgery and re-thermo lesions in three and two patients, respectively (8.2 %). There were two cases of meningitis which required antibiotic treatment. In six patients psychiatric disorders developed and one of these committed suicide due to postoperative depression. CONCLUSIONS: Our results provide preliminary evidence for good long-term seizure outcomes after SAHE. SAHE could be an alternative therapy for MTLE.

[Deep brain stimulation in movement disorders: a Prague-center experience]. / Hluboká mozková stimulace u extrapyramidových poruch pohybu - praiská zkusenost.

Deep brain stimulation (DBS) in the basal ganglia plays an irreplaceable role in the treatment of Parkinson's disease (PD), essential tremor (ET), and some types of dystonia. Electrodes are typically inserted into the subthalamic nucleus (STN), the internal globus pallidus (GPi) and the ventral intermediate nucleus of the thalamus (VIM). Stimulation of the STN is the main objective in PD, GPi in the treatment of dystonia and PD, and VIM stimulation is effective against tremor. In patients indicated for DBS treatment, stimulation eliminates or reduces rigidity (PD), hypokinesia (PD), tremor (ET, PD) and dyskinesias (dystonia, PD). At the Center for Movement Disorders in Prague, DBS has been performed in 127 patients: in 86 patients for PD, 19 patients for dystonia (11 primary generalized dystonia, 5 primary cervical dystonia, 1 segmental craniocervical dystonia), and in 22 patients for tremor (20 ET, 2 other types of tremor). Intraoperatively we have succeeded in eliminating rigidity in 95% of cases of PD, and tremor in 93% of cases of ET. The positive effect of stimulation on dystonia appeared in 95% with a latency of weeks. Transitory intraoperative morbidity occurred in 8%, intracranial hemorrhage in 1%, infectious complications in 6%, and problems with hardware in 7%.

[Significance of radiosurgery for the treatment of meningiomas]. / Význam radiochirurgie v lécbe meningiomu.

Treatment of intracranial meningiomas in the light of their benignity (90%) should ensure minimal risk of recurrence, avoid new neurological deficit and preserve quality of life. Stereotactic radiosurgery has proved its long-term effectiveness and safety with a low complication rate. It can be applied as a method of choice for meningiomas in locations that are too risky for microsurgical removal, meningiomas that usually do not exceed 3 cm in diameter and in patients, who are not candidates for microsurgery because of associated disease. It is a part of multimodal treatment for recurrence after operative resection or after partial removal of large meningiomas, where radical surgery represents a high risk of postoperative morbidity and mortality. Indication of radiosurgical treatment of intracranial meningiomas should be considered for each patient individually in order to choose methods or their combination with the lowest risk of complications.

[Temporal lobe epilepsy in adults and possibilities of neurosurgical treatment: the role of magnetic resonance]. / Temporální epilepsie dospelých a moznosti neurochirurgické lécby: úloha magnetické rezonance.

Temporal lobe epilepsy is the most common type of focal epilepsy diagnosed in adult patients. According to the location of seizure generation it is classified as mesial temporal lobe epilepsy and neocortical lateral lobe epilepsy. Diagnosis of temporal lobe epilepsy can be proved by the combination of the clinical manifestation of partial complex seizures, scalp-video EEG monitoring, results of magnetic resonance imaging (MRI) and imaging of interictal fluoro-deoxy-glucose positron emission tomography. Mesial temporal sclerosis is the most common finding on MRI. Temporal lobe epilepsy is the most surgically amenable diagnosis and results of surgery treatments are clearly superior to the prolonged medical therapy; surgical treatment of the mesial temporal epilepsy with mesial temporal sclerosis has the best clinical results. Except for standard microsurgical approaches such as anterior temporal resection and selective amygdalo-hippocampectomy, stereotactic thermocoagulation amygdalo-hippocampectomy is provided in our epilepsy centre. This alternative approach has comparable clinical outcome to the standard surgery approaches in 2 years clinical follow-ups. MRI is important not only in diagnostic procedures, but also in neuronavigation of surgery approaches, per operation control of the extent of resections and postoperative follow-ups, especially in failed epilepsy surgery.

Stereotactic radiofrequency amygdalohippocampectomy: does reduction of entorhinal and perirhinal cortices influence good clinical seizure outcome?

PURPOSE: Stereotactic radiofrequency amygdalohippocampectomy (SAHE) has been modified recently in our center for the therapy of mesial temporal epilepsy (MTLE). It has promising clinical results comparable with microsurgical amygdalohippocampectomy despite smaller volume reduction of the hippocampus. We hypothesized that the extent of perirhinal and entorhinal cortex (PRC, EC) reduction could explain the clinical outcome. Therefore, we performed, retrospectively, volumetric analysis of PRC and EC and compared it with the seizure control. METHODS: Twenty-six consecutive patients with MTLE treated by SAHE were included. PRC and EC volumes were measured from magnetic resonance imaging (MRI) records obtained before and 1 year after SAHE. The clinical outcome was assessed each year after SAHE using Engel's classification. KEY FINDINGS: Twenty-six patients were analyzed. The volume of PRC decreased by 46 ± 17% (p < 10(-12) ); EC volume decreased by 56 ± 20% (p < 10(-10) ). Two years after the procedure, 73% of patients were classified as Engel's I, 19% as Engel's II; in 2 (8%) the treatment failed (were reoperated). Eighteen patients finished 3 years follow-up; 72% of them were classified as Engel's I, 17% as Engel's II, and in 2 (11%) above-mentioned patients the treatment failed. Thirteen patients finished 4 years of follow-up, 11 of them as Engel's I. There was no significant correlation of the clinical outcome to PRC and EC volume reductions. SIGNIFICANCE: The clinical effect of SAHE is not clearly explained by the volume reductions of PRC and EC (nor of the hippocampus and the amygdala). It promotes opinion that the extent of resection/destruction is not important for seizure outcomes.

Is it possible to avoid hypopituitarism after irradiation of pituitary adenomas by the Leksell gamma knife?

OBJECTIVE: Radiation therapy is one of the treatment options for pituitary adenomas. The most common side effect associated with Leksell gamma knife (LGK) irradiation is the development of hypopituitarism. The aim of this study was to verify that hypopituitarism does not develop if the maximum mean dose to pituitary is kept under 15 Gy and to evaluate the influence of maximum distal infundibulum dose on the development of hypopituitarism. DESIGN AND METHODS: We followed the incidence of hypopituitarism in 85 patients irradiated with LGK in 1993-2003. The patients were divided in two subgroups: the first subgroup followed prospectively (45 patients), irradiated with a mean dose to pituitary <15 Gy; the second subgroup followed retrospectively 1993-2001 and prospectively 2001-2009 (40 patients), irradiated with a mean dose to pituitary >15 Gy. Serum TSH, free thyroxine, testosterone or 17ß-oestradiol, IGF1, prolactin and cortisol levels were evaluated before and every 6 months after LGK irradiation. RESULTS: Hypopituitarism after LGK irradiation developed only in 1 out of 45 (2.2%) patients irradiated with a mean dose to pituitary <15 Gy, in contrast to 72.5% patients irradiated with a mean dose to pituitary >15 Gy. The radiation dose to the distal infundibulum was found as an independent factor of hypopituitarism with calculated maximum safe dose of 17 Gy. CONCLUSION: Keeping the mean radiation dose to pituitary under 15 Gy and the dose to the distal infundibulum under 17 Gy prevents the development of hypopituitarism following LGK irradiation.

Stereotactic radiofrequency amygdalohippocampectomy in the treatment of mesial temporal lobe epilepsy.

PURPOSE: Minimally invasive percutaneous single trajectory stereotactic radiofrequency amygdalohippocampectomy was used to treat mesial temporal lobe epilepsy (MTLE). The aim of the study was to evaluate complications and effectiveness of this procedure. MATERIALS AND METHODS: A group of 51 patients with MTLE was treated using stereotactic thermo-lesion of amygdalohippocampal complex under local anaesthesia. The target was reached through the occipital approach with a single trajectory using MRI stereotactic localisation. Thermocoagulation of the amygdalohippocampal complex was planned according to the individual anatomy of each patient. Amygdalohippocampectomy was performed using a string electrode with a 10-mm active tip, and 16-38 lesions (median = 25) were performed in all patients along the 30- to 45-mm trajectory (median = 35) in the amygdalohippocampal complex. RESULTS: The procedure was well tolerated by all patients with no severe permanent morbidity; meningitis was recorded in two patients (4%), hematoma was detected in four patients, clinically insignificant in three of them, and one patient required temporary ventricular drainage (2%). Thirty-two patients were followed up over at least 2 years, and the clinical outcomes were evaluated by Engel's classification; 25 of them (78%) were Engel I, five (16%) were Engel II, and two (6%) were Engel IV. CONCLUSIONS: Stereotactic amygdalohippocampectomy is a minimally invasive procedure with low morbidity and good results that can be the method of choice in selected patients with MTLE.

Microsurgical and stereotactic radiofrequency amygdalohippocampectomy for the treatment of mesial temporal lobe epilepsy: different volume reduction, similar clinical seizure control.

We compared stereotactic radiofrequency amygdalohippocampectomy (SAHE) with microsurgical amygdalohippocampectomy (AHE) in a group of 33 patients with mesial temporal lobe epilepsy in terms of hippocampal and amygdalar volume reductions and clinical outcome. In 23 subjects treated by SAHE, the hippocampal volume decreased by 58.0% (20.0; median, quartile range), with p = 10(-4), and the amygdalar volume decreased by 55.2% (23.8), with p = 10(-4). Two years after SAHE, 74% of patients were classified as class I, 22% as class II and 4% as class III. In 10 subjects treated by AHE, 83.5% (11.2) of the hippocampal and 53.1% (53.9) of the amygdalar volumes were removed (p = 0.05 and p = 0.005, respectively). Two years after the operation, 50% of the subjects were classified as class I, 30% as class II and 10% as class III and IV. To conclude, SAHE leads to a similar reduction of the amygdalar volume but to a significantly lower reduction of the hippocampal volume than AHE. The clinical outcome of SAHE is comparable with that of AHE.

The use of radiosurgery for the treatment of mesial temporal lobe epilepsy and long-term results.

PURPOSE: To determine the efficacy of gamma knife radiosurgery in the treatment of mesial temporal lobe epilepsy due to mesial temporal sclerosis. METHODS: Between November 1995 and May 1999, 14 patients underwent radiosurgical entorhinoamygdalohippocampectomy with a marginal dose of 18, 20, or 25 Gy to the 50% isodose following a standard preoperative epilepsy evaluation. RESULTS: One patient was classified as Engel Class Ib, three were Engel Class IIc, one was Engel Class IIIa, and two were Engel Class IVb in a subgroup of seven patients who were unoperated 2 years prior to the last visit and at least 8 years after irradiation (average 116 months). The insufficient effect of irradiation led us to perform epilepsy surgery on another seven patients an average of 63.5 months after radiosurgery. The average follow-up period was 43.5 months after the operation. Four patients are seizure-free; one is Engel Class IIb and one is Engel Class IId. One patient cannot be classified due to the short period of follow-up. The frequency of seizures tended to rise after irradiation in some patients. Collateral edema was observed in nine patients, which started earlier and was more frequent in those irradiated with higher doses. It had a marked expansive character in three cases and clinical signs of intracranial hypertension were present in three cases. We found partial upper lateral quadrant anopia as a permanent side effect in two patients. Repeated psychotic episodes (two patients) and status epilepticus (two patients) were also seen after treatment. No significant memory changes occurred in the group as a whole. DISCUSSION: Radiosurgery with 25, 20, or 18-Gy marginal dose levels did not lead to seizure control in our patient series, although subsequent epilepsy surgery could stop seizures. Higher doses were associated with the risk of brain edema, intracranial hypertension, and a temporary increase in seizure frequency.

Repeated treatment of vestibular schwannomas after gamma knife radiosurgery.

PURPOSE: When gamma knife radiosurgery (GKS) does not achieve control of the growth of a tumour, the need to repeat treatment is considered. The results and risks of repeat treatment of patients with a vestibular schwannoma were reviewed to assess its efficacy and safety. METHODS: Between 1992 and 2001, we treated 351 patients with a vestibular schwannoma by GKS, control of the growth of the tumour was not achieved in 32. 26 patients underwntrepeat GKS and five patients had an open microsurgical operation and one stereotactic aspiration of a tumour cyst. RESULTS: Twenty-four of 26 patients were followed up after the repeat GKS for a median of 43 months. 15 tumours became smaller, seven remained unchanged and two enlarged. After the second GKS one patient's hearing deteriorated, one developed facial weakness and three facial spasms. One patient required insertion of ventriculo-peritoneal drainage. An operation to radically resect the tumour was performed in five patients after the first GKS and for a subtotal removal in one after repeated GKS. CONCLUSIONS: In the small proportion of patients (9%) in whom initial GKS does not control the growth of a vestibular schwannoma, most can be controlled by further GKS with a very low risk of a complications.

Stereotactic radiofrequency amygdalohippocampectomy for the treatment of mesial temporal lobe epilepsy: correlation of MRI with clinical seizure outcome.

SUMMARY: Stereotactic radiofrequency amygdalohippocampectomy (AHE) has been reintroduced as an alternative treatment of mesial temporal lobe epilepsy. The aim of this study was to describe MRI changes after stereotactic AHE and to correlate the hippocampal and amygdalar volumes reduction with the clinical seizure outcome. Eighteen patients after stereotactic AHE were included. Volumetry was calculated from pre-operative MRI and from MRI obtained 1 year after the operation. The clinical outcome was examined 1 and 2 years after the treatment. Hippocampal volume decreased by 54+/-19%, and amygdalar volume decreased by 49+/-18%. One year after the procedure, 13 (72%) patients were classified as Engel's Class I (9 as Class IA), 4 (22%) patients as Class II and 1 (6%) patient as Class III. Two years after the operation, 14 patients (82%) were classified as Class I (7 as Class IA) and 3 patients (18%) as Class II. We found 3 surgical complications after the procedure: one small subdural hematoma, and twice a small electrode tip left in operation field (these patients were excluded from the study). In 3 patients, temporary meningeal syndrome developed. Results of radiofrequency AHE are promising. The volume reduction of target structures after AHE is significantly related to the clinical outcome.

Use of the Leksell gamma knife in the treatment of prolactinoma patients.

OBJECTIVE: Pharmacological treatment with dopaminergic agonists (DA) is the treatment of choice for prolactinomas. Surgical and radiation treatment is also indicated in certain situations. We describe our 12-year experience in treating prolactinomas with the Leksell gamma knife (LGK). DESIGN: We followed 35 prolactinoma patients (25.7% microprolactinomas, 74.3% macroprolactinomas) treated with LGK irradiation. The mean follow-up period was 75.5 months. Prior to LGK irradiation, patients were treated with DA and 10 of them (28.6%) underwent neurosurgery. Indications for LGK irradiation were: DA intolerance (31.4%), DA resistance (45.7%) and efforts to reduce the DA dose or shorten the period of administration (22.9%). Pituitary function was monitored regularly at 6-month intervals. The central radiation dose range was 40-80 Gy (median 70 Gy), and the minimal peripheral dose was 20-49 Gy (median 34 Gy). RESULTS: Normoprolactinaemia was achieved in 37.1% of the patients who discontinued DA and in 42.9% of patients who continued DA treatment after LGK irradiation. The median time to prolactin normalization after discontinuation of DA was 96 months. No relapse was seen in any patient. After LGK irradiation, the prolactinoma stopped growing or decreased in size in all but one patient (97.1%). CONCLUSION: LGK treatment resulted in normoprolactinaemia in 80.0% of the patients, all of whom had failed pharmacological treatment due to DA resistance or intolerance. After achieving normoprolactinaemia, no relapse of hyperprolactinaemia was observed in any patient. The size of the adenoma decreased even in those patients in whom it was not changed by previous DA treatment.

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.

Arteriovenous malformations after Leksell gamma knife radiosurgery: rate of obliteration and complications.

OBJECTIVE: Although 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. METHODS: Between 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 cm (median, 3.9 cm). 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 cm (median 2.9 cm). 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. RESULTS: AVM 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%. CONCLUSION: Although 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.

Radiosurgery in ocular disorders: clinical applications.

Radiosurgery using the Leksell Gamma Knife (LGK) applied to ophthalmologic indications is a specific area where the eye target has a very eccentric location, since the eye can move, its fixation is required and the patient is generally treated in a prone position. It was demonstrated that the LGK is sufficiently accurate to be used for ophthalmic radiosurgery. Current spectrum of treated indications includes uveal melanomas, eye metastases, advanced glaucoma, age-related macular degeneration (ARMD), hemangioblastoma, angioreticuloma, pseudotumors and vegetative pain. The results for uveal melanomas are recognized and the value of the LGK in the treatment of glaucoma and ARMD seems promising after initial studies. Gamma Knife radiosurgery of the ciliary body leads to a significant alleviation of pain and reduction in intraocular pressure in advanced glaucoma. The latency of the treatment effect is relatively short. In the majority of patients with ARMD, both ultrasonography and fluorescein angiography demonstrated a regression of the neovascular complex or stabilization after LGK radiosurgery. A number of rare ophthalmologic indications have also been treated by the Gamma Knife in our Center with more or less prominent therapeutic responses.