Klaus A. Leber

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.

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.

Effect of serotonin and its antagonist ketanserin on pial vessels

The effect of serotonin (5-HT) and its antagonist ketanserin on the cerebral circulation was investigated in two series totaling 24 cats using the cranial window technique. 5-HT elicited a marked dilatation of small pial arteries, whereas large arteries tended to constrict. Intravenous administration of ketanserin reversed the constriction of large arteries, causing dilatation, and reduced the extent of small arteries dilatation. In a randomized study, i.v. administration of ketanserin in its solvent versus the solvent alone revealed a strong dilatatory effect of the solvent on pial arteries (17 ± 1.8%), which partly jeopardized a possible constrictory effect of ketanserin, as ketanserin plus solvent induced less dilatation of small pial arteries than the solvent alone. The present data support the view that serotonin exerts a dual effect on cerebral arteries, namely, dilatation of small and constriction of large vessels. The antagonist ketanserin reverses this effect, but the strong dilatatory effect of the solvent alone masks the antiserotoninergic effect.

Corpus callosotomy with radiosurgery.

OBJECTIVEnCorpus callosotomy is a surgical option for medically uncontrolled generalized epilepsy in appropriate patients. Because numerous complications related to open callosotomy are still reported, we performed radiosurgical corpus callosotomy with the gamma knife.nnnMETHODSnBetween October 1992 and June 1995, three patients underwent stereotactic radiosurgery to ablate the anterior third of the corpus callosum. The patients had intractable epilepsy: two had Lennox-Gastaut syndrome, and one had multifocal epilepsy with atonic, tonicoclonic, and atypical absence seizures. The history of seizures ranged from 20 to 37 years duration. Stereotactic radiosurgery was performed with a cobalt-60 gamma knife using a 4-mm collimator, targeted to the rostrum, genu, and anterior third of body of the corpus callosum. Two patients were treated once with 150 and 160 Gy at maximum, respectively, and one patient was treated in two stages with 50 Gy and then 170 Gy at maximum.nnnRESULTSnThe severity and frequency of seizures were significantly reduced in all three patients. The types of seizures associated with the most improved outcome were atonic and generalized tonicoclonic seizures. The mean follow-up period was 38 months. Hospitalization required for this procedure was 3 days. No complications related to irradiation were recorded except transient headache in one patient.nnnCONCLUSIONnThe outcomes suggest that radiosurgical corpus callosotomy may be a promising alternative treatment to open callosotomy.

The role of gamma knife radiosurgery in children.

Abstract. Objects: Despite advances in microneurosurgery, the surgical management of deep-seated lesions is still associated with a high risk. Gamma knife radiosurgery (GKRS), however, has improved the outcome of cerebral tumors and arteriovenous malformations (AVMs) in delicate areas. Methods: Between March 1992 and June 1998, 50 children (age 1–16xa0years) with intracranial lesions were treated with GKRS. There were 12 low-grade gliomas, 12 high-grade gliomas, 7 craniopharyngiomas, 3 hamartomas, 2 meningiomas of the skull base, 2 vestibular schwannomas, 1 pituitary adenoma, 1 choroid plexus papilloma, and 10 AVMs. The mean size of the pathologies was 4.6xa0cm3 (range: 0.21–25.5xa0cm3). A mean marginal dose of 16xa0Gy (8–25xa0Gy) was applied to a mean isodose surface of 50% (35–90%). Clinical and neuroradiological follow-up were analyzed for outcome. Follow-up periods of 45 of these patients ranged from 8 to 79xa0months (mean 36xa0months); 5 patients were lost to follow-up. Neoplasms decreased in size in 15 cases (41%), remained unchanged in 13 patients (35%), and increased in 9 cases (24%). AVMs obliterated in 3 children (38%) within 24xa0months. Neurological follow-up demonstrated improved clinical status in 7 patients (15.5%), stable neurological status in 31 cases (69%) and clinical deterioration in 7 patients (15.5%). The treatment was well tolerated and no complications occurred. Conclusions: GKRS represents a safe and effective treatment option for benign neoplasms or AVMs in pediatric patients and may extend survival times of children with malignant lesions.

Complications after shunting isolated IV ventricles

An isolated IV ventricle in chronically shunted patients is being reported with increasing frequency. Complications associated with posterior fossa shunting, however, have seldom been described. Between January 1986 and December 1995, we treated 292 children younger than 16 years for hydrocephalus: 7 (2.4%) developed an isolated IV ventricle, and 5 of these were symptomatic with posterior fossa signs. These 5 patients required posterior fossa shunting, after which their neurological status improved. However, 1 week and 6 weeks after surgery, respectively, 2 patients developed new cranial nerve deficits related to a slit-like IV ventricle with secondary irritation of the brain stem by the IV ventricular catheter. Shortening the catheter and replacing the valve eliminated the cranial nerve palsies, implying that these complications were not caused by direct injury of the brain stem during placement of the shunt. Alternative surgical techniques and the use of different (flow-regulating) valves may avoid such complications.

Radiosurgery with the first Austrian cobalt-60 gamma-unit : a one-year experience

SummaryDuring the period of one year, from the 21. 4. 1992 to 21. 4. 1993, a total of 201 radiosurgical sessions on 181 patients were performed with the first Austrian Gamma-unit in Graz. 42% of radiosurgical sessions were undertaken for malignomas, 20% for meningiomas, 11.5% for vascular malformations, 9% for neurinomas, 8.5% for low grade astrocytomas and glomus jugulare tumours, 5% for sellar and suprasellar lesions, and 4% for functional disorders. Dose plan data for all the lesions treated are shown. Clinical and imaging data of the first year which are available for 120 patients (66%) are presented and discussed.

Autoregulatory response of pial vessels in the cat

Pial vessel responses to mean arterial pressures (MAP) between 40 and 160 mmHg, induced by withdrawal and reinfusion of blood, were studied in twelve cats under barbiturate- and N2O-anaesthesia, using the cranial window technique and videoangiometry. Very minor changes of pial arterial calibres were noted between MAP 80 and 120 mmHg. During further reduction of MAP, small arteries dilated more than large arteries and measured 43 +/- 4.6% and 30 +/- 1.9% at MAP 40 mmHg, respectively. When MAP was elevated to 140 mmHg, large arteries constricted more than small ones; at MAP 160 mmHg, however, they started to redilate, while small arteries continued to constrict to -13 +/- 2.3%. Within the autoregulatory range, pial veins remained unchanged; at MAPs of 40 and 160 mmHg, venous calibre variations remained below 10%.

Cerebrovascular complications and granuloma formation after wrapping or coating of intracranial aneurysms with cotton gauze and human fibrin adhesives: results from a single-center patient series over a 5-year period

OBJECTnReinforcement of intracranial aneurysms (IAs) by wrapping or coating is a well-established therapeutic approach to those IAs not amenable to any other definitive treatment, but has been associated with complications such as parent artery narrowing, granuloma formation, and ischemic stroke. The goal of this study was to systematically investigate cerebrovascular complications following this procedure.nnnMETHODSnThe authors hospital database was searched for all patients who underwent wrapping or coating of IAs with cotton gauze and human fibrin adhesives between October 2006 and October 2011. The follow-up records of these patients were extracted, including regular clinical visits and vascular imaging.nnnRESULTSnFive hundred sixty-seven patients were treated for IAs over the 5-year period: 303 patients underwent endovascular strategies and 264 underwent craniotomies. Wrapping or coating of IAs was performed in 20 patients (3.5%). Parent artery narrowing occurred in 5 (25%) of the 20 patients and was associated with major ischemic strokes in 4 patients and severe headache in another. Ischemic strokes were associated with parent artery narrowing, which occurred early postoperatively in 2 patients or was a consequence of granuloma formation in 2 patients 1 and 2 months after the procedure, respectively.nnnCONCLUSIONSnThese data should add to the awareness of significant cerebrovascular complications following wrapping or coating of IAs with cotton gauze and human fibrin adhesives and indicate that major ischemic strokes need to be included in the risk/benefit considerations during decision making for such treatment strategies. Patients who receive IA wrapping should be monitored and followed up closely for arterial narrowing and granuloma formation.

Pial Venous Reaction to Sympathetic Stimulation During Elevated Intracranial Pressure

Earlier experiments have shown that a sympathoadrenergic mechanism is able to decrease intracranial pressure by venous constriction and a consequent reduction in cerebral blood volume. In the present study using 16 cats, the intracranial pressure was elevated by two different models (cisternal infusion of mock CSF in 8 cats and brain oedema induced by water-intoxication in 8 cats) to test the hypothesis that cervical sympathetic stimulation is also effective under the circumstance of an elevated ICP. A cranial window technique and multichannel-videoangiometry were used to measure variations in pial venous calibres. The elevation of ICP up to 30 mmHg with brain oedema and 50 mmHg with CSF-infusion per se resulted in marked venous and arterial dilatation in the first model and arterial dilatation only in the second model. Pial venous constriction induced by sympathetic stimulation was significantly less with an elevated ICP. ICP reduction as a consequence of vascular constriction during stimulation remained around 15% between the resting condition and the situation of ICP elevated to 30 mmHg by CSF infusion; at higher ICP levels up to 50 mmHg, the percent ICP reduction with sympathetic stimulation fell to 10%.