Bengt Karlsson

Recurrence of cranial base meningiomas.

OBJECTIVE Long-term data on the natural history of traditionally treated cranial base meningiomas are necessary to judge the benefit of modern cranial base techniques for individual patients and to understand when nonradical surgery of a meningioma is in the interest of the patient. The only available means of obtaining such data is investigation of patients treated before the present surgical era. METHODS The records of 315 patients who were operated on at Karolinska Hospital between January 1, 1947, and December 31, 1982, were reviewed. Of the patients, 10.8% died perioperatively and 9.7% died within 10 years. The remaining patients were followed for 10 to 36 years (mean, 18 yr). RESULTS The 5-year recurrence rate was 4% for patients undergoing radical surgery (Grades 1 and 2) and 25 to 45% for patients undergoing Grade 3 or 4 operations. Follow-up periods longer than 5 years revealed that 16% of Grade 1 and 20% of Grade 2 patients had symptomatic recurrences, whereas a majority of Grade 4 and 5 patients showed symptomatic progression. Forty-two of 69 patients who underwent Grade 4 or 5 operations died as a result of their tumors, usually within 10 years after the first operation. No patients who underwent Grade 4 or 5 operations were free from symptomatic progression after 20 years. The tumor progression or recurrence was usually detected within the 1st 10 years, but late recurrences were seen < or = 25 years after the operation. The worst outcome was found in medial sphenoid wing/clinoidal meningiomas and in tumors invading the cavernous sinus. Subfrontal tumors showed unexpectedly high recurrence rates, with a mortality rate < or = 14% in the late phase. CONCLUSION The findings emphasized the necessity to plan the management of patients with cranial base meningiomas according to a 10- to 20-year perspective. Patients must be followed to evaluate the treatment results and to detect recurrences. Nonradical surgery must be viewed as a temporizing or palliative measure; a continued search for means of radical tumor treatment is warranted in these often surgically difficult tumors.

Prediction of Obliteration after Gamma Knife Surgery for Cerebral Arteriovenous Malformations

OBJECTIVE:To define the factors of importance for the obliteration of cerebral arteriovenous malformations (AVMs), thus making a prediction of the probability for obliteration possible.METHODS:In 945 AVMs of a series of 1319 patients treated with the gamma knife during 1970 to 1990, the relationship

Angiographic long-term follow-up data for arteriovenous malformations previously proven to be obliterated after gamma knife radiosurgery.

OBJECTIVE To investigate whether angiograms obtained 2 years after radiosurgery, proving total arteriovenous malformation (AVM) occlusion, represent the final state of treated AVMs and adjacent normal vessels. METHODS Angiograms were obtained for 48 patients 5 to 24 years after gamma knife radiosurgery and 4 to 17 years after the AVMs had been proven to be totally occluded after the treatment; changes in normal vessels and signs of recanalization were recorded. Ten of the patients developed clinical symptoms attributable to the AVMs or the treatment after having been declared cured, whereas the other patients did not exhibit symptoms. RESULTS There was evidence of AVM nidi at the sites of previously occluded AVMs for two patients and of nidi adjacent to those sites for another two patients. Three of the four recurrent AVMs were associated with hemorrhaging. All patients who experienced hemorrhaging from previously occluded AVMs were < or = 14 years of age at the time of gamma knife radiosurgery. There were signs of segmental narrowing in normal vessels that had been irradiated with high doses (nine patients) or a low dose (one patient). The segmental narrowing decreased with time for four of these patients, was unchanged for four, and increased for two. These vascular changes did not produce clinical symptoms in any of the patients. CONCLUSION There is a small possibility that AVMs may reappear after having been totally occluded after radiosurgery, especially in pediatric patients. Segmental narrowing in normal arteries after radiosurgery is a benign condition that rarely progresses and does not produce clinical symptoms.

Gamma knife surgery for previously irradiated arteriovenous malformations.

OBJECTIVE The goal was to report the treatment results after a second gamma knife treatment and to compare them with the results obtained after a first gamma knife treatment, as well as to investigate whether the models to predict the results after a first treatment are also applicable after gamma knife treatment of previously irradiated arteriovenous malformations. METHODS The number of complications and the posttreatment hemorrhage rate were recorded for 112 patients in the study, and the number of obliterations was recorded for the 101 patients for whom conclusive angiograms were obtained. The results were compared with the expected results after a first gamma knife treatment. RESULTS The observed number of obliterations was 62, which is not significantly different from the predicted number of 65. There were 14 observed and 5 predicted complications. When the risk from the preceding radiation treatment was added, the observed number of complications was similar to the predicted number. Six hemorrhages were observed after the second treatment. Of the 5 patients with unchanged arteriovenous malformation size after both the first and second treatments, 2 experienced hemorrhages after the second treatment, compared with none among the 81 patients for whom the malformation was obliterated or significantly decreased in size after the second treatment. CONCLUSIONS The obliteration rate after gamma knife surgery for previously irradiated arteriovenous malformations is similar to that after primary gamma knife treatment. The complication rate increases with the amount of radiation previously given. The incidence of posttreatment hemorrhages is lower in the latency period if the malformation is affected by the radiation.

CAN THE PROBABILITY FOR OBLITERATION AFTER RADIOSURGERY FOR ARTERIOVENOUS MALFORMATIONS BE ACCURATELY PREDICTED

PURPOSE To investigate how accurate different models predict the probability for obliteration following radiosurgery for an arteriovenous malformation (AVM). METHODS AND MATERIALS The probability for obliteration was calculated for all 838 AVMs with a known treatment outcome and treated at the Karolinska Hospital with Gamma Knife surgery 1970-1993. Four different models were used for the calculation, resulting in four different values of the probability for obliteration. The calculated prediction values were added for each model, and the total number of predicted obliteration compared to that observed in the whole patient material as well as in different subgroups. RESULTS Three of the four models predicted the total number of obliterations accurately. In two of those three models, the accuracy of the prediction was dependent on AVM volume and treatment dose. In one model only, the prediction was accurate and independent of all investigated parameters. CONCLUSIONS The probability for obliteration was accurately predicted by one of the models analyzed. In this model, the probability for obliteration was related to the dose to the AVM periphery only. The AVM volume had no independent impact on the probability for obliteration. There was a trend that AVMs with a central location had a better obliteration rate than predicted.

Thirty years' experience with Gamma Knife surgery for metastases to the brain

OBJECT The aim of this study was to analyze factors influencing survival time and patterns of distant recurrences after Gamma Knife surgery (GKS) for metastases to the brain. METHODS Information was available for 1855 of 1921 patients who underwent GKS for single or multiple cerebral metastases at 4 different institutions during different time periods between 1975 and 2007. The total number of Gamma Knife treatments administered was 2448, an average of 1.32 treatments per patient. The median survival time was analyzed, related to patient and treatment parameters, and compared with published data following conventional fractionated whole-brain irradiation. RESULTS Twenty-five patients survived for longer than 10 years after GKS, and 23 are still alive. Age and primary tumor control were strongly related to survival time. Patients with single metastases had a longer survival than those with multiple metastases, but there was no difference in survival between patients with single and multiple metastases who had controlled primary disease. There were no significant differences in median survival time between patients with 2, 3-4, 5-8, or >8 metastases. The 5-year survival rate was 6% for the whole patient population, and 9% for patients with controlled primary disease. New hematogenous spread was a more significant problem than micrometastases in patients with longer survival. CONCLUSIONS Patient age and primary tumor control are more important factors in predicting median survival time than number of metastases to the brain. Long-term survivors are more common than previously assumed.

Combined embolization and gamma knife radiosurgery for cerebral arteriovenous malformations

In a study of 46 patients with cerebral arteriovenous malformations (AVMs) the value of combining embolization and gamma knife radiosurgery was assessed. In 35 patients with large grade III to V AVMs (Spetzler-Martin system) staged combined treatment was planned. In 11 patients, radiosurgery complemented embolization for a residual AVM. The number of embolization sessions ranged from 1 to 7 (median 2). Twenty-six patients needed multiple embolization sessions. In 28 patients the grade of AVMs decreased as a result of embolization. In 16 patients collateral feeding vessels developed after embolization which made delineation of the residual nidus difficult. The time lag between the last embolization and radiosurgery ranged from 1 to 24 months (median 4). Nineteen of 35 large grade III to V AVMs were possible to treat by radiosurgery following embolization. In the 46 patients complications occurred in 9 from embolization and in 2 from radiosurgery. Two patients had transient and 9 had permanent neurologic deficits. It is concluded that embolization facilitates radiosurgery for some large AVMs and therefore this combined treatment has a role in the management of AVMs.

Even the smallest remnant of an avm constitutes a risk of further bleeding

SummaryA case with an ill-defined arteriovenous malformation in the parieto-occipital region is presented. Open surgery was unsuccessful in removing the AVM totally, and treatment with gamma knife radiosurgery was then attempted. At 14 months after this treatment the AVM was believed to be obliterated. The patient had a new intracranial haemorrhage 59 months after radiosurgery. Renewed angiography showed an obvious AVM outside the previously irradiated area. Retrospective analysis of the angiogram at 14 months after radiosurgery revealed early filling of a draining vein as a sign of residual AVM at this time. Renewed radiosurgical treatment was performed. It is believed that an ill-defined margin, laminar flow, and effects of previous surgery might add to difficulties in a proper visualisation and delineation of an AVM. Further, a small remaining shunt may be overlooked if the angiogram is not carefully analysed or if the angiogram is of inferior quality. It should be stressed that partial or almost total obliteration of an AVM is no protection against rebleeding.

Stereotactic Radiosurgery for Tectal Low-Grade Gliomas

We report 7 cases with low-grade gliomas in the tectal region of the midbrain. This series started in 1979 and all tumors were treated by radiosurgery using the Leksell Gamma Knife. All cases were treated by using a single isocenter with the 14 mm collimator. Doses administered ranged from 14 to 35 Gy delivered to the 50-70% isodose line. All tumours but one responded to the treatment and disappeared or ceased growing. In the first two treated cases, the dose was chosen by the early experience from the AVMs, with 30 and 35 Gy as the peripheral dose. These cases developed severe radio-induced oedema with aggravating symptoms and permanent deficits. We conclude that radiosurgery is effective in the treatment of deeply located low-grade gliomas. Cases accepted for treatment should be carefully selected and the peripheral dose should not exceed 14Gy to avoid uncontrolled radio-induced changes.

Recurrent tumor vs radiation effects after Gamma Knife radiosurgery of intracerebral metastases: Diagnosis with PET-FDG

Objective Our objective was to differentiate radiation effects from tumor progression in metastases stereotaxically irradiated with the multicobalt unit (Gamma Knife). Materials and Methods Eleven patients with stereotaxically irradiated cerebral metastases were examined with PET using [18F]fluorodeoxyglucose (FDG) to differentiate recurrent tumor from radiation effects. Results Six patients had increased uptake of FDG, and clinical, radiological, and pathological findings confirmed the diagnosis of recurrent metastases. These patients had an unfavorable prognosis and were all dead within 54 weeks after radiosurgery. Five patients had lesions without an increased accumulation of FDG. Four of these patients were alive after a total follow-up of 1.7 years, while one patient died of a peptic ulcer 56 weeks after radiosurgery. Conclusion Positron emission tomography with FDG was of obvious prognostic value in this small series of patients and was clearly superior to CT and MR in the distinction between tumor recurrence and radiation effects (verified necrosis in one case).