Christer Lindquist

Gamma Knife Surgery for Cerebral Metastases. Implications for Survival Based on 16 Years Experience

Our experience with radiosurgery of brain metastases is based on 160 patients with 235 tumors treated over a 16-year period. In this material, 94% growth control was achieved. Radiosurgery appears to be an effective, low-morbidity substitute for surgical resection followed by whole brain radiotherapy and even indicated for multiple metastases and distant new tumors. More patients receive an effective treatment with less neurologically related deaths.

Lesion topography and outcome after thermocapsulotomy or gamma knife capsulotomy for obsessive-compulsive disorder: relevance of the right hemisphere.

OBJECTIVESnObsessive-compulsive disorder is a common mental disorder, notorious for its chronicity and intractability. Stereotactic lesions within the anterior limb of the internal capsule have been shown to provide symptomatic relief in such refractory cases, but only few systematic evaluations have correlated anatomic lesion location with individual postoperative outcome.nnnPATIENTS AND METHODSnBetween 1976 and 1989, extremely disabled and otherwise intractable patients with a chronic deteriorating clinical course of obsessive-compulsive disorder underwent bilateral thermocapsulotomy (n = 22) or radiosurgical gamma knife capsulotomy (n = 13) at the Karolinska Hospital, Stockholm. Clinical morbidity was monitored prospectively pre- and postoperatively by using standardized psychiatric rating scales. In 29 patients (thermocapsulotomy, n = 19; gamma knife capsulotomy, n = 10), both psychiatric and magnetic resonance imaging follow-up data (median, 8.4 yr) were available.nnnRESULTSnA right-sided anatomically defined lesion volume was identified in all successfully treated patients. This common topographic denominator was defined in the approximate middle of the anterior limb of the internal capsule on the plane parallel to the anterior commissure-posterior commissure line at the level of the foramen of Monro and 4 mm above on the plane defined by the internal cerebral vein. This region was unaffected in patients with poor outcomes. On the left side, no particular lesion topography was associated with clinical outcome. Topographic differences of lesion overlap between good and poor outcome groups were significant for the right side (Fishers exact test, P < 0.005).nnnCONCLUSIONnThe current anatomic long-term analysis after thermocapsulotomy or gamma knife capsulotomy for obsessive-compulsive disorder reveals common topographic features within the right-sided anterior limb of the internal capsule independent of treatment modality.

Functional Neurosurgery - A Future for the Gamma Knife?

The Gamma Knife is currently the only radiosurgical device which has been used in functional neurosurgery. This mode of utilization is possible because the instrument can make lesions in normal brains with a volume as small as 50 mm3. The experience of functional radiosurgery accumulated at the Karolinska Institute over 21 years is reviewed, and the possible implications of the new developments in imaging techniques for the future of functional radiosurgery are considered. The review covers gamma thalamotomy for pain and tremor, radiosurgery for trigeminal neuralgia, gamma capsulotomy for severe anxiety and obsessive-compulsive neurosis, and Gamma Knife surgery for focal epilepsy. The important role of stereotactic MRI localization in functional radiosurgery is pointed out, and a preliminary report of the recent experience with stereotactic magnetoencephalography combined with stereotactic MRI for physiological and anatomic target localization is given. It is concluded that functional radiosurgery should only be performed with radiation of very small volumes of brain, as the very high doses required would be devastating if delivered to even small volumes.

Gamma knife surgery for recurrent solitary metastasis of a cerebral hypernephroma: case report

Gamma knife surgery employing a central dose of 70 Gy and a peripheral dose of 25 Gy caused progressive necrosis and shrinkage of a recurrent solitary metastasis of a cerebral hypernephroma, as verified by computed tomographic scan 2 and 4 months after treatment. Gamma knife surgery was an effective palliative treatment for this cerebral metastasis and was an alternative to craniotomy with microsurgical removal.

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.

Potential complications following radiotherapy for meningiomas.

BACKGROUNDnThe rationale for radiotherapy of meningiomas is based on retrospective studies utilizing life-table statistics and historical controls. Most of these report minimal morbidity and high efficacy, while one study of radiation therapy for benign diseases reported a high complication rate during long-term follow-up. These reports were at variance with our personal experience in three patients. This study was therefore undertaken to corroborate the previous reports by retrospectively investigating possible adverse effects and efficacy.nnnMETHODSnThe charts at Karolinska hospital were searched to identify all patients with meningiomas who were treated with conventional fractionated radiotherapy between 1975 and 1995. Surgical radicality was assessed according to Simpson. The patients were followed until recurrence, death, or a minimum of 5 years.nnnRESULTSnForty-five out of 1,820 patients were treated with fractionated radiotherapy. Fifty-six percent of these patients experienced serious complications from fractionated radiation treatment. The complications encompassed neuropsychological and neurologic motor and sensory deficits and were severe enough to cause hospitalization or a major change in lifestyle. Seventy-five percent of all subtotally resected and radiated meningiomas recurred during follow-up.nnnCONCLUSIONnOur historical data from a heterogenous group of consecutive patients undergoing fractionated radiation therapy in meningioma management showed an unexpectedly high rate of complications and failed to corroborate previous historical reports of low morbidity and tumor control. Dose planning and radiation treatment has improved. Our data indicate a need for prospective investigations.

Electrophysiological Aid in High Thoracic Sympathectomy for Palmar Hyperhidrosis

High upper thoracic sympathectomy using microsurgical techniques aided by electrical stimulation of the sympathetic chain is described. Use of the microscope facilitates identification and dissection of the sympathetic chain and minimizes the risk of pleural damage. Electrical stimulation of the sympathetic chain establishes the correct functional level for surgical excision. At the correct level, the threshold for piloerection, sudomotor response, and decrease in blood flow of the ipsilateral hand to electrical stimulation was minimal, and a six-fold increase in stimulus current causing current spread was required to dilate the ipsilateral pupil. After identification of the proper level, surgical excision can be done without risking postoperative Horners syndrome. Excision of the appropriate ganglia and intervening sympathetic chain with placement of surgical clips on the proximal and distal nerve stumps provides tissue for histological analysis, decreases the opportunity for regeneration, and facilitates localization on postoperative x-rays.

Prediction of Results following Gamma Knife Surgery for Brain Stem and Other Centrally Located Arteriovenous Malformations: Relation to Natural Course

Two models for predicting the results of Gamma Knife surgery for brain stem and other centrally located arteriovenous malformations (AVMs) are presented. By using these models, the probability of total obliteration and the risk of complications can be predicted. The model to predict the probability for obliteration is based on the following two observations. First, there is a positive relationship between the minimum dose given to the AVM nidus and the incidence of obliteration. Second, there is a negative relationship between the AVM nidus volume and the minimum dose given in the obliterated cases. The risk estimation model is also based on two observations. First, centrally located AVMs carry a higher risk of complications than those located peripherally. Second, the average dose to volumes which are large for radiosurgery is related to the incidence of complications. The findings of this study may be used to estimate the consequences of Gamma Knife treatment for every individual case prior to the treatment. This makes a comparison between different treatment options and no treatment possible. The risk of hemorrhage without any treatment is also quantified.

Department of Neurosurgery, Karolinska Institute: 60 Years

The Swedish neurosurgical school was created during the 1920s by Herbert Olivecrona, who became the first professor of neurosurgery at the Karolinska Institute. He pioneered procedures for the treatment of arteriovenous malformations and acoustic neuromas. He was among the first to make direct attacks on berry aneurysms. Many outstanding neurosurgeons in Europe were trained by him. Clinical research to refine and minimize surgical interventions has continued to be the most important feature of the neurosurgery department at the Karolinska Institute. Lars Leksell, Olivecronas successor, was a leader in stereotactic surgery and the creator of radiosurgery. His tool, the gamma knife, is in worldwide use today. Leksell and his students have defined the indications for radiosurgery and introduced stereotactic techniques into microsurgery. Today, 3000 neurosurgical procedures are performed annually in the four operating rooms of the department of neurosurgery. More than 300 of the procedures are performed with the gamma knife, and at least one-third of the patients are foreign referrals. There is a strong emphasis on clinically oriented research and development. There are research programs for radiosurgery, management of pain, neurooncology, treatment of traumatic brain injury, and treatment of vasospasm after subarachnoid hemorrhage.

Radiosurgery patterns of practice.

We distributed a questionnaire on radiosurgery patterns of practice to members of the International Stereotactic Radiosurgery Society (ISRS). Responses were obtained from physicians at 52 facilities, who had treated more than 13,000 patients. Most respondents were found to work within a multidisciplinary team, and averaged 17.3 specialist-hours devoted per patient on the day of radiosurgery. These results will enable radiosurgeons to determine if their practice differs from the norm and to adjust their practice standards, if appropriate.