Biomedical subjects

C Lindquist

Publications and source records attributed to C Lindquist.

At least 19 recordsLinked to original sources

PubMed1997

Obsessive compulsive disorder and the right hemisphere: topographic analysis of lesions after anterior capsulotomy performed with thermocoagulation.

Considerable but uncontrolled evidence suggests that stereotactic capsulotomy by means of thermolesions may provide symptomatic relief for patients with otherwise therapy refractory "malignant" obsessive compulsive disorder (OCD). Unlike in other functional stereotactic interventions, target localization for capsulotomy is based upon anatomical definition only. Few systematic attempts have been made to correlate the site and size of the capsular lesions with postoperative clinical outcome. Between 1976 and 1989 bilateral thermo-capsulotomy (TC) was performed in 22 OCD patients. In 19 patients complete quantitative pre- and postoperative psychiatric rating of OCD symptoms and long-term postoperative MRI studies were available. Cohorts of patients fulfilling criteria for good or poor outcome were contrasted, cases with intermediate treatment effect being excluded. Median postoperative MRI follow-up was 8.4 years (2.4-20.3 y). 9/19 patients fulfilled criteria for good postoperative outcome. In these patients all lesion sites overlapped covering a small area within the right anterior limb of the internal capsule. Lesions within the group of patients with poor outcome (n = 5) were located elsewhere, mostly further anterior in the internal capsule. Differences of lesion overlap between the two outcome groups were significant for the right side (Fisher's Exact Test: p < 0.005). Common topographic features of lesion sites within the right internal capsule were identified in OCD patients responding favourably to capsulotomy.

Adult↗

PubMed1997

Annual risk for the first hemorrhage from untreated cerebral arteriovenous malformations.

To estimate the annual risk for the first hemorrhage, survival and life table statistics were used to analyze data from 2262 patients with cerebral arteriovenous malformations (AVM). We found that the risk for hemorrhage increases with increasing age. A validity test revealed, however, that life table statistics used on the total patient material underestimated the annual risk for hemorrhage, especially for patients 20-50 years of age. A method based on the fact that the distribution of the time at risk until the initial hemorrhage (= age at first rupture) reflects the risk for hemorrhage in untreated AVM was therefore also employed. The analysis yielded three conclusions: 1) the annual risk of hemorrhage increases with age; 2) small AVM are less prone to rupture; and 3) the risk of hemorrhage is higher in women during their fertile years as compared to males in the same age group. The risk related to age, AVM size and location assessed by survival statistics in the subgroup of patients with a known date for the initial hemorrhage gave similar results.

Adolescent↗

PubMed1997

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 between patient, AVMs, and treatment parameters on the one hand and the obliteration of the nidus on the other was analyzed. RESULTS: The obliteration rate increased both with increased minimum (lowest periphery) and average dose and decreased with increased AVM volume. The minimum dose to the AVMs was the decisive dose factor for the treatment result. The higher the minimum dose, the higher the chance for total obliteration. The curve illustrating this relation increased logarithmically to a value of 87%. A higher average dose shortened the latency to AVM obliteration. For the obliterated cases, the larger the malformation, the lower the minimum dose used. This prompted us to relate the obliteration rate to the product minimum dose (AVM volume)1/3 (K index). The obliteration rate increased linearly with the K index up to a value of approximately 27, and for higher K values, the obliteration rate had a constant value of approximately 80%. For the group of 273 cases treated with a minimum dose of at least 25 Gy, the obliteration rate at the study end point (defined as 2-yr latency) was 80% (95% confidence interval = 75-85%). If obliterations that occurred beyond the end point are included, the obliteration rate increased to 85% (81-89%). CONCLUSION: The probability of obliteration of AVMs after gamma knife surgery is related both to the lowest dose to the AVMs and the AVM volume, and it can be predicted using the K index.

Adolescent↗

PubMed1997

Radiosurgical lesions in the normal human brain 17 years after gamma knife capsulotomy.

OBJECTIVE: To our knowledge, this is the first long-term follow-up study of high-dose single-session irradiation to the human brain and provides new data concerning late tissue reactions after irradiation to small target volumes. The long-term lesional brain changes in 14 patients subjected to bilateral gamma knife capsulotomy for otherwise intractable anxiety disorders were retrospectively analyzed by magnetic resonance imaging. METHODS: The prototype gamma unit was used for the radiosurgical procedure, and the collimators provided rectangular cross-sectional fields with an anteroposterior diameter of 3 mm and a transverse diameter of 5 or 11 mm. Maximum target doses were 120 to 180 Gy. Magnetic resonance imaging was performed 15 to 18 years (mean, 17 yr) after treatment, and dose-volume histograms were calculated for the dose distributions. RESULTS: One patient had been irradiated twice on one side. In all but one of the remaining 27 targets, lesions with a volume of less than 100 mm3 were revealed by magnetic resonance imaging. The volumes of the lesions were confined within the volume corresponding to a minimum dose of approximately 110 Gy, with one exception. In one of three targets receiving a maximum dose of 120 Gy, no lesion was detected. There were no late radiation effects such as cyst formations, telangiectasias, hemorrhagic infarctions, or neoplasms. CONCLUSION: This investigation indicates that a minimum dose of 110 Gy, with the currently used 4-mm collimator, to the edge of the target volume is required to create a lesion. The results prove that gamma knife surgery can be used in functional neurosurgery for producing small permanent lesions in the normal human brain.

Adult↗

PubMed1997

Third ventricle colloid cysts: a consecutive 12-year series.

A continuous follow-up review of colloid cysts including aspects of natural history and evaluation of treatment options is necessary to optimize individual treatment. Thirty-seven consecutive patients with colloid cyst of the third ventricle seen at Karolinska Hospital between 1984 and 1995 were reviewed. Five patients were admitted in a comatose state, and two died despite emergency ventriculostomy. Three had recurrent cysts following previous aspiration procedure. During the study period, patients underwent a total of 10 ventriculostomies, 10 aspirations, 26 microsurgical operations, and two shunt operations. Twenty-four of 26 microsurgical operations were transcallosal and two were transcortical. Twenty-four operations (22 transcallosal and two transfrontal approaches) without permanent morbidity were performed by four surgeons. Transient memory deficit from forniceal traction was noted in 26%. The remaining two transcallosal operations, which led to permanent morbidity or mortality, were performed by two different surgeons. Aspiration of cysts performed by four different surgeons carried a 40% risk of transient memory deficit (10% permanent) and an 80% recurrence rate. One patient was found to be cured on radiological studies obtained at the 5-year follow-up review. Seven cysts were followed by means of radiological studies with no treatment for 6 to 37 months. Five of these cysts grew, indicating that younger patients with colloid cysts will probably need surgical treatment. The main causes of unfavorable results were: 1) failure to investigate symptoms that proved fatal; 2) subtotal resection; and 3) surgical complications. Transcallosal microsurgery produced excellent results when performed by experienced surgeons. A colloid cyst of the foramen of Monro is a disease that should be detected before permanent neurological damage has occurred. Permanent morbidity or mortality should not be accepted in modern series of third ventricle colloid cysts.

Adolescent↗

PubMed1997

Radiosurgery for cerebral AVMs in children and adolescents: the neurobehavioral outcome.

Eight patients, ranging in age from 9 to 18 years, were treated for arteriovenous malformations using gamma knife radiosurgery and were evaluated an average of 6 years after treatment to record potential effects of radiosurgery on cognitive and neuropsychological performance. Tests for general intelligence, nonverbal intelligence, memory and its components, and attention performance were administered to patients and compared with test results of age-matched siblings or first cousins. No statistically significant difference was found between the performance of patients and controls in any of the tests administered. Additionally, a specially designed questionnaire completed by the patients, their parents, and their teachers revealed that the patients' emotional and relational behavior was stable and unchanged after treatment. No correlation was found between the neurocognitive test performance and the lesion volumes irradiated, but the lesion site was found to contribute to the type of deficit recorded after treatment. The less invasive nature of the radiosurgical approach, combined with the brevity or absence of hospitalization, presumably contributed to the patients successful physical, mental, and emotional recovery.

Adolescent↗

PubMed1997

Magnetic resonance imaging of obliterated arteriovenous malformations up to 23 years after radiosurgery.

The authors report outcomes in 18 patients with arteriovenous malformations (AVMs) who were treated with gamma knife radiosurgery and in whom magnetic resonance (MR) imaging was obtained a mean of 14 years (range 8-23 years) after treatment and 10 years (range 4-17 years) after confirmed obliteration of the AVM. All patients were asymptomatic after radiosurgery and during the time of the study. In five patients (28%), cyst formation was observed that corresponded to the site of the obliterated AVM. Cyst formation and contrast enhancement on MR imaging could not be statistically correlated to the radiation dose. In 11 (61%) of the 18 patients, contrast enhancement that was not related to a recanalization of the nidus was observed in the target area. In three patients (17%), an increased T2-weighted signal was detected at the site of previous AVM; this was interpreted as gliosis or demyelination, which appeared to be dose dependent. The study illustrates that cyst formation, contrast enhancement, and an increased T2-weighted signal can be observed in asymptomatic patients in the area that was targeted for AVM radiosurgery up to 23 years after the procedure. The report provides new and essential information about long-term effects on normal tissue after radiosurgery and provides a basis for the interpretation of MR studies in the follow up of small AVMs treated by radiosurgery.

Adolescent↗

PubMed1996

Gamma knife pallidotomy in advanced Parkinson's disease.

Posteroventral pallidotomy as a treatment for Parkinson's disease (PD) has been the subject of increasing interest. We treated 4 nondemented patients with advanced PD, 2 with severe bradykinesia and a declining response to medication, and 2 with marked clinical fluctuations. All patients received 180 Gy delivered in one sitting to the right posteroventral pallidum site, used by Laitinen and colleagues, adjusted as needed, to avoid the optic tract. Only 1 patient changed significantly. Dyskinesia completely resolved on the side contralateral to the lesion in this patient. This same patient also became transiently demented and psychotic. The other 3 patients suffered no clearly identifiable beneficial or harmful effects. Follow-up magnetic resonance imaging scans of the brain at 1 year revealed lesions exactly where targeted although of unequal sizes. Our negative experience forces us to conclude that either larger volumes of tissue must be ablated, that physiologic monitoring is required for placing a lesion, that our subjects were poor candidates for the procedure, or that surgical ablation and radiation cause tissue damage of different types with different results.

Aged↗

PubMed1996

Neuroimaging studies of postobliteration nidus changes in cerebral arteriovenous malformations treated by gamma knife radiosurgery.

BACKGROUND: Following radiosurgical treatment, the majority of patients with arteriovenous malformations (AVMs) are periodically examined by means of computed tomography (CT) and magnetic resonance imaging (MRI) to assess the attainment of nidus obliterations, as well as adverse radiation effects in the surrounding brain. However, few neuroimaging studies of the long-term results following complete obliterations, confirmed by angiography, have been published to date. METHODS: CT, MRI, magnetic resonance (MR) angiographic and angiographic images, obtained after angiographic confirmation of complete nidus obliteration, were reviewed in 11 AVM patients treated with gamma knife radiosurgery. The period between angiographic confirmation of nidus obliteration and these most recent examinations was 12-84 months (mean, 29 months). RESULTS: In ten patients who were assessed by CT, the obliterated nidus was shown to be isodense (eight cases). A significant time-related decrease in contrast enhancement was observed within 1 to 2 postobliteration years (five/seven cases). Eight patients were evaluated by MRI. On T1-weighted imaging, the nidus was shown to be hypointense (six cases) or a mixture of hypointense and isointense areas (two cases). On T2-weighted imaging, nidus intensity varied more than than observed on T1-weighted imaging, and time-related intensity increases were observed (two/seven cases). No flow-signal void was demonstrated in any of these cases. In four of the seven cases, in which serial postobliteration follow-up MRI studies were conducted, significant gadolinium enhancement persisted 3 years or more after obliteration (maximum of 7 years). No vascular abnormalities were demonstrated in seven patients who were assessed by conventional angiography and/or MR angiography. CONCLUSIONS: Radiosurgery-induced changes in a nidus may continue for several years after angiography has shown complete AVM obliteration.

Adolescent↗

PubMed1996

Effect of Gamma Knife surgery on the risk of rupture prior to AVM obliteration.

The incidence for hemorrhage in non-obliterated arteriovenous malformations (AVM) during the first two years following Gamma Knife (GK) surgery was compared to the calculated incidence in untreated patients. There was a decrease in the incidence of hemorrhage as compared to the natural course. This difference was statistically significant. The actual number of hemorrhages during the first two years was 49 in a series of 1604 patients. Additionally, 41 hemorrhages occurred beyond the two years following treatment over the entire follow up time span of up to 24 years. For the first two years the calculated incidence was roughly two times higher than the observed incidence. This impact on the natural history was detectable already within six months after the treatment for the malformations totally covered with at least 25 Gy. The relation between a high minimum and a high average dose on the one hand and a lower risk for hemorrhage on the other hand was statistically significant. Low treatment doses and high age correlated to a higher risk. Neither hemorrhage prior to treatment nor time interval between presenting hemorrhage and treatment seemed to influence the risk for post treatment hemorrhage. The risk for permanent neurological deficit or death due to AVM rupture during the latency period between the time of treatment and total nidus obliteration was less than 0.5% for small AVM and 2-4% for large ones during the first two years. Of the 24 patients with sequelae following AVM rupture after treatment 14 died and 10 remained with neurological deficit of different degrees. However, all survivors were self sufficient.

Adult↗

PubMed1996

Microsurgery with the Steiner-Lindquist stereotaxic guide.

The Steiner-Lindquist microsurgical stereotaxic guide was used for operations for intra-axial lesions in 15 patients. The lesions were identified by stereotaxic CT or MRI and stereotactic co-ordinates were then calculated and set for the guiding laser beam. The beam was used for planning the craniotomy and its path followed during the microsurgical dissection, until the lesion was reached. Seven lesions were situated in eloquent areas of the brain and could not have been safely attacked without the aid of stereotaxic localization. Five of these and two other lesions were quite small, and would have been difficult to find without jeopardizing normal brain structures. For the remaining lesions the stereotaxic laser guide was facilitatory, but not indispensible. Radical removal was achieved in 11 of the 15 lesions. The Steiner-Lindquist microsurgical guide incorporates the freedom of standard microsurgical techniques with the safety of operating in a stereotaxically defined space.

Adolescent↗

PubMed1996

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.

Combined Modality Therapy↗

PubMed1996

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, Olivecrona's 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.

Academies and Institutes↗

PubMed1996

Clinical experience with stereotactic digital subtraction angiography with distortion correction software.

Recently developed software for correction of the geometric distortion in digital subtraction angiography was tested clinically. Localization and subsequent radiosurgical treatment of intracranial arteriovenous malformations was undertaken in 60 patients. During each angiographic series, a series of grid images was also acquired. All images were transferred to a workstation where the grid images were compared to a previously stored ideal image of the grid. A distortion correction was then performed on the grid images. The same pixel-by-pixel correction was applied to the respective angiographic images. The target was outlined on corrected subtracted images on the monitor. The outlined regions of interest and reference points were transferred to another workstation for dose planning, and the treatment was subsequently executed in the Gamma Knife unit. The clinical applicability of the distortion correction program was tested and possible sources of error examined. The experience gained is being used for further development of the software and for smoother data management and reduction of the processing time.

Adolescent↗

PubMed1996

Positron emission tomography using 18F-fluorodeoxyglucose in patients with stereotactically irradiated brain metastases.

Thirty-one patients with intracranial metastases were examined with positron emission tomography (PET) using 18F-fluorodeoxyglucose (FDG) as a tracer. The PET study was prompted by growth of the tumor in spite of therapy, or regrowth after an initially favorable response. Increased accumulation of FDG was seen in 14 patients (group 1) and decreased in 17 (group 2). Patients in group 1 had verified tumor growth in 9 of 14 cases. The median survival after radiosurgery was 12.3 months. One patient in this group is still alive after open surgery of a recurrent metastasis. Six patients in group 2 are still alive. The median survival after radiosurgery was 19.9 months. Verified radiation reaction/necrosis was found in 5/17 and viable tumor tissue in 2. The survival time in group 2 was significantly longer than in group 1. PET is superior to computed tomography and magnetic resonance imaging in the differentiation between recurrence and radiation reaction/necrosis. However, temporary radiation effects may mask remaining tumor tissue, and repeat PET studies may sometimes be necessary.

Adult↗

PubMed1996

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.

Adolescent↗

PubMed1996

Stereotactic radiosurgery for trigeminal neuralgia: a multiinstitutional study using the gamma unit.

A multiinstitutional study was conducted to evaluate the technique, dose-selection parameters, and results of gamma knife stereotactic radiosurgery in the management of trigeminal neuralgia. Fifty patients at five centers underwent radio-surgery performed with a single 4-mm isocenter targeted at the nerve root entry zone. Thirty-two patients had undergone prior surgery, and the mean number of procedures that had been performed was 2.8 (range 1-7). The target dose of the radiosurgery used in the current study varied from 60 to 90 Gy. The median follow-up period after radiosurgery was 18 months (range 11-36 months). Twenty-nine patients (58%) responded with excellent control (pain free), 18 (36%) obtained good control (50%-90% relief), and three (6%) experienced treatment failure. The median time to pain relief was 1 month (range 1 day-6.7 months). Responses remained consistent for up to 3 years postradiosurgery in all cases except three (6%) in which the patients had pain recurrence at 5, 7, and 10 months. At 2 years, 54% of patients were pain free and 88% had 50% to 100% relief. A maximum radiosurgical dose of 70 Gy or greater was associated with a significantly greater chance of complete pain relief (72% vs. 9%, p = 0.0003). Three patients (6%) developed increased facial paresthesia after radiosurgery, which resolved totally in one case and improved in another. No patient developed other deficits or deafferentation pain. The proximal trigeminal nerve and root entry zone, which is well defined on magnetic resonance imaging, is an appropriate anatomical target for radiosurgery. Radiosurgery using the gamma unit is an additional effective surgical approach for the management of medically or surgically refractory trigeminal neuralgia. A longer-term follow-up review is warranted.

Adult↗

PubMed1996

Gamma knife radiosurgery in 11 hemangioblastomas.

One suprasellar, one mesencephalic, and nine cerebellar hemangioblastomas were treated with the gamma knife in 10 patients (median age 48 years) in Stockholm between 1978 and 1993. Four patients had von Hippel-Lindau disease, a dominant inherited trait predisposing to multiple hemangioblastomas. Six hemangioblastomas were treated with radiotherapy at a median margin dose of 25 Gy (20-35 Gy) before 1990 and the next five with a median of 10 Gy (5-19 Gy). Computerized tomography or magnetic resonance images were available for 10 of the 11 hemangioblastomas at a median follow-up time of 26 months (4-68 months) after radiosurgery. The solid part of six hemangioblastomas shrank in a median of 30 months, whereas four hemangioblastomas were unchanged at a median of 14 months. Five hemangioblastomas had an adjoining cyst and three of these cysts had to be evacuated after radiosurgery. One solitary hemangioblastoma later developed a de novo cyst that also needed evacuation. One patient with two cerebellar hemangioblastomas (margin dose 25 Gy each) developed edema at 6 months and required a shunt and prolonged corticosteroid treatment. The combined follow-up data of the 23 hemangioblastomas in 15 patients from previous literature and the present series indicate that, first, a solitary small- or medium-sized hemangioblastoma usually shrinks or stops growing after radiosurgery. The recommended margin dose is 10 to 15 Gy. Second, the adjoining cyst often does not respond to radiosurgery but requires later, sometimes repeated evacuation.

Adult↗