The excellent treatment results obtained with traditional radiosurgery have stimulated attempts to broaden the range of intracranial disorders treated with radiosurgical techniques. For major users ...of radiosurgery this resulted in a gradual shift from treating vascular diseases in a single session to treating small, well delineated primary tumors on a fractionated basis. In this paper we present the technique currently used in Montreal for the fractionated stereotactic radiotherapy of selected intracranial lesions.
The regimen of six fractions given every other day has been in use for "fractionated stereotactic radiotherapy" in our center for the past 5 years. Our current irradiation technique, however, evolved from our initial method of using the stereotactic frame for target localization and first treatment, and a "halo-ring" with tattoo skin marks for the subsequent treatments. Recently, we developed a more precise irradiation technique, based on an in-house-built stereotactic frame which is left attached to the patient's skull for the duration of the fractionated regimen. Patients are treated with the stereotactic dynamic rotation technique on a 10 MV linear accelerator (linac).
In preparation for the first treatment, the stereotactic frame is attached to the patient's skull and the coordinates of the target center are determined. The dose distribution is then calculated, the target coordinates are marked onto a Lucite target localization box, and the patient is placed into the treatment position on the linac with the help of laser positioning devices. The Lucite target localization box is then removed, the target information is tattooed on the patient's skin, and the patient is given the first treatment. The tattoo marks in conjunction with the target information on the Lucite target localization box are used for patient set-up on the linac for the subsequent 5 treatments. The location of the target center is marked with radio-opaque markers on the target localization box and verified with a computerized tomography scanner prior to the second treatment. The same verification is done prior to other treatments when the target center indicated by the target localization box disagrees with that indicated by the tattoo marks. The new position of the target center is then determined and used for treatment positioning.
The in-house-built frame is inexpensive and easily left attached to the patient's skull for the 12 day duration of the fractionated regimen. Positioning with the Lucite target localization box verified with tattoo marks ensures a high level of precision for individual fractionated treatments.
From October 1988 to April 1990, 9 patients with metastatic brain disease (11 lesions) underwent stereotactic radiosurgery. All patients but two had recurrent metastatic disease after previous brain ...irradiation. The patients were treated with a single dose of 20 Gy, delivered to spherical target volumes ranging in diameters from 10 mm to 30 mm and prescribed to the 90% isodose surface. All tumors treated showed a favorable response to the treatment, with 4 patients achieving a complete radiological disappearance of the tumor. The majority of the patients experienced a rapid clinical improvement of their symptoms. No complications attributable to the radiosurgical treatment were seen. Stereotactic radiosurgery appears to be an effective and safe treatment for patients with recurrent metastatic brain disease.
We present a case of tension pneumocephalus after burr hole evacuation of bilateral chronic subdural hematomas. Subsequent treatment was effected with combined twist drill closed system drainage and ...continuous intrathecal infusion of a physiological solution. The clinical entity, tension pneumocephalus, and the use of continuous subarachnoid infusion and drainage as a method of cerebral reexpansion are discussed.
This is a retrospective review of 52 patients with metastatic brain disease who underwent stereotactic radiosurgery at McGill University in Montreal. The radiosurgical treatment was performed with ...the dynamic rotation technique in which there is continuous and simultaneous movement of treatment couch and machine gantry of a 10 MV linac. All patients were treated with a single isocenter and a median dose of 1800 cGy was delivered. In 88% of the cases radiosurgery was given after failure from whole brain conventional irradiation. All 52 cases were assessed with brain CT post radiosurgery. The median follow up time was 6 months (range 1-37 months) and the response rate (partial or complete) was 64%. Only 4 patients (7%) developed late complications related to the treatment. These findings are similar to the literature. Stereotactic radiosurgery is a well tolerated, effective and minimally invasive treatment technique which has a high response rate in selected patients with small, well delineated metastatic brain lesion. Its definitive value as a single therapy or combined with whole brain conventional radiotherapy is being studied in prospective and randomized trials.
Tirilazad mesylate, a 21-aminosteroid free-radical scavenger, has been shown to ameliorate cerebral vasospasm and reduce infarct size in animal models of subarachnoid hemorrhage (SAH) and focal ...cerebral ischemia. In preparation for performing large-scale clinical trials in humans with aneurysmal SAH, the safety of varying doses of tirilazad was tested in a randomized, double-blind, vehicle-controlled, sequential dose-escalation study at 12 Canadian neurosurgical centers. Two hundred forty-five patients with an aneurysmal SAH documented by angiography were enrolled in the study sequentially within 72 hours of hemorrhage. The patients were assigned to one of three dosage tiers: receiving 0.6 mg/kg, 2 mg/kg, or 6 mg/kg tirilazad or vehicle per day intravenously in divided doses through Day 10 following the SAH. All patients also received oral nimodipine. No serious side effects of tirilazad treatment were identified at any of the three doses, despite close monitoring of hepatic and cardiac toxicity. A trend toward improvement in overall 3-month patient outcome was seen in the 2 mg/kg per day tirilazad-treated group compared to the outcomes in the vehicle-treated groups. We conclude that tirilazad mesylate is safe in SAH patients at doses up to 6 mg/kg per day for up to 10 days and is a promising drug for the treatment of patients with aneurysmal SAH.
Stereotactically guided external beam irradiation may be a useful form of treatment for small, well-circumscribed, but surgically inaccessible, primary brain tumors that are either benign or of low ...malignant potential. Between March 1988 and December 1991, 10 children and adolescents with previously untreated primary brain tumors were treated with stereotactic external beam irradiation (SEBI) using a linac-based dynamic technique. Eleven lesions were treated in the 10 patients. Treatment was given using a collimator diameter of 1.5-4 cm (median 2 cm). Single fractions of 18, 20, and 25 Gy were used for 3 lesions in 2 patients. A fractionated schedule delivering a median dose of 42 Gy in 6 fractions over 2 weeks was used in the remaining 8 patients. Morbidity related to treatment was minimal. Three patients suffered a temporary worsening of preexisting neurological symptoms and/or signs at 2, 5, and 5 months posttreatment, with subsequent recovery in all. With a median follow up post-SEBI of 17.5 months (range 5-47 months), improvement in neurological findings related to the lesion was noted for 5 treated lesions; 6 remained clinically stable. Seven of the 11 treated lesions improved radiologically, and only 2 showed evidence of progressive disease. Stereotactic external beam irradiation represents a potentially valuable therapeutic option for selected primary brain tumors in the pediatric and adolescent age group. Morbidity related to the treatment appears acceptable in frequency and type, and preliminary data with regard to response are encouraging. However, in order to assess the impact of such treatment on long-term tumor control and survival, further experience with a larger cohort of patients followed for a longer period of time will be necessary.
Between December 1986 and June 1990, 112 patients (116 lesions), underwent treatment with dynamic stereotactic radiosurgery at McGill University. Of the treated lesions, 59 were arteriovenous ...malformations and 53 were a variety of other neoplastic conditions. In 86 lesions, the treatment was delivered in a single fraction and the treatment of the remaining 30 lesions was fractionated. Complications attributed to treatment developed in seven of the 112 patients (6.3%). No relationship was found between complications and prescribed dose, fractionation, collimator diameter, type and anatomical region of the lesion that was treated, or previous irradiation. Although extensive clinical experience will be necessary to determine optimal total doses, the potential role of fractionated treatment, and the tolerance of critical structures to radiosurgery, the relatively low incidence of complications in our series allows us to conclude that radiosurgery is well tolerated by the vast majority of patients.
O artigo faz avaliação de 52 pacientes com metástase cerebral tratados com radiocirurgia estereotática na Universidade McGill, em Montreal. A radiocirurgia foi realizada com a técnica dinâmica em ...que, ao mesmo tempo, giram a mesa e a cabeça do acelerador linear de 10 MV. Todos os pacientes (56 tratamentos ao todo) foram tratados com um único isocentro e uma dose única mediana de 1800 cGy na periferia da metástase. Em 88% dos casos a radiocirurgia foi usada após falha de tratamento radioterápico fracionado em todo cérebro. Todos os 52 casos tiveram avaliação com CT pós radiocirurgia. O seguimento mediano foi de 6 meses (variou entre 1 e 37 meses) e a taxa de resposta, parcial ou completa, foi de 64%. Apenas 4 pacientes (7%) tiveram algum tipo de complicação tardia relacionada ao tratamento. Estes achados vão de encontro com dados da literatura. A radiocirurgia é tratamento pouco agressivo, bem tolerado e com alta taxa de resposta para lesões locais e pode ser útil para pacientes selecionados. O seu valor definitivo, como tratamento único ou combinado com radioterapia em todo cérebro, está sendo avaliado de forma prospectiva e randomizada.
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