PubMed Health⌕ Search

Biomedical subjects

C B Ostertag

Publications and source records attributed to C B Ostertag.

At least 19 recordsLinked to original sources
PubMed1997

Supratentorial World Health Organization Grade 2 astrocytomas and oligoastrocytomas. A new pattern of prognostic factors.

BACKGROUND: Prognostic factors for adult patients with supratentorial World Health Organization (WHO) Grade 2 astrocytomas and poorly defined. METHODS: The prognostic importance of pretreatment patient- and tumor-related factors was analyzed retrospectively in 197 adult patients with supratentorial astrocytomas (n = 153) or oligoastrocytomas (n = 44) using the multivariate Cox proportional hazards model. Endpoints were death and date of malignant transformation. All patients were treated similarly between 1979 and 1992 with iodine-125 implants as the primary treatment. RESULTS: A new prognostic pattern was detected. Unfavorable prognostic factors with regard to survival were 1) a tumor volume > or = 20 mL; 2) a performance status < or = 80; and 3) age > or = 40 years for the female subpopulation. Midline shift (another important tumor-related factor after univariate analysis) was highly correlated with tumor volume and therefore not included in the multivariate model. Risk factors of malignant transformation were 1) a tumor volume > or = 20 mL; 2) an enhancement in the computed tomography scan; and 3) age > or = 40 years for the female subpopulation. Prognostic factors created subsets of patients with 5-year survival rates ranging from as low as 5% to as high as 79%. CONCLUSIONS: Any treatment decision or evaluation of treatment efficacy should take into account the strong influence of both patient- and tumor-related factors. Any further study design should consider the detected interaction between gender and age and the importance of tumor volume.

Adult↗
PubMed1997

Significant reduction of seizure incidence and increase of benzodiazepine receptor density after interstitial radiosurgery in low-grade gliomas.

Epilepsy is the leading symptom in low grade gliomas. In order to evaluate the effect of interstitial radiosurgery on seizure incidence the authors retrospectively analysed the outcome of 80 patients with temporal grade-II astrocytomas and a history of epilepsy. Patients were treated by 125-iodine temporary implants using 60 Gy as reference dose. The dose rate was 9.6 +/- 1.6 cGy/h. Median follow-up was 4.1 years. In 20 patients benzodiazepine receptor imaging was performed using single photon emission computed tomography and iomazenil. Treatment with carbamazepine alone led to a significant reduction in seizure incidence with 28% of patients being seizure-free (p < 0.05). Interstitial radiosurgery led to a further reduction of seizures rendering 40% of patients seizure-free after 3 months. After 6 months only 21% of patients still had seizures that were refractory to medical treatment (p < 0.01). SPECT imaging revealed that all tumours had a significant reduction of benzodiazepine receptors which also applied to the surrounding brain. After interstitial radiosurgery of tumours, receptor density increased in brain adjacent to the tumour (0.68 to 0.94 ratio ipsi to contralateral brain, p < 0.01) coincident with significant tumour shrinkage. Thus, in epileptogenic temporal low grade gliomas, interstitial radiosurgery not only reduced the tumour burden but also effectively treated the concomitant epilepsy, resulting in 79% of patients being seizure-free after combined treatment by radiosurgery and anticonvulsive medication. These results compare favourably to the outcome after resection in lesional epilepsy raising the issue of radiosurgery as a less invasive alternative to open epilepsy surgery.

Adult↗
PubMed1997

Effect of LINAC radiosurgery on regional cerebral blood flow, glucose metabolism and sodium-potassium AtPase in skull base meningiomas and metastasis.

Stereotactic radiosurgery is an elegant alternative to microsurgery in both skull base meningiomas and solitary brain metastasis. Though efficacy for both entities has been established prognostic variables pertaining to individual tumour biology have not yet been identified. Therefore the authors measured regional glucose utilisation, thallium-uptake and blood flow in 20 patients (10 meningiomas, 10 metastasis) before and after LINAC radiosurgery. Measurements were performed using SPECT and stable xenon-CT. The mean tumour dose given was 16.3 and 19.5 Gy in meningiomas and metastasis respectively. Metastatic tumours were hypermetabolic in comparison to contralateral normal brain and responders to radiosurgery showed a lower tumour/brain ratio than non-responders (1.43 vs 0.91 respectively, p < 0.01). Meningiomas did not exhibit hypermetabolism and therapeutic outcome was not related to glucose utilisation. Thallium-uptake, however, was closely related to therapeutic response in meningiomas (1.37 vs 2.2 in responders vs non-responders, p < 0.01). This relationship could not be established in metastatic lesions. Blood flow was widely distributed in both meningiomas and metastasis (26-72.8 and 30.2-70.8 ml/100 g/min). rCBF did not correlate with therapeutic outcome. Using FDG-SPECT and thallium-201-SPECT the authors were able to distinguish between tumours likely to respond to stereotactic radiosurgery and those not prone to respond. Furthermore the methodology can be used to monitor therapeutic response in treated tumours before morphologic changes occur.

Adult↗
PubMed1997

[Stereotactic treatment of movement disorders].

Stereotactic surgery for movement disorders is currently undergoing a re-evaluation. A new understanding of the pathophysiology makes the surgical lesion a logical step for the aleviation of both hyperkinetic symptoms such as tremor and hypokinetic symptoms like bradykinesia. Advances in imaging and electrophysiological control render these procedures more accurate and safer. Indications are medically refractory, Parkinsonean tremor, essential tremor, cerebellar tremor, bradykinesia and L-Dopa induced dyskinesis. The standard procedure is ablative surgery, i.e. thalamotomy for tremors and pallidotomy for bradykinesia, dystonia and L-Dopa induced dyskinesias. Deep brain stimulation is a novel alternative for selected patients which is currently evaluated. Neural transplantation of autologus, fetal or genetically manipulated cell suspensions into the striatum for the time being is experimental.

Brain Mapping↗
PubMed1997

The risk of interstitial radiotherapy of low-grade gliomas.

BACKGROUND AND PURPOSE: The risk of side effects of low activity (i.e. <20 mCi) Iodine-125I (125I) interstitial radiotherapy was analyzed in patients with low-grade gliomas. MATERIALS AND METHODS: Permanent (247 patients) or temporary 125I-implants (268 patients) were used with a median reference dose of 60 Gy and 100 Gy, respectively, which was calculated to the outer rim of the tumour. The mean dose rate for temporary implants was low (median, 10 cGy/h). Risk factors were obtained from the multivariate proportional-hazards model. RESULTS: Radiogenic complications occurred in 39/515 patients (28 patients with transient symptoms and 11 patients with progressive symptoms). The most important risk factor was the volume of the intratumoural 200 Gy isodose. Available experimental data have associated a high dose zone in this range with the size of the treatment induced radionecrosis. Rapid tumour shrinkage (decrease of the tumour volume > or =50%) within the first 6 months with subsequent centripetal movement of non-pathologic tissue into the high dose zone and a reimplantation were additional risk factors. Radiation injury after rapid tumour shrinkage could be better avoided with temporary implants. A 200 Gy isodose volume <4.5 ml corresponded to an estimated risk of radiogenic complications <3%. There was a steep increase of the risk beyond this limit. Translation of the 200 Gy isodose volume in terms of the treatment volume and the reference dose allows rational treatment planning. The estimated risk of a temporary implant with an applied reference dose of 60 Gy and a treatment volume <23 ml was <3%. CONCLUSIONS: The intratumoural necrotizing effect of a low activity 125I implant limits its application to small treatment volumes. Radiation injury outside the treatment volume can be better avoided with temporary implants in the case of rapid tumour shrinkage.

Adolescent↗
PubMed1996

Stereotactic management of lesions of the pineal region.

OBJECTIVE: The relevance of the computed tomography-guided stereotactic approach for the management of lesions of the pineal region is analyzed. METHODS: In a retrospective analysis conducted between 1985 and 1993, the risk profile, the diagnostic accuracy, and the therapeutic relevance of the stereotactic approach in 106 patients was studied. Survival analysis was used to assess the reliability of the stereotactically obtained diagnosis in terms of follow-up observation. RESULTS: A histological diagnosis was obtained in 103 of the 106 patients. In three patients, a conclusive diagnosis could not be established because of intraoperative complications. One lesion was misdiagnosed as a pineocytoma instead of a pineoblastoma. Two of the 106 patients died; 9 patients experienced perioperative morbidity. In 38 patients, the stereotactic approach was also useful for therapy. Cyst aspiration and/or internal drainage was performed in 18 patients with symptomatic cystic lesions, and radiosurgical treatment with use of interstitial 125iodine was performed in 16 patients with low-grade tumors and in 4 patients with solitary metastases. In 12 patients, the obtained tissue diagnosis was the basis for deferring additional therapy. In 43 patients with germ-cell tumors, pineoblastomas, or malignant gliomas, a stereotactic biopsy was the starting point for additional radiotherapy/chemotherapy. Open tumor resection played a minor role (five patients). CONCLUSION: The stereotactic approach to the pineal region is a relatively safe procedure in experienced hands. The diagnosis obtained by computed tomography-guided stereotactic biopsy is a valid basis for treatment decisions. Long-term follow-up observation of the benign lesions is necessary for a definite confirmation of diagnostic accuracy.

Adolescent↗
PubMed1995

Interstitial iodine-125 radiosurgery for cerebral metastases.

The current study evaluates the efficacy of interstitial 125-iodine radiosurgery (brachytherapy) in 93 patients with circumscribed, spherical, mostly solitary metastases. In all patients the histological diagnosis was established by stereotactic biopsy. The treatment results of three therapeutic regimens have been examined retrospectively: Group A (38 patients) had interstitial radiosurgery with a reference tumour dose of 60 Gy in combination with percutaneous radiotherapy (40 Gy). Group B (34 patients) was treated by interstitial radiosurgery alone (reference dose 60 Gy). Group C (21 patients with recurrent metastases after previous radiotherapy/surgery) was treated by interstitial radiosurgery alone (reference dose 60 Gy). Median survival after interstitial radiosurgery was 17 months in group A, 15 months in group B, 6 months in group C. Favourable prognostic factors were a Karnofsky performance rating > or = 70, solitary metastasis, absence of disseminated disease, and a time interval > 1 year between diagnosis of the primary tumour and diagnosis of the cerebral metastases. Interstitial radiosurgery plus percutaneous radiotherapy did not prove to be superior to interstitial radiosurgery alone. No patient died of a locally irradiated metastasis. We conclude that interstitial radiosurgery achieves control of the growth of solitary spherical cerebral metastases in any location without radiation toxicity.

Adult↗
PubMed1995

Interstitial radiosurgery of low-grade gliomas.

The treatment of patients with low-grade gliomas remains a subject of controversy, especially with respect to new treatment modalities such as interstitial radiosurgery (brachytherapy), radiosurgery, and stereotactic radiotherapy. In a retrospective analysis conducted between 1979 and 1991, the authors studied the results of interstitial radiosurgery in 455 patients with low-grade gliomas (World Health Organization (WHO) Grade I+WHO Grade II) with regard to survival time, quality of life, the risk of malignant transformation, and the risk profile of the treatment concept. Interstitial radiosurgery with iodine-125 was performed using permanent (1979-1985) or temporary implants (after 1985) with low-dose rates (< or = 10 cGy/hr) and a reference dose of 60 to 100 Gy calculated to the outer rim of the tumor. The 5- and 10-year survival rates in patients with pilocytic astrocytomas (97 patients) were 84.9% and 83%, and in patients with WHO Grade II astrocytomas (250 patients) 61% and 51%, respectively. Five-year survival rates for patients with oligoastrocytomas (60 patients), oligodendrogliomas (27 patients), and gemistocytic astrocytomas (21 patients) were 49%, 50%, and 32%, respectively. In the group with WHO Grade II gliomas, young age and a good performance status were associated with a better prognosis. Unfavorable factors were midline shift, enhancement on computerized tomography (CT) scan, and tumor recurrence after previous radiotherapy or surgery. Tumor location had no influence on the prognosis (247 patients in this series had deep-seated tumors). Malignant transformation was the major cause of death. Important risk factors for malignancy were the patient's age, tumor enhancement in CT scan, and tumor recurrence after previous surgery or radiotherapy. Perioperative mortality was 0.9% and perioperative morbidity was 1.7%. Radiogenic complications were observed in 2.7% of all patients, most often in larger tumors and after using permanent implants. The authors conclude that interstitial radiosurgery represents a specific treatment modality for selected patients with unifocal circumscribed low-grade gliomas with a diameter of less than 4 cm in any location. The efficacy of this treatment lies in the same range as the best results after surgery and radiotherapy.

Adolescent↗