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.

Long-term outcome of 89 low-grade brain-stem gliomas after interstitial radiation therapy.

Between 1974 and 1985, 89 patients suffering from histologically confirmed, nonresectable low-grade astrocytomas located in the brain stem were entered into a retrospective study. Iodine-125 (125I) was implanted in 29 patients and iridium-192 (192Ir) in 26 patients. Computerized tomography revealed that 78% of the tumors in these patients were located chiefly in the mesencephalic region, 70% were circumscribed, and 78% were contrast-enhanced. Thirty-four patients underwent biopsy without prior aggressive tumor-specific therapy such as chemotherapy or external beam irradiation. Among these, 70% of the tumors were located predominantly in the pons, 74% were diffuse, and 59% were hypodense or isodense after contrast enhancement. Long-term follow-up investigations indicated that life expectancy after interstitial radiation therapy with 125I implanted directly by catheter either permanently or temporarily showed a more favorable trend than that after treatment with 192Ir. Interstitial radiation therapy with 125I appears to be an effective treatment for slowly proliferating, differentiated, well-delineated, nonresectable brain-stem gliomas. This technique makes it possible to achieve radiosurgical tumor control and, when carefully applied, represents the least traumatic treatment. Reduction of the tumor mass brings about improvement of the clinical symptoms. Further investigations on the biological behavior of brain-stem gliomas and prospective randomized long-term follow-up studies are necessary to evaluate the different kinds of treatment available for these patients.

Stereotactic interstitial irradiation of diencephalic tumors with iridium 192 and iodine 125: 10 years follow-up and comparison with other treatments.

The only possible treatment of non-removable tumors of the diencephalon or recurring tumors invading the diencephalon after partial resection or percutaneous radiotherapy is interstitial irradiation (Curie therapy). With the CT/MRI stereotactic method, biopsy for histological tumor classification can be performed and 125I or 192Ir implanted, provided the neuroimaging methods show the delimitation of the tumor, its diameter does not exceed 3 cm and, given the patient's condition, focal irradiation seems advisable. As of 31 August 1987, a total of 1883 cases had been stereotactically biopsied and interstitially irradiated. The indications and results are reported in 204 patients under 18 years of age with diencephalic and deep-seated astrocytomas, after a follow-up period of up to 10 years; the data were compared for tumor resection, percutaneous irradiation, and for interstitial irradiation. The latter proved to be the most effective treatment.

Neuropsychological assessment of the transcallosal approach.

The long-term consequences of partial callosal lesions were examined in 7 neurosurgically treated patients. Detailed clinical and neuropsychological assessment of the interhemispheric transfer (multimodal sensory and motor tasks) as well as memory and attention tests were used. The results revealed some disconnection symptoms with minor clinical significance, which could not be attributed to particular sites of the corpus callosum, except the splenium. It is questionable whether the reported memory and attention impairments are caused by the callosal lesion or by extracallosal pathology. The results indicate that the transcallosal approach is a safe and feasible alternative in the management of pathological midline processes in the brain.

Piracetam improves visuomotor and cognitive deficits in early Parkinsonism--a pilot study.

The influence of Piracetam on Parkinsonism was studied in 18 patients and 18 matched controls. Clinical, visuomotor and psychometric variables were measured. Piracetam improved visuomotor reaction time (RT) and accuracy in 6 mildly affected and tracing time in 6 moderately affected patients, the clinical condition and the organic brain syndrome in all patients investigated. The improvement of the prolonged RT seems to be correlated with bradyphrenia. No drug influence could be observed in the prolonged interhemispheric transfer time. As the mildly affected patients displayed the clearest effect of Piracetam, its administration in early and mild stage of parkinsonism is recommended.

Long-term effects of partial callosal lesions. Preliminary report.

Ten patients with partial callosal lesions were investigated with a broad scale neuropsychological assessment. Nine patients with a variety of lesions affecting midline structures have been operated using a direct transcallosal approach, one patient with a callosal lipoma remained unoperated. Sophisticated studies of the interhemispheric transfer of somaesthetic and perceptual motor tasks, as well as psychometric testing related to parameters of memory and attention performance were applied. The results indicate that there is no clear correlation between the site of callosal lesion and clinical symptoms. Although special disconnecting symptoms due to callosal dissection could be found, they didn't reach clinical significance. The most severe symptoms of impairment were caused by the extracallosal pathology. The results indicate that the transcallosal approach is a safe and feasible alternative in the management of pathological lesions in the midline region.

X-ray and magnetic resonance stereotaxy for functional and nonfunctional neurosurgery.

By means of new plastic stereotactic ring and head fixers, stereotactic procedures can be combined with MRI, with stereotactic coordinates obtained from the MRI images. The method was rechecked against CT stereotaxy and shows a good correspondence of the target coordinates. With MRI stereotaxy, structures near bony regions will be more accessible than with CT stereotaxy. Moreover, the MRI procedure seems to have advantages for functional therapy without the necessity of contrast ventriculography.

[Analysis of movement in extrapyramidal motor diseases using a computer]. / Bewegungsanalyse extrapyramidalmotorischer Erkrankungen mit Hilfe eines Prozessrechners.

Normals are able to move their limbs in a continuous spectrum of speeds. In contrast patients with so called extrapyramidal disorders show typical changes of movement. Short ballistic movements of the upper limb were analysed by a joystick connected with a computer in 57 patients with different extrapyramidal disorders (parkinsonsyndrome, essential tremor, torsion dystonia, chorea and intention tremor) and in 22 normals. Patients with parkinsonsyndrome and with torsion dystonia move the upper limb slower than normals and all other patients. Their movements show breaks. All patients execute aimed movements less precisely than normals. Most unprecise are the movements of patients with essential tremor. Oscillation of movements of all patients deminish, but less than in normals. Patients with parkinsonsyndrome show smallest oscillations at the beginning of each movement. Patients with intention tremor differ not from normals at the beginning, but show still the highest oscillations at the end of movement. Holding the target they correct most frequent. We discuss, that striatum generates timing and strength of ballistic movement and cerebellum apeases oscillation of movement and frequency of correcting while holding a target.

CT-stereotaxy in the clinical routine.

Up to now more than 600 patients have been treated according to the previously described method of CT-stereotaxy. In order to use this method, a special holder for the stereotactic device is required. This device must be exactly adjustable to the centre of the CT gantry within two spatial directions. The accuracy of the method is higher than 1 mm.

Stereotactic treatment of brain lesions. Biopsy, interstitial radiotherapy (iridium-192 and iodine-125) and drainage procedures.

Integrating CT imaging techniques into stereotactic procedures makes it easy to puncture cysts, take biopsies from neoplastic and nonneoplastic lesions, and place radioactive material in tumors at exact and reproducible sites. A stereotactic program of interstitial radiotherapy in deep-seated brain tumors has been applied in 326 cases as of December 31, 1979 (270 cases using iridium-192 and 56 cases using iodine-125). The use of iodine-125 is now favored since it requires less radiation protection due to its soft 28-35 keV radiation; at the same time, however, it possesses a comparable half life of 60 days. In 126 cases, stereotactic biopsy was used exclusively for diagnostic purposes followed by open craniotomy or conventional radiation. Cystic brain tumors (i.e., craniopharyngiomas and cystic low grade gliomas) were permanently drained by insertion of Rickham reservoir catheters in 61 cases. Stereotactic ventriculocisternostomies were carried out in cases of hydrocephalus and drainage of suprasellar arachnoid cysts was performed in 15 cases. A simple method of projecting CT images onto stereotactic X-ray pictures provides an exact mapping of lesions within the actual stereotactic brain space. The results of this series of patients strongly suggest that exploratory craniotomies and free-hand punctures can no longer be advocated. No radiation treatment should be considered without histological confirmation. The more clearly the volume of a tumor can be defined, the more favorable the results of interstitial irradiation in otherwise unresectable tumors.

[A simple method for the transfer of tomography scan layers to the X-ray film, especially in functional neurosurgery (author's transl)]. / Ein einfaches Verfahren für die Ubertragung von Tomographie-Scan-Schichten auf das Röntgenbild, insbesondere für die funktionelle Neurochirurgie.

The article describes a new method enabling the transfer of CT scan layers to the X-ray film with simple means.

[Objectivation of tremor and motion disorders via computerisation (author's transl)]. / Die Objektivierung von Tremor und kinetischen Störungen mit Hilfe eines Prozessrechners.

The quantitative analysis of motion disorders of the upper extremities can be performed by means of a joystick connected with a minicomputer. Therefore a random squarewave curve is drawn on a computer display and the patient must follow it with the joystick. The deviation of the two curves are recorded, analysed and documented numerically and graphically.

Computer-assisted stereotactic brain operations by means including computerized axial tomography.

With a computerized program system for stereotactic brain operations it becomes possible for the first time to react even before running a possible risk, e.g., in case of punctures in the midbrain, the brain stem, or in the hypothalamus, by simulating the operative procedure even before starting the operation itself. This is effected by the ability to change the penetration angle of the electrode or by choosing a different point of trepanation. The inclusion of computerized axial tomography, especially through the presentation of the CT scan, made to measure with the help of the linear transformation, and of the input of the cranial and ventricular coordinates through a digitizer, together with the coordinates resulting from the X-ray picture, brings the definition of the target point to a still greater optimum. Thus the safety and the precision of the stereotactic operation have been improved even further.

Treatment of small cerebral gliomas with CT-aided stereotaxic curietherapy.

In cases of stereotaxic irradiation of small tumors, CT makes possible a precise determination of tumor volume and dosage and permits exact positioning of the therapy probe. Iridium 192 wires are interstitially implanted in the tumor (mostly gliomas Grades I-III) after biopsy. The results with 98 CT-controlled patients (from a series of 213 implantations in midline tumors) have provided new information about the method of treating small cerebral gliomas.

[Use of pocket calculators in stereotactic operations (author's transl)]. / Programmierbare Taschenrechner bei stereotaktischen Hirnoperationen

We report a pocket calculator program which performs the calculation of the target parameters for a stereotactic apparatus (System Riechert-Mundinger).

A computer programme system for stereotactic neurosurgery.

A computer programme system is reported which allows a simulation of a stereotactic operation. It incorporates the determination of intracerebral structures and the electrode tract by means of boney reference points as well as the calculation of the parameters for the stereotactic apparatus. It contains further a library of brain sections, by which the electrode tract within the target structures can be shown on a computer display.

The entity of non occlusive mesenteric ischemia: strophanthin effect on mesenteric blood flow in experimental animals.

Digitalis glycosides have the well known positive inotropic effect on the heart. Their effect on extracardiac vascular smooth muscle receives increasing attention. In experimental animals a significant decrease in mesenteric blood flow and an increase in mesenteric vascular resistance could be shown. Angiography of main mesenteric arteries, smaller arteries, and arterioles reveal typical vasoconstriction. Angiomorphometric measurements show good correlation between the decrease in vascular diameter and the increase in vascular resistance.

Determination of intracerebral structures using osseous reference points for computer-aided stereotactic operations.

Computer-aided sterotactic neurosurgery can be improved and simplified by using craniocerebral parameters for the calculation of subcortical target points and avoiding an air-filling of the ventricles. This was achieved by selecting 403 pneumo-encephalographic studies at random, measuring the craniocerebral parameters according to age and sex. There is a correlation between the bony cranium and the brain axis. We established a formula and a table to determine in the plain X-ray the entrance of the foramen of Monroi with a standard deviation of +/- 1.5 mm and the inclination of the intracerebral basic line we used (foramen Monroi-commissura posterior). With this information various subcortical targets can be determined by means of computer programs.