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Biomedical subjects

K Weigel

Publications and source records attributed to K Weigel.

At least 37 records · Page 2Linked to original sources
PubMed1987

Stereotactic mesencephalotomy versus multiple thalamotomies in the treatment of chronic cancer pain syndromes.

Two neurosurgical centers, Bologna (Italy) and Freiburg (FRG), have compared results obtained with stereotactic mesencephalotomy (SM; Bologna) and multiple thalamotomies (MT; Freiburg) in the surgical treatment of chronic cancer pain syndromes. In total, 161 patients were operated, 109 in Bologna and 52 in Freiburg. In SM the lesions were single and centered on the spinothalamic tract at the mesencephalic level, while in MT the lesions were multiple in the thalamic nuclei (ventrocaudal parvocellular nucleus, nucleus limitans, lamella medialis, centromedian nuclei). The following results emerged after 2-7 months' follow-up: (1) in an antalgic sense, SM was much more beneficial, with 91 patients (83.5%) pain-free after the operation versus 27 patients (51.9%) who had only an attenuation of the pain syndrome after MT; (2) SM, compared to MT, is burdened by mortality and a higher morbidity [2 deaths (1.8%) vs. 0; 3 anesthesia dolorosa and 8 severe gaze palsies (10.1%) vs. only 1 case of permanent aphasia (1.9%)].

Chronic Disease↗
PubMed1987

Sensitivity and specificity of brain stem potentials as a means of differentiating cochlear and retrocochlear disorders (acoustic neuromas).

Between 1980 and 1985 we examined a fairly large group of patients for retrocochlear disorders. Every patient was examined by at least two procedures, registration of brain stem potentials and CT; we had also magnetic resonance images taken of some of these patients. We diagnosed a total of 37 acoustic neuromas in 34 of the patients examined. From our study a conclusion can be drawn about the sensitivity and specificity of brain stem potentials as evidence of an acoustic neuroma. The rate of false negative diagnoses is about 6%. The false positive rate is considerably higher, and it is discussed in detail. The clinical utility of brain stem potentials is illustrated with two case histories. Because of the method's low false negative rate, cochlear disorders diagnosed by registering brain stem potentials need not as a rule be confirmed by modern imaging procedures.

Adult↗
PubMed1986

Computerized tomography-guided stereotactic dentatotomy.

The CT stereotactic technique of dentatotomy is described and illustrated with two examples. With this combined technique, ventriculography or pneumencephalography is no longer needed to determine the target point. In addition, due to the direct representation of anatomic structures in the CT, abnormal positions of the dentate nucleus may be taken into consideration in the determination of the target point and approach for the coagulation probe.

Adult↗
PubMed1985

Ventricular somatostatin-like immunoreactivity in patients with basal ganglia disease.

The concentrations of somatostatin-like immunoreactivity (SLI) in lateral ventricular fluid of patients with extrapyramidal motor disease were determined by specific radio-immunoassay. Mean SLI levels were significantly lower in patients with Parkinson's disease (mean +/- SEM); 42.9 +/- 2.9 fmol/ml) and in patients with dystonic syndromes (39.4 +/- 3.2) than in patients with benign essential tremor (65.3 +/- 9.7). The lowest levels were found in patients with athetosis (34.7 +/- 5.4). In parkinsonian patients somatostatin levels correlated with the degree of akinesia, rigidity and autonomic disturbances.

Adult↗
PubMed1985

Supratentorial space occupying lesions following infratentorial surgery early diagnosis and treatment.

Supratentorial complications of infratentorial surgery are rare. In the last 3 years we have operated on 187 patients with infratentorial lesions and have observed an incidence of 3.7% of supratentorial haemorrhages. Postoperative intracranial air, as shown by early postoperative CT control, was encountered mainly in a subdural frontal location and within the interhemispheric fissure. We performed no surgical decompression of the air accumulation because of the lack of clinical symptoms. Predisposing factors for the development of supratentorial complications remote from the surgical area are hypertonia, female sex, brain atrophy and preoperative shunting procedures. Measures to avoid these complications are discussed.

Adult↗
PubMed1985

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.

Brain Neoplasms↗
PubMed1985

[Influence of the volume of peridural morphine bolus injections on morphine concentration in the cisterna magna of the dog].

14 dogs received randomly a bolus injection of either 2 mg morphine in 10 ml isotonic saline solution or 2 mg morphine in 1 ml isotonic saline solution epidurally at T6. An epidural infusion of 0.16 mg morphine/0.06 ml/h was applied immediately following the 1 ml bolus injection of morphine. Cisternal cerebellomedullary CSF samples were taken at varying intervals to determine free morphine immunoreactivity by radioimmunoassay. Within 20 min after the 10 ml bolus injection the peak CSF morphine concentration of 3594 +/- 910 ng/ml was reached. Following this, CSF morphine levels decreased exponentially and after 48 h 8 +/- 3 ng/ml were measured. The peak CSF morphine concentration of 139 +/- 51 ng/ml was, however, reached only after 2 h following the 1 ml bolus injection plus the infusion treatment. Despite the additional infused amount of 7.68 mg over 48 h the CSF morphine concentrations decreased also exponentially and after 48 h 16 +/- 4 ng/ml were measured. One may conclude, therefore, that the risk of respiratory depression is negligible under epidural infusion treatment following an initial "Low-Volume"-bolus injection of 2 mg morphine, a recommendable method for treating post-operative pain. High-volume bolus injections of morphine should generally be abandoned in epidural treatment of pain.

Animals↗
PubMed1984

[Recurrence following burr hole trephination of chronic subdural hematomas].

In a consecutive series of 100 patients suffering from Chronic subdural haematomas, which were treated by burr-hole evacuation and closed external drainage, in 23 patients repeated operations became necessary. The reasons for further operations were: true recurrences in 11 cases, superimposed haematomas in five cases and haematomas on the opposite side in seven cases. All these patients were treated again by burr-hole evacuation and closed external drainage. In contrast to the common opinion craniotomy and removal of the membranes was not necessary in any case.

Aged↗
PubMed1983

Sequential morphological changes in the dog brain after interstitial iodine- 125 irradiation.

Iodine- 125 seeds (3.55 mCi) were stereotactically implanted into the subcortical white matter of the left coronal gyrus in six beagle dogs. Morphological changes were studied at intervals ranging from 25 to 368 days after implantation. In all of the animals, there was a calcifying necrosis 3 to 6 mm in diameter with an adjacent small zone of demyelination. There were no signs of delayed radiation damage outside the demyelinated perifocal zone. The central tissue necrosis was sharply delineated and did not increase in size after 70 days, i.e., an accumulated dose of 18,000 cGy. In addition, widespread vasogenic edema was present in the homolateral hemisphere. The morphological changes observed differed in many aspects from those found with other radioactive sources, such as gold-198, yttrium-90, or iridium-192. The low energy gamma radiation, the absence of beta radiation, and the half-life of 60.2 days makes iodine-125 a favorable radioactive source to produce a well-defined necrosis without delayed radiation damage in the surrounding brain.

Animals↗
PubMed1982

Regional heterogeneity of L-[3-(3)H]tyrosine incorporation into rat brain proteins during severe hypoglycemia.

Regional protein synthesis was investigated during severe, insulin-induced hypoglycemia in anesthetized, artificially ventilated rats. Three minutes after the cessation of spontaneous EEG activity, animals received a single injection of L-[3H]tyrosine and were killed 30 min later. Autoradiographs revealed an almost complete inhibition of amino acid incorporation in the cerebral cortex, hippocampus, and caudate-putamen of hypoglycemic rats. Thalamus and spinal cord were less affected, and in hypothalamus, cerebellum, and brainstem the pattern of [3H]tyrosine incorporation was identical in control and experimental animals. The areas showing severely reduced protein biosynthesis during hypoglycemia coincide with those exhibiting extensive breakdown of energy metabolism, reduced cerebral metabolic rate for glucose, and high susceptibility to persistent cell damage. High-resolution autoradiography employing tritiated amino acids permits the assessment of regionally impaired protein biosynthesis and may thus be useful for the identification of neuronal populations at risk during hypoglycemia of varying degrees and of those cells most likely to recover after glucose infusion.

Animals↗