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Biomedical subjects

R Steinmeier

Publications and source records attributed to R Steinmeier.

26 records · Page 2Linked to original sources
PubMed1993

Cerebral hemodynamics in subarachnoid hemorrhage evaluated by transcranial Doppler sonography. Part 2. Pulsatility indices: normal reference values and characteristics in subarachnoid hemorrhage.

In previous publications on the diagnostic value of transcranial Doppler sonography (TCD), conflicting results concerning predictive capacities for evaluating vasospasm by measuring flow velocities were reported, and the necessity to examine pulsatility indices (PIs) was stressed. PIs are known to give useful information on cerebral hemodynamics in cases of stenosis of the extracranial internal carotid artery and cerebral arteriovenous malformations. Whether the examination of PIs can give additional information in cases of subarachnoid hemorrhage (SAH) and allow prediction of impending delayed ischemic deficits (DIDs) is still unclear. Normal reference values for the Gosling pulsatility index, the Pourcelot resistance index, and the first Fourier pulsatility index were established in a series of 97 normal subjects. A significant increase in the indices was found as age increased, and there was a strong relation between the indices. There were no statistically significant differences between the right and left sides. An inverse relation was found between the flow velocity and PIs in the middle cerebral artery. In a prospective study of 455 follow-up TCD examinations in 66 SAH patients treated routinely with nimodipine, three different groups were analyzed separately: Group I, patients without DIDs; Group II, patients with DIDs; and Group III, patients with neurological deficits not strictly classifiable as DIDs. The analysis of all three groups together showed a typical time course after the onset of SAH: initially elevated PIs normalized around the tenth day after bleeding. According to Fisher grading, the amount of subarachnoid blood influences the increase in PIs significantly.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Pituitary microcirculation: physiological aspects and clinical implications. A laser-Doppler flow study during transsphenoidal adenomectomy.

The anterior and posterior pituitary lobes (AL and PL, respectively) are assumed to differ in the type of vascular supply and structure of their microvascular networks. Animal experiments have shown that the pituitary microvascular flow differs between the two lobes, being extremely high in the PL and low in the AL. For technical reasons, it has hitherto not been possible to study pituitary microflow in humans. Laser-Doppler flowmetry (LDF) is now a well-established method for real-time monitoring of microcirculation, applicable also in humans. In a prospective clinical study, the microflow in the AL and PL was measured during transsphenoidal microsurgery in 52 patients with adenomas of different size, growth characteristics, and endocrinological activity. The mean microflow in the PL (177.7 +/- 12.6 [flux]) was found to be about six times higher than that in the AL (27.4 +/- 2.7 [flux]). No difference in the laser-Doppler fractional volume of the lobes could be detected (0.73 +/- 0.06 [] vs. 0.77 +/- 0.07 [], where [] designates the ratio of the alternating current output to the direct current output signals). Microflow within the pituitary lobes was influenced neither by the histological type nor the size of the adenoma. Additionally, LDF signal-averaging triggered by the electrocardiogram allowed detection of different characteristic pulsatile microvascular flow patterns in the AL and PL. Our findings provide strong physiological support for the idea that the angioarchitecture of the pituitary lobes differs. With this method, the AL and PL can be identified objectively during surgery. LDF might provide useful information concerning intraoperative surgical approach.

Adenoma↗
PubMed1989

Evaluation of prognostic factors in cerebral arteriovenous malformations.

In a retrospective study of 48 patients who underwent elective surgery for cerebral arteriovenous malformations, a statistical analysis of demographic, clinical, and neuroradiological data was undertaken in order to discover the best predictors of operative morbidity. In addition, the predictive value of different clinical grading systems as applied to this series was compared. All patients had a computed tomographic scan and a positive angiogram before surgery. Complete resection was proven angiographically. The univariate Mann-Whitney-Wilcoxon rank sum test, the Fisher exact test, Spearman's rank correlation coefficient analysis, and multivariate logistic regression were used as statistical methods. Duration of surgery, the development, of either new deficits or an increase in the preoperative neurological signs immediately after surgery, and rehabilitation (as measured by the Karnofsky index) were taken as target variables for the difficulty of operation and for postoperative morbidity, respectively. The largest diameter of the nidus of the arteriovenous malformation, eloquence of the adjacent brain, and deep venous drainage showed the most consistent correlation with these target variables. Intracerebral hematoma and other single factors, such as the age of the patient or localization of the arteriovenous malformation did not affect the outcome. The clinical grading scale of Spetzler and Martin provided better prediction of surgical risks than other proposed systems.

Adult↗
PubMed1988

[Tumors and space-occupying abnormalities of the skull calotte].

Clinical and demographic data as well as the course of illness were analyzed in a retrospective study of 50 patients with a primary tumor or a malformation of the calvarial bones. The most frequent histological diagnosis was "eosinophilic granuloma of bone" (found in 42% of cases), followed by hemangioma, osteoma, dermoid, epidermoid and malignant tumors, and fibrous dysplasia. Local recurrence was observed in 1 patient with ossifying fibroma and 1 with a dermoid tumor, while further dissemination of illness was observed in 3 patients with "eosinophilic granuloma". In these cases, systemic drug therapy is needed. The necessity of an intensive search for further signs of illness and long follow-up periods in patients with primary localized histiocytosis X is stressed.

Adult↗
PubMed1987

[Clinical experience with intradisk chymopapain administration in lumbar intervertebral disk displacement].

In a retrospective study, complications following 157 chemonucleolyses (CNL) with chymopapain in 139 patients wer studied and the kind of pathological changes as found in the operation after CNL compared with those found in patients who were operated on because free sequesters were suspected on discography. The indications for CNL followed the accepted criterion of clinically, neuroradiologically or electromyographically detected alteration of a lumbar nerve root with clinical signs of sciatica. Free sequesters were found at subsequent operation much more often in those cases with primary indications for CNL, which showed signs of sequestration at discography, than in those who had had poor results after CNL. Discography as a means of finding previously undetected free sequesters should not be abandoned. In addition to procedure-related reactions and unspecific complications, as well as immediate or delayed occurrence of severe backache, significant leucocytosis was observed on the first postoperative day. Probably immunological reactions such as severe hypotension after several hours, nausea and vomiting or rise of temperature, also occurred. In ten cases delayed urticarial or large erythematous efflorescences were observed. These reactions do obviously not correspond to the picture of anaphylaxis of the reagine-type such as is mostly described in the mechanism of chymopapain allergy.

Adult↗