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Biomedical subjects

A Aschoff

Publications and source records attributed to A Aschoff.

72 records · Page 4Linked to original sources
PubMed1991

Commercial external ventricular drainage sets: unsolved safety and handling problems.

Twelve commercially available sets for drainage of cerebrospinal fluid were tested for handling, design, features for fixation of the ventricular catheter, reliability of the anti-reflux valve, obstruction, efficiency of the air ventilation filter caps, accuracy of flow measurement and adjustment of flow, quality of material, adjustment, and cost. All systems showed considerable deficiencies in their reliability and handling. None of them can be recommended without certain restrictions and they should all be revised.

Brain Diseases↗
PubMed1991

Three-dimensional time-of-flight MR-angiography and the surgical indication of brainstem cavernomas.

This study was designed to assess the diagnostic value of 3D time-of-flight MR-angiography in cerebral cavernomas. In seven patients, nine out of ten cavernomas were removed by microsurgery. While MR-angiography demonstrated well branches of brain arteries adjacent to the lesions, no flow signal in the vascular malformations was observed. On the other hand, there was a high intensity signal induced by methaemoglobin in those three patients with brainstem cavernomas who had experienced a significant bleeding attack seven months prior to admission. It had a spotted appearance in MR-angiography with volumes of the largest spots around 1.8 cm3. It is suggested that this spot signal could be used as a path marker for the surgical approach in brainstem cavernomas.

Adult↗
PubMed1991

Therapeutic risks of anti-siphon devices.

Anti-Siphon devices need a siphon length of about 25 cm H2O to activate them. SCD and ASD show a dependence on the prepressure. The subcutaneous pressure can obstruct Anti-Siphon devices.

Humans↗
PubMed1990

Commissural connections between the auditory cortices of the rat.

The pattern of commissural connections of the rat auditory cortex (AC) was investigated with injections of wheat germ agglutinated horseradish peroxidase into the AC. Homotopic and heterotopic patches of neurons were retrogradely labeled in the contralateral hemisphere. Each injection labeled neurons at the corresponding contralateral site, i.e. the homotopic site. In addition, retrogradely labeled neurons were found at non-corresponding locations in contralateral AC, i.e. at heterotopic locations. The pattern of heterotopic labeling changed systematically with the injections. Mapping rules were established that led to the parcellation of areas 41 and 36 into 6 fields. Four fields were defined in Krieg's area 41 (primary AC) and two fields in Krieg's area 36 (secondary AC). In area 41 the heterotopic connection is not reciprocal; in area 36, however, heterotopic projections are organized reciprocally. Contrary to the visual cortex, homotopic and heterotopic projection neurons were equally distributed across the cortical laminae. With double-label experiments it could be shown that a considerable number of the neurons in area 41 bifurcate and project to homotopic as well as to heterotopic sites in the contralateral hemisphere. We conclude that in the AC there are several subtypes of neurons projecting to the contralateral hemisphere; it would be of interest whether these anatomical differences are manifested by physiological differences.

Animals↗
PubMed1990

Lower limb compartment syndrome following lumbar discectomy in the knee-chest position.

We report on two cases of compartment syndrome following lumbar discectomy in the knee-chest position. This complication has only been described once since 1953. Seven cases of compartment syndrome following other surgical procedures were found in the literature. Any increases in tissue pressure of a muscle compartment exceeding 35-40 mmHg over a longer period of time can result in this complication for example, too tight cast, space-occupying intrafascial bleeding, or postischemic swelling. The diagnosis is purely clinical and is based on the typical combination of extremely painful edema with rapid onset of sensory loss and subsequent motor deficits. The muscle necrosis leads to myoglobinaemia and myoglobinuria, recognizable by brown urine. The therapy consists of urgent fasciotomy of swollen compartments without skin suture. The prognosis is highly dependent on the time of the surgical decompression: within 6 hours serious deficits are avoidable; after 24 hours irreversible necrosis of muscle occurs. It seems that the possibility of a compartment syndrome is a specific, but a rare risk of a prolonged knee-chest position.

Adult↗
PubMed1990

Cystic degeneration following severe spinal trauma. Clinical observations in 30 patients.

Secondary, in most cases ascending neurological deterioration following severe spinal trauma has been known since the beginning of this century. The alterations are caused by cystic cord degeneration and probably are due to venous circulatory disturbances. In a review of the literature 680 cases were found. The present paper describes findings in our 30 patients. Modern diagnostic methods provide exact localization and evaluation of the cysts. These can then be drained microsurgically. Short-term success is good in many cases, long-term developments will be observed carefully. The functional loss of only one segment can, depending on the level of the original lesion, result in dramatic consequences for the patient.

Adult↗
PubMed1990

Nimodipine: evidence for clinically significant gastrointestinal side-effects.

Nimodipine, now widely used for treatment and prevention of cerebrovascular spasm, is regarded as a safe drug. Despite a preferential action on cerebral vessels, there is clinical and experimental evidence of effects on systemic vascular and intestinal smooth muscle cells. Gastro-intestinal side-effects, however, have not been reported in clinical studies dealing with treatment of vasospasm following subarachnoid haemorrhage. We report on a patient with subarachnoid haemorrhage who developed an acute life-threatening pseudo-obstruction of the colon, a variant of adynamic ileus, while being treated with intravenous nimodipine. The relationship between this complication and calcium antagonist therapy is discussed and therapeutic strategies are presented. We conclude that neurosurgeons and neurologists should be aware of calcium antagonist--related ileus in patients treated with nimodipine.

Colonic Diseases↗
PubMed1989

[Safe placement of atrial shunt catheters using intracardiac ECG. Initial experiences with a new ECG adapter system in 33 patients].

In 1960 Robinson inaugurated the method of placing atrial shunt catheters with the help of intracardiac ECG monitoring. Vulnerability to artifacts and problems with electrical safety (which have since been solved) led to its disuse. A newly developed ECG adapter proved free from artifacts and was practicable in 33 patients. 31 shunts were correctly placed without requiring time-consuming radiography. 2 extracardiac false positions were clearly identifiable by means of true negative results, which after correction showed a typical atrial ECG. The ECG method is compared with 9 other positioning methods. It seems to be superior to the conventional chest x-ray and equal to fluoroscopy. However, the method is not on a par with sophisticated measuring techniques such as intracardiac pressure monitoring or intravasal sonography.

Adolescent↗
PubMed1988

Distribution of cochlear efferents and olivo-collicular neurons in the brainstem of rat and guinea pig. A double labeling study with fluorescent tracers.

In rat and guinea pig, cochlear efferents to the two ears were labeled simultaneously with different fluorescent tracers. It was found that in both species only few (1-3%) olivo-cochlear neurons were double-labeled and project to both cochleae. In most periolivary regions large olivocochlear neurons (OCN) projecting to the ipsilateral and contralateral side are intermingled and form a continuous cell column between the facial nucleus and lateral lemniscus. In a second series of experiments in rat, cochlear efferents and ascending olivo-collicular neurons were labeled. Olivo-cochlear and olivo-collicular neurons are intermingled in the lateral superior olive (LSO) and in the ventromedial periolivary region. No double-labeled neurons were found that project to the cochlea and the inferior colliculus.

Amidines↗
PubMed1988

Origin of cochlea efferents in some gerbil species. A comparative anatomical study with fluorescent tracers.

The distribution and the projection patterns of olivo-cochlear neurons (OCN) was studied in three species of gerbils (Meriones unguiculatus, Meriones tristrami, Pachyuromys duprasi) using fluorescent tracers (Fast blue, Diamidino yellow) in double labeling experiments. In all gerbil species up to 1600 retrogradely labeled neurons were found in the superior olivary complex. Small OCN were located inside or at the margins of the lateral superior olive. A second set of larger OCN was seen bilaterally in the periolivary region of the superior olivary complex forming an independent cell population within the trapezoid body. The exact locations of small and large OCN varied among the particular species. Quantitative results suggested that a gradual loss of large OCN might be a general feature of species with highly specialized frequency selectivity.

Amidines↗
PubMed1987

Different origins of cochlear efferents in some bat species, rats, and guinea pigs.

The origin of olivocochlear efferents was studied in the rat, the guinea pig, and the bats Rhinolophus, Rhinopoma, Tadarida, and Phylostomus by retrograde labeling with HRP and the fluorescent dye fast blue. In all species with the exception of Rhinolophus rouxi two types of cochlear efferents could be found: small neurons located in the lateral superior olive (LSO) and larger ones located bilaterally in the periolivary region. In bats and rats small olivocochlear neurons (OCN) were found only in the ipsilateral LSO. In guinea pigs some small OCN were found also in the contralateral LSO. Large OCN were found in all animals except Rhinolophus. They were organized in a horseshoelike nucleus that extended in a rostrocaudal direction and bent rostrally around the medial superior olive (MSO). This nucleus contains several periolivary nuclei described separately by other authors. In Rhinol. rouxi somata of all olivocochlear efferents are concentrated in a single nucleus between the MSO and LSO, which we therefore call the nucleus olivocochlearis. This nucleus stains for acetylcholinesterase. We consider its neurons to be similar to small OCN, because they are small, associated with the LSO, and only ipsilaterally labeled. This fits well with the fact that Rhinolophus lacks an efferent innervation of outer hair cells (Bishop: Ph.D. Thesis, University of North Carolina, Chapel Hill, '86; Bruns and Schmieszek: Hear. Res. 3:27-43, '80), which are normally innervated by large OCN (Guinan et al: J. Comp. Neurol. 221:358-370, '83).

Amidines↗
PubMed1982

Fluorescent compounds as retrograde tracers compared with horseradish peroxidase (HRP). II. A parametric study in the peripheral motor system of the cat.

Fluorescent compounds which are currently used as retrograde tracers were tested in the cat peripheral motor system and compared with horseradish peroxidase (HRP). The tracers were either injected into forelimb muscles or applied to the proximal end of transected forelimb nerves. The remaining muscles of the limb has been carefully denervated. Following intramuscular injection all fluorescent compounds labeled spinal cord motoneurons, the DAPI compounds labeled endothelial cells in addition. In the nerve application mode tracer positive motoneurons were only observed when propidium iodide (PI) and the DAPI compounds were used, whereas bisbenzimide (BB), nuclear yellow (NY) and primuline did not label any cells. The fluorescence of BB labeled motoneurons were predominantly located in the cytoplasma. NY positive motoneurons showed a different localization of the fluorescent label between the different neurons of the same motornucleus: in some neurons it was exclusively located in the nucleus, in others predominantly in the cytoplasma, in the majority in both compartments. The intracellular distribution of the BB and the NY label was independent of the pH of the fixation fluid. The fluorescent tracers labeled the motoneuronal cell columns in their complete rostrocaudal extent and in a position identical to the one obtained with HRP. However, some substances (PI, fast blue) labeled less motoneurons of a motornucleus than did HRP, none of the fluorescent tracers labeled more. The results are discussed under several aspects: use of the investigated fluorescent compounds as single tracers; use of several tracers in the same animal to map collateral projections of one and the same neuron; use of several tracers in the same animal to establish the topographical relation between several independent neuronal populations.

Animals↗
PubMed1981

Single preganglionic sympathetic neurons of the cat branch intraspinally and project through different rami communicantes albi--a retrograde double labelling study with fluorescent tracers.

Evidence is presented that in lumbar segments of the cat, two neighbouring rami communicantes albi (white rami, WR) may contain axons of one and the same preganglionic sympathetic neurone (PSN). This was shown with bisbenzimide (Bb) and propidium iodide (PI) applied in the same cat to the central cut ends of two WR (PI to WRL1, Bb to WRL2). PSN, double labelled from both these sites, were observed in the intermediolateral and intercalate nuclei of the L1 segment. It is postulated that axons of PSN branch intraspinally and project through different WR.

Animals↗
PubMedDate not supplied

Magnetization transfer measurements in normal-appearing cerebral white matter in patients with chronic obstructive hydrocephalus.

PURPOSE: The purpose of this work was to assess the presence of subtle changes in normal-appearing white matter on T2-weighted MR images in patients with chronic obstructive hydrocephalus using magnetization transfer (MT) measurements. METHOD: In 12 patients with chronic obstructive hydrocephalus, MT ratios (MTRs) of normal-appearing rostral (PR) and caudal (PC) periventricular white matter, of the genu (CG) and the splenium (CS) of the corpus callosum, and of the thalamus (TH) were measured and compared with those of 16 healthy control subjects. RESULTS: We found a significantly lower MTR in chronic obstructive hydrocephalus than in the normal group for PR, PC, CG, and CS but not for TH. CONCLUSION: Our study shows that MT measurements give additional information that cannot be gained by conventional SE MRI, suggesting that chronic obstructive hydrocephalus is associated with diffuse white matter damage that also affects normal-appearing cerebral white matter.

Adult↗
PubMedDate not supplied

Indomethacin for brain edema following stroke.

Conventional therapies for raised intracranial pressure (ICP) frequently are not effective. We report a patient with raised ICP following a large hemispheric stroke. After conventional therapies had failed, indomethacin was repeatedly administered. After bolus infusion (50 mg), the ICP fell by a mean of 8.1 mm Hg, and the mean arterial blood pressure increased by a mean of 7.1 mm Hg, leading to a mean increase in the cerebral perfusion pressure by 15.3 mm Hg. After 1 h, the ICP had returned to baseline values after most infusions. Continuous infusion of indomethacin was not effective. We conclude that indomethacin may reduce elevated ICP over a short time in patients with ischemic brain edema even after conventional therapy has failed.

Adult↗