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Biomedical subjects

M R Gaab

Publications and source records attributed to M R Gaab.

85 records · Page 5Linked to original sources
PubMed1985

Acute effects of nimodipine on the cerebral blood flow and intracranial pressure.

The effects of nimodipine, a calcium antagonist with preferential cerebrovascular activity, on the global and regional cerebral blood flow (CBF and rCBF), the intracranial pressure (ICP), and the cerebral perfusion pressure (CPP), were investigated in an acute study. The rCBF of 54 patients was measured by the Xe133 inhalation method under identical conditions before and 60 min after oral administration of nimodipine. 12 patients with focal cerebral circulation disturbances of arteriosclerotic origin, who had suffered a cerebral accident (TIA, PRIND, minor stroke) no more than 3 weeks previously, were given a placebo (test-retest controls) and 25 patients of the same diagnosis and age group were given 40-80 mg nimodipine orally. 11 patients with acute subarachnoid hemorrhage (SAH) from ruptured anterior communicating artery aneurysms and clinical and angiographic signs of vasospasm (Hunt- and Hess grade 3) were likewise treated with nimodipine by the oral route. 6 patients with cerebral vasospasm received nimodipine in i.v. doses of 0.5-2 mg/h. The cerebral blood flow, assessed on the basis of the initial slope index (ISI), before and after the medication, was compared by statistical methods. 12 patients with head injury were given nimodipine intravenously in a dose of 0.5-2 mg with continuous monitoring of the ICP and the blood pressure. The pressure values were evaluated continuously by computer, with calculation of the perfusion pressure, and tested for statistical significance. Oral nimodipine therapy resulted in a significant (14%) increased of the CBF (taking account of the arterial pCO2), the improvement of blood flow being even more pronounced in the hypoperfused regions.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1985

Intracranial effects of nicardipine.

Preliminary investigations indicated that the calcium antagonist nicardipine improved cerebral vascular circulation and cerebral metabolism. Therefore we examined the effect of nicardipine on the cerebral vessels, cerebral oxygen tension, and intracranial pressure (ICP) in patients with cerebrovascular disturbances. In patients with previous minor stroke undergoing surgery for extra-intracranial anastomosis, we applied nicardipine topically to the operation site by means of a perfusor and measured the diameter of the cerebral vessels. After several minutes, the topically applied nicardipine produced marked dilatation in the small arterial cortical vessels and relaxation of vasospasm. In the two patients studied so far, we observed a rapid increase in the cerebral PO2, which remained elevated after the initial peak as long as the infusion continued. With a lower dose the increase in the intracranial pulse amplitude (PAICP) was antagonized by the considerable drop in blood pressure which occurred after 10 mg h-1 nicardipine. The results indicate that nicardipine dilates the cerebral vessels and increases the cerebral oxygen tension.

Blood Pressure↗
PubMed1984

[Intracranial pressure recording. Principles, technics, results and possibilities].

Methods for continuous ICP recording were further developed. Intraventricular pressure measurement requires puncture of the brain, and is susceptible to infection. For routine applications, therefore, preferential use is made of miniaturized pressure transducers which, without the need to open the dura, are simply implanted epidurally. In the absence of disorders of blood clotting, no complications, in particular no infections, were observed in more than 900 measurements. In the case of rapidly growing intracranial space-consuming processes, considerable intracranial pressure differences giving rise to intracranial mass shifts and even incarceration occur. These pressure gradients can also be measured and treated clinically. The pathological intracranial pressure curve shows typical wave dynamics with A, B, C and D waves, and pulsation changes. In intensive care, measurement permits rapid detection of complications, selective treatment and prognostic information, including the temporal definition of brain death. In neurological and neuropediatric diagnosis, ICP measurement differentiates between active hydrocephalus and cerebral atrophy/dystrophy, and here, as also in cystic cerebral changes, subdural effusions, etc., helps clarify the indication for surgery. In the case of "pseudo tumour cerebri", too, ICP measurement permits objectivation. In addition, it is also possible to determine directly the intracranial reserve space and the CSF dynamics (bolus/infusion test, pulse wave analysis).

Atrophy↗
PubMed1984

Hydrocephalus in infancy and childhood: diagnosis and indication for operation.

Improvement of the prognosis for children suffering from hydrocephalus requires prompt diagnosis and reliable indication of surgical treatment. Today, intrauterine hydrocephalus is detectable within the first three months of pregnancy; in infancy, before the cranial sutures have fused, pathological growth of the head is the principal sign confirming together with anatomical examinations (ultrasound, CT scan) the indication of operative treatment. In later childhood, surgical treatment is only definitely indicated by symptoms and morphological examination of clearly active hypertensive hydrocephalus. Intermittently normotensive hydrocephalus (not "normal-pressure-hydrocephalus"!) showing symptoms adapted to childhood, however, often requires exact examination of intracranial pressure dynamics, including quantitative volume provocation test. "Step-by-step-procedure" is advisable (Table III).

Cerebrospinal Fluid Shunts↗
PubMed1984

ICP monitoring.

Within the last two decades, the measurement of intracranial pressure (ICP) advanced from basic research to a useful method in clinical practice. The recording of ICP in clinical diagnosis and therapy requires the knowledge of physical, anatomical and pathophysiological fundamentals, of the different measurement principles and of typical, pathognomonic intracranial pressure patterns. This data will be described in this article. The ICP, and its effects, are based on the anatomy of the almost closed rigid skull which is divided into three "compartments" by pressure-resistent septa (falx, tentorium), and which opens into the spinal dura cavity as a 4th compartment. The pressure is distributed by the CSF, whereby hydrostatic laws must be considered. The brain itself is visco-elastic, and its physical characteristics change in pathological conditions. The pathophysiological effects of intracranial hypertension must be divided into generalized pressure effects and directed pressure actions. The generalized pressure effects are caused by the disturbance of the cerebral blood flow (CBF); their understanding requires the knowledge of the characteristic Pressure-Volume (P/V)-Diagram of the craniospinal space, which can be described by mathematical approximations. The directed actions of an elevated ICP are based on pressure gradients (unequal pressure distribution), which are produced by more rapidly growing local intracranial lesions. These pressure differences cause cerebral mass movements with brain stem incarceration, whereby the "pressure = force per area" - rule must be considered. These anatomical and functional basics are of great importance for the measurement technique; for reliability and safety of ICP registration, the elastic forces of the dura and the brain, the pressure distribution as well as the operative procedure and invasivity of the measurement technique have to be regarded. For clinical routine, less invasive methods using miniaturized transducers for epi- or subdural implantation are favorized above the registration of ventricular pressure, which, however, has its special indications. These problems will be described. Besides a registration of the spontaneous ICP fluctuations, a quantitative determination of the P/V-diagram (compliance, elastance, PVI) and of parameters of the CSF dynamics (resistance, CSF production, Pss) may be useful in clinical practice. In diagnosis, invasive methods with artificial volume load may be used, the techniques will be explained.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1982

Atraumatic rCBF measurement: an aid in the timing of surgery and the management of spasm following SAH.

We tested the ability of a non-invasive regional cerebral blood flow (rCBF) measurement to show vasospasm. The correlations between the flow values, the clinical condition, the CT scan and angiography were also studied. During none of the measurements were there any negative side effects on the patients. A bad clinical condition was usually accompanied by low flow data during the rCBF investigation. In accordance with local clinical signs (e.g., hemiparesis) we observed corresponding local hypoperfusion. These results were also confirmed by several follow-up studies in which good correlations between the rCBF findings, the angiography and the CT scan were found. As the rCBF investigation can be repeated within a very short time, we used this method for the testing of vasoactive drugs. Nimodipine (Bayer) showed promising results which suggest further clinical investigations. The main problem connected with the rCBF measurement is the limited ability of the patient to cooperate. For the detection of vasospasm the low resolution both in localisation and depth of this method is of only minor importance. We partly overcame this disadvantage by developing a special respirator enabling us to investigate artificially ventilated patients. We think that the measurement of rCBF is an important aid for the timing of the operation.

Cerebral Angiography↗
PubMedDate not supplied

Maffucci's syndrome as cause of chronic liquorrhea.

We present the case of a 14-year-old girl suffering from Maffucci's syndrome, a rare ailment belonging to the group of osteochondrodysplasias. At the age of 6 months, a diffuse swelling first appeared in the girl's right cheekbone region and the periauricular area. Because of recurrent meningitis with massive otoliquorrhea, several surgical revisions were performed, beginning at the age of 4 years. The histological and immunohistochemical diagnosis showed hemangioma and lymphangioma with enchondroma. As a peculiarity of our patient's diagnosis, we found multiple bone defects apparently caused by venous and lymphomatous angiomatosis. There was also enchondromatosis of the skull base and the upper cervical vertebrae, which caused the recurrent otoliquorrhea and rhinoliquorrhea. A fistula closure was undertaken through a retromastoidal, suboccipital approach and fascial graft of the posterior cranial fossa.

Adolescent↗
PubMedDate not supplied

Expression of multidrug transporters in dysembryoplastic neuroepithelial tumors causing intractable epilepsy.

OBJECTIVE: Dysembryoplastic neuroepithelial tumors (DNT) are relatively benign brain lesions that often cause medically intractable epilepsy. There is mounting evidence that multidrug transporters such as P-glycoprotein (P-gp) or multidrug resistance-associated proteins (MRP) play an important role in the development of resistance to antiepileptic drugs (AED). MATERIAL AND METHODS: In the present study, we examined the expression of several multidrug transporters in 14 cases of DNT. The peritumoral brain tissue as well as 9 cases of arteriovenous malformations (AVM) served as controls. P-gp, MRP2, MRP5 and breast cancer resistance protein (BCRP) expression was evaluated qualitatively and quantitatively using immunohistochemistry. RESULTS: All transporters were overexpressed quantitatively in DNT, but each revealed a different labeling pattern. P-gp and BCRP were predominantly located in the endothelium of brain vessels. MRP5 was detected primarily in endothelial cells, but notably also in neurons. The expression of P-gp, MRP2 and MRP5 was low in AVM, whereas BCRP demonstrated strong staining. Examination of MDR1 gene polymorphisms revealed no correlation with P-gp expression whereas the MRP2 exon 10 G1249A polymorphism was associated with different MRP2 labelling. CONCLUSIONS: Our results show that multidrug transporters are overexpressed in DNT. This finding supports the view that several of these transport proteins may play an important role in the mechanisms of drug resistance in epileptic brain tissue.

Adolescent↗