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Biomedical subjects

O Gratzl

Publications and source records attributed to O Gratzl.

At least 55 records · Page 3Linked to original sources
PubMed1996

A new screwing device for fixing a microdialysis probe in critical care patients.

We describe a new, easy method which extends the use of clinical microdialysis to neurotrauma patients who primarily do not need a decompressing surgical intervention. In all head trauma patients in whom a Camino ICP-monitor is indicated a second hole (2 mm in diameter) is made, and the MD probe is fixed using the new screwing device. Before clinical use the system was tested during postmortem, confirming correct cortical placement of the probe in almost all cases. Two case reports are presented including their metabolic values. An extension to patients with non-traumatic brain disorders might be a future aspect.

Adolescent↗
PubMed1996

Microdialytic monitoring during a cardiovascular operation.

In an aorta-coronary bypass operation, the heart is excluded from the circulation for many minutes, leading to ischemia. During this time the heart is cooled in order to mitigate damage. Microdialysis has been shown to be very suitable for detecting ischaemic changes e.g. in brain. We therefore used this method to study the time courses of several neurochemical parameters which have been shown to indicate ischaemia in animal models (ascorbic acid, glutathione, cysteine, uric acid, glucose, lactate and pH), during such a bypass operation. Three patients were investigated, the microdialysis probe being inserted into the interventricular septum of the heart. Our results show that microdialysis is technically feasible in the human heart in a clinical setting, although the operation becomes more demanding for the surgeon. All the above-mentioned parameters could be detected in the heart muscle. Some of them showed changes characteristic of ischaemia, and the effects of cooling on the metabolism could also be noted. Long term measurements are planned to enable delayed damage to be disclosed.

Coronary Artery Bypass↗
PubMed1996

Application of glutamate in the cortex of rats: a microdialysis study.

Glutamate, a major neurotransmitter in the brain, is also involved in pathophysiological processes resulting in secondary lesions following ischaemia or trauma. In the present study we investigated the relationship between glutamate excitotoxicity free radical induction (indicated by ascorbic acid level) and glucose-lactate metabolism. Monosodium glutamate was applied through microdialysis probes (500 mM in perfusate) into the cortex of rats for 30 minutes and ascorbic acid (ASC), glucose (GLUC) and lactate (LAC) were measured in dialysates. Glutamate produced a cortical lesion with an average volume of 12.7 +/- 1.4 mm3. Analysis of dialysates revealed a significant increase of ASC (325 +/- 52% of baseline) and LAC (677 +/- 86%) in the core lesion. In the lesion periphery a non-significant and short-lasting elevation was measured for both parameters with a second microdialysis probe (about 1.3 mm frontally to the first probe). A concomitant decrease of GLUC was found in both probes, reaching 29 +/- 8% and 60 +/- 7% of basal levels in the core and periphery of the lesion, respectively. In addition, we studied the delivery characteristics of several glutamate concentrations (10, 100 or 1000 mM in perfusate) during a 90-minute application into the cortex. The delivery of glutamate from the perfusate to the brain was about 33-38% in the first 30 min and afterwards 11 25% of the total in the perfusate. The results show that cortical application of glutamate changes the composition of the extracellular fluid, which could contribute to the development of the lesion.

Animals↗
PubMed1996

Different aspects of hearing preservation in surgery of vestibular schwannoma in women and men.

Pre-operative and postoperative auditory function was reviewed retrospectively in 98 patients with vestibular schwannomas. According to their hormonal status, women were categorized as "premenopausal" and "postmenopausal". Before surgery, 48% of the women (65% premenopausal) and 16% of the men presented with sudden hearing loss. The degree of auditory function before operation was similar for women and men. Preservation of pre-operative hearing was possible for 41% of the women (21% premenopausal) and 59% of the men. Further details of the surgery and the results of histopathological examination were also compared for women and men. Our results support substantial evidence that hearing preservation after surgery of vestibular schwannoma is easier to accomplish for men than for women. The finding of significantly more sudden hearing loss in premenopausal women may suggest a hormonal influence on tumour growth, which may also be partially responsible for the difference in hearing prognosis between women and men.

Adolescent↗
PubMed1996

Magnetic resonance imaging of vertebrobasilar ectasia in trigeminal neuralgia.

Vertebrobasilar ectasia is a rare cause of typical trigeminal neualgia. In a recently published large series only thirty-one (2%) of 1404 consecutive patients with vascularly determined neuralgia were found to have vertebrobasilar compression. We present three patients with trigeminal neuralgia caused by vertebrobasilar ectasia, who were evaluated with high resolution magnetic resonance imaging (MRI). MRI studies provided accurate information on the anatomical location and course of the ectatic vessel in the cerebellopontine angle and the caused mass effect on the brainstem. With gadolinium-enhancement vascular compression of the trigeminal nerve was demonstrated clearly. Surgery confirmed compression of the fifth nerve by an ectatic and tortuous vertebrobasilar artery in two cases. Following microvascular decompression neither patient experienced further pain. The third patient was treated with a ventriculoperitoneal shunt, as he developed occlusive hydrocephalus caused by the vertebrobasilar dolicho-ectasia. MRI is useful in the evaluation of trigeminal neuralgia as it excludes other aetiologies such as tumour or arteriovenous malformation, but also demonstrates cranial nerve compression by ectatic vertebral arteries.

Basilar Artery↗
PubMed1996

Computer assisted brain surgery for small lesions in the central sensorimotor region.

The capacity of a new optical navigation device is demonstrated by six microsurgical procedures for small subcortical lesions within the central sensorimotor strip. This small series is aimed at less invasive resection in this functionally critical region, independently of primary diagnosis and outcome. Guided by high resolution CT imaging data five brain tumours and one cavernous angioma was selectively located and most sparingly removed without additional sensorimotor deficit. In two cases improvement of a pre-operative paresis was observed immediately after surgery. Thanks to light-weight freehand pointing instruments and a ranging accuracy of +/- 1 mm, damage to functionally important brain areas and vessels was avoided by using uncommonly oblique, e.g., transsulcal ways of access which would hardly have been possible even with guidance by conventional stereotaxy. The demanding systematic cortical stimulation of the precentral gyrus applied in three cases was only sensitive in infiltrating tumours-e.g., low grade astrocytomas-where for want of adjuvant therapy it was essential to proceed to the extreme limits of resection. In general, precise anatomical localisation by computer aided surgery (CAS) is sufficient in small central lesions which guarantees minimally invasive surgery. The potential of this new, soon commercially available optical navigation system in (neuro) surgery, quality control and teaching is discussed.

Adult↗
PubMed1996

Microdialytic monitoring during cerebrovascular surgery.

Using microdialysis, levels of metabolites in the extracellular fluid of the cerebral cortex were monitored during neurovascular surgery (9 aneurysm and 5 extra-intracranial bypass operations). Our aim was to use microdialysis to detect any local ischemia which might be caused by brain retraction or temporary clipping. Parameters were therefore quantified whose levels in the dialysate are known to be influenced by ischemia (on-line pH, ascorbic acid, uric acid, glutathione, cysteine, glucose, lactate, glucose:lactate ratio). In the aneurysm series, on-line pH fell after introduction of the retractor, and in the majority of cases the other parameters also showed changes in accordance with ischemic conditions in the region of the probe. These changes disappeared at the end of retraction, or sometimes even before. During the bypass operations, there were no marked changes in on-line pH or in any of the measured parameters. However, in some of these patients values for the glucose:lactate ratio, ascorbic acid and uric acid lay outside the suggested basal levels for minimally disturbed cortex, indicating possible changes in metabolism caused by inadequate perfusion (carotid artery occlusion). We conclude that microdialysis is a sensitive method of detecting intraoperative changes in cerebral metabolism.

Ascorbic Acid↗
PubMed1995

Experimental and clinical monitoring of glucose by microdialysis.

The aim of this investigation was to assess the use of cerebral extracellular glucose as a parameter for microdialytic monitoring in neurosurgical critical care patients. Samples were collected from four patients with severe head injury and one with subarachnoid haemorrhage for periods of 4.5-67 h. Glucose and lactate were analysed in the dialysates. The ratios of glucose to lactate were calculated to partially allow for changes in microdialytic conditions over time. On-line pH was measured for up to 3 days in three patients. In experiments with spontaneous hypertensive rats we found that extracellular glucose became unmeasurable in the ischemic zone after middle cerebral artery occlusion. Similarly, in 3 patients glucose became undetectable for several hours, and glucose/lactate tended to decrease during measurement. This was accompanied by high ICP in one patient, and by a hypoxic episode in another. In the two other patients glucose/lactate ratios showed a rising trend. Findings indicate that glucose, and the glucose/lactate ratio show some correlations with clinical course and are promising parameters for cerebral monitoring and therapeutic decision making.

Adult↗
PubMed1995

Preoperative and postoperative auditory and facial nerve function in cerebellopontine angle meningiomas.

Preoperative and postoperative facial nerve and auditory function were reviewed retrospectively in 13 cases of cerebellopontine angle meningiomas. According to their location within the posterior fossa and with special reference to the internal auditory canal, they were classified into a premeatal and a retromeatal group. All the tumors were removed by an otoneurosurgical team by use of a retrosigmoid approach. Postoperative results (1 year after operation) were compared within the two groups with respect to preservation of hearing (normal hearing in 31% and preservation of preoperative hearing in 69% of the cases) and facial nerve function (no or mild postoperative impairment in 69% of the cases). Both preoperative and postoperative impairment of facial nerve and auditory function prevailed in the premeatal group. For preservation of vital vascular and central nervous structures, subtotal resection with consecutive fractionated radiation therapy had to be performed in 30% of the cases. Our results provide substantial evidence that in cerebellopontine angle meningiomas a precise preoperative study of tumor location will assist in improving individual operative strategy and thus postoperative functional results.

Adult↗
PubMed1994

Neurochemical monitoring and on-line pH measurements using brain microdialysis in patients in intensive care.

We will report on our preliminary findings using microdialysis to monitor three patients in intensive care with either severe head injury (SHI) or severe subarachnoid hemorrhage (SAH) for up to 72 hours. In addition, basal levels in uninjured brain were assessed during an extra-intracranial bypass operation. Samples were collected hourly or half-hourly (flow rate 2 microliters/min, perfusion medium 0.9% saline). Parameters measured were the antioxidants ascorbic acid, uric acid, glutathione and cysteine. In 2 patients, the pH of the dialysate (pHD) was also measured on-line with a specially constructed flow-through meter, and glucose and lactate levels were assessed in the dialysate. In patient 1 (SHI), there was practically no cerebral perfusion pressure because of high ICP; cysteine and lactate levels were very high and glucose not measurable. In patient 2 (SAH) a hypoxic episode was accompanied by increased uric acid and decreased glucose. In patient 3 (SHI), the pHD reflected normalisation of blood gases after hyperventilation. Results indicate that parameters are in the range known from experimental studies, and can be correlated with clinical situations. The pHD as valuable indicator of metabolic changes is also feasible bedside.

Acid-Base Equilibrium↗
PubMed1994

Levels of water-soluble antioxidants in astrocytoma and in adjacent tumor-free tissue.

The aim of the present study was to investigate the oxidative status in astrocytoma. Samples of brain tissue from the centre to the periphery of the tumor were obtained from 11 astrocytoma patients undergoing computer tomography-guided stereotaxic operation, who had been previously treated with the corticosteroid dexamethasone. Part of the sample was investigated histologically for clarification of tumor type, and the presence of neoplastic and non-neoplastic tissue and necrosis. The rest was used for the quantification of the antioxidants ascorbic acid, uric acid, glutathione and cysteine by high performance liquid chromatography, and for quantification of DNA. Levels of antioxidants were calculated as micrograms/g fresh tissue and mumol/g DNA, a parameter related to cell content. There was significantly more DNA in neoplastic samples than in non-neoplastic ones, indicating increased cell density. Uric acid (micrograms/g fresh tissue) was significantly increased in neoplastic compared with non-neoplastic tissue, and levels were even higher in necrotic tissue. There were no significant differences between neoplastic and non-neoplastic tissue levels of ascorbic acid, glutathione or cysteine, expressed as micrograms/g fresh tissue. However, when levels of these three compounds were expressed as mumol/g DNA, i.e. taking into account the higher cell density, ascorbic acid, glutathione and cysteine were significantly reduced in neoplastic samples compared with non-neoplastic ones. Results thus show that there are differences between the antioxidant levels in astrocytoma and non-neoplastic tissue, providing additional support for the hypothesis that free radicals play a role in tumor growth.

Adult↗
PubMed1994

Diagnosis and management of abscesses in the basal ganglia and thalamus: a survey.

A review is made of the current management strategies of abscesses in basal ganglia and thalamus, based on a review of the literature and three of our own cases. Clinical picture, aetiology, diagnostic, surgical treatment and outcome are discussed. Stereotactic abscess puncture in combination with temporary drainage and rinsing of the abscess cavity in combination with systemic medication of antibiotics has become the management of choice with satisfactory results.

Adult↗
PubMed1993

[Is early diagnosis possible in cerebral aneurysm? Symptoms of saccular cerebral aneurysms before the occurrence of massive subarachnoid hemorrhage. Literature review and discussion].

Cerebral aneurysms may manifest as subarachnoid hemorrhage. Approximately two fifth of the patients with subarachnoidal hemorrhage complained of early symptoms prior to the major hemorrhage. The complaints may be headache as the most likely, cranial nerve palsies, different vegetative symptoms, transient neurologic deficits, etc. Considering the good outcome of surgical repair of cerebral aneurysms before a major hemorrhage occurs makes it evident that early diagnosis of intracerebral aneurysm is crucial. In the following we will discuss early signals and warning symptoms with respect to literature and personal experiences.

Adult↗
PubMed1993

[Cerebral microdialysis in neurological and neurosurgical research and clinical application in neurology and neurosurgery].

Microdialysis of the cerebral extracellular space (CES) provides information on the cortical metabolic state by measurement of the concentrations of metabolites and transmitters as well as of the extracellular pH. In trauma patients, this kind of monitoring should reveal damage from secondary cortical ischemia in an early, hopefully reversible state. The method further allows in vivo measurement of drug levels in the CES and investigation of their effect on metabolism. Although microdialysis has mainly been used experimentally, it is now beginning to be applied clinically. We report on our experience with both experimental and clinical work.

Animals↗
PubMed1993

Randomized placebo-controlled trial of single-dose antibiotic prophylaxis with fusidic acid in neurosurgery.

In neurosurgery, the antibiotic prophylaxis of choice has not yet been determined. The ideal drug should have an appropriate antimicrobial spectrum and favourable pharmacokinetic properties. In addition it should be nontoxic and easy to apply. We therefore conducted in 90 patients a prospective, randomized, placebo-controlled, double-blind trial in clean neurosurgery at increased risk of wound infection using a single pre-operative dose of 500 mg fusidic acid. Fusidic acid is a steroid-like antibiotic with a serum half-life of about 10 hours and excellent activity against gram-positive bacteria, including methicillin-resistant staphylococci. The neurosurgical infection rates for craniotomies, posterior fossa surgery and implantation of foreign bodies were 2.4% in the treatment group and 9.1% in the placebo group, respectively. This difference is statistically significant at a 95% confidence level.

Adolescent↗
PubMed1993

Penetration of fusidic acid into human brain tissue and cerebrospinal fluid.

Penetration of fusidic acid into brain tissue in six patients and cerebrospinal fluid in seven patients was determined. Tissue samples, taken during surgery revealed drug levels at about 7% of simultaneous serum concentrations. In contrast, cerebrospinal fluid concentrations were below 1% of serum levels. Since serum- and tissue levels of fusidic acid were far above the minimal inhibitory concentration (MICs) of staphylococci and streptococci, and since it has a long serum half-life of about 10 hours, it is a promising candidate for prophylaxis in neurosurgery.

Adult↗
PubMed1993

Cytokine gene expression in primary brain tumours, metastases and meningiomas suggests specific transcription patterns.

To obtain an insight into the network of cytokine gene transcription in the brain tumour microenvironment, we investigated the expression of genes encoding for interleukin (IL)-1 alpha, IL-1 beta, IL-2, IL-4, IL-5, IL-6, IL-10, interferon (IFN)-gamma, granulocyte-macrophage colony-stimulating factor, tumour necrosis factor (TNF)-alpha and transforming growth factor (TGF)-beta 1, -beta 2 and -beta 3 in freshly excised brain tumour samples and autologous peripheral blood mononuclear cells. Tissue specimens from 15 primary brain tumours, three brain metastases, five meningiomas, autologous peripheral blood mononuclear cells (PBMC) and three brain tumour cell lines were tested by reverse polymerase chain reaction. Despite the presence of T-lymphocytes, cytokine gene transcripts typically detectable upon T cell receptor triggering could not be observed in central nervous system tumours of diverse histology. In primary brain neoplasms, transcription of genes encoding for the inhibitory cytokines TGF-beta and IL-10 was detectable in more than 50% of samples. IL-6 transcripts could only be detected in malignant gliomas. In brain metastases, virtually no cytokine gene transcripts could be observed. Surprisingly, TGF-beta transcripts were also detected in all meningiomas. Thus, transcription of genes encoding for inhibitory factors appears to prevail in primary brain neoplasms.

Adolescent↗