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Biomedical subjects

T Czech

Publications and source records attributed to T Czech.

At least 73 records · Page 4Linked to original sources
PubMed1995

Clinical experience with a new pressure-adjustable shunt valve.

The pressure-adjustable valve system Codman Medos allows valve pressure adjustment in 18 steps between 30 and 200 mm H2O. A series of 90 patients, 15 children and 75 adults, who were shunted with this new programmable valve, is reported. Indication for shunt insertion were various types of hydrocephalus in 79 cases, malfunction of a medium pressure membrane valve shunt system in 9 cases and an arachnoid cyst and pseudotumour each in one case. The valve pressure was programmed prior to insertion to 200 mm H2O in the adults and according to age in children and was modified postoperatively according to the clinical course. Underdrainage with subdural fluid collections appearing in 5 patients could be managed by valve pressure adjustment alone in 2 cases. One malfunctioning of the valve mechanism was due to mechanical obstruction. At the time of follow-up, 7 to 29 months after operation, outcome was excellent in 64 patients, good with marked improvement but residual symptoms in 19 patients and unchanged in 7 patients. The possibility of adjusting the valve pressure to the patient's demands was frequently used in children and adult normal pressure hydrocephalus patients with satisfying clinical results.

Adolescent↗
PubMed1995

Cephaloceles - experience with 42 patients.

Forty-two patients with 44 cephaloceles treated between 1966 and 1993 are presented. Eighteen lesions were occipital, 2 parietal, 1 at the anterior fontanelle, 11 sincipital, and 12 basal. In recent years computerized tomography (CT) and magnetic resonance imaging (MRI) provided better information on the site and nature of the lesion as well as on associated malformations. Different malformations were associated more frequently with the cranial vault lesions. Cerebrospinal fluid (CSF)-rhinorrhea was the most frequent clinical sign in the basal lesions. Excision of the cele was performed in all but one case. The age at the time of surgical treatment ranged from 1 day to 11 years. Seven patients were shunted. Post-operative complications were persisting CSF-leaks in 5 patients needing operative revision and 2 infections. The outcome was good in the anterior lesions and in the occipital meningoceles.

Child↗
PubMed1995

The retrosigmoid approach to acoustic neurinomas: technical, strategic, and future concepts.

The retrosigmoid approach continues to be the most widely employed strategy for the surgical resection of acoustic neuromas. The results with respect to facial nerve function are uniformly reported to be quite high. The great emphasis currently is upon improving results with regard to the conservation of useful hearing. This paper focuses on the anatomical and strategic surgical factors that we currently consider to be important to maximizing our current results. The future aspects of this trend toward improved success in conserving hearing in these patients is also discussed.

Humans↗
PubMed1995

Clonidine: an adjunct in isoflurane N2O/O2 relaxant anaesthesia. Effects on EEG power spectra, somatosensory and auditory evoked potentials.

We investigated the effect of clonidine in 19 patients having lumbar disc surgery under nitrous oxide/isoflurane/relaxant anaesthesia. The EEG, spinal and cortical somatosensory evoked potentials, and the brainstem auditory evoked potentials were recorded. After equilibration of the general anaesthetic, two successive infusions of clonidine (5 micrograms.kg-1) were given. After the second infusion of clonidine, the plasma concentration increased from 0.2(SEM 0.05) to 6.4(SEM 0.06) ng.ml-1 (p < 0.05). In the EEG, delta-activity was maintained, but the beta-fraction, and the 95% and 50% spectral frequencies were reduced. Total EEG power progressively decreased from 296(152-397) microV2 to 108(51-240) microV2. The somatosensory evoked spinal potential (N13) decreased in amplitude, (1.77(SEM 0.35) microV to 1.59(SEM 0.35) microV, p < 0.05) and increased in latency (14.37(SEM 0.29) ms to 14.69(SEM 0.31) ms, p < 0.05). The central conduction time increased from 6.47(SEM 0.16) ms to 6.92(SEM 0.25) ms, ns. There was no effect on the cortical somatosensory potentials, or the brainstem auditory evoked potentials. According to the EEG spectral indices, anaesthesia appeared to deepen despite a reduction in the end expiratory isoflurane concentration from 0.53(SEM 0.07) to 0.28(SEM 0.06) vol%, which indicated a reduction in anaesthetic requirements following clonidine.

Adult↗
PubMed1995

Propagation of interictal epileptic activity in temporal lobe epilepsy.

We recorded interictal spikes with closely spaced scalp electrodes and sphenoidal electrodes in four patients with temporal lobe epilepsy. We used multiple dipole modeling to study the number, three-dimensional intracerebral location, time activity, and functional relationship of the neuronal sources underlying the epileptic spike complexes. In all patients, we found two significant sources generating the interictal spikes which showed considerable overlap in both space and time. Source 1 was located in the mesiobasal temporal lobe and generated a restricted negativity at the ipsilateral sphenoidal electrode and a widespread positivity over the vertex. Source 2 could be attributed to the lateral temporal neocortex and was associated with a relatively restricted negativity at the ipsilateral temporal electrodes and a more widespread positivity over the contralateral hemisphere. The sources were well separated in space, with an average distance of 45 mm between them. The time activities of both sources showed similar biphasic patterns, with the mesial source leading the lateral source by approximately 40 msec, suggesting propagation of interictal epileptic activity from the mesiobasal to the lateral temporal lobe.

Adult↗
PubMed1994

Growth hormone-prolactin-thyrotropin-secreting pituitary adenoma in atypical McCune-Albright syndrome with functionally normal Gs alpha protein.

The McCune-Albright syndrome (MAS) comprises a triad of physical signs: localized bone lesions termed polyostotic fibrous dysplasia, café-au-lait pigmentation of the skin, and autonomous hyperfunction of multiple endocrine systems, including overproduction of GH and T4. A somatic activating point mutation in the gene for the alpha-subunit of the G-protein (Gs alpha) in the affected tissue has been claimed to be the underlying defect. A 29-yr-old patient with MAS, showing polyostotic fibrous dysplasia associated with acromegalic features, underwent endocrinological studies, including oral glucose tolerance test and pituitary stimulation test, and magnetic resonance imaging, revealing elevated plasma concentrations of GH, PRL, and secondary hyperthyroidism due to pituitary macroadenoma infiltrating the sphenoid cavity and extending to the suprasellar space. Subsequently, reduction of tumor mass by a transsphenoidal and a subsequent subfrontal operation led to only marginal amelioration of the excessive hormone production. Postsurgery octreotide and bromocriptine therapy induced near-normalization of hormone concentrations. Immunohistochemistry of tumor tissue confirmed the plurihormonal character, but DNA sequence analysis did not detect any of the two known activating mutations in the Gs alpha gene. Furthermore, biochemical tests revealed normal Gs alpha function, ruling out other mutations that lead to constitutive Gs alpha activation. Our study documents that MAS is a heterogeneous disease. Some, but clearly not all, patients have oncogenic mutations of the gene coding for Gs alpha. Any gene acting down-stream of Gs can theoretically be predicted to result in the same phenotype. In addition, hyperthyroidism of MAS may be secondary to a TSH-producing pituitary macroadenoma.

Adenoma↗
PubMed1993

Haemorrhage in intracerebral arteriovenous malformations: detection with MRI and comparison with clinical history.

Fifty-one patients with 59 angiographically proven cerebral arteriovenous malformations (AVMs) were examined by high-field MRI to detect blood breakdown products. Results were correlated with the history of intracranial bleeding. Evidence of previous episodes of haemorrhage was seen in 10 of 12 patients (83.3%) with verified bleeding, in 4 of 9 patients (44.4%) with symptoms which could suggest bleeding and in 6 of 30 patients (20%) with negative histories. Because of the known rebleeding rate and the increased risk of associated complications, identification of the subgroup who had had haemorrhage and should therefore be considered for surgery may be beneficial. MRI can make a contribution to management by demonstrating prior haemorrhage in patients with an inadequate clinical history.

Adolescent↗
PubMed1993

Clinical evaluation of a new epidural pressure monitor.

Comparative measuring of epidural pressure using the Spiegelberg probe 1 and ventricular fluid pressure was carried out in 15 neurosurgical intensive-care patients. Deviations in both directions were established, with a trend toward overestimating ventricular pressure in epidural pressure measuring (r = 0.77). Individual pulsations, spontaneous wave courses and therapy-induced pressure changes were reflected without delays. There were no complications observed with probe implantation periods for up to 6 days. The system has been shown to be mechanically stable and easy to implant. We believe the device to be fit for trend monitoring of intracranial pressure. As with other epidural pressure monitoring systems, false assessments of ventricular pressure may lead to wrong decisions as to required therapy.

Adult↗
PubMed1993

Electroencephalographic burst suppression by propofol infusion in humans: hemodynamic consequences.

The hemodynamic effects of a propofol infusion adjusted to achieve and maintain a burst-suppression pattern [episodes of depressed background activity (electrical silence) more than 4 s alternating with a high-voltage slow activity], were studied in 10 patients without cardiorespiratory disease undergoing elective neurosurgical interventions. Propofol infusion was started after a bolus dose of 1 mg/kg at a rate of 20 mg.kg-1 x h-1, reduced after 30 min to 15 mg.kg-1 x h-1, and terminated after 60 min (1926 +/- 346 mg cumulative propofol dose, maximal serum concentration 9.2 +/- 2.9 micrograms/dL; mean +/- SD). Hemodynamic data and arterial blood samples were collected during a sedated, resting control period, and then every 15 min during drug infusion. Lactated Ringer's solution was infused at a rate sufficient to maintain pulmonary capillary wedge pressure at or above control levels (20-30 mL.kg-1 x h-1). Burst-suppression pattern in the electroencephalogram was achieved after 15.7 +/- 3.2 min and maintained until 10.9 +/- 2.6 min after the propofol infusion was terminated. Significant decreases (% of control, Friedman and Wilcoxon Wilcox test, P < 0.05) were found in heart rate (19%), mean arterial pressure (20%), cardiac index (23%), and left ventricular stroke work index (26%). No adverse consequences were caused by the propofol or crystalloid infusion. The results demonstrate that doses of propofol sufficient to silence the electroencephalogram are associated with venodilating and myocardial depressant properties. However, propofol can be administered with minimal hemodynamic risk in healthy patients when cardiac filling pressures are maintained by intravenous fluid administration.

Adult↗
PubMed1992

Comparative analysis between epidural (Gaeltec) and subdural (Camino) intracranial pressure probes.

The new fiberoptic Camino system has recently been introduced for clinical intracranial pressure (ICP) monitoring. We compared the subdural Camino system with the well-established epidural Gaeltec system in both in vitro and clinical conditions. In the in vitro experiments the intracranial vault was simulated by a tightly closed, fluid-filled box (0.9% sodium chloride) with the two probes inside. We simulated pulsating waveforms with a jet ventilator. No difference between the simulated curve patterns and values could be detected. In the clinical studies, both probes were implanted in 10 patients who had either head injuries, subarachnoid hemorrhage, or intracerebral hemorrhage. The in vivo comparison revealed no significant difference between the two systems in the recorded pressures in group 1 (ICP less than 20 mm Hg). The subdurally placed Camino probe showed insignificantly lower ICP values than did the extradural Gaeltec probe. Although group 2 (ICP greater than 20 mm Hg) waveforms were nearly identical, significant differences (p less than 0.01) in pressure measurements (systolic, diastolic, and mean) occurred (Camino, 18 +/- 3 mm Hg; Gaeltec, 27 +/- 3 mm Hg). Correlation coefficients for mean ICP values were 0.82 in group 1 and 0.49 in group 2. Problems with the Camino probe were usually mechanical and occurred in 2 patients. The problems were either easy to recognize or manifested as an ostensibly pathologic curve. No infection occurred with either system during or following implantation. The dissimilar characteristics of the two probes can be ascribed to their different extradural and subdural implantation sites. The Gaeltec probe was more durable over the period of implantation, which averaged 98 hours and ranged from 44 to 298 hours.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Porcine model for studying the passage of non-depolarizing neuromuscular blockers through the blood-brain barrier.

A method has been developed for blood-brain barrier disruption to provide reproducible access to the cerebrospinal fluid of the cerebello-medullary cistern. The technique was used successfully to investigate transfer of pancuronium to the cerebral CSF compartment in pigs. After osmotic disruption of the blood-brain barrier, pancuronium concentrations increased significantly in the cerebrospinal fluid.

Animals↗
PubMed1991

Clinico-radiological spectrum of giant intracranial aneurysms.

A review of a series of 56 patients with a giant intracranial aneurysm showed that 28 presented with signs related to the mass effect and 19 with subarachnoid hemorrhage (SAH). Additional clinical signs observed were seizures, ischemia, and endocrinological disturbances. Fourty-five aneurysms involved the carotid artery territory and eleven the vertebrobasilar system. On computed tomography (CT) images partially thrombosed aneurysms (23 cases) showed 1) a marginal or central "target" appearance on contrast enhanced scans corresponding to the non-thrombosed lumen as demonstrated by angiography, 2) capsular enhancement in 16 cases and 3) calcifications in 9. SAH occurred in 13 and 6 cases of non-thrombosed and partially thrombosed aneurysms, respectively. Magnetic resonance imaging (MRI) in 6 cases showed several layers of thrombosis in 4 cases and a small signal void close to the parent artery. In one case of a non-thrombosed aneurysm, thrombosis was mimicked by flow artifacts of MRI.

Cerebral Angiography↗
PubMed1991

Effect of sufentanil on intracranial pressure in neurosurgical patients.

The effects of sufentanil on intracranial pressure, mean arterial pressure, cerebral perfusion pressure and heart rate were studied in 20 neurosurgical intensive care unit patients. Epidural intracranial pressure probes were implanted in patients who suffered head injury, intracerebral haemorrhage or underwent tumour resection. Sufentanil was given intravenously in sequential doses of 0.5, 1.0 and 2.0 micrograms/kg. Fifteen minutes elapsed after each dose. The patients were allocated to either group 1 (baseline intracranial pressure less than 20 mmHg) or group 2 (baseline intracranial pressure greater than 20 mmHg). Intracranial pressure did not change significantly in either group. Therefore the falls in mean arterial pressure with the highest dose in both groups and with 1.0 micrograms/kg in group 2, closely reflect corresponding reductions in cerebral perfusion pressure. As sufentanil in itself exerts no effects on intracranial pressure, concomitant haemodynamic changes are the critical factor for an adequate cerebral perfusion pressure.

Adult↗
PubMed1990

[Computed perimetry for the follow-up of optic neuropathy in pseudotumor cerebri].

Computerized static perimetry must be regarded as the method of choice for monitoring the course of optic neuropathy in cases of pseudotumor cerebri. A discrete peripheral visual field depression is the first sign of optic nerve damage. If cranial hypertension persists the visual field depression gradually spreads toward the center. Ultimately central visual acuity deteriorates continuously. If the intracranial hypertension is reduced in good time the visual field defects are largely reversible and optic atrophy can be prevented.

Diagnosis, Computer-Assisted↗
PubMed1990

Surgical treatment of epilepsy.

Seventy patients with intractable epilepsy were surgically treated. Thirty-three patients underwent a stereotactic procedure and in all as a first-stage operation fornicotomy was performed. Because of inadequate results in 14 patients, an additional stereotactic intervention was necessary; the targets were amygdala, thalamus, and Forel's H-field, and the final outcome of these patients was 9 (27%) seizure-free, 19 (58%) improved, and 5 (15%) unchanged. In 3 patients a selective amygdalo-hippocampectomy was performed with 2 seizure-free patients and one with improvement. Topectomy in focal epilepsy in 5 patients resulted in freedom from seizures in all cases. In 23 patients a lobectomy was performed; 10 (43%) were seizures-free, 8 (35%) were improved, and 5 (22%) were unchanged. In 6 patients only a pathological lesion was resected. Our results speak in favour of ablative surgery. However, stereotactic operations are indicated in cases with secondary generalization and dissipated foci on the dominant hemisphere.

Adult↗
PubMed1988

[Results of electrocoagulation of Gasser's ganglion in 250 patients with idiopathic trigeminal neuralgia].

In 250 patients with tic doulourex an percutaneous radiofrequency coagulation of the gasserian ganglion has been performed. In 92.2% of the cases the patients were post-operatively painfree. The follow-up extended in 122 cases over 7 years. In these patients a pain recurrency was noted in 27%. On behalf of low invasivity of the procedure the radio-frequency coagulation of the gasserian ganglion is a recommendable operation with low risk and high efficiency especially in old patients.

Adult↗