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At least 1,225 records · Page 68Linked to original sources
PubMed1990

Intact parathyroid hormone in primary hyperparathyroidism.

In 49 patients with primary hyperparathyroidism, intact parathyroid hormone (PTH) was measured with a recently developed immunoradiometric assay, and midregional PTH fragments (sequence 44-68) were measured with an established radioimmunoassay technique. In 47 normal subjects, the concentration of intact PTH ranged from 2.0 to 6.8 pmol/l, and in 49 patients with primary hyperparathyroidism it ranged from 6.4 to 80.0 pmol/l. In contrast, midregional PTH fragments were normal in seven of 49 patients with primary hyperparathyroidism. In five healthy controls and in 12 patients with surgically confirmed primary hyperparathyroidism and serum calcium levels below 3.0 mmol/l, a rapid calcium loading test was performed. In healthy controls, intact PTH was in the low normal to subnormal range within 2.5-5.0 min, and had recovered within 15 min of calcium infusion. In patients with primary hyperparathyroidism, the calcium infusion also led to a 30-50 per cent decrease in intact PTH levels within 5.0-7.5 min after injection, with a slow recovery after 10-15 min. In six of the patients with only slightly elevated basal intact PTH, a suppression to the normal range was observed. In 24 patients (16 patients with a solitary adenoma and eight patients with four-gland hyperplasia) the intact PTH levels were followed intraoperatively during parathyroidectomy, revealing a significantly different rate of decline for single adenomas compared with hyperplasia during the first 15 min after removal of the primary enlarged gland. Intact PTH values remained constantly elevated in one patient with primary hyperparathyroidism and an unsuccessful neck exploration. These results confirm that (a) the measurement of intact PTH in patients with primary hyperparathyroidism is superior to the measurement of midregional fragments; (b) PTH secretion in primary hyperparathyroidism is not totally autonomous; and (c) intraoperative monitoring of intact PTH values could be used to monitor the success of surgery.

Adenoma↗
PubMed1994

Cardiac rhythm disturbances due to caval occlusion during hepatic cryosurgery.

Cryoablation is used to treat inoperable hepatic malignancy. We investigated the safety of cryoablation close to the inferior vena cava. Our sheep model showed that it was impossible to create an iceball around the inferior vena cava (IVC) unless this vessel was clamped. When subsequently the IVC was clamped and frozen for 30 min, the anesthetized spontaneously breathing sheep (n = 3) exhibited cardiac arrhythmias typical of hyperkalemia on release of the clamp. The plasma potassium in these sheep rose from a baseline mean (SD) of 5.0 (0.7) mmol/liter to 9.5 (0.9) mmol/liter after release of the clamp at the end of the freeze. These sheep also developed acute hypercapnoea and acidosis. These changes were avoided in subsequent sheep by assisting ventilation mechanically and hyperkalemia and arrhythmias were not seen in this group. Iceball cracking did not occur and the IVC remained intact in all cases. This work suggests that during hepatic cryotherapy of lesions close to the IVC, intraoperative monitoring of potassium is indicated, particularly if caval occlusion is required to achieve adequate iceball thermal distribution.

Acidosis, Respiratory↗
PubMed1999

Laser doppler imaging of activation-flow coupling in the rat somatosensory cortex.

Activation-flow coupling (AFC) provides a physiological basis for mapping cerebral activation using cerebral blood flow (CBF) as a surrogate marker for neuronal function. Laser Doppler offers a minimally invasive approach for measuring changes in cerebral blood flow but the spatial resolution of this technique is limited by the number of individual probes that can be used. Recently, laser Doppler imaging (LDI) scanners, which use computer-driven optics to scan and measure LD changes in two dimensions, have successfully measured flow changes in the exposed cortex of animals. Here we demonstrate the use of an LDI device through a thinned skull to determine the spatiotemporal characteristics of AFC in alpha-chloralose anesthetized rats in response to electrical forepaw stimulation. The spatial and temporal characteristics of the AFC response measured by LDI are in agreement with prior results obtained using a single LD probe. These results suggest a promising role for LDI in the characterization of the spatiotemporal characteristics of AFC in animal models and possibly for intraoperative monitoring in the human brain.

Animals↗
PubMed2005

Conventional microsurgical endarterectomy.

In the 1990's, carotid endarterectomy (CEA) has matured to a widely performed, standard intervention with well defined successive steps. The key feature of microsurgical CEA is the use of the operating microscope for magnification of the surgical field and microsuture of the arteriotomy. Further measures contributing to the success of microsurgical CEA include intraoperative monitoring of cerebral blood flow, selective shunt placement and neuroprotection during arterial cross-clamping. In experienced hands, the operation is not difficult and goes without complication in the great majority of patients. An overall complication rate of 6-8% combining mortality, major morbidity and minor morbidity is acceptable in view of the often multimorbid patients undergoing the operation. However, a rate of major morbidity/mortality not exceeding 1-2% is a realistic goal for microsurgical CEA. On the long-term, the rate of restenosis needing treatment should not exceed 1-2%. To preserve objectivity and quality control of CEA, the clinical results should be assessed independently of the surgeon by a neutral observer, ideally a neurologist.

Carotid Stenosis↗
PubMed2005

Improvement of brain tissue oxygen and intracranial pressure during and after surgical decompression for diffuse brain oedema and space occupying infarction.

BACKGROUND: We evaluated the perioperative and intraoperative changes of intracranial pressure (ICP) and partial pressure of brain tissue oxygen (PtiO2) after decompressive craniectomy in patients with diffuse brain oedema and space occupying infarction. METHODS: Ten patients suffering from medically intractable raised intracranial pressure (ICP) were included. The underlying diseases and causes for elevated ICP were diffuse brain oedema after subarachnoid haemorrhage (n = 3) and head injury (n = 3), or space occupying infarction of the middle cerebral artery territory due to vasospasm after SAH (n = 4). Continuous perioperative and intraoperative monitoring of PtiO2 and ICP was performed at the side of decompression. FINDINGS: ICP and PtiO2 improved significantly in a uniform pattern during bone flap removal and dura opening, irrespective of the underlying disease (mean ICP from 52 mmHg to 8 mmHg, mean PtiO2 from 9 mmHg to 25 mmHg). ICP, PtiO2, and cerebral perfusion pressure were further improved in the subsequent 12 hours after surgery, as compared to the preoperative 12 hours. CONCLUSIONS: Decompressive craniectomy seems to be a successful option in the treatment of intractable intracranial hypertension with associated cerebral hypoxia. These positive effects may last for several hours after the procedure irrespective of the underlying disease.

Brain↗
PubMed2002

Rehabilitation of hearing and communication functions in patients with NF2.

Most patients with neurofibromatosis type 2 (NF2) lose hearing either spontaneously or after removal of their neurofibromas. The patient may benefit from conventional hearing aids if, due to modern microsurgery and intraoperative monitoring the integrity of the cochlea and the 8th nerve is preserved. With lost auditory function but preserved electrical stimulibility of the 8th nerve a cochlear implant may be appropriate. But if the patients have no remaining 8th nerve to stimulate, there is no benefit from cochlear implants. Until some years ago, vibrotactile aids, lip-reading, and sign language have been the only communication modes available to these patients. With auditory brain stem implants it is now possible to bypass both the cochlea and the 8th nerve and to stimulate the cochlear nucleus directly. Stimulation of the devices produces useful auditory sensations in almost all patients. Testing of perceptual performance indicated significant benefit from the device for communication purposes, including sound-only sentence recognition scores and the ability to converse on the telephone. Also lip-reading is significantly improved with brain stem implants. The successful work of an auditory brainstem program center depends very much on the close interdisciplinary collaboration between the Departments of Neurosurgery and ENT-surgery. In the future new developments like speech processing strategies and new designed electrodes accessing the complex tonotopic organization of the cochlear nucleus may further improve rehabilitation in these patients who would have been deaf some years ago.

Auditory Pathways↗
PubMed2000

Reconstructive surgery of the extracranial arteries.

The first carotid endarterectomy (CEA) is usually accredited to Eastcott who reported in 1954 the successful incision of a diseased carotid bulb with end-to-end anastomosis of the internal carotid artery (ICA) to the common carotid artery (CCA). During the following years surgeons were quick to adopt and improve the intuitively attractive procedure. But by the early to mid 1980s several leading neurologists began to question the growing number of CEAs performed at that time. Six major CEA trials were then designed which are now completed or nearing completion. Most conclusive data are available from the North American Symptomatic Carotid Endarterectomy Trial (NASCET) for symptomatic carotid disease, and from the Asymptomatic Carotid Atherosclerosis Study (ACAS) for asymptomatic carotid disease. The key result of these studies is that CEA is beneficial to high grade symptomatic and asymptomatic carotid stenosis. While the benefit in symptomatic disease is clear, it may be negligible in asymptomatic patients suffering from other medical conditions, the most important being coronary artery disease. Since the conclusions from the different studies vary significantly, guidelines and recommendations with regard to CEA have been issued by a number of interest groups, so-called consensus conferences. The best known guidelines are published by the American Heart Association (AHA). However, the practice of interest groups to issue guidelines is currently being criticized, the main reason being that interest groups have different ideas and all claim the right to issue guidelines. At present we recommend CEA for symptomatic high-grade stenosis in patients without significant coincident disease. With regard to asymptomatic stenosis we suggest surgery to otherwise healthy patients if the stenosis is very narrow or progressive. Preoperative evaluation has changed over the years. Currently we recommend duplex sonography in combination with intra- and extracranial magnetic resonance angiography (MRA). Concurrent coronary artery disease is a major consideration in the perioperative management, and the use of a specific algorithm is recommended. Surgery is performed under general anaesthesia with intraoperative monitoring such as electroencephalography (EEG) and transcranial Doppler (TCD). A temporary intraluminal shunt is used selectively if after cross-clamping the flow velocity in the middle cerebral artery (MCA) falls to below 30 to 40% of baseline. For years we employed routine barbiturate neuroprotection during cross-clamping. At the present time we use barbiturate selectively, if the flow velocity in the MCA falls to below 30 to 40% of baseline and if the use of a temporary intraluminal shunt is not possible due to difficult anatomic conditions. The reason to abandon systematic barbiturate protection was to accelerate recovery from anaesthesia. Our patients are monitored overnight on the ICU or a surveillance unit. Routine hospitalization after surgery is 5 to 7 days with a control duplex sonography being performed prior to discharge. A number of details with regard to surgical technique and perioperative management are a matter of discussion. Our surgical routine is described here step by step. Such management resulted in 6 major complications among the 402 cases with 4 of cardiopulmonary and 2 of cerebrovascular origin. For the future we can expect the development of percutaneous transluminal techniques competing with standard carotid endarterectomy. At the present time several comparative studies are under way. Irrespective of the technical approach to treat carotid stenosis, several other issues have to be clarified before long. One of the major unresolved items is the timing of treatment after completed stroke. In this regard prospective trials need to be performed. Although numerically not as important as carotid stenosis, vertebral artery (VA) and subclavian artery (SA) stenoses are more and more accepted as indication for surgical

Carotid Arteries↗
PubMed1998

Preliminary evaluation of a prototype spatially resolved spectrometer.

Near infrared spectroscopy (NIRS) has become an established research tool and is now being explored in several clinical settings [7]. However, until recently NIRS has not been fully quantified and changes have been difficult to interpret [4]. A new development by Hamamatsu Photonics, called the Spatially Resolved Spectrometer (SRS), proposes to be able to give a quantitative measure of oxygen saturation. We have incorporated the SRS into a multimodality monitoring system in three different clinical situations: 1) patients undergoing routine cardiopulmonary bypass, 2) head injured patients and 3) patients undergoing right-sided carotid endarterectomy. The importance of this investigation is in the development of the SRS machine which shows potential as a useful clinical tool. The results demonstrated good correlation between SRS and jugular venous oximetry (SjO2) in about 50% of patients. Although these results are encouraging, this study suggests that the SRS, in its present form, is not a reliable clinical monitor of cerebral oxygen saturation.

Brain↗
PubMed2002

The evaluation of brain CBF and mitochondrial function by a fiber optic tissue spectroscope in neurosurgical patients.

The brain of neurosurgical patients are exposed to various manipulations in the ICU or during surgery. Under such conditions brain O2 balance may become negative and as a result brain vitality and function will deteriorate. In order to evaluate brain vitality in real time it is important to measure more than one parameter. The multiparametric monitoring system used in our previous study to monitor comatose patients (Mayevsky et al., Brain Res. 740: 268-274, 1996) was changed into a "simplified" tissue spectroscope for real time monitoring of brain O2 balance. Mitochondrial function was evaluated by monitoring the NADH redox state by surface fluorometry. Microcirculatory blood flow was assessed by laser Doppler flowmetry. The combined optical probe was located on the surface of the brain during various neurosurgical procedures and the responses were recorded and presented in real time to the surgeon. A total of 32 patients were monitored during various procedures. The results could be summarized as follows: 1. Hypercapnia led to 3 different types of responses. In two patients the 'stealing' like event was recorded. In the other 7 patients the responses to high CO2 was not detectable. In the last group of 6 patients a clear CBF elevation was recorded with variable response of mitochondrial NADH. 2. Our monitoring device was able to evaluate the efficacy of the STA-MCA anastomosis during aneurysm surgery. 3. A significant correlation was recorded between CBF and NADH redox state during changes in blood pressure, papaverine injection, spontaneous drop in blood supply to the brain or during releasing of high ICP levels. We conclude that in order to evaluate the metabolic state of the brain during neurosurgical procedures it is necessary to monitor both CBF and mitochondrial NADH by using the tissue spectroscope.

Brain↗
PubMed1988

The transoral approach to the anterior superior cervical spine. A review of 29 cases.

The transoral surgical approach is the most direct operative approach to pathology ventral to the brain stem and superior spinal cord. This approach is useful in the treatment of extradural compressive cervicomedullary lesions in selected patients. Twenty-nine patients with ventral extradural brain stem or cervical cord compressive lesions who were treated via the transoral surgical approach are presented. Their evaluation, treatment, and long-term outcome will be reviewed (median follow-up, 24 months). Specific features of the transoral procedure, including intraoperative monitoring, methods of retraction, and microsurgical techniques that contributed to minimal operative morbidity (3%) and zero operative mortality, will be discussed.

Humans↗
PubMed1994

Monitoring of rectal, epidural, and intraventricular temperature in neurosurgical patients.

We will report our accumulated experience in monitoring of brain temperatures in neurosurgical patients. The intraventricular temperature was monitored with a thermocouple designed for the purpose. This thermocouple was introduced through a plastic catheter, which was also used for monitoring intracranial pressure. The rectal and epidural temperature was simultaneously measured, with commercially available thermocouples. Human brain temperature is higher than the central core temperature, and there is also a temperature gradient within the brain, with the central parts being warmer than the surface. The relationship between rectal, epidural and intraventricular temperatures is maintained during anaesthesia. We have also shown that it is possible to lower the temperature of the human brain.

Acetaminophen↗
PubMed1995

Motor evoked potentials: appropriate positioning of recording electrodes for diagnosis of spinal disorders.

The interpretation of normal and pathological findings of motor evoked potential obtained by the use of transcranial magnetic stimulation depends on adequate examination technique, including the appropriate positioning of the recording electrodes over the muscle. On the basis of knowing the location of the motor end plate zones in muscles, magnetic stimulation of the motor cortex of 30 healthy adults was performed in order to explore the influence of the position of the surface recording electrodes on potential parameters and to establish the standard location of the recording electrodes over the biceps brachii, medial vastus, anterior tibial and abductor hallucis muscles for diagnostic use in spine disorders. The cortical latencies and peak-to-peak amplitudes of the evoked potentials were analysed by varying the location of the recording electrodes and the stimulus intensities. The latencies were significantly shorter when the different electrode lay more proximally over the muscle belly. Reproducible potentials with sharp negative onset and maximum amplitude were recorded with a separation of 5-7.5 cm between the different electrode, located over the motor end plate area, and the different electrode, located over the distal myotendinous junction. This implies that the parameters of evoked potentials depend on the position and separation distance of the recording electrodes over the muscles and that it is possible to record the potentials using a lower stimulus intensity and, above all, on relaxed muscles, which may prove to be applicable for intraoperative monitoring of the spinal cord using magnetic stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Surgical treatment of achalasia: a retrospective comparative study.

A retrospective study carried out on 74 patients among 101 consecutive cases of achalasia of the esophagus operated from 1967 to 1989 is reported. On 21 patients observed between 1967 and 1975, a standard transabdominal Heller cardiomyotomy was performed (group A). From 1976 to 1989, the treatment of choice was a Heller myotomy associated with a modified Dor's fundoplication. In 80 consecutive cases (group B) the extension of myotomy was regulated by intraoperative monitoring of lower esophageal sphincter pressure. A 5-year follow-up with questionnaires, physical examination, and barium swallows was carried out on 16 patients in group A and on 58 patients in group B. In 75.6% of the cases (56 patients) follow-up examinations included esophageal manometry and 24-hour esophageal pH monitoring. Recurrence of dysphagia was recognized in 3 cases in group A (18.7%) and in 2 cases in group B (3.4%) (P = 0.053); postoperative gastroesophageal reflux, measured as a percentage of total reflux time, showed a significantly lower mean value in group B than in group A (1.8% vs. 4.1%, P < 0.01). This study suggests that an anti-reflux procedure lowers postoperative gastroesophageal reflux after Heller myotomy. Due to the low incidence of postoperative reflux and the negligible recurrence of dysphagia, Heller myotomy associated with a modified Dor's fundoplication may represent the surgical treatment of choice for achalasia of the esophagus.

Adult↗
PubMed1993

Selective posterior rhizotomy: experience of 30 cases.

The increasing interest in selective posterior rhizotomy for reduction of spasticity in children with cerebral palsy and other neurological disorders comes from the selectivity that this procedure has achieved with intraoperative electromyographic monitoring. Thirty patients were operated on between April 1989 and October 1991. Spasticity was of cerebral origin in 27 cases and secondary to spinal cord lesion in 3 others. A reduction in the abnormally high muscle tone was observed in all cases, mainly in the lower extremities, but also, to a lesser degree, in the upper extremities. All patients showed functional improvements that depended on the individual preoperative condition. Even severely disabled patients with quadriplegia and intellectual impairment, whose spasticity interfered with their daily care, had a significantly improved quality of life after rhizotomy. These patients became much looser, with better swallowing and less drooling, and were much more easily managed by their caretakers. Preliminary results with follow-up from 1 to 30 months indicates that selective posterior rhizotomy is a safe procedure which contributes to significant functional improvement in spastic patients.

Adolescent↗
PubMed1996

A multimedia perioperative record keeper for clinical research.

OBJECTIVE: To develop a multimedia perioperative recordkeeper that provides: 1. synchronous, real-time acquisition of multimedia data, 2. on-line access to the patient's chart data, and 3. advanced data analysis capabilities through integrated, multimedia database and analysis applications. DESIGN: To minimize cost and development time, the system design utilized industry standard hardware components and graphical. software development tools. The system was configured to use a Pentium PC complemented with a variety of hardware interfaces to external data sources. These sources included physiologic monitors with data in digital, analog, video, and audio as well as paper-based formats. DEVELOPMENT: The development process was guided by trials in over 80 clinical cases and by the critiques from numerous users. As a result of this process, a suite of custom software applications were created to meet the design goals. The Perioperative Data Acquisition application manages data collection from a variety of physiological monitors. The Charter application provides for rapid creation of an electronic medical record from the patient's paper-based chart and investigator's notes. The Multimedia Medical Database application provides a relational database for the organization and management of multimedia data. The Triscreen application provides an integrated data analysis environment with simultaneous, full-motion data display. CONCLUSION: With recent technological advances in PC power, data acquisition hardware, and software development tools, the clinical researcher now has the ability to collect and examine a more complete perioperative record. It is hoped that the description of the MPR and its development process will assist and encourage others to advance these tools for perioperative research.

Database Management Systems↗
PubMed1990

Neurosurgical applications of topographic mapping.

Sophisticated spectral analysis and mapping of the EEG with computer techniques provides objective and reliable diagnostic information, which is superior to that obtained by naked-eye observation, even by experienced clinicians. In our department, a topographic system was introduced as one of major adjuncts to EEG examination in 1980, and we devised our own software (dynamic topography, compound dynamic topography, deviation ratio topography) to facilitate its clinical application. Topographic mapping is applied to assessment of the dominant hemisphere, evaluation after medical and surgical treatment, spatial localization of epileptic foci, and intraoperative monitoring for cerebral hypoperfusion. Besides these surgical applications, topographic analysis has contributed to human neurophysiology, for instance in determining the participation of the dentatethalamic tract in movement-related cortical potentials. Our experience of the neurosurgical and neurophysiological applications of topographic mapping will be presented.

Aged↗
PubMed1975

[Surgical treatment in coronary heart disease (author's transl)].

This paper describes the operative techniques appropriate to the treatment of coronary heart disease. The chapters deal with general preliminaries and indications for surgery, the selection of bypass material, surgical instruments for coronary opertaions, the methods of extracorporeal circulation, the distal coronary anastomosis, the proximal aortal anastomosis, intraoperative monitoring of results, intra- and postoperative myocardinal infarction, the fate of venous bypass grafts, operative treatment of the ruptured ventricular septum and papillary muscle, and ventricular aneurysmectomy.

Coronary Artery Bypass↗