Biomedical subjects

H Nornes

Publications and source records attributed to H Nornes.

At least 19 recordsLinked to original sources

PubMed1999

Surgical treatment of anterior circulation aneurysms.

The purpose of this paper is to present the results, assessed by an independent observer, of surgical treatment of 428 consecutive patients harbouring aneurysms of the anterior circulation, together with a review of relevant anatomy and operative strategy. At follow-up (mean 5.6 years) 89.3% lived at home and were independent, 5.1% lived at home but needed some kind of assistance, 2.0% lived in institution, whereas information was unavailable in 3.6% of living patients. Two hundred and fifty-three patients (64.5%) had unchanged employment status, 0.3% worked in sheltered environment, whereas 30.9% went out of work due to their subarachnoid hemorrhage (SAH). Information about employment status was unavailable in 4.3%. For aneurysms of the internal carotid, anterior communicating and middle cerebral artery, respectively, mortality was 3.2, 3.9 and 5.6%, whereas 92.0, 88.1 and 89.0% of surviving patients lived at home and were independent and 67.0, 63.6 and 63.0% had unchanged employment status. Three-months mortality of all causes was 4.2%. In the postoperative period 53 (12.4%) patients developed clinical signs of vasospasms, 6 (1.4%) had cardiac infarction, 4 (0.9%) lung oedema, 4 (0.9%) deep vein thrombosis, and 7 patients (1.6%) infection. During the follow-up period shunt-dependent hydrocephalus developed in 4.2% and 0.2% had a subsequent SAH from the same aneurysm. Forty-three patients were on anticonvulsive therapy.

Adolescent↗

PubMed1999

Transcranial Doppler ultrasonography-guided management of internal carotid artery closure.

OBJECTIVE: To emphasize the integrated use of transcranial Doppler ultrasonography (TCD) in the management of internal carotid artery (ICA) closure. METHODS: Thirty-three patients being considered for ICA closure underwent TCD assessment, vasomotor reserve testing/estimation, and carotid artery test occlusion with concomitant middle cerebral artery (MCA) blood velocity (V(MCA)) monitoring, including calculation of the MCA pulsatility index. Twelve of these patients proceeded to undergo ICA sacrifice. Sequential TCD sonograms guided their postoperative treatment. RESULTS: ICA aneurysms and neck neoplasms affected the TCD results and vasomotor reserve insignificantly, whereas carotid-cavernous fistulae induced characteristic circulatory alterations. The 10 subjects who tolerated ICA sacrifice hemodynamically all showed an initial decrease in the ipsilateral V(MCA) to > or =60% of the preocclusion value and a progressively decreasing MCA pulsatility index during carotid artery test occlusion. The two patients who developed hemodynamic cerebral infarctions exhibited a decrease in V(MCA) to <60% and a MCA pulsatility index that remained stable after a vast initial reduction. Postoperative hypervolemic and hypertensive support was safely titrated in all patients who received postoperative TCD surveillance, providing an ipsilateral V(MCA) of > or =80% of the preocclusion value. ICA closure permanently altered the cerebral circulatory pattern. CONCLUSION: The hemodynamic outcome of ICA sacrifice can be correctly predicted by using the TCD occlusion test. TCD provides the means to titrate the extent of postoperative hypervolemic/hypertensive support.

Adolescent↗

PubMed1998

Varying impact of common carotid artery digital compression and internal carotid artery balloon test occlusion on cerebral hemodynamics.

BACKGROUND: The purpose of this study was to compare the cerebral hemodynamic changes brought about by common carotid artery (CCA) digital compression and angiographic internal carotid artery (ICA) balloon occlusion. METHODS: Bilateral transcranial Doppler ultrasonographic monitoring of the middle cerebral artery blood velocity (VMCA) was performed in 12 subjects with neck neoplasms or traumatic carotid-cavernous fistulas. The MCA pulsatility index (PIMCA) and hemodynamic tension (Uhem MCA) were calculated. RESULTS: Common carotid artery compression provoked the largest drop in ipsilateral VMCA, PIMCA, and Uhem MCA. Common carotid artery compression caused a steal of blood from the intra- to the extracranial circulation, with the discrepancy in hemodynamic findings between CCA and ICA test occlusions being dependent on the quantity of reversed ipsilateral ICA blood flow. CONCLUSION: If the carotid artery is to be sacrificed, permanent ICA closure is the procedure of choice with respect to the occurrence of cerebral ischemic lesions in patients with neck neoplasms and ICA flow reversal during CCA compression.

Adolescent↗

PubMed1997

Cerebral haemodynamics in internal carotid artery trial occlusion.

The purpose of this study was to analyse the cerebral haemodynamic changes brought about by trial occlusion of the internal carotid artery (ICA). Sixteen patients with surgically inaccessible cerebral aneurysms, carotid cavernous fistulas or neck neoplasms were monitored with transcranial Doppler ultrasonography (TCD) during 90-120 s angiographic ICA balloon occlusion or ICA closure with a Selverstone clamp. The blood velocity (V) was registered continuously in both middle cerebral arteries (MCA) while the pulsatility index (PIMCA) and haemodynamic tension (Uhem MCA) were calculated. ICA closure led to an instantaneous drop in the ipsilateral VMCA, PIMCA and Uhem MCA. The VMCA thereafter increased gradually until reaching a stable level. The subjects were grouped into those with initial drops in VMCA to > or = 60% of pre-occlusion value (group 1) and those that fell to < 60% (group 2), respectively. In group 1 autoregulatory mechanisms made the PIMCA decline further, while the Uhem MCA remained unaltered during ICA closure. In group 2, however, the PIMCA did not change further, while the Uhem MCA increased slightly. The cerebral haemodynamic features during ICA test occlusion were thus essentially different in the two groups. On re-opening the ICA, there was an overshoot in VMCA and Uhem MCA. Contralaterally, the VMCA was increased during ICA occlusion. Seven of the patients later had their ICA closed permanently. While none of five group 1 patients developed haemodynamic complications, two group 2 individuals experienced haemodynamic stroke. Assuming ICA sacrifice is feasible when test occlusion results in an ipsilateral initial reduction in VMCA to > or = 60% of pre-occlusion value, the corresponding limit for the Uhem MCA is > or = 40%. In the pre-operative evaluation of the haemodynamic risk related to ICA loss, TCD emerges as a reliable method. It also seems to allow for the reduction of test occlusion time to 90-120 s.

Adolescent↗

PubMed1996

Cerebral haemodynamic considerations in obstructive carotid artery disease.

46 subjects with obstructive carotid artery disease were investigated with transcranial Doppler ultrasonography. Their baseline blood velocities (V) in the middle, anterior and posterior cerebral artery (MCA, ACA and PCA) and in the extracranial internal carotid artery (ICA) were measured and the pulsatility index (PI) calculated for each vessel. Thereafter the vasomotor reserve in both MCAs was tested. Typical patterns of V, PI and vasomotor reactivity are presented. Arterial collaterals were recognized by their relatively increased velocities. We demonstrated a close association of the baseline variables V and PI and the total vasomotor reactivity (hypocapnic plus no, hypercapnic response) by calculating an index of Uhem related to the cerebrovascular tone. The Uhem index is expressed by: Uhem index = VMCA.PIMCA/VPCA.PIPCA The relationship between Uhem index and the total vasomotor reactivity seemed to correspond to a hyperbolic curve. The hyperbolic tangent of Uhem index and total vasomotor reactivity correlated highly significantly, r = 0.8203, p < 0.0001, n = 49, the best fit for the regression line was Y = -0.005 + Uhem index 51.3. On the 99% significance level an Uhem index > or = 0.94 indicated normal total cerebral vasomotor reactivity in contrast to an impaired reactivity when < or = 0.81. Findings in 20 patients investigated post hoc supported the validity of our concept.

Adult↗

PubMed1996

Haemodynamic classification of symptomatic obstructive carotid artery disease.

63 subjects with symptomatic obstructive carotid artery disease were investigated with transcranial Doppler ultrasonography. Their blood velocities at rest (V) in the middle and posterior cerebral artery (MCA and PCA) and in the extracranial internal carotid artery were measured and the pulsatility index (PI) and Uhem index (VMCA.PIMCA/VPCA.PIPCA) calculated. The vasomotor responses in both MCAs were also tested. The subjects were divided into groups based on the findings on physical examination and cerebral computed tomography. In the patient group with lacunar/territorial infarction we found in the stroke hemisphere: VMCA > VPCA, PIMCA = PIPCA and normal values for the Uhem index and total vasomotor reactivity. In the patient group with watershed infarction this hemisphere was characterized by: VMCA < VPCA, PIMCA < PIPCA and subnormal scores for the Uhem index and total vasomotor reactivity. Displaying features from both stroke groups, we obtained in the hemisphere of interest in patients with transient ischaemic attacks: VMCA = VPCA, PIMCA < PIPCA and normal values for the Uhem index and total vasomotor reactivity. Five patients with clinical evidence of stroke but with negative cerebral computed tomography findings had scores similar to those of the watershed group of patients. For the stroke patients, individual measurements of V, PI and total vasomotor reactivity failed to clearly identify to which stroke group a subject might belong. However, such an identification was achieved in all subjects when using the Uhem index. The Uhem index data in patients with transient ischaemic attacks suggest two subgroups with different pathogenesis underlying, the ischaemic events.

Adult↗

PubMed1995

Expression screening reveals an orphan receptor chick ovalbumin upstream promoter transcription factor I as a regulator of neurite/substrate-cell contacts and cell aggregation.

A rat homologue of chick ovalbumin upstream promoter transcription factor I (COUP-TF I) was isolated using an expression cloning method developed to isolate neurite outgrowth inhibitors. Overexpression of COUP-TF I in 3T3 fibroblasts resulted in reduction of stable contact formation between neurites and transfected cells. Additionally, COUP-TF I enhanced retinoic acid response element-dependent reporter gene expression in 3T3 fibroblasts, indicating that COUP-TF I can modulate transcriptional activation in these cells. Our data suggest that COUP-TF transcription factors are involved in the regulation of cell surface molecules during neruogenesis.

3T3 Cells↗

PubMed1994

Superselective angiography, embolisation and surgery in treatment of arteriovenous malformations of the brain.

We prospectively evaluated a diagnostic and therapeutic procedure combining superselective angiography, endovascular embolisation and surgery in arteriovenous malformations (AVM) of the brain. Our aim was to achieve the best possible result exposing the patients to the lowest possible risk. During a 3 year period 48 patients were studied, of whom 22 (46%) were treated by incomplete preoperative embolisation and subsequent complete surgical removal of the AVM. All angiography and embolisations were performed with the Tracker catheter system using polyvinyl alcohol particles and/or platinum fibre coils. The other 26 patients were treated as follows: incomplete embolisation in 11 (23%), complete embolisation in 2 (4%), angiography and surgery in 3 (6%) and combined embolisation and radiation in 7 (15%); 3 patients were excluded from any therapy after superselective angiography. The total number of acute complications and permanent sequelae were 8 (17%) and 3 (6%) respectively. We concluded that superselective cerebral angiography, a relatively safe procedure, should play an important role in deciding treatment strategies for AVMs of the brain. The risks of combined embolisation and surgery are probably lower than those of either alone. In a few cases surgery or embolisation alone carries an unequivocally lower risk, and combined therapy is not justifiable.

Cerebral Angiography↗

PubMed1994

Prospective neuropsychological investigation of patients with supratentorial arteriovenous malformations.

Thirty-one patients subjected to direct radical excision of a supratentorial arteriovenous malformation (AVM) participated in a comprehensive neuropsychological assessment both pre-operatively and at 4 and 12 months after surgery. The sample constitutes a consecutive series of patients who could complete the neuropsychological assessment before surgery. At the pre-operative assessment the mean results of all the tests fell very close to the average performance of age-equivalent normative samples. Postoperatively, the mean results showed a mild to moderate deterioration of performance on most cognitive and perceptual tasks by 4 months after surgery and a return approximately to the premorbid level by 12 months. Twelve of 15 patients with pre-operative epileptic seizures remained seizure free on medication during this first postoperative year, while two developed seizures de novo. Headache was cured or markedly reduced in all 16 patients incapacitated by headache prior to surgery. No definite emotional or affective changes after surgery were reported by the patients or their relatives. Comparison of pre-operative test results of patients with right-sided and left-sided AVM showed significant differences on five of 24 test parameters. Postoperatively, the number of statistically significant differences increased to nine test parameters at 4 months and ten at the 12-month assessment. The increase in number of statistically significant differences appears to reflect a moderate focal impact of the surgical intervention on cognitive functions in six of the 31 patients (19%). Postoperative improvement of test performance exceeding what may be ascribed to practice effects and chance fluctuations was only encountered in one patient. The present results therefore lend little empirical support to the so-called 'cerebral steal' hypothesis.

Adolescent↗

PubMed1993

Transcranial Doppler in neurosurgery.

This chapter describes the use of the transcranial Doppler apparatus in neurosurgery. The principles of Doppler insonation, the techniques of recording and the use of activation techniques is described. The relationship between blood flow and blood velocity is discussed, and the interaction of various pharmacological agents. The establishment of normal values for the laboratory and various vessels insonated is emphasised. The use of indices particularly the pulsatility index is described together with its variations. Cerebral vascular reactivity measurements and the interaction of Doppler recordings with raised intracranial pressure, useful in assessment of cerebral perfusion pressure as in head injury and in terminal cases, is documented. The use of transcranial Doppler in management of head injury and subarachnoid haemorrhage is described. The latter is probably the most useful routine place for Doppler measurement in neurosurgical practice and the documentation of the onset and progress of vasospasm is the final portion of the chapter.

Blood Flow Velocity↗

PubMed1992

A comparison of transcranial Doppler and cerebral blood flow studies to assess cerebral vasoreactivity.

BACKGROUND AND PURPOSE: The aim of this study was to determine the ability of transcranial Doppler ultrasonography when used to assess cerebral vasoreactivity. The results of this method were compared with regional cerebral blood flow measurements. METHODS: Forty-three patients with symptoms suggesting cerebrovascular disease took part. Transcranial Doppler findings in the middle cerebral arteries were compared with regional cerebral blood flow in the corresponding perfusion territories before and after acetazolamide administration. RESULTS: There was a significant positive correlation between the absolute increase in cerebral blood flow in milliliters per 100 g per minute and the percent increase in velocity (r = 0.63). The right-left, side-to-side difference of the acetazolamide response obtained by the two methods also showed a positive correlation (r = 0.80). Control limits obtained from healthy subjects were used for both the blood flow increase (absolute values and asymmetry in absolute values) and the velocity increase (percent increase and asymmetry in percent increase). The two methods then agreed in their evaluation of vasoreactivity in 74 (86%) of the 86 middle cerebral artery perfusion territories; 20 (23%) were assessed by both methods as having a reduced vasodilatory reserve. Eleven hemispheres with a slightly reduced regional cerebral blood flow response to acetazolamide were not detected by transcranial Doppler, whereas all territories with a marked reduction were identified by Doppler. Only one hemisphere with a normal cerebral blood flow increase after acetazolamide administration was assessed by Doppler as having reduced vasoreactivity. CONCLUSIONS: Transcranial Doppler and the acetazolamide test may be used in clinical situations to assess cerebral vasoreactivity.

Acetazolamide↗

PubMed1991

[Meningoencephalocele].

A total of 52 children with meningoencephalocele were operated during a 23 year period. The anomaly was located frontally in nine children, occipitally in 34 children and infratentorially in nine children. Because of progressive hydrocephalus, 18 children underwent shunt procedures shortly after the initial surgical correction. The prognosis was related to the localization and the content of the cell sac, and to additional congenital anomalies. Nine children died and five are severely disabled. For 38 children the result is good, with no major disabilities. In the case of children with meningoencephalocele the possibility of surgical correction should be considered shortly after birth.

Encephalocele↗

PubMed1991

[Neuroradiologic intervention in intracranial arteriovenous malformations].

23 patients with intracranial arteriovenous malformations and durafistulas were embolized. 13 underwent embolization with polyvinylalcohol and silk threads as the only means of therapy, while six were also operated on, and four received radiation after considerable reduction of the nidus had been achieved. No death or major complications occurred in these patients. The authors considered the embolization to be successful in all cases.

Adult↗

PubMed1991

[Pseudotumor cerebri].

Pseudotumor was diagnosed in six patients aged three to 38 years during an eight year period. The diagnosis was based on headache, choked disks and normal cerebrospinal fluid and CT scans. Other symptoms were visual impairment, VIth nerve palsy and ataxia. Sagital sinus trombosis was excluded by angiography or magnetic resonance imaging. Pharmacological treatment with digitoxin, acetazolamide, furosemide or corticisteroids reversed clinical symptoms and signs in two patients. In the other four, shunt surgery with cerebrospinal fluid diversion to the right atrium or the peritoneal cavity rapidly reversed clinical symptoms and signs.

Adolescent↗

PubMed1991

Steady-state lumbar infusion tests in the management of children with craniosynostosis.

Sixty lumbar steady-state infusion tests were used as a guideline in the management of 30 children with craniosynostosis during a 3-year period. The primary decompressive procedure was performed during the same anesthetic period and was made more extensive in cases with pathological outflow resistance (Ro) values. In 11 children with scaphocephaly the test revealed normal to moderately increased cerebrospinal fluid (CSF) Ro. In 6 children with oxycephaly, 4 with trigonocephaly or combined forms, especially in 7 children with syndromic forms, the need for decompressive surgery was usually more obvious. Also, many of these demonstrated severely increased CSF outflow resistance (above 12 mmHg/ml per min). Spinal infusion tests were particularly helpful in the management of severe syndromic or familial cases where the indication for repeat or further extensive decompression was sometimes difficult to assess on clinical and radiological grounds.

Cerebrospinal Fluid↗

PubMed1990

Pseudotumour cerebri-neurosurgical considerations.

Pseudotumour was diagnosed in six patients aged 3-38 years during an 8 years period. The diagnosis was based on headache, papilloedema, normal CT scan and cerebrospinal fluid (CSF) composition. Additional clinical symptoms were nausea, VIth nerve palsy, ataxia, blurred vision and frank visual reduction over time. Sagittal sinus thrombosis was ruled out by angiography or magnetic resonance imaging. In five of the six patients lumbar steady state infusion tests were performed to evaluate intracranial hydrodynamics and CSF resorbtion. All patients demonstrated a markedly increased opening pressure (range 13 to 48 mm Hg). CSF outflow resistance ranged from upper normal to pathologically increased levels (8-19 mm Hg/ml/min). Combined epidural intracranial pressure/middle cerebral artery blood velocity monitoring in 3 patients revealed a great number of B waves and a labile cerebral vasomotor state. Pharmacological treatment was tried with digitoxin, acetazolamide, furosemide and/or corticosteroids. Two patients did well on long-term treatment with digitoxin and furosemide, respectively. In the other four patients the clinical development was unsatisfactory on medical treatment alone. They were subsequently operated with implantation of a lumboperitoneal, cisternoatrial or cisternoperitoneal shunt. Shunting rapidly reversed clinical signs and symptoms, except for a partial persistent visual loss in an 18 years old boy who had experienced symptoms for 3 years resistant to pharmacological treatment.

Adolescent↗

PubMed1990

Continuous recording of middle cerebral artery blood velocity in clinical neurosurgery.

Intracranial pressure, arterial blood pressure, and middle cerebral artery blood velocity were monitored for periods from 1 to 10 days in 30 neurosurgical intensive care patients. The recordings revealed rapid changes in the cerebral perfusion and gave insight into individual cerebral haemodynamic states. Twenty patients consistently showed CO2 reactivity within normal limits, between 2.5 and 5% per mm Hg (19-38% per kPa). Severely impaired CO2 reactivity, considerably below 1% per mm Hg (7.5% per kPa) was observed in four patients. Three of these patients died, while the fourth patient survived in a persistent vegetative state. Seven patients demonstrated pressure-passive blood velocity changes throughout the observed CPP range. The four patients with severely impaired CO2 reactivity all belonged to this group. The recordings from three of the remaining 23 patients showed signs of MCA blood velocity autoregulation with a lower regulatory limit of about 40-45 mm Hg. This observation is in keeping with findings from electromagnetic flowmetry on brain arteries in the neurosurgical operating field, and supports blood velocity measurements as a relevant index of brain perfusion in clinical neurosurgery and neuro-intensive care settings.

Blood Flow Velocity↗

PubMed1990

Haemodynamic aspects of clinical cerebral angiography. Concurrent two vessel monitoring using transcranial Doppler ultrasound.

To overcome the technical limitations which have precluded noninvasive Doppler ultrasound in investigation of rapid cerebral haemodynamic responses in two cerebrovascular beds at the same time, we have modified a commercial 2 MHz pulsed Doppler instrument with online spectrum analysis. Two probes are activated intermittently, recording eight averaged Doppler-shifted spectra from each probe sequentially. Concurrent recordings of blood velocity in both middle cerebral arteries were performed during 25 selective iohexol carotid angiography runs in 13 patients with near normal cerebral vasculature. The technique permitted the differentiation between the specific responses confined to the recipient vascular bed, and the general responses occurring in remote brain areas as well. The specific response to iohexol was biphasic; a significant decrease in blood velocity occurred less than 4 s after the bolus entry, probably due to the high viscocity of iohexol. Between 4 and 12 s. blood velocity was significantly increased, reflecting the cerebrovascular response to hypertonic solutions. The blood velocity on the opposite side increased from less than 4 s through 45 s after iohexol. This concurs with studies using electromagnetic flowmetry, and suggests that these general responses are elicited by anxiety, discomfort and pain. Thus, no general responses were seen during angiography under general anaesthesia. Eight patients investigated during catheter flushing with normal saline showed a biphasic specific response reciprocal to that due to iohexol. A significant blood velocity peak occurred less than 4 s after the bolus entry, followed by a decrease between 4 and 60 s. The saline injections produced no pain and evoked no significant general response.

Adolescent↗