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Biomedical subjects

I Hørven

Publications and source records attributed to I Hørven.

At least 19 recordsLinked to original sources
PubMed1995

Doppler study of the ophthalmic artery in patients with carotid occlusive disease.

Assessing the adequacy of collateral circulatory pathways has become increasingly important in the investigation of cerebral circulation. Using transorbital Doppler ultrasonography (TOD), we examined the ophthalmic artery (OA) in patients with hemodynamic significant internal carotid artery (ICA) occlusive disease. The velocity and the direction of flow in the OA were studied in 45 patients (occlusion n = 27, stenosis > 75% n = 18), and in 30 age matched controls, under baseline conditions and within 30 minutes after the i.v. administration of 1 g acetazolamide as a vasodilatory stimulus. Based on the direction of flow before and after acetazolamide, the 45 patients could be separated into four groups with increasing degree of ICA lesions. In group I the OA flow was anterograde, but the velocity decreased after acetazolamide. In group II the OA direction became retrograde after acetazolamide, indicating collateral flow to the brain. In patients with retrograde OA flow following acetazolamide injection (group II-IV), the vessel reacted similarly to an intracranial artery, with marked increase in velocity when vasoreactivity was tested. TOD and the acetazolamide test provide useful information about potential collateral OA flow to the brain in patients with ICA occlusive disease.

Adult↗
PubMed1995

Ocular hemodynamic changes in patients with high-grade carotid occlusive disease and development of chronic ocular ischaemia. I. Doppler and dynamic tonometry findings.

Ophthalmic artery blood flow pattern and the pulsatile ocular blood volume changes in patients with hemodynamically significant carotid occlusive disease are described. Using transorbital Doppler ultrasonography and dynamic tonometry 45 patients with high-grade internal carotid artery stenosis or occlusion and 15 healthy controls were examined. The measurements were performed under baseline conditions and 30 min after 1 gi.v. acetazolamide administration. The velocity in the ophthalmic artery was significantly lower in patients compared with controls. Pulsatile ocular blood volume was also lower in patients than in controls under baseline conditions, and a further reduction was found after acetazolamide, despite the significant decrease of intraocular pressure. A different reaction was observed in eyes with chronic ocular ischaemia.

Acetazolamide↗
PubMed1995

Ocular hemodynamic changes in patients with high-grade carotid occlusive disease and development of chronic ocular ischaemia. II. Clinical findings.

Ocular changes due to chronic ischaemia are described in 45 patients with hemodynamically significant carotid occlusive disease. Regarding the ophthalmic artery flow before and after vasodilatory stimulus, the patients were divided into four different groups. Eyes with permanent anterograde ophthalmic artery flow had evidence of embolic features, but no signs of chronic hypoperfusion. In the group where anterograde ophthalmic artery flow changed to retrograde after 1 g intravenous acetazolamide, the patients had symptoms of critical ocular perfusion, but only subtle structural changes could be demonstrated. Chronic ocular ischaemic syndromes were found in the cases with retrograde ophthalmic artery flow, especially where bilateral severe carotid obstruction was present.

Acetazolamide↗
PubMed1994

Ocular and cerebral blood flow measurements in healthy subjects. A comparison of blood flow velocity and dynamic tonometry measurements before and after acetazolamide.

The ocular and cerebral blood flow was studied in 15 healthy subjects using transcranial Doppler ultrasonography (2 MHz). The blood flow velocity in the precerebral carotid arteries, in the ophthalmic artery and in the middle cerebral artery was measured under baseline conditions and after i.v. administration of 1 g acetazolamide. To measure the intraocular pressure and the corneal indentation pulse amplitude, a dynamic tonometer was used. Pulsatile ocular blood volume was calculated from these values. After one single dose of acetazolamide a significant decrease in ophthalmic artery flow velocity, and a significant increase both in internal carotid and in middle cerebral artery velocity was found. A significant decrease in intraocular pressure and in pulsatile ocular volume after acetazolamide was also demonstrated. These findings suggest that the acute effect of acetazolamide may be associated with a reduced ocular blood flow, explaining some of the reduction in IOP.

Acetazolamide↗
PubMed1993

Acute conjunctivitis. A comparison of fusidic acid viscous eye drops and chloramphenicol.

Fucidic acid viscous eye drops 1% given twice daily was compared with chloramphenicol eye drops 0.5% given 6 times daily in patients with acute conjunctivitis. Patients were recruited from 38 general practitioners in Norway. The mean duration of treatment was 6.6 days for Fucidic acid, 6.2 days for chloramphenicol. There was no major differences between the two groups in the bacteriological findings, and there was no significant difference in response to treatment. The use of fusidic acid in a carbomer vehicle as in Fucithalmic, has proved to give a long-lasting antibiotic concentration in the tear fluid, which allows the preferable twice daily application.

Acute Disease↗
PubMed1992

A new hereditary syndrome with a bleeding tendency, extreme miosis, spasms, dyslexia, thrombocytopathia etc. Pupillometric, evaporimetric, and ophthalmological observations.

A recently described familiar syndrome consists of the following components: A bleeding tendency with thrombocytopathia, miosis, muscular weakness and spasms, ichthyosis, asplenia, dyslexia, and headache. Four definite and 2 probable patients have been identified in 4 generations. In the present study, the pupillary behaviour was scrutinized in two 'definite' cases with the infrared, binocular pupillometer. The forehead sweating pattern was also investigated with an Evaporimeter. The basal pupillary widths were: 1.25-1.75 mm. Only minor responses were noted upon topical stimulation with an indirectly acting pupillodilating agent (OH-amphetamine). A directly acting sympathicomimetic drug (phenylephrine) exerted a more marked influence on the pupil, indicating a relative supersensitivity. The evaporimetric pattern in the forehead seemed to be within reference limits, at variance with what is the case in Horner's syndrome. Further findings were: the orbit seemed to be smaller than normal; a bilateral VI. cranial nerve palsy was identified, and a marked upward gaze palsy coexisted with pupils with Argyll Robertson's traits. There is no readily acceptable explanation for the ocular abnormalities. The disorder underlying the pupillary abnormality may possibly be located in the upper mesencephalon.

Adult↗
PubMed1988

Cluster headache-like headache, Hageman trait deficiency, retrobulbar neuritis, and giant aneurysm. Autonomic function studies.

A 56-year-old, previously reported woman with cluster headache-like headache with bouts of unilateral (the side of predominance changing through the years) severe headache had a familial history (three generations) of partial Hageman factor deficiency and bleeding episodes. A giant aneurysm was found to be lodged in the anterior communicating artery on the left side. Clinically, the features were atypical for cluster headache: onset at a young age (14 years), episodes of retrobulbar neuritis appearing at the side of pain, etc. Studies of forehead sweating indicated that the right side was the pathologic one, from an autonomic point of view, as did pupillometric studies. However, during attacks, which were left-sided at the time, forehead sweating was marked laterally on the left side and on the upper eyelid, but not on the right. The "signal" usually reaching the autonomically stigmatized side during attacks of cluster headache, therefore, did not seem to reach the sweat glands on that (the right) side during the attack in the present case. This headache may, therefore, be distinct from cluster headache, both from a clinical and from an autonomic function point of view.

Autonomic Nervous System↗
PubMed1982

Chronic paroxysmal hemicrania. VI. Precipitation of attacks. Further studies on the precipitation mechanism.

In four of the approximately 40 cases of chronic paroxysmal hemicrania (CPH) that are known so far, attacks that are similar to the spontaneous ones may be precipitated by head movements or pressure against certain points in the neck. Head flexion was used as the precipitation procedure in a 34-year-old female who was studied several times in the course of five years. Attacks occur within 5-40 sec, and the pain is preceded by tearing and conjunctival injection. External rubbing or external compression of the common and internal carotid arteries on the symptomatic side did not produce attacks. The combination of head flexion and external compression of the common or internal carotid arteries on the symptomatic side invariably produced an attack of usual severity and within the usual time. This investigation would seem to render unlikely the possibility of a primary vascular mediation of the signal from the neck to the ocular region. Sympathetic fibres are the likely mediators of the impulses from the neck to the ocular area.

Adult↗
PubMed1982

Intra-ocular pressure levels during extracorporeal circulation in man.

Intra-ocular pressure, arterial blood pressure and central venous pressure were recorded before, during and after open-heart surgery in 12 patients. In contrast to previous findings by others, no increase in intra-ocular pressure was observed during the perfusion period. The discrepancy may be explained by differences in composition of the priming solution and the degree of haemodilution during perfusion. Attention should be paid to any sudden increase in central venous pressure after the end of extracorporeal circulation, as this may produce a corresponding increase in intracranial pressure.

Adult↗
PubMed1981

Intra-ocular pressure before, during and after extracorporeal circulation in pigs.

Variations in intra-ocular pressure (IOP) were demonstrated before, during and after extracorporeal circulation in pigs. Most probably both the observed increase and reduction in IOP may be explained by corresponding changes in blood osmolality, blood pressure and body temperature. In contrast to clinical findings, no increase in IOP was observed during the period of extracorporeal circulation.

Animals↗
PubMed1981

The effect of haemodilution on arterial blood pressure, central venous pressure, intracranial and intra-ocular pressures in pigs.

During the open-heart surgery, haemodilution is performed before extracorporeal circulation is started by the sampling of autologous blood and substituting an electrolyte solution. Following extracorporeal circulation, first the machine-blood and then the autologous blood is reinfused. The haemodilution and reinfusion procedures lead to alterations in blood osmolality and tissue fluid distribution, initiating changes in arterial blood pressure, central venous pressure, intracranial and intraocular pressures. These changes were studied in pigs. It is believed that these potentially hazardous pressure alterations can be minimized through proper handling of the procedure. This study presents some of the mechanisms involved.

Animals↗
PubMed1980

Chronic paroxysmal hemicrania (CPH). The clinical manifestations. A review.

Eight definite and 10 possible cases of CPH are known to the authors. Decisive diagnostic features in the differential diagnosis versus ordinary cluster headache (Horton's headache) seem to be: the presence of headache every day, a high maximum daily attack frequency (greater than or equal to attacks/24 hours) and an absolute indomethacin effect. There is increasing evidence for a female preponderance in CPH. It emerges from this study that there frequently (or invariably?) is a pre-CPH stage with atypical attack pattern, usually lasting several years. Pregnancy seems to have a rather clear ameliorating effect on attack frequency and severity. In other patients, the very onset of headache is immediately after delivery. The importance of recognizing this special headache from a clinical point of view is clear since this disabling disorder can be completely abolished by drug therapy.

Age Factors↗