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Biomedical subjects

J Van Gijn

Publications and source records attributed to J Van Gijn.

At least 19 recordsLinked to original sources
PubMed2004

Characteristics of intracranial aneurysms in patients with familial subarachnoid hemorrhage.

BACKGROUND: Compared with sporadic aneurysms, familial aneurysms rupture at an earlier age and are more often located at the middle cerebral artery. Other characteristics of familial aneurysms may also differ from sporadic aneurysms. The authors compared the size of ruptured aneurysms and the number of aneurysms between patients with familial subarachnoid hemorrhage (SAH) and those with sporadic SAH. METHODS: The authors included all patients with familial SAH admitted to the University Medical Center Utrecht (UMCU) and their first-degree relatives with proven aneurysmal SAH, including admissions elsewhere. As reference group the authors used a consecutive series of patients with sporadic SAH admitted to the UMCU from December 1995 to March 1997. Criteria for sporadic SAH were absence of a positive family history and exclusion of aneurysms in first-degree relatives by means of MR angiography. The authors dichotomized sizes of aneurysms into small (</=10 mm) and large (>10 mm). Size and number of aneurysms between patients with familial SAH and sporadic SAH were compared with relative risks (RR) with corresponding 95% CI. RESULTS: The authors found 58 patients with familial SAH (48 with information on aneurysm size) and 88 patients with sporadic SAH. Twenty of 48 patients with familial SAH (41%) had large aneurysms, versus 17 (19%) with sporadic SAH (RR 2.1, 95% CI 1.2 to 3.6). Fifteen of 58 patients with familial SAH (26%) had multiple aneurysms, versus 9 (10%) with sporadic SAH (RR 2.5, 95% CI 1.2 to 5.4). CONCLUSIONS: Familial aneurysms are generally larger at time of rupture and more likely to be multiple than sporadic aneurysms. The development of large and multiple aneurysms may be related to genetic factors that determine defects of the arterial wall.

Academic Medical Centers↗
PubMed2004

Anticipation and phenotype in familial intracranial aneurysms.

BACKGROUND: In familial intracranial aneurysms there is evidence for genetic heterogeneity, probably from mutations at separate loci. OBJECTIVES: To compare demographic and clinical features in patients of families with familial intracranial aneurysm and different patterns of inheritance; and to compare the ages of patients with subarachnoid haemorrhage (SAH) in affected parent-child pairs to determine whether there is anticipation. METHODS: Pedigrees for 53 families with familial intracranial aneurysms were constructed, divided into patterns of inheritance suggestive or not suggestive of autosomal dominant transmission. Demographic and clinical features were compared. The age at time of SAH in affected parent-child pairs was compared using the Wilcoxon test. RESULTS: No differences in demographic or clinical features were found between families compatible with an autosomal dominant pattern of inheritance and those with a non-dominant pattern. In families with affected members in two successive generations the age at time of SAH in parents was 55.2 years and in children 35.4 years (mean difference, 19.8 years, p<0.001). CONCLUSIONS: Phenotypes are similar in families with and without a probable autosomal dominant pattern of inheritance. Thus in future genetic studies on familial intracranial aneurysms, stratification according to phenotype is not likely to be useful. Anticipation probably occurs, as affected parents are significantly older at the time of SAH than their affected children.

Adult↗
PubMed2003

Informed consent in trials for neurological emergencies: the example of subarachnoid haemorrhage.

BACKGROUND: In patients with acute life threatening diseases, and in their relatives, the ability to make a balanced decision on participation in a clinical trial may be impaired. OBJECTIVES: To assess what relevant information could be recalled by patients who were living independently after a subarachnoid haemorrhage, and by their relatives; and to determine how these patients and relatives had reacted to the informed consent encounter. METHODS: Twenty months (range 7 to 31) after treatment for subarachnoid haemorrhage, 49 patients and 47 relatives who had participated in one of two randomised trials on medical management were interviewed. The interview consisted of items on: spontaneous recall and knowledge of trial design; understanding of the trial design and the informed consent procedure; the amount and clarity of the information given; and reasons for participating. Finally patients and relatives were asked whether they would participate again in similar circumstances. RESULTS: One third of the patients recalled having participated in a clinical trial. Thirteen per cent of the patients and 20% of the relatives felt that the information supplied had not been sufficient. Nine per cent of the patients and half the relatives had read the written information. None of the patients and one relative thought that participation had been obligatory. Twenty eight per cent of the patients and 94% of the relatives felt in retrospect that they had been capable of making an adequate decision. Virtually all patients and relatives would participate again in similar circumstances. CONCLUSIONS: Many patients and their relatives have little recall of the informed consent procedure and the essentials of acute subarachnoid haemorrhage trials. However, most were satisfied with the overall procedure and would participate again.

Decision Making↗
PubMed2002

Collateral circulation via the ophthalmic artery or leptomeningeal vessels is associated with impaired cerebral vasoreactivity in patients with symptomatic carotid artery occlusion.

BACKGROUND AND PURPOSE: In patients with carotid artery occlusion (CAO), collateral flow may reduce the risk of ischemic stroke. Collateral flow via the ophthalmic artery (OphthA) and flow via leptomeningeal vessels have been considered secondary collaterals, which are recruited only if the primary collateral circulation via the circle of Willis is insufficient. The aim of this study was to investigate whether patients with symptomatic CAO who have secondary in addition to primary collaterals have a worse flow state of the brain than those without secondary collaterals, as measured by vascular reactivity testing. METHODS: We studied 70 patients with symptomatic CAO who were independent for their daily activities. In all patients, collateral circulation through the circle of Willis was present. Vascular reactivity, measured by means of transcranial Doppler sonography with carbogen inhalation, was compared between patients with and without secondary collaterals. RESULTS: CO2 reactivity was lower in 64 patients with (mean +/- standard deviation 8 +/- 14%) than in 6 patients without secondary collaterals (33 +/- 18%) resulting in a mean difference of 24% (95% confidence interval 12-37%; p < 0.01). CONCLUSIONS: Patients with symptomatic CAO with collateral circulation through the OphthA or through leptomeningeal vessels in addition to collaterals via the circle of Willis have a worse hemodynamic status of the brain than those with Willisian collaterals only. Therefore the presence of these collaterals may indicate insufficiency of collateral blood flow via the circle of Willis.

Aged↗
PubMed2002

CT patterns and long-term outcome in patients with an aneurysmal type of subarachnoid hemorrhage and repeatedly negative angiograms.

The fate of patients with subarachnoid haemorrhage, an aneurysmal pattern of haemorrhage on CT and two or more negative angiographies is unknown. We studied the long-term outcome of patients with three negative angiograms (n = 15) and compared the pattern of hemorrhage of these patients with that of patients with perimesencephalic hemorrhage (n = 73). We reviewed the CT scans of all patients and we followed up the patients with three negative angiograms. The mean period of follow up was 65 months; the number of patient years was 81. In five of the 15 patients with an aneurysmal pattern of hemorrhage the CT scan showed a hemorrhage resembling an anterior circulation aneurysm; in the other 10 patients the center of hemorrhage was behind the chiasm but extended too far in anterior or lateral cisterns to meet the criteria of a true perimesencephalic hemorrhage ('extended perimesencephalic pattern'). During follow up no episodes of proven aneurysmal rupture had occurred. Three patients subsequently had serious vascular events; one patient (with an extended perimesencephalic pattern) died suddenly; two patients with a pattern of hemorrhage suggestive of an anterior circulation aneurysm were left disabled, one from two episodes of cerebral ischemia and another from a spontaneous intracerbral hemorrhage. In contrast to patients with perimesencephalic hemorrhage who have an uneventful clinical course and an excellent outcome, patients with three negative angiograms and an aneurysmal pattern of hemorrhage are still at some risk of vascular complications and poor outcome. Subdivisions according to the center of hemorrhage once the anterior cisterns are involved is not helpful in identifying patients with good or poor outcome.

Brain Ischemia↗
PubMed1999

[Clinical researchers and the pharmaceutical industry. Usefulness and need for an independent steering committee].

Clinical trials for testing the efficacy of new drugs in patients are subject to guidelines issued by the European Union ('Good clinical practice'). These guidelines address, in great detail, the relationship between the physician-investigator and the patient, and also that between the sponsoring industry and the physician-investigator (a deplorable exception being the financial arrangement). A major omission is the lack of safeguards for an appropriate and robust design of the study. This applies to the choice of measures of outcome and possible subgroups, interim analyses and stopping rules, entry and management of data, and the final analysis. It is therefore mandatory that the sponsoring industry allows full and early participation by senior clinicians in the design and execution of a clinical trial, through a steering committee.

Clinical Trials as Topic↗
PubMed1999

[50 years of clinical trials; a new direction in medicine].

In 1998 the medical community commemorated the completion of the first truly randomised trial, the Medical Research Council Streptomycin Study. This invention is at least as important as Harrison's clocks, which in the 18th century solved the problem of measuring longitude at sea. Naturally the idea of randomised controls had evolved from previous notions. Obtaining informed consent remains essentially a matter between patient and physician, but in the meantime four other interested parties have joined in: governing bodies, the pharmaceutical industry, medical journals, and the mass media. In order to keep all these forces in check, lawmakers should protect the weakest parties against the more powerful ones. There is a great deal to be done in the next 50 years.

Ethics, Medical↗
PubMed1996

Automatic embolus detection compared with human experts. A Doppler ultrasound study.

BACKGROUND AND PURPOSE: Transcranial Doppler ultrasound (TCD) reliably detects the occurrence of microembolic signals (MES). Unfortunately, TCD monitoring is a time-consuming and mentally strenuous procedure. The purpose of this study was to assess whether automatic embolus detection software devices acting as a "stand-alone system" are able to identify MES in patients with solid cerebral microemboli. METHODS: Ten records of TCD monitoring of the middle cerebral artery in patients with symptomatic high-grade carotid artery stenosis were analyzed for the moments at which MES occurred by four observers and three automatic detection software devices (RB11 on TC2000, Pioneer Version 2.10, and Embotec). The results of the three software systems were assessed on the basic assumption that MES were present if at least three of the four observers agreed. RESULTS: The average number of 1-second periods in which MES were detected by the four observers per tape ranged from 5 to 39. The overall kappa values (and SEs) for chance-corrected interobserver agreement between the four observers ranged from .94 (.02) to .99 (.01). The agreement between the software devices and the observers was lower, with kappa values (and SEs) ranging from .18 (.17) to .93 (.07). The RB11 and Embotec systems achieved a kappa value higher than 0.4 in all tapes. The Pioneer system failed to reach a kappa value of 0.4 in three tapes. The RB11 showed a sensitivity of 70% for detecting MES, the Embotec 62%, and the Pioneer 44%. CONCLUSIONS: In patients with symptomatic high-grade carotid artery stenosis, a high degree of agreement in the detection of moments of MES can be achieved between observers. The three automatic detection software devices reached less agreement. Supervision of TCD monitoring and assessment of MES by an experienced observer is still necessary.

Carotid Stenosis↗
PubMed1995

Noradrenaline concentrations and electrocardiographic abnormalities after aneurysmal subarachnoid haemorrhage.

Serial ECGs and serial assessment of plasma noradrenaline concentrations were carried out in 37 consecutive patients with aneurysmal subarachnoid haemorrhage and 18 operated controls. Electrocardiographic abnormalities reflecting possible signs of cardiac ischaemia occurred significantly more often in patients than in controls. By contrast, plasma noradrenaline concentrations were much higher in controls than in patients. Plasma noradrenaline concentrations were higher in patients with poor outcome, particularly after the third day, but showed covariance with established predictors of outcome such as the Glasgow coma scale score on admission, the amount of extravasated blood on the initial CT, and age. In conclusion, high plasma noradrenaline concentrations do not explain the occurrence of electrocardiographic abnormalities, and are not useful as independent predictors of poor outcome or secondary complications.

Adult↗
PubMed1992

Infarction after aneurysm rupture does not depend on distribution or clearance rate of blood.

BACKGROUND AND PURPOSE: We sought to determine the contribution of the amount, distribution, and clearance rate of extravasated blood in relation to occurrence of infarction and outcome in patients with aneurysmal subarachnoid hemorrhage. METHODS: We prospectively studied 59 consecutive patients with aneurysmal subarachnoid hemorrhage admitted within 72 hours by means of serial computed tomographic scanning, close clinical observation, and assessment of outcome after 3 months. RESULTS: Infarction occurred in 17 of the 59 patients. The arterial territories involved hardly reflected the distribution of subarachnoid blood in the basal cisterns on computed tomography, and even the side of the infarcts corresponded only weakly with the side on which most extravasated blood was seen. Infarction occurred twice as often in patients with large amounts of subarachnoid blood; this difference was not significant on its own but is in agreement with previous studies. A low clearance rate of cisternal blood was not related to the occurrence of infarction; a relation between clearance rate and poor outcome was largely explained by the amount of subarachnoid blood on the initial computed tomogram and by a low Glasgow Coma Scale score on admission. CONCLUSIONS: The fact that infarction is related to the total amount but not to the distribution or clearance rate of extravasated blood argues against a direct role of extravasated blood and in favor of systemic factors, dependent on the severity of the initial hemorrhage.

Cerebral Infarction↗
PubMed1990

Sex-linked variation in creatine kinase release, and its dependence on oestradiol, can be demonstrated in an in-vitro rat skeletal muscle preparation.

Creatine kinase (CK) release from male and female rat soleus muscles was studied for 4.5 h in vitro, under basal conditions and after electrical stimulation. Basal CK release was greater from male than from female muscles, and CK release from male muscles increased significantly when the muscle tension in the in-vitro set-up was increased. CK release after electrical stimulation was also more marked in male soleus muscles. Pretreatment of male rats and ovariectomized female rats with oestradiol for 3 weeks attenuated the enzyme efflux, but ovariectomy 24 h before in females, or oestradiol administration 24 h before in males, did not affect the release of CK in vitro. The data show that sex-linked differences in CK efflux are still present, under both basal and stimulated conditions, when muscles are isolated from the intact animal, and that hormone treatment of the intact animal affects these properties in the isolated muscle in vitro.

Animals↗