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H Markus

Publications and source records attributed to H Markus.

At least 19 recordsLinked to original sources
PubMed2005

CHHIPS (Controlling Hypertension and Hypotension Immediately Post-Stroke) Pilot Trial: rationale and design.

RATIONALE: High and low blood pressure (BP) levels are common following acute stroke, with up to 60% of patients being hypertensive (SBP > 160 mmHg) and nearly 20% having relative hypotension (SBP < or = 140 mmHg), within the first few hours of ictus, both conditions being associated with an adverse prognosis. At present, the optimum management of blood pressure in the immediate post-stroke period is unclear. OBJECTIVE: The primary aim of the Controlling Hypertension and Hypotension Immediately Post-Stroke (CHHIPS) Pilot Trial is to assess whether hypertension and relative hypotension, manipulated therapeutically in the first 24 h following acute stroke, affects short-term outcome measures. DESIGN: The CHHIPS Pilot Trial is a UK based multi-centre, randomized, double-blind, placebo-controlled, titrated dose trial. SETTING: Acute stroke and medical units in teaching and district general hospitals, in the UK. PATIENTS: The CHHIPS Pilot Study aims to recruit 2050 patients, with clinically suspected stroke, confirmed by brain imaging, who have no compelling indication or contraindication for BP manipulation. STUDY OUTCOMES: The primary outcome measure will be the effects of acute pressor therapy (initiated < or = 12 h from stroke onset) or depressor therapy (started < or = 24 h post-ictus) on death and dependency at 14 days post-stroke. Secondary outcome measures will include the influence of therapy on early neurological deterioration, the effectiveness of treatment in manipulating BP levels, the influence of time to treatment and stroke type on response and a cost-effectiveness analysis.

Acute Disease↗
PubMed2004

Endothelial nitric oxide gene haplotypes and risk of cerebral small-vessel disease.

BACKGROUND AND PURPOSE: Genetic influences are important in multifactorial cerebral small-vessel disease (SVD) and may act via endothelial dysfunction. Nitric oxide (NO) synthesized by endothelial nitric oxide synthase (eNOS) is a key mediator of endothelial function. We determined the role of 3 potentially functional eNOS polymorphisms (T-786C, intron 4ab, G894T) located toward the 5' flanking end of the gene as risk factors for SVD and different SVD subtypes: isolated lacunar infarction (n=137) and ischemic leukoaraiosis (n=160). METHODS: Three hundred patients with SVD and 600 community controls were studied. Genotypes were determined through polymerase chain reaction with or without restriction fragment digestion. Nitrate (NO(x)) levels were determined in a subgroup by use of a Griess method. Polymorphisms were tested individually and in combination with haplotype analysis. RESULTS: The intron 4a variant was protective against SVD. This effect was confined to isolated lacunar infarction (odds ratio, 0.55; 95% confidence interval, 0.35 to 0.86; P=0.01). Haplotypes encountered were significantly different in this subtype compared with controls (P=0.001), with the -786C promoter/intron 4a combination particularly underrepresented. NO(x) levels were associated with the T-786C locus (P=0.03) but only in the presence of the intron 4a allele (P=0.07 for interaction). CONCLUSIONS: The intron 4ab insertion/deletion genotype was associated with isolated lacunar infarction. Haplotype and functional studies suggested that the protective effect of the 4a variant could be mediated through changes in eNOS promoter activity and increased NO levels. The specific association with isolated symptomatic lacunar infarction and not ischemic leukoaraiosis may reflect different etiopathogeneses of the 2 subtypes. Lack of NO could predispose to localized microatheroma in proximal arterioles rather than diffuse arteriosclerosis affecting distal perforating vessels.

Aged↗
PubMed2004

Genes for stroke.

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Dementia, Multi-Infarct↗
PubMed2002

[Experiences with the psychometric system combitest in the evaluation of the postnarcotic arousal period].

Since the introduction of new German health legislation, operations formerly performed on an in-patient basis have been transferred to the out-patient sector. Due to this development evaluating the postnarcotic arousal period has become increasingly important. Vigilance, reactivity and state of health determine a patient's well-being and time of discharge after an operation and consequently influence economical and legal issues. Former studies investigating the arousal period have mainly focused on patient interviews and assessment of patients by staff. The aim of our study was to objectivize postnarcotic vigilance and reactivity (critical flicker fusion frequency and multiple choice reaction) using neurophysiological monitoring (psychometric system Combitest 2: CFF, EWR, MWR). The applied methods have been defined as valid, reliable and sensitive tools to investigate this question. Inter-individual and gender-specific differences as well as variations due to the type of anaesthetic employed can be detected. The study participants assessed the test battery's practicability and overall described this method as easy to use. Vigilance (CFF), basic and complex sensomotor reactivity (performance in simple and multiple choice tests) were restored after a postanaesthetic phase of 90 minutes (narcotics applied: isofluran and propofol). The results show that the use of modern anaesthetics does not justify the current medical and legal claim to 6 hours of postanaesthetic observation. The computer-supported psychometric system Combitest 2 has recently been used to assess the arousal phase after application of different types of anaesthetical procedures (TIVA, volatile, balanced) and has been found to be superior to parameters traditionally used to assess discharge criteria (time until patient opens eyes, orientation concerning time and location, time spent in postanaesthetic recovery room). Besides employing our study methods, subjective factors such as well-being and pain sensation should also be evaluated when determining the time of a patient's discharge.

Analgesics, Opioid↗
PubMed2001

A survey of neuroimaging research in European neurological departments.

In the international neurological literature, neuroimaging research plays an important role. Neuroimaging techniques are also of steadily increasing importance for clinical diagnosis and treatment monitoring. Therefore, neuroimaging research activities were surveyed by a questionnaire, which was completed by 100 neurological centres across Europe. It showed that most groups use magnetic resonance imaging (MRI), fMRI, computerized tomography (CT) and single photon emission computerized tomography (SPECT). Positron emission tomography (PET) and ultrasound are also employed by nearly half of the centres. Neuroimaging research involves co-operation amongst typically five to 10 disciplines. Cerebrovascular disease, dementia, cognitive disorders, epilepsy, movement disorders, brain tumours and multiple sclerosis are frequently being studied. Many groups rely on small budgets, have few full-time scientists and limited access to expensive resources. There is little exchange of scientists amongst laboratories. It was felt that funding and co-operation needed improvement in order to maintain a high standard in neuroimaging research.

Data Collection↗
PubMed2001

Mr angiography in cerebrovascular disease.

MR angiography has become a realistic diagnostic option for patients with neurovascular disease. MR angiography is not a single imaging sequence, but a collection of related methods for obtaining angiographic data. As a guide for practice, we review the literature on MR angiography in a spectrum of neurovascular indications with particular attention paid to choice of technique. The principles underlying the different techniques available are also presented. Summers, P. E.et al.

Carotid Artery Diseases↗
PubMed2001

Severely impaired cerebrovascular reactivity predicts stroke and TIA risk in patients with carotid artery stenosis and occlusion.

Cross-sectional studies suggest that impaired cerebral haemodynamics is associated with symptomatic status in patients with carotid stenosis and occlusion, but there is relatively little prospective data confirming this association. Transcranial Doppler ultrasonography was used to determine the reactivity of the middle cerebral artery to 8% carbon dioxide in air in 107 patients with either carotid occlusion (n = 48) or asymptomatic carotid stenosis (n = 59). Subjects were followed prospectively until stroke, transient ischaemic attack (TIA), death or study end. Mean duration of follow-up was 635 days. No patients dropped out due to operation before an end-point was reached, or were lost to follow-up. There were 11 ipsilateral ischaemic events during follow-up (six strokes, five TIAs). Exhausted ipsilateral middle cerebral artery reactivity (>20% increase in ipsilateral middle cerebral flow velocity in response to 8% carbon dioxide) predicted ipsilateral stroke and TIA risk in the whole group (P: < 0.00001) and in the carotid occlusion (P: = 0.019) and carotid stenosis (P: = 0.015) groups alone. It also predicted the risk of ipsilateral stroke alone in all three groups. Cox regression was performed, controlling for age, gender, hypertension, diabetes, smoking, ipsilateral CT infarct, degree of contralateral stenosis and the presence of ipsilateral stenosis versus occlusion. Exhausted reactivity remained an independent predictor of ipsilateral stroke and TIA (odds ratio 14.4, 95% confidence interval 2.63-78.74, P: = 0.0021). In contrast, the pulsatility index of the middle cerebral artery was a poor predictor of the risk of stroke. Reactivity to 6% carbon dioxide also predicted the risk of stroke and TIA, but slightly less effectively than reactivity to 8% carbon dioxide. Severely reduced cerebrovascular reactivity predicts the risk of ipsilateral stroke and TIA in patients with carotid occlusion, and to a lesser extent in asymptomatic carotid stenosis. Particularly in the former group, a study is required to determine whether revascularization reduces the risk of stroke in patients with exhausted reactivity.

Carotid Stenosis↗
PubMed2001

Cortical representation of the orbicularis oculi muscle as assessed by transcranial magnetic stimulation (TMS).

OBJECTIVES: To analyze characteristic features and details on motor-evoked potentials (MEPs) of the orbicularis oculi muscle resulting from cortical transcranial magnetic stimulation (TMS) in normal subjects as a basis for further investigations on motorcortical representation in patients presenting with facial nerve diseases. STUDY DESIGN: MEPs of the orbicularis oculi muscle resulting from focal cortical TMS with a figure-8-shaped coil were investigated in 17 healthy subjects with special regard to amplitude and onset latency as a function of the coil position on the head surface along the interaural line and in the anterior-posterior direction. The results were then compared with our data on lower-lip mimetic muscles and on the frontalis muscle obtained in previous studies. RESULTS: Bilateral reproducible responses could be observed at coil positions varying from 1 to 13 cm lateral to the vertex. During moderate muscle activation, maximum responses (mean amplitude 0.75 +/- 0.44 mV contralateral, 0.74 +/- 0.36 mV ipsilateral) were obtained at a mean stimulus position of 8.6 +/- 1.6 cm lateral and 2.0 +/- 2.2 cm anterior to the vertex for contralateral responses, and of 8.6 +/- 2.0 cm lateral and 2.8 +/- 2.4 cm anterior to the vertex for ipsilateral responses, respectively. Voluntary muscle activation by forced eye-closure was associated with a further increase in mean amplitudes. At rest, bilateral responses could be elicited in 15 subjects (88.2%). During moderate muscle activation, the shortest mean onset latencies were obtained at the optimum stimulus position on the interaural line, both for contralateral (10.2 +/- 1.3 ms) and ipsilateral (10.6 +/- 1.5 ms) MEPs. Comparing our data on the orbicularis oculi muscle with those obtained on lower-lip muscles and on the frontalis muscle, there was a considerable overlap of coil positions from which reproducible MEPs could be elicited in all three groups of mimetic muscles, but with the orbicularis oculi area being placed between forehead and lower-lip motorcortical areas. CONCLUSIONS: A statistically significant separation of the cortical representation areas of forehead, orbicularis oris, and lower-lip mimetic muscles is possible by focal cortical TMS reflecting a kind of somatotopic organization of the face-associated motorcortex. Compared with the results on lower-lip and forehead muscles, orbicularis oculi muscle responses show characteristics of both.

Adult↗
PubMed2001

SonoVue in transcranial Doppler investigations of the cerebral arteries.

BACKGROUND AND PURPOSE: The authors investigated the safety and diagnostic potential of a new ultrasound contrast agent (SonoVue) using transcranial color-coded duplex sonography (TCCS). METHODS: Forty patients were enrolled in a multicenter, open-label (on-site), blind (off-site), randomized, dose-ranging crossover study. SonoVue was administered as an intravenous bolus injection of 4 different dosages (0.3, 0.6, 1.2, and 2.4 mL). Efficacy was evaluated as (1) off-site assessment of global quality of the Doppler investigation (based on color or power Doppler images and spectral analysis) at baseline and following each dose of SonoVue according to a 4-point scale (from very poor to excellent imaging of blood flow) and (2) duration of clinically useful signal enhancement and color or power Doppler visualization of blood flow. Additional on-site efficacy assessments performed following each dose of SonoVue included confidence in diagnosis and global consequences of contrast enhancement on diagnosis. Safety evaluations included clinical laboratory tests, neurological examination, injection site tolerability, and incidence of adverse events and their relationship to the study agent. RESULTS: All doses of SonoVue significantly improved the global quality of Doppler examinations (P < .05). The median duration of clinically useful enhancement was dose related (P < .001) and ranged from 2 to 6 minutes at the highest dose. The administration of the contrast agent changed a nondiagnostic study to a diagnostic one in 66% of patients and increased the confidence in diagnosis in 74% of cases. No serious adverse events were recorded following SonoVue administration. The observed adverse reactions were all transient and mild in intensity. CONCLUSIONS: The results obtained from this multicenter study demonstrate that the administration of SonoVue to patients with ischemic cerebrovascular disease who undergo TCCS examination of cerebral vessels improves the visualization of intracranial arteries, providing a dose-dependent contrast enhancement and a clinically useful duration of signal enhancement related to the dose. During this multicenter study, SonoVue proved to be a safe and well-tolerated compound.

Analysis of Variance↗
PubMed2001

Increased common carotid intima-media thickness in UK African Caribbeans and its relation to chronic inflammation and vascular candidate gene polymorphisms.

BACKGROUND AND PURPOSE: Individuals of African Caribbean descent who live in the United Kingdom have an increased risk of stroke. The reasons for this are not fully understood, but differences in genetic predispositions or other novel stroke risk factors could play a role. US blacks have been reported to have increased common carotid artery wall thickness, or intima-media thickness (IMT), measured by ultrasound. We measured carotid IMT in UK African Caribbeans compared with UK whites and determined whether different distributions of polymorphisms in potential candidate vascular genes or differences in measures of chronic inflammation or infection could account for any difference. METHODS: In a population study, common carotid artery IMT was measured in 202 white men and 89 African Caribbean men. The distribution of polymorphisms in ACE, paraoxonase 1, paraoxonase 2, and methylenetetrahydrofolate reductase genes was determined. Serum C-reactive protein and Helicobacter pylori seropositivity were determined. RESULTS: Carotid IMT was increased in African Caribbeans even after controlling for cardiovascular risk factors, including homocysteine and social class: beta=0.113, 95% CI 0.036 to 0.189, P=0.004. There was a significant interaction with smoking and mean IMT (P=0.022), and the difference in both measures of IMT between ethnic groups was largely limited to individuals who had never smoked. There were significant ethnic differences in the distributions of 3 of the 4 candidate genes studied (ACE, paraoxonase 1, and methylenetetrahydrofolate reductase). H pylori seropositivity was increased in African Caribbeans (78.7% versus 53% in UK whites). However, neither the genetic polymorphisms nor H pylori seropositivity was related to IMT, and ethnic differences in their distribution did not account for the increased IMT seen in African Caribbeans. CONCLUSIONS: Carotid IMT is increased in UK African Caribbeans even after controlling for conventional risk factors. There are highly significant ethnic differences in the distribution of many potential cerebrovascular candidate genes. Although those we examined did not explain the ethnic differences in IMT, other genetic predispositions or environmental exposures could account for these differences.

Adult↗
PubMed2001

[Condition of patients after surgical wisdom tooth extraction under general anesthesia with different premedication variants--a prospective study based on a post-anesthesia questionnaire].

Evaluation of the modified "postanaesthesiological questionnaire" pointed to a subtle influencing of the condition of patients who had undergone 3rd molar surgery in general anaesthesia by using different premedication variants: "Atropine, Pethidine and Midazolam" (group A) and "Atropine, Midazolam and S-Ketamin" (group B). The combination in group B seems to be more suitable. On the one hand, a lower incidence of unwanted side-effects was found and, on the other hand, remarkable positive effects were observed. Of particular significance with this combination was also the more effective suppression of postoperative pain. The Propofol-supplemented general anaesthesia prepared in this way and administered using a nasal intubation technique found the full approval of the patients. Postoperative pain therapy was effective and also inexpensive, costing just 8.20 DM per patient, according to current prices calculated by Magdeburg University Hospital.

Adult↗
PubMed1999

[Possible one-dimensional determination of cortical representative fields of mimetic lower lip muscles by transcranial magnetic stimulation].

BACKGROUND: Recent reports as well as results from animal studies indicate changes of cortical organization in patients with facial palsy with a decrease in size of the face-associated cortical representation area. With regard to these alterations, there are no detailed reports in the literature about the possibility of a cortical mapping of mimetic muscles by TMS. METHOD: In 21 healthy volunteers we investigated the amplitude and the onset latency of motor evoked potentials (MEPs) from the depressor anguli oris and depressor labii inferioris muscles during cortical transcranial magnetic stimulation by use of a figure-8-shaped coil (double 70 mm coil) as a function of the scalp positions stimulated in order to establish a reproducible representation area along the interaural line. RESULTS: Cortical evoked MEPs characterized by onset latencies of 6-30 ms were elicited by contralateral and ipsilateral stimulation from coil positions between 4 and 13 cm lateral to the vertex. Maximal responses (mean amplitude 1.5 +/- 0.8 mV contralateral, 0.8 +/- 0.5 mV ipsilateral) with shortest mean onset latencies (11.5 +/- 1.5 ms contralateral, 12.2 +/- 2.8 ms ipsilatral) were observed at a coil position of 10 cm latral to the vertex. CONCLUSION: TMS offers a noninvasive method of one dimensional quantification of the cortical representation area of lower lip mimetic muscles.

Brain Mapping↗
PubMed1999

Improved automated detection of embolic signals using a novel frequency filtering approach.

BACKGROUND AND PURPOSE: Asymptomatic embolic signal detection with the use of Doppler ultrasound has a number of potential clinical applications. However, its more widespread clinical use is severely limited by the lack of a reliable automated detection system. Design of such a system depends on accurate characterization of the unique features of embolic signals, which allow their differentiation from artifact and background Doppler speckle. We used a processing system with high temporal resolution to describe these features. We then used this information to design a new automated detection system. METHODS: We used a signal processing approach based on multiple overlapping band-pass filters to characterize 100 consecutive embolic signals from patients with carotid artery disease as well as both episodes of artifact resulting from probe tapping and facial movement and episodes of Doppler speckle. We then designed an automated detection system based both on these embolic signal characteristics and on the fact that embolic signals have maximum intensity over a narrow frequency range. This system was tested in real time on stored 5-second segments of data. RESULTS: The value of peak velocity at maximal intensity discriminated best between embolic signals and artifact and allowed differentiation with 100% sensitivity and specificity. Relative intensity increase, intensity volume, area under volume, average rise rate, and average fall rate appeared to discriminate best between embolic signals and Doppler speckle. For the majority of embolic signals, the intensity increase was spread over a narrow frequency or velocity range. The automated system we developed detected 296 of 325 carotid stenosis embolic signals from a new data set (sensitivity, 91.1%). All 200 episodes of artifact from a new data set were differentiated from embolic signals. Only 2 of 100 episodes of speckle were misidentified as embolic signals. CONCLUSIONS: Using a novel system for automated detection, which utilizes the fact that embolic signals have maximum intensity over a narrow frequency range, we have achieved detection with a high sensitivity and high specificity. These results are considerably better than those previously reported. We tested this initial system on short 5-second segments of data played in real time. This approach now needs to be developed for use in a true online system to determine whether it has sufficient sensitivity and specificity for clinical use.

Artifacts↗
PubMed1997

Delayed improvement in carotid artery diameter after carotid angioplasty.

BACKGROUND AND PURPOSE: Carotid percutaneous transluminal angioplasty (PTA) is a new method of treating carotid artery stenosis. There has been concern about restenosis after carotid PTA. This study was performed to ascertain the change in percent stenosis 1 year after carotid PTA. METHODS: Twelve patients with symptomatic carotid stenosis were treated by PTA, and the anatomic result was studied by digital subtraction angiography at 1 year, supplemented by duplex ultrasound examinations at 1 month and 6 months. RESULTS: The mean severity of stenosis treated, measured by the common carotid method, was 82% (range, 69% to 98%). The immediate result of PTA was a reduction in the severity of stenosis in all patients to a mean of 51% (P<.005). Six of the 12 patients showed a further improvement in lumen diameter of > or = 14% at 1-year angiographic follow-up from a mean stenosis of 47% (range, 24% to 76%) immediately after PTA to 28% (range, 0% to 52%) at 1 year. This indicates an active process of remodeling in response to carotid PTA. PTA initially reduced the stenosis by > or = 20% in 9 of the 12 arteries, and 8 of these remodeled or remained largely unchanged compared with only 1 of the 3 with a suboptimal initial dilation. In 3 patients the lumen diameter improved by < 5%. Three other patients restenosed with an increase in stenosis after PTA of 9%, 16%, and 66% at 1 year, but all were asymptomatic. The duplex findings showed that remodeling occurred at variable times between PTA and 1 year. CONCLUSIONS: Remodeling of the carotid artery after PTA has not been described before. Our results confirm that carotid angioplasty has an acceptable patency rate at 1 year. It has been suggested that endovascular treatment of carotid stenosis should include placement of a stent. Our results indicate that this may not be necessary unless the initial PTA result is a reduction in stenosis of < 20%.

Aged↗
PubMed1996

How good is intercenter agreement in the identification of embolic signals in carotid artery disease?

BACKGROUND AND PURPOSE: There has been concern regarding the reproducibility of the detection of embolic signals, particularly in patients with carotid artery stenosis in whom the signals are of low intensity. No published studies have examined inter-center agreement in reporting specific embolic signals or the factors responsible for any lack of agreement. We examined reproducibility between two centers in which widely differing proportions of embolic signals have previously been reported in patients with carotid artery stenosis. METHODS: Recordings from the middle cerebral artery of eight patients with ipsilateral carotid artery stenosis in whom embolic signals had been detected during a previously study were independently examined by three experienced observers in one center and by one experienced observer in another center. We calculated agreement within and between centers by estimating the probability that one observer would identify a specific embolic signal if other observers had identified it (a probability of 1 indicates complete agreement). The influence of different characteristics of the embolic signal on the probability of its detection as an embolic signal was determined. RESULTS: A high level of agreement in the identification of specific embolic signals was found. This was similar between all observers (.90), between the three observers in one center (.89), and between observers in the two different centers (.94). The probability of detection was independently related to the relative intensity of the embolic signal (P<.0001). It was less (although significantly) independently related to the position of the embolic signal in the cardiac cycle (P=.02), with signals in systole being more reliably detected. There was no independent relationship between the probability of detection and either the duration of the embolic signal or the velocity at the maximum intensity increase. The use of threshold intensity as a criterion for embolic signal detection increased interobserver agreement but reduced the sensitivity in detecting signals. CONCLUSIONS: The high level of interobserver agreement suggests that the technique is sufficiently reproducible for clinical use.

Blood Flow Velocity↗