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Biomedical subjects

E B Ringelstein

Publications and source records attributed to E B Ringelstein.

At least 127 records · Page 7Linked to original sources
PubMed1998

[Hereditary neural amyotrophy (HNA): clinical and molecular genetic basis].

Hereditary neuralgic amyotrophy (HNA) and hereditary neuropathy with liability to pressure palsies (HNPP) are hereditary focal neuropathies. In this study we describe three families suffering from HNA. These families were examined clinically and electrophysiologically. Linkage analysis with markers from distal chromosome 17 was performed in a three-generation family. HNA could be separated from HNPP in all three families based on clinical and electrophysiological findings. HNA was characterised by recurrent episodes of painful brachial plexus lesions. In contrast to HNPP, no evidence for generalised neuropathy was found in the HNA families. Linkage analysis confirmed the HNA locus on distal chromosome 17. Additionally, we were able to refine the HNA locus to a 16 cM region on chromosome 17q24-q25.

Amyloid Neuropathies↗
PubMed1998

[Clinical significance of echocontrast enchancement in neurovascular diagnosis. Review of experience following a year of use].

AIM OF THE STUDY: To evaluate the potential and limitations of echocontrast enhancement using Levovist in a non selected consecutive cohort of neurological patients with insufficient native ultrasound investigations. METHODS: In 91 patients an indication for echocontrast application was seen after an insufficient extracranial (n = 17), transtemporal (n = 54), and transforaminal (n = 20) Doppler- und color-coded Duplex sonography. Levovist was injected at a concentration of 400 mg/ml and 200-400 mg/ml for the transcranial and extracranial approach, respectively. The effect of the echocontrast enhancement was assessed semiquantitatively with respect to signal enhancement, imaging quality, and diagnostic confidence. RESULTS: In a total of 83 patients (91%) the signal enhancement led to a moderate to high imaging quality allowing to reach 67 definite neurovascular diagnoses (74%). In subgroup analysis, the amount of sufficiently confident examinations was significantly higher for the transtemporal and transforaminal (both 80%) than for the extracranial approach (47%). The latter was mostly due to artificial signals derived from adjacent neck vessels. CONCLUSION: Levovist constitutes a safe and highly effective diagnostic tool especially for the transtemporal and transforaminal neurosonographical imaging. By means of a differentiated application of echocontrast agents, its cost-effectiveness can be increased and the need for other potential invasive and expansive neuroimaging methods can be further reduced.

Adult↗
PubMed1998

Cerebral hemodynamics during induced tachycardia in routine electrophysiologic studies: a transcranial Doppler study.

Supraventricular and ventricular tachyarrhythmia are established causes of syncope. We investigated the mean blood flow velocities (Vmean) of the middle cerebral arteries (MCA) during routine cardiac electrophysiologic studies in patients with supraventricular and ventricular tachyarrhythmias in order to evaluate the changes in cerebral hemodynamics associated with pre-syncopal and syncopal states. Thirty-two patients with a history of supraventricular (n = 14) or ventricular (n = 18) tachyarrhythmias were investigated in the nonsedated, post-absorptive state in supine position. Vmean was assessed in both MCAs by means of transcranial Doppler under resting conditions, during atrial and ventricular pacing at constant rates (n = 28) and during induction of tachyarrhythmia (n = 4). Mean arterial blood pressure (MABP) and heart rate were also recorded. Seven patients suffered pre-syncope at a heart rate of 187 +/- 45 bpm (mean +/- SD) with an average drop of 44% in the Vmean MCA, and statistically insignificant changes in MABP. Five patients suffered syncope during tachyarrhythmia (mean heart rate 283 +/- 42 bpm) with a reduction of 69% in the Vmean MCA. MABP could be assessed in two of those patients and showed a drop of 15 and 43 mmHg, respectively. During tachyarrhythmia pre-syncope and syncope are associated with an average reduction in Vmean MCA by 44% and 69%, respectively. The decrease in MCA blood flow velocity is a more important predictive factor for the development of pre-syncope and syncope than the MABP.

Adult↗
PubMed1998

Echocontrast enhanced transcranial colour-coded duplex offers improved visualization of the vertebrobasilar system.

OBJECTIVES: By means of transcranial colour-coded duplex sonography (TCCD) through the foramen magnum, the intracranial vertebral arteries (VAs) and the basilar artery (BA) can be investigated. In this study we evaluated the additional diagnostic value of echocontrast administration in patients with an insufficient pre-contrast TCCD investigation of the vertebrobasilar system. MATERIAL AND METHODS: In 22 patients the intracranial VAs and the proximal, middle and distal BA were evaluated before and after the application of 4 g of the echocontrast agent Levovist. The length of the different vessel segments visualized on colour mode before and after echocontrast, and the diagnostic benefit and the diagnostic confidence were assessed. RESULTS: Echocontrast enlarged in each vessel segment the length that could be visualized. Using echocontrast, in 5/22 patients (23%) definite and probable pathological findings unnoted in the native scans were detected. In 12 additional patients (55%) the investigator and the clinician became confident with the vascular diagnosis by echocontrast to a degree that angiography could be avoided. In only 3/22 patients (14%) no gain and in 2/22 patients (9%) an insufficient diagnostic gain was noted. CONCLUSIONS: Our study demonstrates that echocontrast provides effective Doppler signal enhancement and considerably increases the diagnostic gain of TCCD in the intracranial vertebral and basilar vasculature.

Adult↗
PubMed1998

Noninvasive determination of language lateralization by functional transcranial Doppler sonography: a comparison with the Wada test.

BACKGROUND AND PURPOSE: Functional transcranial Doppler ultrasonography (fTCD) can assess event-related changes in cerebral blood flow velocities and, by comparison between sides, can provide a measure of hemispheric perfusional lateralization. It is easily applicable, insensitive to movement artifacts, and can be used in patients with less than perfect cooperation. In the present study we investigated the validity of fTCD in determining the hemispheric dominance for language by direct comparison of fTCD with intracarotid amobarbital anesthesia (Wada test). METHODS: fTCD and the Wada test were performed in 19 patients evaluated for epilepsy surgery. By the Wada test, 13 patients were classified as left-hemisphere dominant and 6 as right-hemisphere dominant for language. fTCD was based on the continuous bilateral measurements of blood flow velocities in the middle cerebral arteries and event-related averaging during a cued word generation task previously shown to activate lateralized language areas in normal adults. RESULTS: In 4 patients fTCD assessment was not possible because of lack of an acoustic temporal bone window. In the remaining 15 candidates, determination of language dominance was concordant with the Wada test in every case. Moreover, the correlation of the lateralization measures from both procedures was highly significant (r=.92, P<.0001). CONCLUSIONS: This strong correlation validates fTCD as a noninvasive and practical tool for the determination of language lateralization that can be applied for clinical and investigative purposes.

Adolescent↗
PubMed1998

Factor V Leiden mutation is a risk factor for cerebral venous thrombosis: a case-control study of 55 patients.

BACKGROUND AND PURPOSE: Different coagulation disorders have been associated with cerebral venous thrombosis (CVT). Until now, fewer than 50 patients have been reported with CVT and the factor V Leiden (FVL) mutation. Although the prevalence of FVL-positive patients with CVT ranged from 10% to 25%, it was as low as 0.5% to 3% in the control groups. Most other studies had not systematically searched for concomitant risk factors or previous thromboembolic events. To better define the relevance of the FVL mutation in conjunction with additional risk factors in CVT, we conducted the present case-control study. METHODS: Fifty-five patients with CVT were compared with 272 healthy controls. A standardized interview regarding established risk factors for venous thrombosis and the patients' and their families' histories for thromboembolic events was performed. The presence of the FVL mutation was determined by polymerase chain reaction on DNA obtained from peripheral blood leukocytes. RESULTS: Of 55 patients, 8 (14.5%) were heterozygous for the FVL mutation compared with 17 of 272 controls (6.25%). The relative risk for the presence of FVL was 2.55 (95% confidence interval, 1.04 to 6.26; P=0.04). Additional risk factors for CVT were frequently found in both the presence and absence of FVL. Recurrence of venous thromboembolic events was more frequent in patients with the FVL mutation (5 of 8 patients, 62.5%) than in those without this anomaly (8 of 47 patients, 17%; P<0.005). CONCLUSIONS: Our study confirms the FVL mutation as the most relevant hereditary risk factor for CVT. Coexisting risk factors are usually involved in the initiation of CVT. Patients with the FVL mutation are at an increased risk for recurrent venous thrombosis.

Adolescent↗
PubMed1998

Collateralization of an occluded internal carotid artery via a vas vasorum.

BACKGROUND: Reopening of an occluded internal carotid artery (ICA) is often seen in dissections but only rarely occurs in atherothrombotic occlusion of the internal carotid artery. CASE DESCRIPTION: A 60-year-old man suffered a minor stroke with dysphasia in March 1995. Color-coded duplex ultrasonography of his neck arteries revealed a left ICA occlusion. He was placed on a regimen of aspirin and followed up clinically and with ultrasonography. At follow-up 18 months later, the patient was asymptomatic. On duplex ultrasonography his left occluded ICA was found to be reopened, with a residual, proximal, high-grade stenosis. However, intra-arterial digital subtraction angiography demonstrated a persistent ICA occlusion and a vas vasorum originating from the carotid bulb and draining into the ICA distal to the occlusion. CONCLUSIONS: The rare collateralization of an occluded ICA by vasa vasorum seems to take several months. It can be a pitfall in the ultrasound diagnosis of carotid artery occlusive disease.

Carotid Artery, Internal↗
PubMed1998

Consensus on microembolus detection by TCD. International Consensus Group on Microembolus Detection.

Transcranial Doppler ultrasound is capable of detecting microembolic material, both gaseous and solid, within the intracranial cerebral arteries. To avoid discrediting this promising and exciting new technique, experts in this field met in January 1997 in Frankfurt, Germany, to discuss the limitations and problems of embolus detection and to determine guidelines for its proper use in clinical practice, as well as in scientific investigations. In particular, the authors suggest that studies report the following parameters: (1) ultrasound device, (2) transducer type and size, (3) insonated artery, (4) insonation depth, (5) algorithms for signal intensity measurement, (6) scale settings, (7) detection threshold, (8) axial extension of sample volume, (9) fast Fourier transform (FFT) size (number of points used), (10) FFT length (time), (11) FFT overlap, (12) transmitted ultrasound frequency, (13) high-pass filter settings, and (14) recording time. There was agreement that no current system of automatic embolus detection has the required sensitivity and specificity for clinical use.

Humans↗
PubMed1998

Potential and limitations of echocontrast-enhanced ultrasonography in acute stroke patients: a pilot study.

BACKGROUND AND PURPOSE: Ultrasonography (US) is a well-established method used to assess the brain-supplying arteries in the acute stroke setting. However, several technical and anatomic limitations are known to reduce its diagnostic accuracy and confidence level. Echocontrast agents (ECA) are known to improve the signal-to-noise ratio by enhancing the intensity of the reflecting Doppler signal. We undertook this prospective study to evaluate the diagnostic value of ECA in a consecutive, nonselected cohort of acute stroke patients with insufficient native US investigations. METHODS: During a 1-year period, 25 patients were examined within 48 hours of the onset of stroke. The need for ECA was due to an insufficient transtemporal (n=18), transforaminal (n=4), or extracranial (n=3) imaging of arteries potentially involved in the ischemic event. In 12 patients, a diagnostic suspicion could natively be raised, whereas in the other 13 patients, the strongly reduced image quality did not allow for any neurovascular conclusions. Four grams of Levovist was injected at a concentration of 200 mg/mL and 400 mg/mL for the extracranial and transcranial insonations, respectively. The effect of the echocontrast enhancement was assessed with respect to (1) signal enhancement, (2) image quality, (3) final diagnostic confidence, and (4) the need for additional neurovascular imaging methods. RESULTS: In all but one patient (96%), a strong signal enhancement was noted, leading to a moderate (n=11) or strong improvement (n=10) of the transcranial image quality. Thus in a total of 18 patients (72%), the echoenhancement provided a neurovascular diagnosis of sufficient confidence. This led to the confirmation of the previously suspected findings and disclosed three further occlusions and four stenoses of the intracranial arteries. In contrast, for the three extracranial examinations the image quality was not sufficiently improved because of persistent color artifacts derived from adjacent neck vessels. Besides the seven patients with inconclusive examinations, five patients with conclusive echoenhanced US studies (48% in total) demanded additive neurovascular imaging studies, based on the clinical decision of the attending physicians. This led to confirmation of all high-confident sonographic diagnoses. CONCLUSIONS: In summary, in approximately three fourths of our acute stroke patients with insufficient native US investigations, echocontrast enhancement enabled a reliable neurovascular diagnosis, allowing the cancellation of additive neurovascular imaging procedures in half of our cohort. Our preliminary results suggest that ECA can reasonably support the early cerebrovascular workup in the acute stroke setting.

Acute Disease↗
PubMed1998

Reproducibility of functional transcranial Doppler sonography in determining hemispheric language lateralization.

BACKGROUND AND PURPOSE: Since functional transcranial Doppler ultrasonography (fTCD) allows convenient and fully automated quantification of language lateralization, it seems ideal for longitudinal studies of perfusion changes during deterioration as well as recovery of language functions. However, during serial examinations, the technical, stochastic, and physiological variabilities of cerebral blood flow velocities (CBFV) have to be considered. Therefore, before fTCD is accepted as a tool for evaluation of changes in lateralization in the diseased state, its reliability in healthy subjects needs to be determined. METHODS: We performed fTCD during a word generation task based on a previously validated technique with automated calculation of the averaged CBFV differences in the middle cerebral arteries providing an index of lateralization (LI). RESULTS: (1) The accuracy of the LI as assessed by the confidence interval was better than 1% of the mean hemispheric difference. (2) On repeated examination, LIs obtained from 10 subjects showed a high test-retest reproducibility (Pearson product moment correlation coefficient r = 0.95, P < 0.0001). (3) On 10 repeated assessments of LI in the same subject, no practice effects were detected. CONCLUSIONS: Functional TCD is a suitable and very robust tool for the longitudinal quantitative measurement of cerebral language lateralization.

Adult↗
PubMed1998

PCR-based strategy for the diagnosis of hereditary neuropathy with liability to pressure palsies and Charcot-Marie-Tooth disease type 1A.

Charcot-Marie-Tooth disease type 1A (CMT1A) and hereditary neuropathy with liability to pressure palsies (HNPP) are inherited peripheral neuropathies. In most cases these disorders are caused by either the duplication (in CMT1A) or the deletion (in HNPP) of a 1.5-megabase DNA fragment on chromosome 17p11.2, which contains the peripheral myelin protein 22 gene (PMP22). We developed a rapid and simple quantitative PCR assay for the detection of the CMT1A duplication or the HNPP deletion. The assay is based on the quantitative determination of the copy number of a 240-base pair DNA fragment from exon 4 of the PMP22 gene. Quantification was done on an automated fluorescence sequencer. Using this method we analyzed four families with the HNPP phenotype. In these families we identified the deletion in all affected individuals. To test the validity of the method, we compared the quantitative PCR results from 50 DNA samples, including 15 samples from individuals with HNPP, 15 samples from CMT1A patients, and 20 from normal controls, with the results obtained by Southern blot analysis. Concordant results were obtained in 49 of the 50 cases.

Blotting, Southern↗
PubMed1998

Transient ischemic attacks caused by trumpet playing.

We report a young musician who experienced transient ischemic attacks during trumpet playing. Cardiovascular examination revealed a patent foramen ovale; Doppler ultrasound of the middle cerebral arteries detected microembolic signals with increased rates during trumpet playing and Valsalva maneuver. After operative occlusion of the foramen ovale, the symptoms disappeared and no microembolic signals could be detected.

Adolescent↗
PubMed1998

Inhibition of growth and induction of differentiation of glioma cell lines by oncostatin M (OSM).

The neuropoietic cytokines of the interleukin-6 family are a group of structurally and functionally related polypeptides. We studied the effect of the multifunctional neuropoietic cytokines, including oncostatin M (OSM), leukemia inhibitory factor (LIF) and interleukin-6 (IL-6), on anaplastic glioma cell lines. Growth and morphology of the glioma cell lines were affected differently. While IL-6 and LIF exerted no or only small minor morphological changes and growth retardation, OSM induced a marked change in morphology and a strong suppression of growth. OSM treated cells were characterized by enlargement and the formation of multiple, thin processes thus resembling mature cultured astrocytes. The growth inhibitory effects were dose dependent with a maximum exerted by addition of 50 ng/ml OSM. The inhibition of DNA synthesis by OSM could be abolished by antibodies blocking either the activity of OSM or the OSM-receptor component, gp130.

Antibodies↗
PubMed1998

Correlation of neuropsychological, morphological and functional (regional cerebral blood flow and glucose utilization) findings in cerebral microangiopathy.

UNLABELLED: Cerebral microangiopathy, indicated in MRI by lacunar infarctions (LIs) and deep white matter lesions (DWMLs), is said to be accompanied by vascular dementia, which is reportedly caused by LI and DWML. METHODS: To confirm this assumption, 57 patients with cerebral microangiopathy were assessed for changes in regional cerebral blood flow (rCBF) and glucose utilization (rMRGlu) in both white matter and cortex, and these findings were correlated to the results of extensive neuropsychological testing (cognitive, mnestic and attentiveness tests), as well as to MRI findings. A special head holder ensured reproducibility of positioning during measurement of rCBF (99mTc-HMPAO SPECT) and rMRGlu (18F-FDG PET) and MRI. White matter and cortex were quantified with regions of interest defined on MRI and superimposed to corresponding PET/SPECT slices. The rMRGlu was calculated according to Sokoloff, and rCBF was determined from normalization to the cerebellum. LI and DWML were graded by number and extent. Brain atrophy was classified as no to slight inner and/or outer atrophy (Group A) or moderate-to-severe inner and outer atrophy (Group B). RESULTS: Even in severe DWMLs and in multiple LIs, rCBFs and rMRGlu values were not reduced. Analysis of variance identified atrophy and neuropsychological deficits as the main determinants for reduced rCBF and rMRGlu values (p < 0.05). However, 60% of patients (19 of 31) with neuropsychological deficits in attentiveness tests and 61% of patients (23 of 38) with mnestic deficits belonged to Group A and revealed decreased rCBF and rMRGlu values. Neuropsychological deficits correlated well with decreased rCBF and rMRGlu, whereas MRI patterns, such as LI and DWML, did not. CONCLUSION: We conclude that LI and DWML are epiphenomena that morphologically characterize cerebral microangiopathy. Dementia or neuropsychological deficits, however, are exclusively reflected by functional criteria (rCBF and rMRGlu), as long as cerebral atrophy does not occur.

Aged↗
PubMed1998

Measurement of temporal asymmetries of glucose consumption using linear profiles: reproducibility and comparison with visual analysis.

AIM: One approach to regionally analyze temporal glucose consumption consists in drawing linear profiles over the maximal values measured in the temporal cortical ribbon. The aim of our study was to test the reproducibility of this method and to compare its diagnostic performance to that of visual analysis in patients with complex partial seizures (CPS). METHODS: Regional cerebral glucose consumption (rCMRGIc) was measured interictally in 25 CPS patients and 10 controls using F-18-deoxyglucose and the positron emission tomography (PET) camera ECAT EXACT 47. The PET scans were visually analyzed for the occurrence of unilateral temporal hypometabolism. Furthermore, rCMRGIc was quantified on six contiguous coronal planes by manually tracing maximal values of temporal glucose consumption, thus creating line profiles of temporal glucose consumption for each side. Indices of asymmetry (ASY) were then calculated from these line profiles in four temporal regions and compared to the corresponding 95% confidence intervals of the control data. All analyses were performed by two observers independently from each other and without knowledge of the clinical findings. RESULTS: The agreement between the two observers with regard to focus lateralization was 96% (kappa = 0.93) on visual analysis and 100% (kappa = 1) on quantitative analysis. There was an excellent agreement with regard to focus lateralization between visual and quantitative evaluation (kappa = 0.8). CONCLUSION: Quantitation of local temporal rCMRGIc by using linear profile analysis is highly reproducible; for the lateralization of epileptogenic foci, however, this method does not possess significant advantages over the visual evaluation of the scans.

Adult↗
PubMed1998

PET and SPECT in medically non-refractory complex partial seizures. Temporal asymmetries of glucose consumption, benzodiazepine receptor density, and blood flow.

AIM: In contrast to medically refractory complex partial seizures (CPS), only limited knowledge exists on cerebral perfusion and metabolism in medically non-refractory CPS. The aim of this study was to investigate the frequency of temporal asymmetries in regional cerebral glucose consumption (rCMRGlc), regional cerebral blood flow (rCBF), and regional cerebral benzodiazepine receptor density (BRD) in this group of patients. METHODS: The study included 49 patients with medically non-refractory cryptogenic CPS (age: 36.0 +/- 16.1 years). rCMRGlc was studied with F-18-FDG-PET (FDG), rCBF with Tc-99m-ECD-SPECT (ECD), and BRD with l-123-iomazenil-SPECT (IMZ). All studies were performed interictally and within four weeks in each patient. Duration of epilepsy ranged from 0.1 to 42 years (median 4.0 years). SPECT was performed with the triple-headed SPECT camera Multispect 3, PET with the PET camera ECAT EXACT 47. Using linear profiles, glucose consumption, as well as uptake of ECD and IMZ, were measured in four temporal regions of interest (ROIs), and asymmetry indices were calculated (ASY). The results were compared to 95% confidence intervals determined in control subjects. RESULTS: Thirty-five of the 49 (71%) patients had at least one significantly elevated ASY; temporal rCMRGlc was asymmetrical in 41% of the patients, temporal BRD in 29%, and temporal rCBF in 24%. One patient had an asymmetry of all three variables, two of temporal rCMRGlc and BRD, three of temporal rCMRGlc and rCBF, and another four of rCBF and BRD. Fourteen patients had an isolated temporal asymmetry in rCMRGlc, seven in BRD, and four in rCBF. A discrepancy in lateralization between the three modalities was not observed. CONCLUSION: The majority of patients with medically non-refractory CPS have focal abnormalities of blood flow and metabolism in their temporal lobe. In this group of patients, FDG-PET demonstrates abnormalities with the highest frequency of the three modalities studied, followed by IMZ-SPECT, and ECD-SPECT.

Adolescent↗
PubMed1997

AVERAGE: a Windows program for automated analysis of event related cerebral blood flow.

Functional transcranial Doppler sonography (fTCD) is used to measure changes in brain perfusion during different states of brain activity by evaluating flow velocities within the major brain arteries. We developed a computer program called AVERAGE which can be used with various TCD devices and allows for subtle quantitative off-line analysis of Doppler flow signals. AVERAGE supports data transformation, heart beat analysis, noise reduction, trigger signal and marker modification, artifact analysis and artifact rejection, as well as data reduction. Perfusion differences and their time course within two different arteries can be analyzed by parametric and non parametric statistical methods. This is important, for instance, in studies on hemispherical dominance during mental task processing. Each data processing step is supported by graphical output. If investigated bilaterally with interhemispheric analysis even minimal activations can reliably be detected and quantified with a sensitivity known from positron emission tomography approaches.

Attention↗