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Biomedical subjects

G Gahn

Publications and source records attributed to G Gahn.

At least 19 recordsLinked to original sources
PubMed2006

[Miller Fisher syndrome: case report and review with discussion of differential diagnosis and nosology].

We report a 52-year-old patient with Miller Fisher syndrome and discuss Wernicke's encephalopathy as one important differential diagnosis. This article focuses on diagnostic criteria and possible nosological relations between Miller Fisher syndrome, Guillain-Barré syndrome with ophthalmoplegia, Bickerstaff's brainstem encephalitis, and acute ophthalmoparesis without ataxia.

Diagnosis, Differential↗
PubMed2004

Transcatheter closure of patent foramen ovale (PFO) in patients with paradoxical embolism. Periprocedural safety and mid-term follow-up results of three different device occluder systems.

AIMS: Interventional PFO closure has previously been reported to reduce the risk for recurrent thromboembolic events. The aim of the present study was to evaluate three different occluder systems in respect to (a) the safety and practicability and (b) the mid-term risk of recurrent thromboembolic events. METHODS AND RESULTS: Since 08/98 until 12/02, 307 consecutive patients (138 women, 169 men, mean age 43 years) with a symptomatic PFO underwent PFO closure using the PFO-Star ( n=177), Amplatzer PFO occluder ( n=69) and CardioSeal/Starflex ( n=61 ). Implantation was successful in all patients. Periinterventional complications occurred in 9 patients (5x ST-segment elevations, 1x arteriovenous fistula, 2x TIA, 1x device dislodgement). All of them were reversible and not associated with a specific type of device. During the median follow-up of 24 months (25/75th percentiles: 14/37 months), the annual risk of recurrence was 0.6% for TIA, 0% for stroke and 0.2% for peripheral embolism (PFO-Star: 0.8%, Amplatzer PFO occluder: 0.7% and CardioSeal/Starflex: 1.0%). CONCLUSION: Interventional PFO closure appears to be safe and a promising technique in symptomatic PFO patients with a low incidence of periinterventional complications and recurrent thromboembolic events using three different devices (PFO-Star, Amplatzer PFO occluder or the CardioSeal/Starflex).

Adult↗
PubMed2001

Basilar and middle cerebral artery reserve: a comparative study using transcranial Doppler and breath-holding techniques.

BACKGROUND AND PURPOSE: A 1997 report suggests that the posterior circulation of the normal brain has diminished vasoreactivity compared with the anterior circulation. To further study this, we quantified and compared the vasodilatory capacities of the middle cerebral (MCA) and basilar artery (BA) territories in response to changes in PaCO(2), as indices of respective cerebrovascular reserve (CVR). If posterior circulation CVR is indeed physiologically lower than that of the MCA, it might indicate a greater risk of low-flow ischemia distal to basilar obstructive cerebrovascular lesions and provide a rationale for earlier treatment of such lesions with interventional techniques. We also wished to establish normal baseline CVR values for the posterior circulation. METHODS: Twelve patients with signs and/or symptoms suggestive of posterior circulation disease but without flow-limiting obstructive changes and 11 normal controls were entered into the study. With the use of transcranial Doppler techniques, alterations in blood flow velocity in response to sequential breath-holding trials of varying duration were simultaneously monitored in both MCAs and the BA. CVR was measured as the percent velocity increase (during breath-holding) from resting baseline values. RESULTS: No significant differences were found in CVR between the MCA and BA territories in or between patients and controls. CONCLUSIONS: Our study suggests that the anterior and posterior circulations have similar reserve capacities in individuals without flow-limiting cerebrovascular obstructive lesions and that the BA territory, relative to the MCA territory, is not at increased risk for low-flow stroke on the basis of limited reserve potential.

Adult↗
PubMed2001

Ultrasound in acute stroke: a review.

Ultrasound is widely used for assessment of neurovascular disease, mainly during the subacute or chronic phases of cerebral ischaemia. The availability of aggressive and potentially harmful treatments for acute ischaemic stroke demands fast, and noninvasive examination of the intracranial vasculature. Current ultrasound techniques have the potential to provide essential information about the intracranial arteries in acute stroke. Application of echo-enhancing agents promises to effectively extend current techniques. The clinical significance of sonography in acute stroke needs to be evaluated prospectively and compared with other radiological techniques.

Carotid Arteries↗
PubMed2001

Echo-enhanced transcranial color-coded duplexsonography to study collateral blood flow in patients with symptomatic obstructions of the internal carotid artery and limited acoustic bone windows.

We prospectively evaluated 30 consecutive patients with echo-enhanced transcranial color-coded duplexsonography (TCCD) and correlative transfemoral digital subtraction angiography to assess the diagnostic efficacy of echo-enhanced TCCD for evaluation of collateral pathways through the circle of Willis in patients with limited acoustic bone windows and critical symptomatic carotid disease. Echo-enhanced TCCD detected collateral blood flow through the anterior communicating artery in 16 of 18 patients (sensitivity 89%, 95% CI 65-99%) and was false positive in one out of 12 patients without collateral flow (specificity 92%, 95% CI 59-100%). For the posterior communicating artery, sensitivity was 11/14 (79%, 95% CI 49-95%) and specificity was 15/16 (94%, 95% CI 70-100%). Echo-enhanced TCCD enables to study collateral blood flow through the communicating arteries of the circle of Willis with high sensitivity and specificity in patients with obstructions of the internal carotid artery and limited acoustic bone windows.

Aged↗
PubMed2000

Contrast-enhanced transcranial color-coded duplexsonography in stroke patients with limited bone windows.

BACKGROUND AND PURPOSE: Thickening of the temporal bone in stroke-age patients may obviate sonographic evaluation of the circle of Willis in 20% to 30% of patients. We assessed the diagnostic efficacy of contrast-enhanced transcranial color-coded duplexsonography (TCCD) for noninvasive evaluation of the circle of Willis in stroke patients with limited bone windows. METHODS: Of 171 consecutive patients who presented with ischemic symptoms in the middle cerebral artery (MCA) territory, 49 patients (32 female, 17 male; age range, 70.5+/-10.6 years) had no detectable colorflow signals from the circle of Willis by TCCD because of limited acoustic windows. These 49 patients received an IV injection of a sonographic contrast-enhancing agent, Levovist (Schering; Berlin, Germany), and were re-examined. Correlative imaging studies of the circle of Willis were obtained in 42 of 49 of these patients. RESULTS: In 38 of 49 patients, contrast-enhanced TCCD enabled full visualization of the circle of Willis bilaterally; in an additional five patients, contrast-enhanced TCCD revealed only the portion of the circle of Willis ipsilateral to the probe through one temporal bone. In six of these 43 patients, contrast-enhanced TCCD showed MCA stenosis and MCA occlusion in three; three of the six cases of MCA stenosis and all three cases of the MCA occlusion were found on the symptomatic side. In six of 49 patients, no colorflow signals were obtained after contrast enhancement. All contrast-enhanced TCCD findings were confirmed by CT angiography, transfemoral digital subtraction angiography, MR angiography, or a combination of all three correlative studies. Levovist produced no serious adverse events. CONCLUSION: In stroke-age patients with limited acoustic windows, contrast-enhancement with Levovist can markedly increase the sensitivity of TCCD and increase the detection of clinically relevant intracranial arterial disease.

Aged↗
PubMed1999

Dodecafluoropentane ultrasonic contrast enhancement in carotid diagnosis: preliminary results.

To assess the efficacy in carotid diagnosis of an investigational dodecafluoropentane ultrasonic contrast enhancing agent, we compared B-mode, color flow, and duplex Doppler findings in 16 patients with common carotid artery bifurcation disease after dodecafluoropentane and saline injections. Dodecafluoropentane produced enhanced backscatter in all patients for 4 to 20 min (mean, 8.4+/-4.74 min) after intravenous injection. In six patients this enhancement improved the color flow and pulsed Doppler signal detection in areas of sonographic shadowing. The enhanced color flow information changed the diagnostic impression in one case. Dodecafluoropentane produced enhanced backscatter in the carotid artery in all patients, and for a mean duration longer than that reported for other agents. It has the potential to improve the efficacy of carotid ultrasonic evaluation.

Aged↗
PubMed1999

Cerebrovascular reserve before and after vertebral artery angioplasty.

The selection of patients with severe vertebrobasilar artery stenosis for angioplasty is based mainly on clinical experience rather than on controlled data. We present a patient with severe vertebral artery stenosis in whom we could document the positive effect of angioplasty on posterior circulation hemodynamics by using transcranial Doppler sonography.

Aged↗
PubMed1997

Comparison of transcranial sonography, magnetic resonance imaging, and single photon emission computed tomography findings in idiopathic spasmodic torticollis.

Various lines of evidence suggest that the basal ganglia and thalamus are involved in the pathogenesis of idiopathic dystonia, but unfortunately neuroradiological and pathological data are sparse and controversial. In this study, we have examined 10 patients with spasmodic torticollis by neuroimaging techniques, including transcranial sonography (TS; n = 10), conventional (n = 10) and diffusion-weighted (n = 5) magnetic resonance imaging (MRI), and single photon emission computed tomography (SPECT; n = 10), employing [123I]iodobenzamide (IBZM) as a ligand with a high affinity to the D2 receptor. In seven patients, TS showed small hyperechogenic lesions in the medial segments of the lentiform nucleus contralateral to the side of head deviation. In accordance with the site of TS abnormalities, diffusion-weighted MRI displayed a hyperintense lesion in only one patient, while standard MRI of this area was normal in all patients. SPECT revealed a slight but statistically nonsignificant reduction of IBZM tracer uptake in an area corresponding to the dorsal portions of the striatum in 9 of the 10 patients. TS findings support the hypothesis that structural alternations of the pallidothalamic circuit contralateral to the side of head deviation are involved in the pathogenesis of idiopathic spasmodic torticollis. TS may be more sensitive in detecting basal ganglia alterations than MRI.

Adult↗
PubMed1997

[Ultrasound contrast media for neurovascular applications].

Ultrasound is widely used in the assessment of neurovascular diseases. In spite of its effectiveness there are considerable limitations such as low flow detection in carotid disease or limited bony windows in transcranial Doppler. One approach to overcome these limitations is the use of ultrasound contrast enhancing agents. The usefulness of ultrasound contrast enhancing agents Levovist, EchoGen and BY 963 in neurovascular applications has been evaluated. Contrast enhanced colourflow Doppler for the diagnosis of carotid disease has been investigated in three small trials and might be effective for improving the diagnostic yield in severe disease. Contrast enhanced transcranial colourflow Doppler has been relatively more widely explored also with promising results. Based on the combined findings out of these preliminary investigational trials, it appears to be reasonable to undertake larger trials for assessment of usefulness of ultrasound contrast agents for a variety of neurovascular applications.

Brain↗
PubMed1995

Preoperative and postoperative follow-up in high-grade gliomas: comparison of transcranial color-coded real-time sonography and computed tomography findings.

Twenty patients with high-grade gliomas were prospectively studied by pre- and postoperative transcranial color-coded real-time sonography (TCCS) and CT, to determine the sensitivity of TCCS in the identification of residual tumor and tumor regrowth. Each patient was subjected to preoperative and early postoperative CT (postoperative day 1) and TCCS examinations (postoperative days 6 to 8) and subsequent CT and TCCS follow-up examinations within a time interval of 6 weeks to 3 months. In eight patients, a total of 15 biopsy specimens were intraoperatively obtained from the wall of the resection cavity. Histological findings of intraoperative biopsy specimens showed that hyperechogenic areas adjacent to the resection cavity always contained residual tumor tissue. Early postoperative TCCS identified these hyperechogenic areas in 19 of 20 patients. In 12 patients, postoperative CT revealed contrast enhancement at the resection margin, indicating residual tumor. In these patients the extension of these hyperechogenic areas on TCCS exceeded the contrast-enhancing areas on CT by a mean of 58%. In eight patients, postoperative CT displayed no contrast enhancement along the border of resection. TCCS and histological findings indicated residual tumor in seven of these eight patients. The size of the hyperechogenic lesions identified by postoperative TCCS increased in time and follow-up examinations revealed that tumor regrowth arose from these hyperechogenic areas in all patients. In four patients, tumor regrowth was identified, on average 0.7 months earlier by TCCS than by CT. From these data we conclude that the sensitivity of TCCS in detection of residual tumor and tumor regrowth seems to be superior to CT. The value of TCCS requires further clarification by comparative studies including histology and MRI.

Biopsy↗
PubMed1994

Isolation and quantification of class 1 MHC gene mutants in mouse T cells by immunoselection with a magnetic cell sorter (MACS).

A method is described for determining the frequency of cells with a mutation in an autosomal gene coding for a membrane protein. Using a monoclonal antibody to H-2Kk surface antigen and magnetic cell separation (MACS) more than 10(4)-fold enrichment of the H-2Kk negative population was achieved, as tested with artificial mixtures containing a known number of antigen-negative cells. After a second magnetic sorting mutant frequencies as low as 10(-6) could be measured. The number of clonogenic mutants was evaluated by limiting dilution cloning and verification of the mutant phenotype by FACScan (flow cytometry) analysis in a representative number of clones. The spontaneous frequency of H-2Kk deficient mutants was 0.80 x 10(-6), and this increased after irradiation with 6 Gy X rays to 3.38 x 10(-6) within the next 8 weeks. About 50 mutant clones were screened for the presence of other class 1 antigens on the cell surface by FACScan analysis. All mutants continued to express other class 1 antigens.

Animals↗
PubMed1985

A randomized crossover comparison of two low-dose contraceptives: effects on serum lipids and lipoproteins.

The effect of a triphasic combination of ethinyl estradiol and levonorgestrel upon various lipoprotein parameters was compared to that of a preparation that contained ethinyl estradiol and desogestrel on days 6, 11, 21, and 28 of a control cycle, the third cycle of treatment with either ethinyl estradiol/levonorgestrel or ethinyl estradiol/desogestrel (11 volunteers each), the third cycle of a 3-month washout period, and the third treatment cycle after crossover change of the preparations. Significant increases were found in total triglycerides (15% to 20%) and phospholipids (8%) with both preparations, whereas total cholesterol and lipoprotein Lp(a) were not altered. High-density lipoprotein triglycerides (50% to 60%) and high-density lipoprotein-3 cholesterol (10% to 15%) were elevated by both contraceptives, high-density lipoprotein cholesterol and alpha-lipoprotein cholesterol only by ethinyl estradiol/desogestrel (11%), whereas high-density lipoprotein phospholipids, high-density lipoprotein-2 phospholipids, high-density lipoprotein-3 phospholipids, and high-density lipoprotein-2 cholesterol were not influenced. Both ethinyl estradiol/levonorgestrel and ethinyl estradiol/desogestrel increased apolipoproteins A (14%), A-I (20% to 30%), and A-II (25% to 35%) significantly. Very low-density lipoprotein triglycerides were elevated (30%) only by ethinyl estradiol/desogestrel, and low-density lipoprotein phospholipids (20%) by both ethinyl estradiol/levonorgestrel and ethinyl estradiol/desogestrel, whereas the other parameters, very low-density lipoprotein phospholipids, very low-density lipoprotein cholesterol, pre-beta-lipoprotein cholesterol, low-density lipoprotein triglycerides, low-density lipoprotein cholesterol, beta-lipoprotein cholesterol, and apolipoprotein B, were not significantly changed. Provided that the assumption is correct that high low-density lipoprotein cholesterol and apolipoprotein B and low high-density lipoprotein subfractions and apolipoprotein A are associated with an elevated risk of atherosclerosis, the results seem to represent beneficial rather than deleterious side effects of the low-dose oral contraceptives.

Adult↗