High-resistance Doppler flow pattern in extracranial carotid dissection.

Internal carotid artery dissection is an increasingly recognized cause of cerebrovascular events. The diagnosis is conventionally established on the basis of characteristic clinical symptoms and arteriographic findings. However, the presence of characteristic hemodynamic features detected by ultrasound may already suggest the diagnosis, even in atypical cases. This is demonstrated in 16 (76%) of 22 patients with internal carotid artery dissection. An intense systolic low-frequency Doppler signal of alternating flow direction accessible in the neck, either along the extent of a luminal tapering stenosis or proximal to a severe obstruction at the skullbase, indicated this diagnosis. Resolution or decreasing stenosis may similarly be diagnosed noninvasively, as shown by results from subsequent arteriograms in 14 patients (64%). This occurred suddenly during sequential follow-up between 2 days and 30 weeks (mean, 6 weeks) after the diagnosis was made.

Alcohol-related acute axonal polyneuropathy: a differential diagnosis of Guillain-Barré syndrome.

BACKGROUND: Chronic axonal polyneuropathy is a well-known clinical sequela of excessive alcohol consumption; however, acute axonal polyneuropathy related to alcohol abuse is less well recognized. OBJECTIVE: To describe alcohol-related acute axonal polyneuropathy in 5 chronic alcoholics who developed ascending flaccid tetraparesis and areflexia within 14 days. METHODS: Case series with clinical, laboratory, electrophysiological, and, in 1 patient, biopsy data. RESULTS: All 5 patients consumed a daily average of 250 g of alcohol, and 4 had lost a substantial amount of weight recently. Additional clinical features included painful paresthesia, myalgia, and glove and stocking-type sensory loss. Repeated cerebrospinal fluid examinations failed to show the marked increase of protein concentration with normal cell count typical of Guillain-Barré syndrome, although the protein level was mildly elevated in 1 patient. Blood laboratory findings were consistent with longstanding alcohol abuse. Compound muscle and sensory nerve action potentials were absent or reduced, while conduction velocities were normal or mildly reduced. Three to 4 weeks after onset, needle electromyography displayed moderate to severe fibrillations and positive sharp waves in addition to normal motor unit potentials, indicating an acute axonal polyneuropathy; this was confirmed by sural nerve biopsy in 1 patient. CONCLUSIONS: Excluding other factors, we assume that in these patients the combination of alcohol abuse and malnutrition caused severe acute axonal polyneuropathy. Its distinction from Guillain-Barré syndrome is important because treatment requires balanced diet, vitamin supplementation, and abstinence from alcohol, while immunotherapy may not be indicated.

Thalamic stroke. Presentation and prognosis of infarcts and hemorrhages.

Thalamic strokes in 62 patients selected from the Stroke Data Bank were studied to determine differences among 18 infarctions (INF), 23 localized hemorrhages (ICH), and 21 hematomas with ventricular extension (IVH). Stupor or coma at onset occurred more frequently in the IVH (62%) than in the INF (6%) or ICH (13%) groups and was reflected in significantly lower median Glasgow Coma Scores in the IVH group (7) than in the INF (15) and ICH (14) groups. Although ocular movements were more frequently abnormal in the IVH group compared with the ICH and INF groups, no significant differences were found in the frequency of motor or sensory deficits. Among the 62 strokes, 32 had restricted lesions of the posterolateral (n = 9), anterior (n = 3), paramedian (n = 7), and dorsal (n = 13) portions of the thalamus. Differences in consciousness and in motor, sensory, and oculomotor deficits were found among the topographic subgroups. Stroke-related deaths occurred in 52% of IVH cases, 13% of ICH cases, and no cases of INF. Median lesion volume as detected with computed tomography was greater in hemorrhages (INF, 2 cm3; ICH, 10 cm3; IVH, 16 cm3), with mortality related to increasing hematoma size. Coma, Glasgow Coma Score lower than 9, weakness score greater than 15 of a possible 30, abnormal ocular movements, and fixed pupils were also associated with stroke-related mortality. We conclude that the initial neurologic syndrome does not discriminate infarcts from intrathalamic hemorrhages. Ventricular extension, however, causes significantly more severe deficits and higher mortality.

Symptomatic and asymptomatic high-grade carotid stenoses in Doppler color-flow imaging.

We examined 63 patients with 31 symptomatic and 44 asymptomatic carotid stenoses with Doppler color-flow imaging (DCFI); conventional Doppler duplex had shown a hemodynamic obstruction (greater than or equal to 80% stenosis) in all patients. Analysis of plaque surface morphology demonstrated more ulcerated plaques in symptomatic (43%) than asymptomatic (23%) stenoses. Although the frequency of homogeneous and heterogeneous plaques was not different, calcific lesions were more frequent in asymptomatic (46% versus 29%), and echolucent plaques, probably indicating mural thrombi, were more frequent in symptomatic (29% versus 11%) stenosis. Color-coded hemodynamic patterns, such as jet flow, poststenotic turbulence, or reversed flow, were not different in symptomatic and asymptomatic stenoses. Comparison of DCFI with 30 angiograms showed agreement in plaque surface analysis in 70%. DCFI measurements of area reduction in cross sections correlated with angiography in 85%, while DCFI tended to underestimate the degree of stenosis from diameter reduction in longitudinal cuts. The advanced DCFI technique identified distinct morphologic features but no hemodynamic patterns, separating symptomatic from asymptomatic high-grade carotid stenoses.

Variability of flow patterns in the normal carotid bifurcation.

One hundred and nine carotid bifurcations of 56 healthy subjects were examined by means of a Doppler color flow imaging (DCFI) system. Flow separation was found in 102 (93.6%) bifurcations. Different patterns of the spatial and temporal distribution of flow separation zones could be distinguished: separated flow was either restricted to the proximal external (5.9%), the internal (34.3%) or both carotid arteries (40.2%). In 11.8% zones of secondary flow extended from the internal into the external carotid artery around the flow divider, and in 7.8% the distribution was diffuse. The maximum of reversed flow signals occurred immediately after the systolic peak (73%) but lasted for highly variable intervals throughout the cardiac cycle. This demonstration of the unexpectedly various spatial and temporal patterns of secondary flow phenomena contrasts with concepts from in vitro flow studies. This information about conditions in vivo must be considered in investigations of early atherosclerosis in the human carotid bifurcation.

Preclinical review of cerivastatin sodium--a step forward in HMG-CoA reductase inhibition.

Epidemiological studies have established that elevated concentrations of plasma cholesterol, particularly the low density lipoprotein (LDL) cholesterol, is one of the major risk factors for the development of arteriosclerosis and ischemic heart disease. Treatment with HMG-CoA reductase inhibitors (vastatins) has become the most successful drug treatment in lowering total plasma and LDL cholesterol concentrations in the last years. The vastatins already available for treatment are therapeutically used in a dose-range between 10 and 80 mg/day. The new enantiomerically pure pyridine derivative cerivastatin sodium has demonstrated its efficacy in significantly lower doses in the microgram-range, not only in preclinical but also in clinical studies with daily doses of only 0.1-0.3 mg. The differences in the therapeutic doses are reflected by the Ki- and IC50-values from enzyme inhibition tests in comparison with various HMG-CoA reductase inhibitors. Cerivastatin sodium exhibits much higher enzyme affinity with factors between 70 and almost 200. The Ki-value for cerivastatin sodium was 1.3 x 10(-9) M in comparison to 150 x 10(-9) M for lovastatin. The extremely high enzyme affinity of cerivastatin sodium was also reflected in its high activity in vivo. In acute in vivo studies cerivastatin sodium inhibited the hepatic [14C]cholesterol synthesis from [14C]acetate in both rats and dogs by 50% after oral administration at doses of 0.002 mg/kg body weight (ED50-values). This dose was comparable to 0.3 mg/kg of lovastatin. In subchronic dog studies a dose of 0.03 mg/kg lowered the serum LDL cholesterol concentration by 35% which is comparable with doses of 8-10 mg lovastatin/kg. Interesting results were observed in cholestyramine-primed dogs when 0.1 mg cerivastatin sodium/kg p.o. markedly decreased the serum triglycerides up to 70%. Cerivastatin shows a favourable pharmacokinetic profile with high liver selectivity. Rat studies have shown almost complete absorption and rapid hepatic clearance. Cerivastatin was highly bound to plasma proteins of rats, dogs and humans (>98%). Cerivastatin metabolites were excreted mainly via feces. The metabolism of cerivastatin sodium in man follows two metabolic pathways, demethylation to metabolite M1 and stereospecific hydroxylation to M23. The three major metabolites M1, M23 and the hydroxylated and demethylated metabolite M24 are highly active inhibitors not only in vitro but also in vivo. The human specific metabolites M23 and M24 inhibited the HMG-CoA reductase isolated from rat liver with the same potency as the parent compound cerivastatin sodium (IC50: 1.0-1.2 x 10(-9) M). M1 was slightly less active. Corresponding pharmacological activity was observed in vivo. M23 and M24 inhibited [14C]cholesterol synthesis from [14C]acetate in rat liver with ED50)-values between 0.001 and 0.002 mg/kg body weight which is similar to cerivastatin sodium and M1 exhibited an ED50-value of <0.006 mg/kg The strong inhibitory activity of these metabolites, in addition to cerivastatin's high enzyme affinity may explain the extraordinary pharmacological activity of cerivastatin and its ultra-low dose in man and demonstrates cerivastatin to be the most active HMG-CoA reductase inhibitor amongst all vastatins.

Subepicardial infarction, myocardial impression, and ventricular penetration by sutureless electrode and leads.

Postmortem examination two weeks following implantation of a demand pacemaker with sutureless electrodes demonstrated that (1) the loops of intrapericardial electrode leads indented the myocardium and produced a circumscribed area of subepicardial necrosis, and (2) one of the electrode coils protruded into the right ventricular cavity. The use of extrapericardial electrode leads and left ventricular implantation sites should avoid these problems.

Topography of cerebral infarction associated with carotid artery dissection.

Because the pathogenesis of cerebral ischaemia in internal carotid artery dissection (ICAD) is controversial we studied the topography of cerebral infarction that results from ICAD according to pathophysiology of embolic and haemodynamic stroke. Sixty-four patients with 67 ICADs diagnosed by angiography, Doppler duplex sonography and magnetic resonance imaging (MRI) were studied prospectively during the past decade. According to current pathophysiological concepts, cortical territorial infarcts and large subcortical lenticulostriate infarcts revealed by CT or MRI were classified as embolic, while smaller infarcts in the subcortical junctional zone and infarcts in the cortical borderzone between the middle (MCA) and anterior cerebral artery were interpreted as haemodynamic infarcts. Of the 67 dissections 37 (55%) were associated with brain infarcts, of which territorial MCA infarcts of variable size accounted for 60%. These were combined with infarcts of the anterior and posterior cerebral artery in 5%; 8% of the patients had complete MCA infarction. Large lenticulostriate infarcts were present in 11%. Haemodynamic infarcts involved the subcortical junctional zone in 16% but never the anterior cortical borderzone. Although different abnormal Doppler findings indicated haemodynamically significant carotid obstruction in all symptomatic ICADs, only the characteristic high-resistance Doppler signal was significantly associated with the occurrence of brain infarction (in 66%, P < 0.01). The angiographic features of ICAD did not correlate with the incidence or with the topography of cerebral infarction. Patterns of infarction in ICAD indicate a predominantly embolic causation probably due to thrombus formation in the dissected carotid artery in the presence of severe haemodynamic obstruction, as demonstrated by Doppler sonography.

Mechanisms of infarction in the superficial posterior cerebral artery territory.

Numerous reports have described a variety of clinical syndromes resulting from posterior cerebral artery (PCA) infarction, whereas only a few pathoanatomical and retrospective clinical studies have investigated the underlying mechanisms. Therefore we attempted to determine the causes of infarction in the superficial posterior cerebral artery (PCA) territory by means of a more comprehensive, modern vascular and cardiac study. During a 4-year period 74 consecutive patients (49 men, 25 women) with acute PCA infarction documented on CT (n = 74) and MRI (n = 41) were included in the study. Patients had a neurological examination, vascular studies [extra- and transcranial Doppler (n = 74), magnetic resonance (n = 31) or intra-arterial (n = 22) angiography], cardiac evaluation [ECG (n = 74), transthoracic (n = 74) and transoesophageal echocardiography (n = 30)], and coagulation tests. A cardiac source of embolism was established in 31%, significant vertebrobasilar artery disease in 22%, and PCA stenosis or occlusion in 8% of the patients. Rare causes, such as hypercoagulopathy or paradoxical embolism via a patent foramen ovale, were present in 15%. However, in spite of the comprehensive diagnostic evaluation, the cause of the stroke remained undetermined in 24% of the cases. Apart from complete infarcts of the posterior branches of the PCA, which occurred more frequently in cardioembolic strokes (18%, P < 0.05), the topographical patterns of infarct extension and the coincidence of infarction in the deep territories of the PCA, the cerebellum and brainstem were not significantly different among the causal subgroups. The frequency of haemorrhagic transformation (18%) was highest among cardioembolic strokes (44%, P < 0.001). This prospective study of PCA infarction demonstrated embolism from cardiac and vascular sources as the predominant cause. In contrast to previous studies, we found no evidence of migraine as a cause of PCA infarction, whereas paradoxical embolism was the presumed cause in a considerable number of cases. Whereas the cause of stroke could not reliably be derived from infarct topography, haemorrhagic transformation indicated there had been cardioembolism in most cases.

Good recovery after sublethal ethylene glycol intoxication: serial EEG and CT findings.

The case of a young man with sublethal ethylene glycol poisoning is reported. Complete recovery occurred after 12 days of deep coma and a prolonged flaccid tetraplegia. The lesions of gross degree in the CNS, demonstrated by serial CT, resolved and electrophysiological testing as well as neuromuscular signs improved. The recovery, clinically and radiographically, over 35 days was dramatic. Ethylene glycol intoxication should always be considered in the differential diagnosis of acute severe encephalopathy because complete recovery is possible with correct therapy.

Cerebrovascular involvement in the acute phase of bacterial meningitis.

Cerebral ischaemia is a common complication of bacterial meningitis. Although cerebrovascular involvement in the acute phase of inflammation may be particularly important for the still unacceptably high morbidity and mortality, only, a few studies have investigated cerebrovascular changes in bacterial meningitis. We prospectively investigated changes of intracranial cerebral blood flow velocities (CBFV) in 22 patients (12 men, 10 women, mean age 48 years, 19 years, SD) with bacterial meningitis, by means of transcranial Doppler sonography (TCD). According to previously published criteria the degree of arterial narrowing was assessed and related to the patients' outcome. Elevated CBFVs in the middle cerebral artery were documented in 18/22 patients with markedly increased systolic peak velocities (CBFV of > 210 cm/s) in 7 patients. Serial examinations performed in 11 patients showed elevated CBFV as early as day 1, reaching peak CBFV between day 3 and day 6 after onset of symptoms in most cases. Furthermore, cerebrovascular involvement was also documented by disturbances of physiological slow spontaneous oscillations of blood flow velocities in 5/10 patients examined with TCD. Low Glasgow Coma Scales (< 7) on admission (29% vs 0%), focal cerebral ischaemic deficits (29% vs 7%) and, seizures (43% vs 7%) were more frequent in patients with CBFV of > 210 cm/s. Finally, a poor clinical outcome was significantly related to severe vascular involvement (P < 0.05). In conclusion, cerebrovascular complications are frequently found in patients with bacterial meningitis. TCD is an easily applicable technique for revealing vascular changes non-invasively, even in severely ill patients. Since our data suggest an unfavourable course of the disease in association with increased CBFV in intracranial arteries, probably indicating vasospasm, TCD could potentially be used to identify high-risk patients who could benefit from adjuvant therapeutic interventions.

Carotid artery disease assessed by color Doppler flow imaging: correlation with standard Doppler sonography and angiography.

Carotid artery disease was assessed in 180 patients by means of color Doppler flow imaging. Color Doppler findings in 360 carotid arteries were compared with the results of standard Doppler sonography, and color Doppler findings in 60 bifurcations were compared with the results of intraarterial angiography. The sensitivity of color Doppler for the detection of carotid disease was 100% when compared with angiography. The accuracy of color Doppler in classifying minor (40-60%), moderate (61-80%), and severe (81-90%) stenosis ranged from 91.3% to 97.8% vs standard Doppler sonography, and from 91.7% to 95.8% vs angiography. Whereas all occlusions were identified correctly by both color Doppler and angiography, four pseudoocclusions of the carotid artery were misdiagnosed as occluded. Characteristic features providing reliable criteria of the degree of stenosis are (1) intensity, extent, and duration of color fading; (2) postprocessed systolic peak frequency; (3) plaque extent on serial sonograms; and (4) poststenotic flow patterns. Display of hemodynamic disturbances induced by less pronounced plaques showed highly variable patterns that could not be anticipated from the plaque morphology alone. Thus, color Doppler preserves the advantages of standard Doppler and duplex sonography but provides additional information about otherwise anechoic necrotic and thrombotic material that often causes cerebral embolisms. With atherogenesis, repair mechanisms may be sustained or progression be stopped by reducing the risk factors and instituting medical treatment; thus, the application of this noninvasive technique is important.

Vasoneuronal coupling in migraineurs after subcutaneous sumatriptan: a TCD study.

According to the trigeminovascular model of pain in migraine, sterile neurogenic inflammation of dural vessels stimulates nociceptive fibres of the trigeminal nerve. Sumatriptan, a 5-HT1 receptor agonist, blocks this reaction and mediates vasoconstriction of meningeal arteries. However, it is uncertain, whether sumatriptan also has a vasoconstrictive effect on cerebral arteries, which may influence vasoneuronal coupling and induce secondary cerebral blood flow changes. We studied changes of cerebral blood flow velocity (CBFV) and the pulsatility index (PI) in the posterior cerebral artery (PCA) after stimulus activation before, 10 min and 30 min after subcutaneous application of 6 mg sumatriptan, in order to assess potential vasoactive effects on cerebral circulation. CBFV was recorded from both PCAs simultaneously in 27 migraineurs (twenty women, seven men, mean age 29 years), and arterial blood pressure (BP), heart rate (HR) and respiration rate (RR) were monitored. Although the mean diastolic blood pressure rose significantly from 75 mm Hg to 81 mm Hg (P<0.05) and systolic blood pressure and respiration rates remained constant, average CBFV values remained constant. Similarly, the relative increase of CBFV by visual stimulation, which is clearly higher compared to controls in other studies (55.0% before, 52.6% after 10 min, and 52.4% after 30 min), and absolute mean values for CBFV and PI did not change after visual stimulation. These results provide evidence against the hypothesis that sumatriptan produces vasoconstriction in the intracranial human arterial circulation as a potential risk of cerebral ischemia.

Power Doppler imaging and color Doppler flow imaging for the evaluation of normal and pathological vertebral arteries.

Recently, an ultrasound method for vascular applications using the amplitude of the reflected echosignal for the generation of intravascular color signals has been introduced. We compared the utility of this power Doppler imaging (PDI) with conventional color Doppler flow imaging (CDFI) for examination of vertebral arteries (VA). Forty-nine patients with signs and symptoms suggesting ischemia within the posterior circulation were evaluated. Quality of blood flow visualization by PDI and CDFI at the different VA segments was classified according to a four point scale. Furthermore, combined sonographic findings were correlated with the results of digital substraction and/or magnetic resonance angiography (DSA, MRA). Power Doppler imaging provided a significantly superior visualization of the intertransversal VA, whereas display of the intracranial V4 segment was superior significantly on CDFI. Both methods were complementary for the evaluation of the VA at the origin. With respect to the angiographic findings, combined CDFI and PDI achieved a sensitivity of 90.63% and a specificity of 97.22% for the differentiation of healthy and pathologic VAs. Power Doppler imaging is complementary to CDFI for the sonographic assessment of VA disease. Combined use of PDI and CDFI achieves a high sensitivity and specificity, thus increasing diagnostic confidence.

NO-independent regulatory site of direct sGC stimulators like YC-1 and BAY 41-2272.

BACKGROUND: The most important receptor for nitric oxide is the soluble guanylate cyclase (sGC), a heme containing heterodimer. Recently, a pyrazolopyridine derivative BAY 41-2272, structurally related to YC-1, was identified stimulating soluble guanylate cyclase in an NO-independent manner, which results in vasodilatation and antiplatelet activity. The study described here addresses the identification of the NO-independent site on soluble guanylate cyclase. RESULTS: We developed a photoaffinity label (3H-meta-PAL) for the direct and NO-independent soluble guanylate cyclase (sGC) stimulator BAY 41-2272 by introducing an azido-group into the tritium labeled compound. The synthesized photoaffinitylabel directly stimulates the purified sGC and shows in combination with NO a synergistic effect on sGC activity. Irradiation with UV light of 3H-meta-PAL together with the highly purified sGC leads to a covalent binding to the alpha1-subunit of the enzyme. This binding is blocked by unlabeled meta-PAL, YC-1 and BAY 41-2272. For further identification of the NO-independent regulatory site the 3H-meta-PAL labeled sGC was fragmented by CNBr digest. The 3H-meta-PAL binds to a CNBr fragment, consisting of the amino acids 236-290 of the alpha1-subunit. Determination of radioactivity of the single PTH-cycles from the sequencing of this CNBr fragment detected the cysteines 238 and 243 as binding residues of the 3H-meta-PAL. CONCLUSIONS: Our data demonstrate that the region surrounding the cysteines 238 and 243 in the alpha1-subunit of the sGC could play an important role in regulation of sGC activity and could be the target of this new type of sGC stimulators.

Comparison of flow disturbances in small carotid atheroma using a multi-gate pulsed Doppler system and Doppler color flow imaging.

The capacity of a multi-gate pulsed Doppler (MPD) system and Doppler color flow imaging (DCFI) for the evaluation of flow patterns was studied in 14 patients with 17 nonstenotic carotid plaques (luminal narrowing less than 40%). Plaque morphology was assessed by means of a high-resolution B-mode system with subsequent three-dimensional reconstruction of the lesion surface. MPD velocity profiles obtained proximally, centrally and distally to the plaque (51 analyses) were normal in 31 sites corresponding to 28 undisturbed and 3 turbulent flow patterns assessed by Doppler color flow imaging (90% specificity). Of the 10 irregular MPD flow profiles, DCFI detected turbulence in 7 (70% sensitivity). 10 asymmetric MPD waveforms without irregularities were normal in 7 and turbulent in 3 DCFI studies. These results suggest, that MPD is superior to DCFI for the detection of nonturbulent flow asymmetry nearby small carotid plaques. However, DCFI displays turbulence with a high specificity and reasonable sensitivity and visualizes the morphologic-hemodynamic interaction in carotid atherosclerosis simultaneously.

Carcinogen-induced Mitochondrial DNA Damage in the In Ovo Model.

After experimental exposure of turkey eggs in an in ovo model, the induction of preneoplastic liver lesions (Enzmann et al., 1992and 1995a) and alterations of the mitochondrial (mt) DNA of embryonic turkey livers (Enzmann et al., 1995b) could be demonstrated, showing the sensitivity and usefulness of this short-termed and inexpensive system for carcinogenicity testing. Chemically induced modification of mtDNA may be an important indicator of the carcinogenic potential of substances, as the mt genome may display a higher sensitivity to DNA damaging effects compared to nuclear DNA. To characterize mtDNA damages in ovo, application of diethylnitrosamine (DEN) was performed onto the chorioallantoic membrane (CAM) of the avian embryo. First, the distribution of a model substance after CAM application was measured by autoradiography. MtDNA damage after DEN exposure was demonstrated by gel electrophoresis of isolated mtDNA. Nitrosamine treatment induced a dose-dependent change of mtDNA conformation from supercoiled to relaxed shape, pointing to a possible induction of single-strand breaks.

[Long-term hemodynamic compromise in internal carotid artery dissection: quantitative blood volume flow evaluation using 2D Cine phase-contrast MR imaging]. / Langzeit-Entwicklung von Dissektionen der A. carotis interna: Quantitative Blutvolumenfluss-Untersuchungen mit der 2D cine Phasen-Kontrast MR Technik.

PURPOSE: To use the magnetic resonance (MR) phase-contrast technique as a non-invasive method to determine blood volume flow in internal carotid artery (ICA) dissection, which has variable initial volume flow reduction and long term hemodynamic compromise. ICA dissection can lead to partial or complete recanalization or persistent occlusion, and strong clinical motivation exists for reliable assessment of the blood flow, in particular blood volume flow, in the carotid artery circulation after ICA dissection. MATERIALS AND METHODS: Blood volume flow in the carotid artery circulation was quantified in 28 patients with unilateral ICA dissection and 20 age-matched normal controls. Blood volume flow was measured in the ICAs and the common carotid arteries (CCAs) using 2D cine phase-contrast MR imaging. Final measurements were performed until after at least 6 months the hemodynamic compromise showed no changes by ultrasound and MRA. RESULTS: In long term follow up, 11/28 patients demonstrated remaining vessel occlusion, 10/28 partial and 7/28 complete recanalizations. Patients with ICA occlusion showed a significant contralateral volume flow increase (mean 56 %, p < 0.001) in comparison to normal controls. Patients with partial recanalization demonstrated volume flow rates between 24 ml/min and 188 ml/min in the dissected ICA and a less but significant (p < 0.001) increase in the contralateral volume flow. In patients with complete recanalization, normal volume flow conditions were found for both ICAs and CCAs. CONCLUSION: In ICA dissection, quantitative volume flow determination using 2D cine phase-contrast MR imaging is helpful in the initial assessment and long term follow-up of hemodynamic compromise. ICA dissection demonstrated a partial or complete recanalization in nearly (2/3) of the investigated patients and a persisting vessel occlusion in little more than (1/3). Compensatory contralateral increase in volume flow was found.

Dissociation of musical tonality and pitch memory from nonmusical cognitive abilities.

The main purposes of this study were to replicate, validate, and extend measures of sensitivity to musical pitch and to determine whether performance on tests of tonal structure and pitch memory was related to, or dissociated from, performance on tests of nonmusical cognitive skills--standardized tests of cognitive abstraction, vocabulary, and memory for digits and nonrepresentational figures. Factor analyses of data from 100 neurologically intact participants revealed a dissociation between music and nonmusic variables, both for the full data set and a set for which the possible contribution of levels of music training was statistically removed. A neurologically impaired participant, C.N., scored within the range of matched controls on nonmusic tests but much lower than controls on music tests. The study provides further evidence of a functional specificity for musical pitch abilities.

Aqua-Reslin droplet analysis.

Aerosol droplets were collected, counted, and sorted using a laser system, the Army Insecticide Measuring System, Teflon-coated slides, and magnesium oxide-coated slides. All droplets, for each method and replication, were generated by a London Aire 1820 or a Leco Model 1600. These data indicate that the Army Insecticide Measuring System or Teflon-coated slides are so closely similar to the laser that they could effectively be used in the field without an overwhelming loss in precision.