Extracranial vertebral artery dissections can be diagnosed noninvasively with duplex color-flow imaging. It is therefore a useful method for early diagnosis and follow-up examination.
Transcranial duplex color-flow imaging is a new diagnostic method that allows visual display of blood flow in the basal cerebral arteries. This method allows determination of and correction for the Doppler angle of insonation. Conventional transcranial Doppler sonography has no imaging component and assumes a 0-degree Doppler angle for the calculation of flow velocities. The magnitude of the angle of insonation and the effect on flow velocity estimates have not been clearly defined. In order to evaluate the angle of insonation and the effect of angle correction on velocity readings, 50 patients referred for evaluation of cerebrovascular disease were studied. The mean age was 45 years (range, 24-62 yr). All were examined with conventional transcranial Doppler and transcranial duplex color-flow imaging. Specific vessels of the circle of Willis were identified by location, course, and direction of flow on color-flow images and by depth, direction of flow, and transducer orientation with conventional Doppler sonography. Visually controlled measurements of the Doppler angle of insonation were made by color-flow imaging. The data show that the mean angle of insonation was 33 degrees (+/- 15) in the middle cerebral artery, 35 degrees (+/- 17) in the anterior cerebral artery, 45 degrees (+/- 18) in the posterior cerebral artery, and 15 degrees (+/- 14) in the basilar artery. Angle-corrected peak systolic flow velocities were higher in all vessel segments (middle cerebral = 15%, anterior cerebral = 18%, posterior cerebral = 30%, and basilar = 3%), compared to uncorrected velocity readings by conventional Doppler sonography.(ABSTRACT TRUNCATED AT 250 WORDS)
Diminished activity of uroporphyrinogen I-synthetase in the liver and other tissues may be regarded to be the primary genetic deficiency of acute intermittent porphyria (AIP). Increased production and renal excretion of delta-aminolevulinic acid (ALA) und porphobilinogen (PBG) are secondary phenomena. The neuropsychiatric symptomatology of AIP consists of neuropathy, vegetative crises and exogenous psychoses. In this study electromyographic and neurographic investigations were performed on 20 persons with AIP. 16 patients had experienced attacks of AIP, 10 of them including neuropathy. 4 persons showed the biochemical findings of AIP but had not yet had symptoms. In cases with persistent pareses following porphyric neuropathy denervation signs or sequelae were still present. In patients without clinical symptoms and in latent cases there were normal or borderline findings. Motor nerve conduction velocity was mostly decreased in combination with denervation signs and in a range that indicated a primarily axonal nerve lesion and consequent myelin damage rather than primary demyelinization. The mean motor conduction velocity of n. tibialis was somewhat lower in patients with porphyric crises without neuropathy than in latent cases without any clinical crises. The differences were not significant in other nerves. The findings are discussed under consideration of the electrodiagnostic results of other investigations and of neuropathological and clinical data.
A technique for the imaging of vertebral arteries at their origins and along the longitudinal extracranial course is described. The results of the examination of 108 normal vertebral arteries are shown. The vertebral artery could be distinguished in the pretransverse and intertransverse segment C5-C6 in 100%. The average diameter of the vessel was 3.81 +/- 0.46 mm on the right and 3.88 +/- 0.47 on the left side. The average maximal systolic velocity was 43.0 +/- 8.9 cm/s on the right and 43.3 +/- 9.6 on the left side. In 81% of the cases the vertebral origin could be located on the right and in 65% of the cases on the left side. The technical quality of visualization, especially of the vertebral origin, was greatly influenced by the depth of the examined structure. Examples of pathologic findings, such as hypoplasia, stenosis, and occlusion, demonstrate the practical possibilities of this noninvasive method.
Transcranial color-coded duplex ultrasonography is a new diagnostic procedure allowing the visualization of major intracranial vessels. The purpose of this report is to describe this method and to evaluate its practical potential in the routine examination of basal cerebral arteries. The results from the examination of 96 patients are presented. By means of color coding of Doppler frequencies, the major intracranial vessels were identified by nature of their anatomic location with respect to the echogenic brainstem structures in all subjects. The average maximal systolic velocity was, in the middle cerebral artery, 108 +/- 15 cm/s; in the anterior cerebral artery, 96 +/- 15; in the posterior cerebral artery, 76 +/- 16; and in the basilar artery, 59 +/- 17 cm/s. The determination of the angle between the ultrasonic beam and the examined vessel improved the accuracy of flow velocity measurements in comparison with conventional transcranial Doppler ultrasonography. The exact measurement of blood flow velocity in several segments of the visualized vessel proved helpful in the assessment of pathologic findings, especially in differentiation between a stenosis of the intracranial vessel and a vasospasm.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.