Biomedical subjects
Publications and source records attributed to O J Boespflug.
Transcranial Doppler ultrasonography is the only non invasive examination enabling the reliable measurement of the blood flow velocity in the intracranial arterial trunks. However, it cannot be constantly perfect. It is fully realized in about 10% of the patient. Even incomplete it remains a useful complementary exploration in the management of the cerebral vascular disease.
Over a two year period, 500 intracranial examinations were performed to explore the arteries at the base of the skull (middle, anterior and posterior cerebral) as well as the basilar artery. Exploration of the carotid siphons by the transorbital route is not systematic but used when approach to the vessels by the temporal windows is impossible. The transcranial Doppler examination is particularly indicated in the following circumstances: (1) In patients presenting a tight stenosis on the extracranial internal carotid artery (50 cases). The intracranial effects of extracranial lesions depend on the degree of obstruction and blood supply values at the level of the circle of Willis. (2) During cerebral vascular accidents without extracranial lesions in order to detect possible intracranial involvement (15 cases). Occlusions (5 cases) raised more diagnostic problems than did tight stenoses. (3) In meningeal haemorrhages, in which the degree of spasm can be measured, to provide elements to prognosis (8 cases). (4) In angiomas and intracranial malformations (5 cases). To a certain extent, the examination makes it possible to determine the region concerned by the fistula and, especially, to assess the effects on locoregional circulation. The main drawback of the method is the absence of a temporal window, preventing direct access to vessels at the base of the skull. Moreover, certain arteries are not easily accessible and thus not always found or at least recognized with certitude. However, reliability has improved with experience, and accurate diagnoses can now be made.
Real time mode B echotomography completes ultrasound exploration of supra-aortic trunks. Continuous Doppler recording is essential for detection of vessels and identification of significant lesions. However, it cannot detect arterial wall lesions that have no effect on arterial blood flow but can be at the origin of migrating emboli. The latter can be visualized by echotomography, which localizes the lesion and allows evaluation of its morphologic and anatomic characteristics. The methodology of the examination and normal anatomic findings are summarized and the different types of lesion occurring in the supra-aortic trunks described. The limitations of echotomography are discussed and a description given of a semiology of vascular ultrasonic structures of emboligenic potential.
Vessels of base of skull were inaccessible to conventional ultrasonic image until 1982, when the use of pulsed Doppler emitting a beam of 2 MHz coupled with a frequency analyzer allowed direct exploration of terminal branches of the internal carotid artery (ICA) and the basilar trunk. It is now possible to measure rate of flow in middle cerebral artery (MCA), anterior (ACA) and posterior (PCA) cerebral arteries, communicating arteries and those of basilar trunk. Practical applications of this new method are numerous in cerebrovascular disease: diagnosis of brain stem lesions, evaluation of effects of extracranial lesions, detection and follow up of arteriovenous malformations, functional value of the circle of Willis prior to carotid surgery. Despite certain limitations due to anatomic factors, angiographic confrontations attest the value and reliability of this new examination.
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Ultrasonography by the Doppler technique combined with B-mode echotomography are useful methods in the investigation of disease of the major arteries in the neck supplying the brain. The investigations are described together with the significance of major findings.
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