ISSN:
0942-0940
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary A technique was devised whereby the arterially induced pulsations, in range of intracerebral interfaces that can be detected ultrasonically through the intact skull, could be written out as an analogous wave form. The Rise Times and Delay Times of these range pulsations were measured in patients with cerebrovascular disease or cerebral tumours to determine whether they differed significantly from the normal. In healthy people the Rise Times varied from 30 to 180 milliseconds and the Delay Times from 95 to 250 milliseconds. These wide limits were not surpassed in the diseases stated, nor did averaging of the results from several interfaces in each hemisphere show any significant difference from the normal. One reason for the wide variation in the shape of the recorded waves (which is reflected in the scatter of Rise Times and Delay Times) is that the pulse wave varies in shape and speed of propagation as it spreads peripherally. Any single interface may thus move as a result of different movements of a number of neighbouring domains, each of which may be slightly out of phase with the others. A second reason is that a single interface is recorded on the oscilloscope as a burst of cycles of about 2 microseconds duration. This represents 1.6 millimetres in range. Echoes returning from interfaces separated by less than 1.6 millimetres in range will therefore result in interference of cycles. The recorded movement of any one cycle may therefore represent, to a varying and unknown degree, the movement of more than one interface. It is concluded that, using ultrasonic methods, the detailed study of the individual waveforms written out by the arterially induced movement of intracerebral interfaces is not useful as a diagnostic test.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01403136
