Abstract

Application of infrared transillumination-backscattering sounding method has been designed for noninvasive assessment of changes in the width of the subarachnoid space in humans. To eliminate the influence of blood flow in the scalp on the signals in SAS,two receiving sensors in different distances from emiting sensor have been placed. A dedicated digital algorithm is used to estimate on line the ratio of the powers of received signals,reffered to as two-sensor distal-to-proximal received power quotient, TQ(t). The propagation duct for NIR radiation reaching the distal sensor is the SAS filled with translucent cerebrospinal fluid. Information on slow fluctuations of the average width of the SAS is contained in the slow-variable part of the TQ(t), called the subcardiac component, and in TQ itself. Variations in frequency and magnitude of faster oscillations of the width of that space around the baseline value, dependent on cerebrovascular pulsation,are reflected in instantaneous frequency and envelope of the fast-variable component.Frequency and magnitude of the cerebrovascular pulsation depend on the action of the heart,so this fast-variable component is reffered to as the cardiac component.

Adres: dr n. med. Wojciech Marks
Katedra Chirurgii Urazowej AMG
e-mail: w_marks@wp.pl