THE EFFECT OF ELEVATED INTRACRANIAL-PRESSURE ON THE VIBRATIONAL RESPONSE OF THE OVINE HEAD

Although potentially fatal increases in intracranial pressure (ICP) ca n occur in a number of pathological conditions, there is no reliable a nd noninvasive procedure to detect ICP elevation and quantitatively mo nitor changes over time. In this experimental study, the relationships between ICP elevation and the vibrational response of the head were d etermined. An ovine animal model was employed in which incremental inc reases in ICP were elicited and directly measured through intraventric ular cannulae. At each ICP increment, a vibration source elicited a fl exural response of the animal's head that was measured at four locatio ns on the skull using accelerometers. Spectral analysis of the respons es showed changes in proportion to ICP change up to roughly 20 cm H2O (15 mm Hg) above normal; a clinically significant range. Both magnitud e and phase changes at frequencies between 4 and 7 kHz correlated well (gamma > 0.92) with ICP across the study group. These findings sugges t that the vibrational response of the head can be used to monitor cha nges in ICP noninvasively.