AJP - Regulatory, Integrative and Comparative Physiology, Vol 260, Issue 1 172-R178, Copyright © 1991 by American Physiological Society
Contribution of brain distortion and displacement to CSF dynamics in experimental brain compression
A. Schettini and E. K. Walsh
Research Service, Veterans Administration Medical Center, Richmond, Virginia.
The present study was designed to determine the contribution of brain
distortion and displacement to changes in cerebrospinal fluid (CSF)
dynamics [pressure-volume index (PVI), compliance (C), and outflow
resistance (Ro)] during progressive brain compression and the effect of
compression on brain mechanical properties. In 10 dogs measurements were
made of CSF dynamics, brain elastic behavior, cerebral perfusion pressure,
local cerebral blood flow, and suprainfratentorial intracranial pressure
(ICP) during the incremental expansion of a supratentorial extradural
balloon. PVI appeared more as a measure of the compressibility of the
cerebral vascular compartment than of intracranial bulk compliance.
Reciprocal changes in CSF dynamics behaved as expected when the balloon
expanded predominantly supratentorially causing a moderate increase in ICP.
A significant increase in ICP, however, caused a rise in PVI and a decrease
in compliance. Under these conditions PVI alone could not differentiate
between a falling cerebral perfusion pressure and an increasing
suprainfratentorial ICP gradient. In contrast, the compliance decreased
with balloon expansion while the outflow resistance showed an inverse
correlation with compliance and a linear correlation with baseline ICP; Go,
an elastic response parameter, consistently decreased, implying that C, Ro,
and Go can be used as a trend of intracranial compensatory reserve during
intracranial mass expansion.
