Effect of increased intracranial pressure on the blink reflex in cats

Abstract

During an acute increase in ICP produced by balloon inflation three different phases could be observed. In the first phase (ICP 40-50 mm Hg) the latencies of R 1 and R 2 showed an initial decrease followed by increase in latency. In the second phase (ICP 50-70 mm Hg) R 2 disappeared, whereas R 1 showed marked alterations, prolongation of the latency and duration, and a decreasing amplitude. In the third phase no response could be evoked. The pathophysiological observations correlated with the morphological alterations. Two ischaemic zones with BBB damage which "transsected" the mesodiencephalic and pontomesencephalic border were found. The results suggest that the disappearance of R 2 depends on rostral damage, whereas alteration of R 1 is caused by a pontomesencephalic lesion.

Evoked potentials and brain stem reflexes

“…In agreement with the literature [26,54,55,56,133] our own experimental investigations of the BR during increasing intracranial pressure indicate that R2 can also be influenced by lesions which are located rostral to the facial nuclei [28]. These findings are supported clinically by gross alterations of R2 in space-occupying lesions of the ponto-mesencephalic tegmentum which spare the lower pons and the medulla oblongata (Figs.…”