The effects of an extradural expanding lesion on regional intracranial pressure, blood flow, somatosensory conduction and brain herniation: an experimental study in baboons

Abstract

Intracranial pressure (ICP) differences, change of local blood flow (CBF) using the hydrogen clearance technique, change in the somatosensory evoked potential (SEP) to median nerve stimulation and pupillary size were investigated during progressive elevation of the ICP (using an extradural balloon) in 6 anaesthetized baboons. CBF was measured in the frontal cortex, somatosensory cortex, thalamus (nucleus ventralis posterior lateralis-VPL), medial lemniscus (ML), lateral lemniscus (LL) and caudate nucleus (CN). Conduction along the somatosensory pathway between C2 at the neck and VPL was compared with conduction between VPL and primary somatosensory cortex. The amplitude of the cortical SEP was also studied. ICP gradients between hemispheres developed as the pressure was increased to in excess of 50 mm Hg. CBF was significantly reduced from control in the cortex and VPL on the side ipsilateral to the balloon at 50 mm Hg ICP. A significant decrease in ML flow occurred bilaterally at 70 mm Hg ICP. Conduction time was increased significantly between the right VPL and cortex at a pressure of 50 mm Hg. The amplitude of the cortical response was significantly reduced at 30 mm Hg on the right side and 50 mm Hg on the left. Aniscoria occurred at 50 mm Hg ICP and the pupils became dilated at 70 mm Hg. The SEP was possibly more sensitive than the pupillary reactions as an indication of tentorial herniation in these experiments.

Moderate Hypothermia for 48 Hours After Temporary Epidural Brain Compression Injury in a Canine Outcome Model

“…The exact mechanism of the epidural balloon compression insult is not clear (Habash et al, 1982;Nitta et al, 1990;Pomeranz et al, 1993). Complete ischemia of 90 min alone could cause capillary damage and necrosis.…”

Elevating intracranial pressure reverses the decrease in deoxygenated hemoglobin and abolishes the post-stimulus overshoot upon somatosensory activation in rats

“…However, ICP elevation has been used to study the pathophysiology of hydrocephalus (Azzi et al, 1999). There are two principle methods for ICP elevation: infusion of aCSF (Jallo et al, 1997) and inflation of an infra-or supratentorial balloon (Johnston et al, 1973;Nitta et al, 1990). We have used the aCSF infusion approach since the latter approach is more invasive and results in shift of brain tissue and thus is not suitable for optical in-vivo-measurements through a closed cranial window.…”

Multiparametric Monitoring of Brain Under Elevated Intracranial Pressure in a Rat Model

“…Raised intracranial pressure triggered by head injury, brain tumor, or hematoma causes brain tissue damage, neurological dysfunction, and potential necronal death (Nitta et al, 1990). In view of these factors, scientists have invested considerable effort in developing models for ICP hypertension in laboratory animals.…”

“…An established method for ICP modification is the "balloon" method, in which a balloon is inserted into either the subdural (Johnston et al, 1973) or extradural space (Daley et al, 1995;Fitch et al, 1977;Nitta et al, 1990;Shalit and Cotev, 1974), and inflated with fluid (Daley et al, 1995;Johnston et al, 1973) or gas (Fitch et al, 1977;Shalit and Cotev, 1974). Manipulating the volume of fluid or gas leads to ICP elevation to a desired level.…”

“…Previous studies evaluating ICP have included the measurement of ICP, CSF pressure, the dynamics of the CSF drainage, cerebral blood flow (CBF) and/or vascular resistance, systemic blood pressure, and measurements of phosphocreatine, lactate, and ATP in the brain (Andrews et al, 1988;Botel and Brinker, 1994;Johnston et al, 1973;Morrow et al, 1990;Nawashiro et al, 1995;Nitta et al, 1990;Shalit and Cotev, 1974;Siesjo and Zwetnow, 1970;Sutton et al, 1987;Yamane et al, 1994). To monitor many of these parameters we have developed the multiprobe assembly (MPA) device (Mayevsky and Chance, 1982;Mayevsky et al, 1995;Meilin et al, 1996), which is located on the rat brain surface and affixed to the skull.…”