Presenter of 2 Presentations
INTRACRANIAL PRESSURE AND TISSUE VOLUME PERTURBATIONS IN MIDDLE-AGED RATS AFTER SEVERE INTRACEREBRAL HEMORRHAGE.
INTRACRANIAL PRESSURE AND TISSUE VOLUME PERTURBATIONS IN MIDDLE-AGED RATS AFTER SEVERE INTRACEREBRAL HEMORRHAGE.
Abstract
Background and Aims
After intracerebral hemorrhage (ICH), the hematoma and resultant edema increases intracranial pressure (ICP), often with fatal consequences. Several physiological compliance mechanisms reduce ICP, including tissue compliance, where brain cells reduce in size and increase in density after severe strokes. We hypothesized that these latter mechanisms would be less effective with age.
Methods
In experiment 1, 12-month-old male rats were randomized to receive either a severe striatal ICH via stereotaxic collagenase infusion (n=10), or a sham procedure (n=10). After euthanasia at 24h post-surgery, neuron and astrocyte volume/density and cortical thickness were evaluated for tissue compliance. In experiment 2, 12-month-old male rats received ICP telemetry probe implants after ICH (n=10) or sham procedure (n=10). ICP was measured for 24h when rats were euthanized to assess cerebral edema.
Results
In experiment 1, there was no evidence of tissue compliance despite severe hematoma sizes (83.2±16.6uL, mean±95%CI). However, Aged-Sham neuron volumes were 28.6% smaller on average versus historical Young-Shams, with larger ventricles, suggesting either lesser need or lack of ability to engage tissue compliance with age. Experiment 2 demonstrated that this age-related tissue compliance deficit is not due to negligible mass effect, as at equivalent ICH severity, ipsilateral and contralateral edema were elevated by 2.0% and 1.7%, respectively (p≤0.05), with significantly higher ICP (mean hourly difference of 6.80mmHg, p≤0.0001); ICP spiking events, however, were 84% less frequent with age versus young animals.
Conclusions
The greater ventricle size and smaller parenchymal brain volume of aged rats may permit better ICP compliance following severe ICH.