Changes of somatosensory evoked potentials with increase of intracranial pressure in the rat's brain.
Somatosensory evoked potentials (SEPs) to various combinations of two independent brain compression modalities (localized epidural pressure and intracerebral pressure evoked by an inserted balloon) were investigated in 24 rats. The SEP pattern in response to gradually expanding volume without additional epidural pressure remained unchanged for a certain period. SEP changes occurred only shortly prior to death. On the other hand, remarkable SEP changes were observed in a gradually expanding intracerebral mass, when combined with epidural pressure application at about 50% of the lethal volume. SEP changes in response to intermittent and continuous epidural pressure, in addition to a small intracerebral mass, were investigated too. Intermittent application of minor epidural pressure led to specific P1 changes, which recovered after each pressure step. The same pressure, administered continuously, evoked SEP changes with only partial recovery in some instances. Severe epidural pressure, administered intermittently, gave rise to severe SEP changes with only partial recovery after each step. The same epidural pressure delivered continuously led to SEP changes with very small recovery. SEPs have proved to be a reliable method for signalling brain dysfunction corresponding to various modalities and degrees of intracranial pressure.
Physiologisches Institut der Universität, Münster, F.R.G.
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Witzmann
D000818:Animals; D002540:Cerebral Cortex / Q000502:physiology*; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D007427:Intracranial Pressure / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains