Characterization of Asymmetrical Cerebral Dysfunction Through Seizures During Neonatal Stroke in Immature Rats
Abstract number :
1.151
Submission category :
Year :
2000
Submission ID :
3166
Source :
www.aesnet.org
Presentation date :
12/2/2000 12:00:00 AM
Published date :
Dec 1, 2000, 06:00 AM
Authors :
Neda B Poommipanit, David L Sherman, Nitish V Thakor, E Niedermeyer, William H Trescher, Johns Hopkins Univ, Baltimore, MD; Kennedy Krieger Institute, Baltimore, MD.
RATIONALE: Seizures are often associated with neonatal cerebral hypoxic-ischemic injury. This study demonstrates the use of spectral analysis in characterization of asymmetrical cerebral dysfunction using neonatal seizures during cerebral hypoxic-ischemic injury or stroke in immature rats. METHODS: P14 rats underwent right CCA ligation and subdural electrode placement followed by 40 minutes of hypoxic (8% O2) exposure. EEG recording began immediately after hypoxia and intermittently for 2 hours. RESULTS: One third of the cohorts exhibited episodes of epileptiform activity. The left hemisphere showed seizure activity with greater amplitude than the right. Epileptiform activity typically had a duration of 20 seconds and appeared to be of ?17 Hz, indicated by its power spectrum. In contrast, the interictal EEG activity was extremely shallow, composed of frequency components below 5 Hz. The ratio of ictal to interictal power was higher on the side ipsilateral to the ligation. Animals showing epileptiform activity also showed greater band power depression compared to animals that did not have seizures. All animals showed depressed band power compared to baseline with recovery beginning between 60 and 100 minutes post hypoxic insult (delta, p<0.1; theta, p<0.03; alpha, p<0.05 at 60 minutes and delta, p<0.3; theta, p<0.2; alpha, p<0.3 at 100 minutes). The right hemisphere consistently showed greater depression than the contralateral hemisphere in all band powers (delta, p<0.03; theta, p<0.02; alpha, p<0.03). CONCLUSIONS: The depression in recovery power in both hemispheres compared to baseline indicates cerebral dysfunction induced by hypoxia. Asymmetrical dysfunction is shown by the greater depression in recovery power compared to baseline and the greater interictal power depression compared to ictal power in the right hemisphere, suggesting that the ligation of the right CCA enhances the degree of injury caused by hypoxia. Thus, this study demonstrates the use of spectral analysis to evaluate the acute pattern of asymmetrical cerebral dysfunction in cerebral hypoxic-ischemic injury. (Supported by NIH Grant 37332.)