CORRELATION BETWEEN ICTAL ONSET PATTERNS AND RESPONSES TO ELECTRICAL CORTICAL STIMULATIONS: CORTICO-CORTICAL EVOKED POTENTIAL STUDY
Abstract number :
1.101
Submission category :
4. Clinical Epilepsy
Year :
2009
Submission ID :
9484
Source :
www.aesnet.org
Presentation date :
12/4/2009 12:00:00 AM
Published date :
Aug 26, 2009, 08:12 AM
Authors :
Rei Enatsu, Z. Piao, T. O Connor, K. Horning, W. Bingaman and D. Nair
Rationale: Ictal onset seen on ECoG may manifest as several different patterns. However it is not clear what produces these differences in ictal onset patterns. We hypothesized that neuronal synchrony might be related to these ictal onset patterns. A repetitive spike pattern might be indicative of more synchronous firing state as compared to a paroxysmal fast pattern. We also hypothesize that a more synchronous firing state would be associated with larger amplitude in cortico-cortical evoked potential (CCEP) measurement. Methods: Fifteen patients with intractable focal epilepsy who underwent invasive monitoring for localization of ictal onset zone and functional mapping between 2003 and 2008 were included in the study. These patients were separated to two groups based on ictal onset patterns: paroxysmal fast pattern and repetitive spike pattern. Thereafter 1-Hz electrical stimulation was applied in a bipolar fashion both to ictal onset zone and to normal cortex. We subtracted the CCEP amplitude of the control stimulation from ictal onset stimulation then normalized ictal onset stimulation to control stimulation at maximum stimulus intensity. Thereafter these values were comparable between two groups. Results: The amplitudes subtracting control stimulation from ictal onset were compared. The values associated with repetitive spike pattern distributed higher than paroxysmal fast pattern. With respect to the ratio of the amplitude in ictal onset stimulation to control stimulation at maximum stimulus intensity, these values of repetitive spike patterns were significantly higher than paroxysmal fast pattern (n=20, Mann-Whitney U test; p=0.02). Conclusions: Our study showed that CCEP responses show higher amplitude in repetitive spike pattern than paroxysmal fast pattern. This suggests that repetitive spike patterns may be a result of more synchronous firing state than in paroxysmal fast pattern. CCEP may be useful in evaluating cortical synchronicity. Further studies are needed to validate the clinical and pathological correlation with the present result.
Clinical Epilepsy