CHARACTERISTICS OF PROLONGED AFTERDISCHARGE: CHILDREN WITH MALFORMATIONS OF CORTICAL DEVELOPMENT
Abstract number :
1.179
Submission category :
Year :
2002
Submission ID :
45
Source :
www.aesnet.org
Presentation date :
12/7/2002 12:00:00 AM
Published date :
Dec 1, 2002, 06:00 AM
Authors :
Shiro Chitoku, Hiroshi Otsubo, Shelly K. Weiss, James T. Rutka, Carter O. Snead III, Venita Jay, Ayako Ochi, Masaomi Kitayama. Neurology, The Hospital for Sick Children, Toronto, ON, Canada; Neurosurgery, The Hospital for Sick Children, Toronto, ON, Canad
RATIONALE: To clarify aberrant cortical excitability of malformations of cortical development (MCD), we evaluated characteristics of extraoperative afterdischarges (ADs) and motor responses (MRs) using subdural electrodes.
METHODS: This study evaluated 23 pediatric epilepsy patients (ages 4-18 years). We reviewed amperage thresholds, distribution and propagation of AD and MR for 13 patients with MCD and 10 patients with non-MCD pathologies (normal or gliosis). We collected and analyzed ADs lasting 6 seconds or longer, with or without seizures.
RESULTS: We saw no differences in age, gender, preoperative seizure frequency, and distribution of epileptic regions between groups. We recorded ADs in 12 of 13 MCD and 6 of 10 non-MCD patients. We successfully mapped primary motor functions in all 23 patients. MR thresholds were higher in MCD patients than in non-MCD patients. Closely-related MR and AD thresholds inversely correlated with age in 12 MCD patients (p [lt] 0.01). Age-dependent AD thresholds declined abruptly in MCD so that AD thresholds in 8 MCD patients older than 11 years (mean [plusminus] SD, 5.0 [plusminus] 1.6mA) were lower than those of 3 non-MCD patients (8.7 [plusminus] 3.0 mA, p [lt] 0.05). Nine MCD patients showed ADs in remote sites compared to 2 non-MCD patients.
CONCLUSIONS: Closely-related and higher MR and AD thresholds indicate a less excitable and immature cortex in MCD before adolescence. In adolescents with MCD, low AD thresholds correlate to local hyperexcitability in the malformed dysplastic cortex. Remote ADs in the epileptic dysplastic cortex suggest the aberrant cellular excitability or excitatory circuits of epileptogenesis in MCD.