Polarity Reversal in Ictal Discharges of Patients with BECTS
Abstract number :
1.074
Submission category :
Year :
2001
Submission ID :
2848
Source :
www.aesnet.org
Presentation date :
12/1/2001 12:00:00 AM
Published date :
Dec 1, 2001, 06:00 AM
Authors :
A.K. Kaddurah, MD, Neurology, University of Michigan, Ann Arbor, MI; D.N. Minecan, MD, Neurology, University of Michigan, Ann Arbor, MI; E. Kutluay, MD, Neurology, University of Michigan, Ann Arbor, MI; E.A. Passaro, MD, Neurology, University of Michigan,
RATIONALE: The benign epilepsy of childhood with centro-temporal spikes (BECTS) is the most common benign focal epilepsy of childhood. Only a few cases of ictal recordings in BECTS have been described. The typical interictal discharge is biphasic consisting of an early low amplitude deflection followed by the main phase, which can exhibit a horizontal or oblique dipole. We present 2 ictal recordings from two patients with BECTS and show that the polarity of the ictal discharge is similar to that of the initial early deflection and of opposite polarity to the main interictal discharge. The videos of the two patients will also be shown.
METHODS: Two patients with BECTS had a typical seizure during a video EEG recording. The EEG[ssquote]s were performed on digital 21 channel machines. The ictal and interictal recordings were reviewed on different montages.
RESULTS: Case 1: An 8 year old boy with a 2-year history of seizures had one of his typical events during routine video EEG. Interictal EEG showed a normal background with frequent bilateral independent centro-temporal sharp waves, activated during drowsiness. The right-sided epileptiform discharges displayed an oblique dipole, with bifrontal positivity and negativity at T4. The main phase was often preceded by low amplitude phase of opposite polarity, with bifrontal negativity and posterior positivity. The ictal discharge started with rhythmic alpha activity at the C4-T4 electrodes, followed by rhythmic sharply contoured theta activity, with anterior negativity (F4) and posterior positivity (T4), consistent with the polarity of the low amplitude, early phase.
Case 2: A 6 year old boy with a 2 year history of partial seizures underwent a sleep study (polysomnogram with full video EEG coverage) due to complaint of excessive daytime sleepiness. One seizure was recorded during sleep. Interictal EEG showed frequent bilateral independent centro-temporal biphasic sharp waves with the main phase displaying an oblique dipole (bifrontal positivity and negativity at the midtemporal electrode sites). This was preceded by a smaller amplitude phase of opposite polarity. The ictal recording consisted of rhythmic alpha -theta activity with a polarity similar to that of the initial phase of the discharge.
CONCLUSIONS: The ictal EEG recordings in both patients exhibited an oblique dipole of similar polarity to that of the early initial deflection of the interictal discharges. This would suggest that the lower amplitude early phase in patients with BECTS is more localizing.