Impact of intracranial subclinical seizures on seizure outcomes after SLAH in patients with mesial temporal lobe epilepsy.

OBJECTIVE: To investigate the association between subclinical seizures detected on intracranial electroencephalographic (i-SCSs)recordings and mesial temporal sclerosis (MTS), as well as their impact on surgical outcomes of stereotactic laser amygdalohippocampotomy (SLAH). METHODS: A retrospective review was conducted on 27 patients with drug-resistant mesial temporal lobe epilepsy (MTLE) who underwent SLAH. The number of seizures detected on scalp EEG and iEEG was assessed. Patients were followed for a minimum of 3 years after SLAH. RESULTS: Of the 1715 seizures recorded from mesial temporal regions, 1640 were identified as i-SCSs. Patients with MTS were associated with favorable short- and long-term surgical outcomes. Patients with MTS had a higher number of i-SCSs compared to patients without MTS. The numbers of i-SCSs were higher in patients with Engel I-II outcomes, but no significant statistical difference was found. However, it was observed that patients with MTS who achieved Engel I-II classification had higher numbers of i-SCSs than patients without MTS (P < 0.05). CONCLUSION: Patients with MTS exhibited favorable short-term and long-term surgical outcome after SLAH. A higher number of i-SCSs was significantly associated with MTS in patients with MTLE. The number of i-SCSs tended to be higher in patients with Engel Ⅰ-Ⅱ surgical outcomes. SIGNIFICANCE: The association between i-SCSs, MTS, and surgical outcomes in MTLE patients undergoing SLAH has significant implications for understanding the underlying mechanisms and identifying potential therapeutic targets to enhance surgical outcomes.

Surgical Outcomes and EEG Prognostic Factors After Stereotactic Laser Amygdalohippocampectomy for Mesial Temporal Lobe Epilepsy.

Objective: To assess the seizure outcomes of stereotactic laser amygdalohippocampectomy (SLAH) in consecutive patients with mesial temporal lobe epilepsy (mTLE) in a single center and identify scalp EEG and imaging factors in the presurgical evaluation that correlate with post-surgical seizure recurrence. Methods: We retrospectively reviewed the medical and EEG records of 30 patients with drug-resistant mTLE who underwent SLAH and had at least 1 year of follow-up. Surgical outcomes were classified using the Engel scale. Univariate hazard ratios were used to evaluate the risk factors associated with seizure recurrence after SLAH. Results: The overall Engel class I outcome after SLAH was 13/30 (43%), with a mean postoperative follow-up of 48.9 ± 17.6 months. Scalp EEG findings of interictal regional slow activity (IRSA) on the side of surgery (HR = 4.05, p = 0.005) and non-lateralizing or contra-lateralizing seizure onset (HR = 4.31, p = 0.006) were negatively correlated with postsurgical seizure freedom. Scalp EEG with either one of the above features strongly predicted seizure recurrence after surgery (HR = 7.13, p < 0.001) with 100% sensitivity and 71% specificity. Significance: Understanding the factors associated with good or poor surgical outcomes can help choose the best candidates for SLAH. Of the variables assessed, scalp EEG findings were the most clearly associated with seizure outcomes after SLAH.

The clinical significance of small sharp spikes: A retrospective study of 909 patients in epilepsy monitoring unit.

OBJECTIVES: To determine the incidence and clinical significance of small sharp spikes (SSS) in the patient population of the adult Epilepsy Monitoring Unit (EMU). METHODS: This is a retrospective study of EEG data and medical records from consecutive patients who underwent video-EEG recording in the adult EMU from March 2013 to February 2019. SSS, interictal epileptiform discharges (IEDs), and ictal patterns were identified. RESULTS: Of the 909 patients reviewed, SSS were observed in110 (12.1 %) patients. Epilepsy was present in 101 of the 110 (91.8 %) patients with SSS and in 441 of the 799 (55.2 %) patients without SSS. The incidence of epilepsy was significantly higher in patients with SSS than in those without SSS (OR = 9.1, 95 % CI: 4.5-18.3, P < 0.01). The sensitivity of SSS for epilepsy was 18.6 % and the specificity was 97.5 %. The incidence of SSS was strongly correlated with the frequency of IEDs (OR 1.89; 95 %CI: 1.60-2.24, P < 0.01). When both present, SSS and IEDs were co-lateralized in the same hemisphere. CONCLUSIONS: There is a statistically significant association between SSS and focal epilepsy. SSS have similar clinical implications to IEDs in the lateralization and localization of temporal lobe seizures. SSS can be an epileptiform EEG pattern for temporal lobe epilepsy.

RTTBD-like activity in association with hippocampal ictal discharges in patients with temporal lobe epilepsy.

To determine clinical and intracranial EEG correlates of rhythmic temporal theta bursts of drowsiness (RTTBD) and assess its clinical significance in patients with temporal lobe epilepsy (TLE). A retrospective review of simultaneous scalp and intracranial video-EEG recordings from 28 patients with TLE was evaluated for epilepsy surgery. Scalp RTTBD patterns were identified and their clinical and intracranial EEG correlates were then determined on video-EEG recording using depth and subdural electrodes. Thirty-one RTTBD patterns on scalp EEG were observed in six (21%) of the 28 patients. Five (16%) of the RTTBD patterns occurred during wakefulness and 26 (84%) occurred during drowsiness and light sleep. The mean duration of RTTBD was 10 seconds (range: 3-28 seconds). RTTDB consistently correlated with hippocampal ictal discharges and was time-locked to the hippocampal seizures in which the ictal discharges evolved into rhythmic theta frequency (4-7-Hz) range. Ictal automatisms were observed during five (16%) RTTBD patterns, while cognitive impairment was observed in four (13%) of the 31 RTTBD patterns. Our findings show that scalp EEG correlates of hippocampal ictal discharges can resemble RTTBD and may be associated with ictal symptoms and cognitive impairment, indicating that RTTBD may rarely be an ictal EEG pattern in patients with TLE.

Clinical implications of scalp ictal EEG pattern in patients with temporal lobe epilepsy.

OBJECTIVE: To determine the clinical implications of scalp ictal EEG pattern in patients with temporal lobe epilepsy (TLE). METHODS: Scalp EEG ictal patterns were retrospectively determined in 27 consecutive patients with medically refractory temporal lobe epilepsy who underwent phase-1 scalp video-EEG and phase-2 simultaneous scalp and intracranial video-EEG recordings for pre-surgical evaluation. RESULTS: Of the 192 temporal lobe seizures recorded during phase-1 and phase-2 scalp video-EEG studies, 124 (65%) seizures were associated with theta/alpha (5-9 Hz) ictal onset pattern, and 68 (35%) seizures were associated with delta (2-5 Hz) ictal onset pattern. Fourteen (52%) patients had exclusively theta/alpha ictal onset, 3 (11%) patients had exclusively delta ictal onset, and 10 (37%) patients had mixed theta/alpha and delta ictal onsets. MTLE was observed in 26 patients who had 124 seizures with theta/alpha ictal onset and 59 seizures with delta ictal onset. LTLE was observed in one patient who had 9 seizures with delta ictal onset. Scalp ictal EEG pattern was not significantly correlated with postsurgical seizure outcomes. CONCLUSIONS: Both scalp delta and theta/alpha ictal onset patterns can be commonly found in patients with MTLE. SIGNIFICANCE: Scalp delta ictal onset is not a unique EEG pattern for LTLE as commonly believed.

The first-hour-of-the-day sleep EEG reliably identifies interictal epileptiform discharges during long-term video-EEG monitoring.

PURPOSE: To determine the usefulness of the first-hour sleep EEG recording in identifying interictal epileptiform discharges (IEDs) during long-term video-EEG monitoring. METHOD: We retrospectively reviewed 255 consecutive patients who underwent continuous long-term video-EEG monitoring in the adult epilepsy monitoring unit (EMU) at the University of Chicago. The complete video-EEG recording was reviewed, and the occurrence of IEDs was determined for each patient. We compared the occurrence of IEDs observed during the first-hour sleep EEG recordings with the occurrence of IEDs observed during the complete video-EEG recordings. RESULTS: Overall, IEDs were observed in 134 (53%) of 255 patients during the full long-term video-EEG recording with a mean duration of 4 days. IEDs were identified in the first-hour sleep EEG in 125 (49%) of 225 patients. Comparing to reviewing full records, the first hour sleep EEG identified IEDs in 125 (93%) of 134 patients. Of the IED subtypes, the first-hour sleep EEG identified 92 (94%) of 98 patients with temporal lobe IEDs, 11 (92%) of 12 patients with frontal lobe IEDs, 3 (100%) of 3 patients with parietal lobe IEDs, 1(50%) of the 2 patients with occipital lobe IEDs, 16 (94%) of 17 patients with generalized IEDs, and 2 (100%) 2 patients with multi-focal IEDs. CONCLUSIONS: The first-hour sleep EEG reliably predicts the occurrence of IEDs during the long-term video-EEG recording, and therefore can be a time-efficient tool for identifying patients with IEDs during long-term video-EEG recording in the adult epilepsy monitoring unit.