EEG-based P300 in mesial temporal lobe epilepsy and its correlation with cognitive functions: A case-control study.

OBJECTIVE: P300 is an event-related potential, being explored as an objective tool to assess cognition. This study aimed to investigate the characteristics of auditory and visual P300 in patients with TLE having unilateral HS using electroencephalography (EEG) and to study its correlation with cognition. METHODS: This is a cross-sectional case-control study, where P300 characteristics in thirty patients with unilateral hippocampal sclerosis with refractory epilepsy were compared with fifteen age-, gender-, and years of education-matched healthy controls (M: F-10:5, mean age-28 ±â€¯4.76 years). Among patients, 15 belonged to the right HS group (M: F-9:6, age at onset-12.92 ±â€¯10.22 years, duration of epilepsy-16.67 ±â€¯9.38 years) and 15 to the left HS group (M: F-8:7, age at onset-10.62 ±â€¯7.18 years, duration of epilepsy-15.53 ±â€¯10.14 years). All subjects underwent EEG-based auditory and visual oddball tasks and cognitive assessment. The P300 latencies (in milliseconds) as well as amplitudes (in microvolts) were predicted in EEG and were correlated with cognitive scores. Source localization of P300 was performed with the CLARA algorithm. RESULTS: The auditory P300 latencies in controls, right HS, and left HS were 323.93 ±â€¯40.28, 351.06 ±â€¯47.23, and 328.80 ±â€¯36.03, respectively (p = 0.18) and its amplitudes were 2.3040 ±â€¯1.46, 2.77 ±â€¯1.19, and 2.68 ±â€¯1.78, respectively (p = 0.48). Visual P300 latencies in controls, right HS, and left HS were 365.87 ±â€¯47.37, 359.67 ±â€¯64.45, and 376.00 ±â€¯60.06, respectively (p = 0.51) and its amplitudes were 3.93 ±â€¯2.28, 2.09 ±â€¯1.45, and 3.56 ±â€¯1.74, respectively (p = 0.014). Further, when compared to the control group the cognitive scores were lower in the patient group (p < 0.05). SIGNIFICANCE: In comparison to the controls, patients with right HS recorded lesser amplitude on visual P300 and lower scores on cognitive tests. P300 and cognitive parameters exhibited varied relationship. P300 could be a complementary objective tool to assess cognition in patients with TLE.

Magnetoencephalographic imaging of ictal high-frequency oscillations (80-200 Hz) in pharmacologically resistant focal epilepsy.

OBJECTIVE: Specificity of ictal high-frequency oscillations (HFOs) in identifying epileptogenic abnormality is significant, compared to the spikes and interictal HFOs. The objectives of the study were to detect and to localize ictal HFOs by magnetoencephalography (MEG) for identifying the seizure onset zone (SOZ), evaluate the cortical excitability from preictal to ictal transition, and establish HFO concordance rates with other modalities and postsurgical resection. METHODS: Sixty-seven patients with drug-resistant epilepsy had at least 1 spontaneous seizure each during MEG acquisition, and analysis was carried out on 20 seizures from 20 patients. Ictal MEG data were bandpass filtered (80-200 Hz) to visualize, review, and analyze the HFOs co-occurring with ictal spikes. Source montages were generated on both hemispheres, mean fast Fourier transform was computed on virtual time series for determining the preictal to ictal spectral power transition, and source reconstruction was performed with sLORETA and beamformers. The concordance rates of ictal MEG HFOs (SOZ) was estimated with 4 reference epileptogenic regions. RESULTS: In each subject, transient bursts of high-frequency oscillatory cycles, distinct from the background activity, were observed in the periictal continuum. Time-frequency analysis showed significant spectral power surge (85-160 Hz) during ictal state (P < .05) compared to preictal state, but there was no variation in the peak HFO frequencies (P > .05) for each subgroup and at each source montage. HFO source localization was consistent between algorithms (k = 0.857 ± 0.138), with presumed epileptogenic zone (EZ) comparable to other modalities. In patients who underwent surgery (n = 6), MEG HFO SOZ was concordant with the presumed EZ and the surgical resection site (100%), and all were seizure-free during follow-up. SIGNIFICANCE: HFOs could be detected in the MEG periictal state, and its sources were accurately localized. During preictal to ictal transition, HFOs exhibited dynamic augmentation in intrinsic epileptogenicity. Spatial overlap of ictal HFO sources was consistent with EZ determinants and the surgical resection area.

Hypoxia: can neuropsychological rehabilitation attenuate neuropsychological dysfunction.

Anoxia and hypoxia may be caused by a number of events - heart attack, strangulation, anesthetic accidents, or poisoning. Cognitive dysfunction in hypoxia is well described. The purpose of the study was to examine the efficacy of neuropsychological rehabilitation in hypoxic brain damage. Single-case pre post intervention study design was adopted. The neuropsychological profile was compared pre- and post-neuropsychological rehabilitation. A 30-year-old woman with diagnosis of post- hypoxic encephalopathy underwent cognitive retaining every day for 1 hour. She had a total of 138 sessions over a period of 7 months. Results indicated improvement of cognitive functions post cognitive retraining in most of the cognitive domains. This improvement was also found to have a generalization effect in her every day functioning. Cognitive retraining was found to be useful in hypoxic brain damage. Cognitive retraining combined with other adjunct therapy was found to have significant impact on the patient and the family members. the significant others.