Hemodynamic Changes Associated with Lateralized Periodic Discharges: A Near-Infrared Spectroscopy and Continuous EEG Study.

BACKGROUND: Lateral periodic discharges (LPDs) have been recognized as a common electroencephalographic (EEG) pattern in critically ill patients. However, management decisions in these patients are still a challenge for clinicians. This study investigates hemodynamic changes associated with LPDs and evaluates if this pattern is likely to represent an ictal, interictal, or ictal-interictal continuum phenomenon via non-invasive near infra-red spectroscopy (NIRS) with concurrent with continuous EEG. METHODS: Seventeen patients admitted to the intensive care unit with LPDs on continuous electroencephalogram (EEG) were included. Participants engaged in NIRS recording-with scalp probes on right and left frontal regions simultaneously. Associations between LPDs laterality, primary frequency, NIRS a of cerebral oxygen saturation (SO2), total hemoglobin concentration (tHb), oxygenated hemoglobin concentration (O2Hb), de-oxygenated hemoglobin concentration (HHb), and variables in participant medical history were studied. RESULTS: Hemispheres with LPDs showed higher overall SO2 when compared to non-LPDs hemispheres (57% vs 52%, p = 0.03). Additionally, mildly increased tHb, O2Hb, and mildly decreased HHb concentrations were detected in the hemisphere showing LPDs, but changes were not statistically significant. A higher primary frequency of LPDs was associated with lower cerebral SO2 (Pearson correlation r = - 0.55, p = 0.022) and O2Hb (Pearson correlation r = - 0.52, p = 0.033). In patients with seizure during their EEG recording (64.7%), lower tHb (28.2 µmol/L vs 37.8 µmol/L, p = 0.049) and O2Hb (15.5 µmol/L vs 24.2 µmol/L, p = 0.033) were recorded in the LPDs hemisphere. CONCLUSIONS: This study demonstrates an increased cerebral SO2 in the hemisphere with LPDs, and decreased SO2 and O2Hb when the frequency of LPDs increases. The findings indicate that LPDs increase oxygen demand on the ipsilateral hemisphere. We infer that a threshold of LPDs frequency might exit, when the cerebral oxygen demand begins to supersede the ability of delivery, and saturation decreases.

Proton MR Spectroscopy in Patients with Structural MRI-Negative Temporal Lobe Epilepsy.

BACKGROUND AND PURPOSE: With conventional magnetic resonance imaging (MRI), 20-30% of patients with temporal lobe epilepsy (TLE) have negative pathological MRI findings. Further investigations of the role of magnetic resonance spectroscopy (MRS) in the pre-surgical evaluation of patients with MRI-negative TLE are important to avoid intracranial EEG recording and to better understand the mechanism of the epileptogenic process. This study aimed to compare the measurements of N-acetylaspartate (NAA), creatine (Cr), and choline (Cho) in the hippocampi of MRI-negative TLE patients and normal subjects. METHODS: Twenty patients with MRI-negative TLE and 10 age-matched healthy control subjects underwent MRI and MRS. The concentrations of NAA, Cr, and Cho and the ratios of NAA/Cr and NAA/(Cr+Cho) were measured. Seven of these 20 patients also underwent surgical treatment for TLE. Their pathological results and surgical outcomes were evaluated. RESULTS: In the hippocampi ipsilateral to the seizure side, the NAA/Cr and NAA/(Cr+Cho) ratios were significantly decreased compared with the ratios of the hippocampi contralateral to the seizure side and the normal control hippocampi. There was no significant difference between the hippocampi contralateral to the seizure side and the normal control hippocampi. The pathological results from the patients who underwent temporal lobe resection indicated mild to moderate gliosis and minimal loss of neurons. Five patients were seizure-free during the follow-up period of 9- 47 months (mean 27.7 months). CONCLUSIONS: In MRI-negative TLE, significant reductions in the NAA/Cr and NAA/(Cr+Cho) ratios ipsilateral to the seizure side may help lateralize and localize the epileptogenic zone.

Quality-of-Life Assessment in Patients Treated with Vagus Nerve Stimulation.

Vagus nerve stimulation (VNS) is a novel therapy used in patients with medically intractable epilepsy. We administered a Quality of Life in Epilepsy-10 (QOLIE-10) questionnaire consisting of questions designed to assess the patients' rating of their memory, level of physical and mental well-being, energy, depression, worries about seizures and work, social limitations, and overall quality of life on VNS treatment. The questionnaire was administered before and at 1-3 weeks, 5-7 weeks, 3 months, 6 months, and 9-12 months after the initiation of VNS in 17 patients. QOLIE-10 scores were significantly better after the initiation of the therapy as compared with baseline (P < 0.01). There was no correlation between the improvement in QOLIE-10 scores and the reduction in seizure frequency, decreased severity of seizures, or increased level of energy/alertness. We conclude that VNS therapy is associated with a significant improvement in subjective quality of life.