Low-frequency stimulation of a fiber tract in bilateral temporal lobe epilepsy.

OBJECTIVE: Pharmacoresistant bilateral mesial temporal lobe epilepsy often implies poor resective surgical candidacy. Low-frequency stimulation of a fiber tract connected to bilateral hippocampi, the fornicodorsocommissural tract, has been shown to be safe and efficacious in reducing seizures in a previous short-term study. Here, we report a single-blinded, within-subject control, long-term deep-brain stimulation trial of low-frequency stimulation of the fornicodorsocommissural tract in bilateral mesial temporal lobe epilepsy. Outcomes of interest included safety with respect to verbal memory scores and reduction of seizure frequency. METHODS: Our enrollment goal was 16 adult subjects to be randomized to 2-Hz or 5-Hz low-frequency stimulation of the fornicodorsocommissural tract starting at 2 mA. The study design consisted of four two-month blocks of stimulation with a 50%-duty cycle, alternating with two-month blocks of no stimulation. RESULTS: We terminated the study after enrollment of five subjects due to slow accrual. Fornicodorsocommissural tract stimulation elicited bilateral hippocampal evoked responses in all subjects. Three subjects underwent implantation of pulse generators and long-term low-frequency stimulation with mean monthly seizures of 3.14 ±â€¯2.67 (median 3.0 [IQR 1-4.0]) during stimulation-off blocks, compared with 0.96 ±â€¯1.23 (median 1.0 [IQR 0-1.0]) during stimulation-on blocks (p = 0.0005) during the blinded phase. Generalized Estimating Equations showed that low-frequency stimulation reduced monthly seizure-frequency by 0.71 per mA (p < 0.001). Verbal memory scores were stable with no psychiatric complications or other adverse events. SIGNIFICANCE: The results demonstrate feasibility of stimulating both hippocampi using a single deep-brain stimulation electrode in the fornicodorsocommissural tract, efficacy of low-frequency stimulation in reducing seizures, and safety as regards verbal memory.

The role of cigarette smoking in epilepsy severity and epilepsy-related quality of life.

Empirical evidence suggests that cigarette smoking is common among individuals with epilepsy. However, little is known about relationship between smoking and clinical features of epilepsy. Thus, the aim of the current study was to examine the differences between smokers (n = 43; 58.1% female, Mage = 43.4 years, SD = 11.6) and nonsmokers (n = 49; 63.3% female, Mage = 48.5 years, SD = 15.9) with epilepsy in terms of epilepsy severity (i.e., presence of seizures in the past year, refractory epilepsy status) and epilepsy-related quality of life. As hypothesized, smokers with epilepsy, compared with nonsmokers with epilepsy, were at an increased risk to have experienced seizures in the past year after controlling for the effect of Medicaid status as a proxy for socioeconomic status (odds ratio [OR] = 3.61). Positive smoking status was also associated with lower levels of epilepsy-related quality of life; however, this finding did not remain significant when Medicaid status was taken into consideration. Contrary to the hypotheses, smokers with epilepsy were not at an increased risk of having refractory epilepsy compared with nonsmokers with epilepsy. These findings suggest that cigarette smoking is associated with at least one aspect of epilepsy severity. Thus, in addition to the broader health benefits, smokers with epilepsy should be advised of the increased seizure risk associated with current cigarette smoking. Future work should examine the longitudinal impact of smoking on epilepsy severity, including whether successful smoking cessation ameliorates the seizure risk found in this cross-sectional study.