Bimodal ultradian seizure periodicity in human mesial temporal lobe epilepsy.

BACKGROUND: Mesial temporal lobe epilepsy (mTLE) has been suggested to follow a circadian rhythm. Previous research found an afternoon peak in mTLE seizure occurrence. We evaluated the pattern of seizure occurrence in patients with well-localized mTLE and hypothesized that peak seizure frequency would occur in the afternoon, and that this pattern would not be altered by age, gender, or seizure focus. METHODS: We retrospectively identified consecutive mTLE patients with a seizure-free outcome following anterior temporal lobectomy from 1993 to 2004 with video-EEG captured seizures. We recorded and plotted the 24-h clock time for each seizure and performed cosinor analysis. SAS Proc GLIMMIX was used to fit the linearized transform of the cosinor model. Negative binomial regression fitted by the generalized estimating equations (GEE) method was also performed to estimate and compare the mean seizure rates over a 24-h day. RESULTS: Sixty mTLE patients monitored between 2 and 16 days were analyzed. Mean (standard deviation), median number of seizures per subject were 10.47(7.86), 9.00. Cosinor plots indicated that the function had two modes: 7-8 a.m. and 4-5 p.m. GEE analysis was consistent with peak seizure frequency occurrence at 6-8 a.m. (p<0.0001) and 3-5 p.m. (p<0.01). CONCLUSIONS: We found a bimodal pattern of seizure occurrence in human mTLE, with peak seizure frequencies occurring between 6-8 a.m. and 3-5 p.m. confirming an afternoon peak, as well as a previously unsuspected morning peak in seizure occurrence that provides rationale for future investigations of antiepileptic drug chronopharmacology and informs patient counseling regarding patterns of seizure occurrence.

Impaired navigation in drivers with Parkinson's disease.

Navigating a new route during automobile driving uses the driver's cognitive resources and has the potential to impair driving ability in people with Parkinson's disease (PD). Our aim was to assess navigation and safety errors during a route following task (RFT) in drivers with the illness. Seventy-seven subjects with mild-moderate PD (median Hoehn-Yahr stage = 2.0) and 152 neurologically normal elderly adults, all active and licensed drivers, were tested with a battery of visual, cognitive and motor tests of abilities. Each driver also performed a RFT administered on the road in an instrumented vehicle. Main outcome variables included: number of incorrect turns, times lost and at-fault safety errors. All group comparisons were adjusted for age, gender, education and familiarity with the region. Drivers with PD performed significantly worse on cognitive, visual and motor tests compared to controls, and took longer to finish the RFT. Higher proportions of these drivers made incorrect turns {53.9% in PD versus 21.1% in controls, Odds Ratio (OR) [95% Confidence Interval (CI)] = 2.8 [1.4, 5.7], P = 0.006}, got lost (15.8% versus 2.0%, OR [95%CI] = 4.7 [1.1, 20.0], P = 0.037), or committed at-fault safety errors (84.2% versus 46.7%, OR [95%CI] = 7.5 [3.3, 17.0], P < 0.001). Within the patient group, the navigational and safety errors were predicted by poor performances on cognitive and visual tests, but not by the severity of motor dysfunction. Drivers with PD made more navigation and safety errors than neurologically normal drivers on a RFT that placed demands on driver memory, attention, executive functions and visual perception. The PD group driver safety was degraded possibly due to an increase in the cognitive load in patients with limited reserves. Navigational errors and lower driver safety were associated more with impairments in cognitive and visual function than the motor severity of their disease in drivers with PD.