Abstracts

Rationale: The wicket rhythm (WR) constitutes a benign EEG variant consisting of a 6- to 11-Hz repetition of monophasic and sharply contoured waves in the temporal region, classically thought to be bilateral with variable shifting predominance. When unilateral, WR is often misinterpreted as abnormal. It has been our observation that the WR can be exclusively unilateral, rather than bilateral, with left-sided predominance. The aim of our study was to identify the prevalent laterality of the WR and its clinical significance in relation to epilepsy.Methods: In this retrospective study, we reviewed EEG reports of non-surgical adult patients (ages between 18 and 80 years) who were admitted to the epilepsy monitoring unit (EMU) over a period of nine years. The EMU reports were searched for keywords wicket or wickets. The selected EMU reports were examined for the lateralization of the WR dividing it into three groups: bilateral, exclusively left temporal, and exclusively right temporal. We also collected the age, sex, epilepsy risk factors, duration of EMU admission in days, and EMU final diagnosis of patients in each of the three groups. We compared WR prevalence among the three groups using Chi-square testing, and analyzed the demographic parameters and EMU data in relation to WR lateralization using three-way ANOVA testing.Results: A total of 133 EMU studies recorded wicket activity, consistent with the accepted WR definition. The WR was significantly more prevalent in the left temporal region (69%; p<0.05) as compared to the bilateral (21%) or right temporal (10%) regions. There was no difference in duration of EMU admission among the three groups (mean of 5.00 0.29 days, p=0.57). Female patients had a significantly higher prevalence of WR when compared to male patients (76% vs. 24%), irrespective of WR laterality (p<0.05). There was no difference in age (mean of 55 6 years, p=0.56) or individual epilepsy risk factors among the three studied groups. In all three groups, the predominant final EMU diagnosis was non-epileptic, being 89% in the bilateral temporal WR group, 76 % in the left temporal WR group, and 82 % in the right temporal WR group (p>0.05). There was also no association between the presence of concomitant interictal activity, epileptiform or non-epileptiform, and WR lateralization (p>0.05).Conclusions: Our findings demonstrate that the WR is predominantly unilateral than bilateral, with a strong left temporal preference. The exclusively unilateral WR appears to have no clinical significance similar to the benign bilateral WR, with regard to potential epileptogenicity. We propose redefining the lateralization of the benign WR to be predominantly unilateral. This will help preventing the misinterpretation of this challenging normal EEG pattern.