Abstracts

Rationale: Wicket rhythm (WR) is a theta frequency sharp firing with a comb-shaped pattern (Lebel and Reiher, 1976) and is one of the EEG findings of unknown clinical significance. It is generally regarded as a benign finding and not a surrogate of cortical abnormality or evidence of epileptogenicity. The incidence of WR in a non-selective population reported by Reiher (1977) was 0.9%. Although WR itself is not evidence of an abnormality, actual clinical correlation was sought in patients who have episodic mental status change. Methods: Adult patients, age above 40, visiting the outpatient neurology clinic with presenting symptom of episodic alteration of consciousness had outpatient EEGs in 2003. The working diagnosis included seizure, syncope, TIA, reversible encephalopathy, and memory lapse. 133 consecutive EEG recordings were done and WR was sought out among the EEGs. Abnormal EEG was defined by the presence of epileptiform discharges, focal slowing, and nonspecific encephalopathy. WR was not a criterium to determine abnormal EEG. Clinical correlations were sought in Wicket positive EEGs (WR+EEG). Results: Out of 133 EEGs, 13 WR+EEGs (9.7%) were identified. 54 EEGs were regarded as abnormal out of 133, and all of the 13 WR+EEG (24%) were seen in the group of 54 abnormal EEGs. Among the 13 WR+EEG, 7 (54%) had unilateral WR (acute phenytoin toxicity, dehydration, AED withdrawal, multiinfarct dementia, complex partial seizure (x2), mild cognitive impairment). Four (30%) had bilateral temporal WR (complex partial seizure, migraine, MS, chromium picolinate abuse). One EEG (8%) showed bilateral central WR (episodic dysphonia). One EEG (8%) had bilateral Rolandic WR induced by photic stimulation (PTSD). Conclusions: The incidence of WR in our selected population of episodic confusion was higher than in a previous published report and the causes were heterogeneous. The clinical implication of WR remains nonspecific, but may be a finding in cerebral dysfunction. While our small selective EEG study suggested that WR may still represent a nonspecific abnormality, there is a need for further study to establish whether there is evidence of cortical dysfunction or whether this can continue to be disregarded as a totally benign finding.