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Objective: The electroencephalographic (EEG) terms “brief potentially ictal rhythmic discharges” (BIRDs) and “paroxysmal fast activity” (PFA) are considered distinct entities; however, their definitions overlap, and they may have similar clinical significance. We investigated their clinical significance and their association with seizures and the seizure onset zone (SOZ). Methods: We retrospectively identified an adult cohort (July 2015 to March 2018) whose long-term (>12 h) EEGs in any setting reported BIRDs (>4 Hz, lasting.5–10 s) and/or PFA. Different frequency cutoffs for PFA (>13 Hz or ≥8 Hz) were tested to compare their clinical significance. Patient demographics, clinical history, and EEG features were recorded. Results: We identified 94 patients with BIRDs/PFA out of 3520 patients (3%); 36 were critically ill (12 with epilepsy), and 58 were noncritically ill (all with epilepsy). The frequency of BIRDs/PFA was largely dependent on EEG background: it tended to be slower (theta) in the absence of a posterior dominant rhythm or in the presence of continuous focal slowing in the same region (p =.01). Sixty-two of 94 patients (66%; 32/36 [89%] critically ill, 30/58 [52%] noncritically ill) had electrographic seizures during the recording. The scalp EEG SOZ colocalized with BIRDs/PFA in all cases. BIRDs with faster frequency (also qualifying as PFA by definition) had similar seizure risk to that of slower BIRDs (62%–71%), regardless of frequency cutoff used to define PFA. In addition, 30 of 30 (100%) patients with evolving BIRDs/PFA (which lasted a median of 6 s, range = 2–9.5 s) had electrographic seizures (>10 s), compared to 32 of 64 (50%) with nonevolving BIRDs (median = 1 s, range =.5–3.5 s; p <.01). Significance: A high proportion of patients with BIRDs/PFA had seizures on EEG, regardless of their frequency (i.e. whether they also qualified as PFA), and their location colocalized with scalp SOZ in all cases. BIRDs appear to be a scalp EEG biomarker of uncontr, SCOPUS: ar.j, info:eu-repo/semantics/published

Introduction: Brief potentially ictal rhythmic discharges (B(I)RDs) have been described in neonates and critically ill adults, and their association with seizures has been demonstrated. Their significance in noncritically ill adults remains unclear. We aimed to investigate their prevalence, electrographic characteristics, and clinical significance. Methods: We identified adult patients with B(I)RDs who received long-term EEG recordings either in the epilepsy monitoring unit or in the ambulatory setting. Patients with acute findings on imaging or status epilepticus were excluded. B(I)RDs were defined as very brief (,10 seconds) runs of focal or generalized sharply contoured rhythmic activity greater than 4 Hz, with or without evolution, that were not consistent with any known normal or benign pattern. The clinical history, EEG, and imaging results were retrieved. Each patient with B(I)RDs was matched by age and etiology to a control group with epileptiform discharges but without B(I)RDs in a 1:2 ratio. Results: We identified B(I)RDs in 15 patients of 1,230 EEGs (1.2%). The pattern typically consisted of 0.5 to 4 second runs of sharply contoured alpha activity without evolution. All patients with B(I)RDs had epilepsy, and, when compared with controls with epilepsy but without BIRDs, were more likely to be medically refractory (10 of 15 [67%] vs. 5 of 30 [17%]; P ,0.01). All seizure onsets colocalized to the B(I)RDs, and most were morphologically similar. Conclusions: In noncritically ill patients, B(I)RDs are associated with refractory epilepsy and their location is correlated with the seizure onset area., SCOPUS: cp.j, info:eu-repo/semantics/published