title: Frontal EEG delta/alpha ratio and screening for post-stroke cognitive deficits: the power of four electrodes.
abstract: This study analysed correlations between post-stroke, quantitative electroencephalographic (QEEG) indices, and cognition-specific, functional outcome measures. Results were compared between QEEG indices calculated from the standard 19 versus 4 frontal (or 4 posterior) electrodes to assess the feasibility and efficacy of employing a reduced electrode montage. Resting-state EEG was recorded at the bedside within 62-101 h after onset of symptoms of middle cerebral artery, ischaemic stroke (confirmed radiologically). Relative power for delta, theta, alpha and beta, delta/alpha ratio (DAR) and pairwise-derived brain symmetry index (pdBSI) were averaged; over all electrodes (global), over F3, F4, F7, F8 (frontal) and P3, P4, T5, T6 (posterior). The functional independence measure and functional assessment measure (FIM-FAM) was administered at mean 105 days post-stroke. Total (30 items) and cognition-specific (5 items) FIM-FAM scores were correlated with QEEG indices using Spearman's coefficient, with a Bonferroni correction. Twenty-five patients were recruited, 4 died within 3 months and 1 was lost to follow-up. Hence 20 cases (10 female; 9 left hemisphere; mean age 68 years, range 38-84) were analysed. Two QEEG indices demonstrated highly-significant correlations with cognitive outcomes: frontal DAR (ρ = -0.664, p ≤ 0.001) and global, relative alpha power (ρ = 0.67, p ≤ 0.001). After correction there were no other significant correlations. Alpha activity - particularly frontally - may index post-stroke attentional capacity, which appears to be a key determinant of functional and cognitive outcomes. Likewise frontal delta pathophysiology influences such outcomes. Pending further studies, DAR from 4 frontal electrodes may inform early screening for post-MCA stroke cognitive deficits, and thereby, clinical decisions.
authors: UQ Centre for Clinical Research, The University of Queensland, Brisbane, Australia; School of Medicine, The University of Queensland, Brisbane, Australia.
authors: Emma
authors: E
authors: Schleiger
authors: UQ Centre for Clinical Research, The University of Queensland, Brisbane, Australia; School of Medicine, The University of Queensland, Brisbane, Australia; Acute Stroke Unit, Neurology Department, Royal Brisbane and Women's Hospital, Brisbane, Australia.
authors: Nabeel
authors: N
authors: Sheikh
authors: Department of Occupational Therapy, Royal Brisbane and Women's Hospital, Brisbane, Australia.
authors: Tennille
authors: T
authors: Rowland
authors: School of Medicine, The University of Queensland, Brisbane, Australia; Acute Stroke Unit, Neurology Department, Royal Brisbane and Women's Hospital, Brisbane, Australia.
authors: Andrew
authors: A
authors: Wong
authors: School of Medicine, The University of Queensland, Brisbane, Australia; Acute Stroke Unit, Neurology Department, Royal Brisbane and Women's Hospital, Brisbane, Australia.
authors: Stephen
authors: S
authors: Read
authors: UQ Centre for Clinical Research, The University of Queensland, Brisbane, Australia; Gallipoli Medical Research Foundation, Greenslopes Private Hospital, Brisbane, Australia. Electronic address: finnigan.simon@gmail.com.
authors: Simon
authors: S
authors: Finnigan
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000513:Alpha Rhythm / Q000502:physiology*; D003072:Cognition Disorders / Q000209:etiology* / Q000473:pathology*; D003700:Delta Rhythm / Q000502:physiology*; D004566:Electrodes; D004569:Electroencephalography; D005260:Female; D005625:Frontal Lobe / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D020521:Stroke / Q000150:complications*
keywords: Cognition; Delta/alpha ratio (DAR); Functional independence measure/functional assessment measure (FIM–FAM); QEEG; Stroke; Stroke outcomes