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Table 1 Summary of results

From: Electroencephalography in delirium assessment: a scoping review

Authors

Journal

Design

N Total (Delirium/No Delirium)

Mean Age

% Female

Admission

Dementia

Substance (Ab)use

Delirium Tool

EEG Type

Ana-lysis Meth-od

EEG Set-up

Summary Findings

Allahyari et al. (1976) [42]

Psychiatr Clin

Prospective

30 (30/0)

N.m.

0

Intoxication/ Withdrawal

N.m.

Substance abuse reported and considered in analysis

N.m.

rEEG

Qualitative

10-20 system

Most patients showed a physiological EEG;

1 patient showed generalized paroxysmal spike wave bursts;

4 patients showed diffuse slow activity during delirium tremens, partly accompanied by rhythmic bilateral slow waves

Azabou et al. (2015) [43]

PLoS One

Prospective

110 (22/88)

63,8

29

Sepsis

N.m.

Substance abuse reported but NOT considered in analysis

CAM

rEEG

Qualitative

10-20 system, 13 channels

Absence of EEG reactivity, delta-predominant background, PDs, Synek grade ≥ 3, and Young grade > 1 at day 1 to 3 after admission were predictors of ICU mortality and associated with delirium;

ESZ and PDs in about 20% of all patients

Evans et al. (2017) [44]

Clin Neurophysiol

Prospective

12 (3/9)

66,8

42

Surgery

No subjects with dementia

No patients with substance abuse

CAM, DRS

cEEG

Quantitative

0.1 Hz high pass filter, 70 Hz low pass filter, EMG

Diminished total sleep time and longer latency to sleep onset during first night in hospital associated with greater delirium severity on day 2 after surgery;

Delirious patients slept 2.4 h less and took 2 h longer to fall asleep than non-delirious patients;

Greater waking EEG delta power on day 1 after surgery and less non-REM sleep EEG delta power on night 2 predicted delirium severity on day 2 after surgery

Fleischmann et al. (2019) [45]

Clin EEG Neurosci

Retrospective

376 (31/345)

75,3

39

Mixed

Mixed collective - dementia NOT considered in analysis

N.m.

CAM

rEEG

Quantitative

10-20 system, 256 Hz sampling rate, 70 Hz low pass filter, 50 Hz notch filter

Differentiation of delirious patients vs. normal controls using spectral power at F3-P4 at 2 Hz and C3-O1 at 19 Hz achieved 100% sensitivity and 99% specificity

Fleischmann et al. (2019) [45]

Pilot Feasibility Stud

Retrospective

543

(129/414)

73,6

43

Mixed

N.m.

N.m.

DSM/ ICD

rEEG

Quantitative

10-20 system, 256 Hz sampling rate; 50 Hz discrete FT filter

Significant differences in delirious and non-delirious patients in EEG power, connectivity, and network characteristics;

Global alpha and regional beta band disconnectivity as well as theta band hyperconnectivity in delirious patients;

Abnormalities affected networks engaged in consciousness, attention, memory, executive control, and salience detection

Hunter et al. (2020) [46]

AIMS Neurosci

Prospective

10 (5/5)

63,8

20

Mixed

No subjects with dementia

N.m.

CAM

rEEG

Quantitative

10-20 system, 0.16-52 Hz band pass filter, 9 channels

EEG slowing as well as general loss of directed functional connectivity between recording sites in delirious patients;

3 electrodes were sufficient to differentiate groups, with significantly higher slow-to-fast frequency power ratio in delirious compared to non-delirious patients in C3, P3, T7, or all 3

Jacobson et al. (1993) [47]

J Neurol Neurosurg Psychiatry

Retrospective

34 (18/16)

76,6

65

Mixed

Mixed collective - dementia considered in analysis

No patients with substance abuse

DSM/ ICD

rEEG

Qualitative & quantitative

10-20 system, 16 channels + eye movement

Differentiation of normal vs. encephalopathic records using MMSE scores and relative power in the alpha frequency (up to 94% correctly classified; no sensitivity/specificity provided);

Differentiation of patients with delirium vs. patients with dementia using EEG theta activity, relative power in delta, and brain map rating (up to 93% correctly classified)

Jacobson et al. (1993) [47]

Biol Psychiatry

Prospective

33 (15/18)

75

73

N.m.

Mixed collective - dementia considered in evaluation

No patients with substance abuse

DSM/ ICD

rEEG

Qualitative & quantitative

10-20 system, 16 channels + eye movement

In delirious patients, changes in score of relative power map and changes in relative power in the alpha band significantly associated with changes in MMSE;

In patients with dementia only, changes in score for absolute power maps and changes in absolute power in the delta band were significantly associated with changes in MMSE

Katz et al. (1991) [48]

Int Psychogeriatr

Prospective

28 (10/18)

N.m.

N.m.

N.m.

N.m.

N.m.

N.m.

cEEG

Quantitative

10-20 system, 6 channels

Significantly differences in theta and beta power between delirious and non-delirious patients during hospitalization;

Significant differences in subsequent change of theta, delta, and alpha power between delirious and non-delirious patients

Keijzer et al. (2020) [49]

Resuscitation

Prospective

141 (47/94)

61,7

16

Cardiac arrest

N.m.

N.m.

DSM/ ICD

cEEG

Quantitative

10-20 system, 500 Hz sampling rate, 0.5-30 Hz band pass filtered with Butterworth filter, 21 channels

Delirium associated with longer hospitalization, and more frequent discharge to rehabilitation center or nursing home;

EEG predicted delirium with 91% specificity and 40% sensitivity

Kimchi et al. (2019) [50]

Neurology

Prospective

200 (121/79)

59,2

43

Mixed

No subjects with dementia

N.m.

CAM

rEEG

Qualitative

10-20 system

Generalized theta or delta slowing were associated with delirium;

EEG slowing correlated with delirium severity;

EEG slowing was associated with longer hospitalizations, worse functional outcomes, and increased mortality

Knauert et al. (2018) [51]

J Crit Care

Retrospective

93 (93/0)

56,2

48

Mixed

No subjects with dementia

N.m.

Other

cEEG

Qualitative

10-20 system, 17 channels + eye movement, EMG

Delirious patients without K-complexes or without sleep spindles had more severe encephalopathy and higher odds of death

Koponen et al. (1989) [52]

J Neurol Neurosurg Psychiatry

Prospective

70 (51/19)

73,8

57

Mixed

Mixed collective - dementia considered in analysis

No patients with substance abuse

DSM/ ICD

rEEG

Quantitative

10-20 system, 70 Hz high frequency limit, 16 channels

Significantly reduced alpha power, increased theta and delta activity and slowing of the peak and mean frequencies in delirious compared to non-delirious patients;

Alpha power and various ratio parameters correlated with MMSE score, and delta percentage and mean frequency with the lengths of delirium and hospitalization

Matsushima et al. (1997) [53]

Biol Psychiatry

Prospective

20 (10/10)

53,1

20

acute myocardial infarction.

N.m.

No patients with substance abuse

DSM/ ICD

rEEG

Qualitative & quantitative

10-20 system, 16 channels + eye movement

Delirious patients showed slowing of background EEG activity, particularly on day 2 after admission, and many rapid group, and rapid superimposed on slow eye movements, particularly on day 3;

From days 2 to 3, EEG showed improvement in consciousness, and eye tracking signs of anxiety and tension

Naeije et al. (2014) [54]

Epilepsy Behav

Prospective

64 (64/0)

82

70

N.m.

N.m.

N.m.

CAM

cEEG & rEEG

Qualitative

10-20 system, 21 channels

cEEG detected NCSE in 28% and focal IEDs in 16% of delirious patients; rEEG detected NCSE in 6% and focal IEDs in 16% of delirious patients;

History of cognitive impairment and use of antibiotics and hypernatremia associated with NCSE;

NCSE associated with longer hospitalization and higher mortality rate

Nielsen et al. (2019)

Neurocrit Care

Prospective

102 (66/36)

71

33

Mixed

N.m.

N.m.

CAM

cEEG

Qualitative & quantitative

10-20 system, 1 kHz sampling rate, 1-120 Hz band pass filter, 19 channels + eye movement, EMG

Absence of delirium associated with preserved high-frequency beta activity and cEEG reactivity;

Delirium associated with preponderance of low-frequency cEEG activity and absence of high-frequency cEEG activity;

Sporadic PDs in 15 patients, 13 of which were delirious;

No patient showed evidence of NCSE

Numan et al. (2017) [55]

Clin Neurophysiol

Prospective

58 (18/40)

75,3

53

Surgery

N.m.

N.m.

DSM/ ICD

cEEG

Quantitative

10-20 system, 512 sampling rate, 0.15 Hz high pass filter, 70 Hz low pass filter, 21 channels

Significantly lower average PLI in patients with delirium or recovery from anesthesia compared to non-delirious patients;

Loss of anterior-posterior information flow in alpha band in patients with delirium or recovery from anesthesia;

Significantly lower functional connectivity in alpha band in patients with delirium or recovery from anesthesia compared to non-delirious patients;

77% sensitivity and 85% specificity in discrimination of delirious vs. non-delirious patients; 78% sensitivity and 68% specificity for patients with delirium vs. recovery from anesthesia

Numan et al. (2019) [56]

Br J Anaesth

Prospective

159 (55/104)

76,9

33

Surgery

Mixed collective - dementia NOT considered in analysis

Substance abuse reported but NOT considered in analysis

DSM/ ICD, CAM, DRS

rEEG

Quantitative

10-20 system, 512 Hz sampling rate, 50 Hz notch filter, 0.15 Hz IIR filter, 4 channels

Depending on the cut-off, relative delta power predicted delirium with up to 90% sensitivity and up to 90% specificity (AUROC: 0.75) based on just one minute artifact-free EEG recording

Plaschke et al. (2007) [57]

Anaesthesia

Prospective

37 (17/20)

63,7

27

Mixed

No subjects with dementia

No patients with substance abuse

CAM

rEEG

Quantitative

10-20 system, 0.5 Hz high pass filter, 16 channels

Significantly higher theta power and lower alpha power in delirious compared to non-delirious patients;

No group differences in SAA

Reischies et al. (2005) [58]

Psychiatry Res

Prospective

12 (12/0)

56,7

58

treatment-resistant major depression

N.m.

N.m.

DSM/ ICD, DRS

rEEG

Quantitative

10-20 system, 250 Hz sampling rate, 0.15-50 Hz band pass filter, 50 Hz notch filter, 0.5 Hz high pass filter, 32 channels + eye movement

Compared to baseline, significant increases in delta and theta power and decrease in alpha power during delirium;

Decrease of theta activity at Fz in following 24 h correlated with recovery of awareness and performance of free recall;

Source analysis with LORETA indicated that the main generators of the theta excess during delirium were localized in the anterior cingulate cortex and right fronto-temporal areas

Sambin et al. (2019) [59]

Front Neurol

Prospective

50 (50/0)

84

66

Mixed

Mixed collective - dementia considered in analysis

Substance abuse reported and considered in analysis

CAM

cEEG

Qualitative

10-20 system, 21 channels

NCSE in 12% and interictal discharges in 30% of delirious patients

Sun et al. (2019) [60]

NPJ Digit Med

Prospective

174 (N.m./ N.m.)

N.m.

33

Mixed

No subjects with dementia

N.m.

CAM

N.m.

N.m.

N.m.

Deep learning model achieved detected delirium with 69% sensitivity and 83% specificity

Tanabe et al. (2020) [61]

Br J Anaesth

Prospective

70 (22/48)

70,4

39

Surgery

N.m.

N.m.

CAM, DRS

rEEG

Quantitative

0.1-50 Hz band pass filter with Hamming windowed-sinc FIR filter, 256 channels

Preoperatively, patients with postoperative delirium had significantly higher alpha power, higher alpha band connectivity, but impaired structural connectivity;

Postoperatively, delirium was associated with increased SWA in parieto-occipital and frontal cortex, with accompanying breakdown in functional connectivity;

Changes in connectivity correlated with SWA, delirium severity, interleukin-10, and monocyte chemoattractant protein-1

Thomas et al. (2008) [62]

BMC Neurosci

Prospective

61 (15/46)

86,2

74

Mixed

Mixed collective - dementia considered in analysis

N.m.

DSM/ ICD, CAM, DRS

rEEG

Qualitative & quantitative

10-20 system, 500 Hz sampling rate, 0.03-70 Hz band pass filter, 32 channels, EMG

SAA not associated with delirium or cognitive functions;

Occipital slowing, peak power and alpha decrease, delta and theta power increase, and slow wave ratio increase associated with delirium;

EEG measures were correlated with cognitive performance and delirium severity, but not SAA

Thomas et al. (2008) [63]

J Neurol Neurosurg Psychiatry

Prospective

50 (12/38)

85,8

72

Mixed

Mixed collective - dementia considered in analysis

N.m.

DSM/ ICD

rEEG

Qualitative & quantitative

10-20 system, 500 Hz sampling rate, 0.03-70 Hz band pass filter, 32 channels, EMG

qEEG was substantially better than rEEG in differentiating patients with delirium and dementia, delirium only, and cognitively unimpaired subjects;

Differentiation of patients with delirium vs. with delirium and dementia using qEEG variables activated upper alpha and delta power density with 67% sensitivity and 91% specificity;

Differentiation of patients with delirium vs. cognitively unimpaired subjects using qEEG variables relative theta power density at rest with 83% sensitivity and 60% specificity

Trzepacz et al. (1986) [64]

Int J Psychiatry Med

Prospective

40 (12/28)

40

62

Liver Disease

Mixed collective - dementia NOT considered in analysis

Substance abuse reported but NOT considered in analysis

DSM/ ICD

rEEG

Qualitative

N.m.

Delirium associated with serum albumin < 3.0 g/dl, MMSE scores < 24, impairment in TMT-A and -B, EEG dysrhythmia;

In a subsample, differentiation between delirious and non-delirious patients using MMSE, TMT-A and -B, EEG, and albumin with 100% specificity and 100% sensitivity

Trzepacz et al. (1988) [65]

Biol Psychiatry

Prospective

108 (18/90)

41

65

Liver Disease

N.m.

Substance abuse reported but NOT considered in analysis

DSM/ ICD

rEEG

Qualitative

10-20 system, 16 or 17 channels

Significantly slower dominant posterior rhythm, lower serum albumin, and worse scores in TMT-A and -B and MMSE in delirious compared to non-delirious patients;

Differentiation between delirious and non-delirious patients using TMT-B, EEG, and albumin with 98% specificity and 83% sensitivity

Trzepacz et al. (1989) [66]

J Neuropsychiatry Clin Neurosci

Prospective

46 (23/23)

40,4

60

Liver Disease

N.m.

Substance abuse reported but NOT considered in analysis

DSM/ ICD

rEEG

Quantitative

10-20 system, 120 Hz sampling rate, 4 channels

Significantly worse performance in MMSE, TMT-A and -B, and lower mean peak activity in delirious compared to non-delirious patients;

Mean auditory brainstem evoked potentials were abnormal in both groups, with delirious patients showing a bimodal distribution of latency values and a greater proportion of abnormal values; somatosensory evoked potentials were abnormal only for delirious patients

Trzepacz et al. (1989) [66]

Psychosomatics

Prospective

247 (46/201)

41,3

63

Liver Disease

Mixed collective - dementia NOT considered in analysis

Substance abuse reported but NOT considered in analysis

DSM/ ICD

rEEG

Qualitative

10-20 system, 16 or 17 channels

Significantly lower serum albumin, more EEG dysrhythmia, and worse performance in MMSE, TMT-A and -B in delirious compared to non-delirious patients;

Delirious patients had significantly poorer adaptive functioning and lower occupational, family, and social scale ratings

Vacas et al. (2016) [67]

Anesth Analg

Prospective

23 (8/15)

68

N.m.

Mixed

N.m.

N.m.

DSM/ ICD, CAM

cEEG

Qualitative

10-20 system, 2500 Hz sampling rate; 0.3-35 Hz band pass filter, 4 channels + eye movement, EMG

Moderate agreement between SedLine and polysomnography monitoring;

No differences in delirium occurrence in patients with and without sleep disruption

van Dellen et al. (2014) [68]

Anesthesiology

Prospective

49 (25/24)

75,1

45

Surgery

No subjects with dementia

N.m.

DSM/ ICD, CAM

rEEG

Quantitative

10-20 system, 512 Hz sampling rate, 0.15 Hz high pass filter, 21 channels

Significantly lower mean PLI in the alpha band in delirious compared to non-delirious patients;

Network topology in delirious patients characterized by lower normalized weighted shortest path lengths in the alpha band;

Significantly lower delta band dPLI in anterior regions and higher in central regions in delirious compared to non-delirious patients

van der Kooi et al. (2015) [35]

Chest

Prospective

56 (28/28)

75,5

43

Surgery

No subjects with dementia

N.m.

DSM/ ICD, CAM

rEEG

Quantitative

10-20 system, 512 Hz sampling rate; 0.5-30 Hz band pass filter, 21 channels + eye movement

Differentiation of delirious vs. non-delirious patients using relative delta power from 1 min artifact-free recording of electrodes F8-Pz with 100% sensitivity and 96% specificity

van Sweden, Mellerio (1989) [69]

Biol Psychiatry

Prospective

16 (16/0)

50,8

69

Intoxication/ Withdrawal

N.m.

Substance abuse reported and considered in analysis

N.m.

rEEG

Qualitative

N.m.

All delirious patients had non-convulsive paroxysmal EEG disturbances without a history of epilepsy

  1. AUROC Area under receiver operating characteristic curve, CAM Confusion Assessment Methods, cEEG Continuous EEG, DRS Delirium Rating Scale, DSM Diagnostic and Statistical Manual of Mental Disorders, EEG Electroencephalography, EMG Electromyography, FT Fourier transformation, Hz Hertz, ICD International Classification of Diseases, ICU Intensive care unit, IIR Infinite impulse response, LORETA Low-resolution electromagnetic tomography, MMSE Mini Mental State Examination, N.m. Not mentioned, PLI Phase-lag index, dPLI Directed PLI, rEEG Routine EEG, SAA Serum amyloid A, SWA Slow-wave activity, TMT-A and -B Trail-Making Test A and B