Table 2.
Key study characteristics of studies measuring EEG during delirium.
| Study | Sample characteristics | Study quality | Delirium outcome and measure | EEG characteristics | Main findings relative to the presence of delirium |
|---|---|---|---|---|---|
| Evans et al. (2017) | Participants n = 12 post-orthopaedic surgery Delirium n = 3, non-delirious matched control n = 9 Age = 66.8 (8.2) Sex (F) = 41.7% Country: USA |
5/5 | Outcome: Presence and severity Measure: CAM-ICU and DRS-R-98 |
PSG (electrodes and montage unspecified) 30-second epochs Amount of data unspecified Delta power (did not state is absolute or relative) |
↑Waking delta power, ↓Delta during sleep |
| Fleischmann et al. (2018) | Participants n = 376 Delirium n = 31, non-delirious matched control n = 345 Age = 75.3 (13.3) Sex (F) = 38.8% Country: Germany |
4/5 | Outcome: Presence Measure: CAM-ICU |
EEG (electrode number unspecified) 10/20 montage 20-minute recording 10 second trials F3-P4 electrode power |
↑Delta power |
| Fleischmann et al. (2019) | Participant n = 543 Delirium n = 129, control with normal EEG n = 414 Age = 73.6 (13.9) Sex (F) = 42.9% Country: Germany |
4/5 | Outcome: Presence Measure: DSM-V |
EEG (electrode number unspecified) 10/20 montage 20-minute recording Data segmented into artefact free trials of 10,000 milliseconds Theta, alpha, and beta functional connectivity (weighted phase lag index) |
Alpha disconnectivity Beta disconnectivity Theta hyperconnectivity |
| Koponen et al. (1989) | Participants n = 70 Delirium n = 51, healthy controls n = 19 Age = 73.8 (7) Sex (F) = 57.1% Country: Finland |
4/5 | Outcome: Incidence Measure: DSM-III |
16-channel EEG 10/20 montage 8-second epochs 1024 sample points Relative delta, theta, and alpha power |
↑Delta power ↑ Theta power ↓ Alpha power |
| Matsushima et al. (1997) | Participants n = 20 admitted to coronary care unit Delirium n = 10, non-delirious matches control n = 10 Age = 53.1 (6.4) Sex (F) = 20% Country: Japan |
4/5 | Outcome: Presence Measure: DSM-III-R |
16-channel EEG 10/20 montage 3-second time constant Amount of data unspecified Theta/alpha ratio calculated by ratio of output over time of theta waves to alpha waves |
↑Theta/alpha ratio |
| Numan et al. (2017) | Participants n = 58 post cardiac surgery Delirium n = 18, non-delirious matched control n = 20, recovering from anaesthesia n = 20 Age = 75.3 (6.4) Sex (F) = 51.7% Country: Netherlands |
3/5 | Outcome: Presence Measure: DSM-IV-R and CAM-ICU |
21-channel EEG 10/20 montage First four artefact free epochs of 8-seconds used Spectral density, delta, alpha, and beta functional and directed connectivity (phase lag index, phase transfer entropy, directed phase transfer entropy and minimum spanning tree) |
↑Delta power ↓ Alpha power ↓ Functional connectivity |
| Numan et al. (2019) | Participants n = 159 undergoing surgery Delirium n = 29, possible delirium n = 26, non-delirious matched control n = 104 Age = 76.9 (6.2) Sex (F) = 33.3% Country: Netherlands |
5/5 | Outcome: Presence and severity Measure: DRS-R-98 and CAM-ICU |
3-channel EEG 10/20 montage 5-minute recording 60 seconds artefact free data selected Relative delta power |
↑Delta power Weak correlation of delta power and delirium severity |
| Plaschke et al. (2007) | Participants n = 37 ICU patients following surgery Delirium n = 17, no delirium n = 20 Age = 63.6 (11.6) Sex (F) = 27% Country: Germany |
5/5 | Outcome: Presence Measure: CAM-ICU |
16-channel EEG 10/20 montage Recorded for at least 10 minutes 4-second epochs Relative theta, alpha, and beta power |
↑Theta power ↓ Alpha power ↓ Beta power |
| Plaschke et al. (2010) | Participants n = 114 post cardiac surgery Delirium n = 32, non-delirious matched control n = 82 Age = 69 (8.9) Sex (F) = 21.9% Country: Germany |
5/5 | Outcome: Presence Measure: CAM-ICU |
4-channel BIS Unspecified montage 15–20-minute recording 5-minutes of artefact free data analysed BIS values, relative theta and alpha power, and theta/alpha ratio |
↑Theta power ↓ Alpha power ↑ Theta/alpha ratio ↓ BIS values |
| Reischies et al. (2005) | Participants n = 12 with major depressive disorder, control = 0 Delirium n = 12 Age = 56.7 (9.4) Sex (F) = 58.3% Country: Germany |
3/5 | Outcome: Presence Measure: ICD-10, DRS and DSM-IV |
32-channel EEG 10/20 montage 20-minute recording Twenty 2.1-second epochs Absolute theta power |
↑Theta power |
| Schramm et al. (2012) | Participants n = 30 (severe sepsis n = 5, septic shock n = 25) Delirium n = 23, non-delirious matched control n = 6 Age = 64 (17) Sex = unspecified Country: Germany |
3/5 | Outcome: Presence Measure: CAM-ICU |
16-channel EEG 10/20 montage Epochs or amount of data not specified Classified by severity based on predominant waveform grade I to V |
n.s. EEG slowing |
| Soehle et al. (2015) | Participants n = 81 undergoing cardiac surgery Delirium n = 26, non-delirious matched control n = 55 Age = 72.9 (6.2) Sex (F) = 29.6% Country: Germany |
5/5 | Outcome: Incidence Measure: CAM-ICU flowchart |
2-channel BIS Unspecified montage Sampled in 5-second intervals Burst suppression ratio defined as percentage of epochs in previous 63 seconds that are suppressed BIS values, burst suppression, EEG asymmetry (In total power within 0–30 Hz) |
n.s. Burst suppression |
| Trzepacz et al. (1987) | Participants n = 40 considered for liver transplantation Delirium n = 12, non-delirious control n = 28 Age: median = 40, range = 18-58 Sex (F) = 62.5% Country: USA |
2/5 | Outcome: Presence Measure: DSM-III |
EEG (unspecified electrode number and montage)MDCS to classify EEG abnormality Epochs or amount of data unspecified |
↑Presence of dysrhythmias grades I to III |
| Trzepacz et al. (1988) | Participants n = 108 considered for liver transplantation Delirium n = 18, non-delirious matched control n = 90 Age = 41 (10.9) Sex (F) = 64.8% Country: USA |
4/5 | Outcome: Presence Measure: DSM-III |
16 or 17-channel EEG 10/20 montage MDCS to classify EEG abnormality Epochs or amount of data unspecified |
↑Presence of dysrhythmias grades I to III |
| Trzepacz et al. (1989a) | Participants n = 247 considered for liver transplantation Delirium n = 46, non-delirious matched control n = 201 Age = 41.3 (11.1) Sex (F) = 62.7% Country: USA |
3/5 | Outcome: Presence Measure: DSM-III |
16 or 17-channel EEG 10/20 montage MDCS to classify EEG abnormality Epochs or amount of data unspecified |
↑Presence of dysrhythmias grades I to III |
| Trzepacz et al. (1989b) | Participants n = 46 considered for liver transplantation Delirium n = 23, non-delirious matched control n = 23 Age = 40.4 (13.8) Sex (F) = 52.2% reported for the delirium group only Country: USA |
4/5 | Outcome: Presence Measure: DSM-III |
4-channel EEG 10/20 montage Data recorded for 24-seconds of each ten minutes Theta power (not stated whether absolute or relative), SEP, PVEP, and BAEPs |
↓Somatosensory evoked potentials n.s. BAEP responses n.s. PVEP responses |
| van Dellen et al. (2014) | Participants n = 49 post cardiac surgery Delirium n = 25, non-delirious matched control n = 24 Age = 75.1 (7.6) Sex (F) = 44.9% Country: Netherlands |
5/5 | Outcome: Presence Measure: CAM-ICU and DSM-IV |
21-channel EEG 10/20 montage 30-minute recording First four artefact free epochs of 8-seconds selected Alpha and beta functional and directed connectivity (phase lag index, directed phase lag index, clustering coefficient, path length, small word index |
↓Functional connectivity |
| van der Kooi et al. (2015) | Participant n = 56 post cardiothoracic surgery Delirium n = 28, non-delirious matched controls n = 28 Age = 75.5 (7.3) Sex (F) = 42.9% Country: Netherlands |
5/5 | Outcome: Presence Measure: DSM-IV-TR and CAM-ICU |
21-channel EEG 10/20 montage 30-minute recording First 60-seconds of artefact free data selected for eyes open and eyes closed (15 eyes open derivations and 210 eyes closed derivations) Relative delta power |
↑Delta power |
Note. Age = mean (standard deviation) unless stated otherwise.
↑ indicates statistically significant increase; ↓ indicates statistically significant decrease; n.s. indicates non-significant relationship between delirium and EEG measure.
CAM-ICU = Confusion Assessment Method for Intensive Care Unit; BIS = Bispectral Index Monitoring; EEG = Electroencephalogram; DRS-R-98 = Delirium Rating Scale-Revised-98; DRS = Delirium Rating Scale; DSM-III = Diagnostic and Statistical Manual of Mental Disorders 3rd Edition; DSV-IV = Diagnostic and Statistical Manual of Mental Disorders 4th Edition; DSM-IV-R = Diagnostic and Statistical Manual of Mental Disorders 4th Edition Text Revision; DSM-V = Diagnostic and Statistical Manual of Mental Disorders 5th Edition; ICD-10 = International Classification of Diseases and Related Health Problems 10th revision; SEP = Somatosensory Evoked Potential’ BAEP = Brainstem Auditory Evoked Potential; PVEP = Pattern Visual Evoked Potential; USA = United States of America.