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Table 1 Patients’ characteristics and EEG description at ICU admission

From: Electroencephalography for prognostication of outcome in adults with severe herpes simplex encephalitis

Variables

Total

n = 214

mRS 0–2

n = 57

mRS 3–6

n = 157

p-value

Patients

 Age (years)

63 [53; 72]

57.4 [44.4; 69.1]

65.4 [56.3; 75.4]

< 0.01

 Male sex

111 (51.9)

30 (52.6)

81 (51.6)

0.89

Reason for ICU admission

 Altered mental status

105 (49.1)

26 (45.6)

79 (50.3)

0.11

 Seizure

54 (25.2)

20 (35.1)

34 (21.7)

 

 Other*

55 (25.7)

11 (19.3)

44 (28)

 

Glasgow coma scale¤

 Score

9 [6; 12]

10 [7; 13]

8.5 [6; 12]

0.06

 < 8, indicating coma

73/203 (36)

16/55 (29.1)

57/148 (38.5)

0.21

Temperature§

    

 Degrees (°C)

38.8 [38.1; 39.2]

38.5 [38; 39]

39 [38.2; 39.2]

0.07

 ≥ 38.3 °C, indicating fever

142/201 (70.6)

33/53 (62.3)

109/148 (73.6)

0.12

Focal signs

33/211 (15.6)

12/57 (21.1)

21/154 (13.6)

0.19

CSF

 HSV 1 genotype

175/183 (95.6)

44/47 (93.6)

131/136 (96.3)

0.43

 Leukocytes (/mm3)$

51 [12; 150]

100 [31; 200]

38.5 [9; 125]

0.01

 Lymphocytes (%)

88 [61; 96]

85.4 [36.5; 205.8]

69.7 [25.2; 270]

0.37

 Protein level (g/l)

0.7 [0.5; 1.1]

0.7 [0.5; 1]

0.7 [0.5; 1.2]

0.85

 Glycorachia

4 [3.2; 4.5]

3.9 [3.4; 4.6]

4 [3; 4.4]

0.20

 Hypoglycorachia

18/165 (10.9)

4/46 (8.7)

14/119 (11.8)

0.66

Abnormal MRI at admission

188/190 (98.9)

53/55 (96.4)

135/135 (100)

0.02

Invasive mechanical ventilation

138 (64.5)

28 (49.1)

110 (70.1)

< 0.01

EEG

Time between ICU admission and stdEEG (in days)

1 [0; 2]

1 [0; 1]

1 [0; 2]

0.16

EEG recorded with sedation

81/211 (88.4)

20/56 (35.7)

61/155 (39.4)

0.63

Background rhythm

 Low voltage

32/209 (15.3)

11/55 (20)

21/154 (13.6)

0.26

 Asymmetry in voltage

25/213 (11.7)

4/57 (7)

21/156 (13.5)

0.20

 Asymmetry in frequency

65/213 (30.5)

17/56 (30.4)

48/157 (30.6)

0.98

 Discontinuous rhythm

21/213 (9.9)

5/57 (8.8)

16/57 (28)

0.79

Maximal background frequency recorded

 Alpha (> 7 Hz)

60 (28)

23 (40.4)

37 (23.6)

0.05

 Frequency not specified

45 (21)

11 (19.3)

34 (21.7)

 

 < 7 Hz

109 (50.9)

23 (40.4)

86 (54.8)

 

Minimal background frequency recorded

 Alpha (> 7 Hz)

23 (10.7)

10 (17.5)

13 (8.3)

0.12

 Frequency not specified

52 (24.3)

11 (19.3)

41 (26.1)

 

 < 7 Hz

139 (65)

36 (63.2)

103 (65.6)

 

Presence of lateralized periodic discharges (LPDs)

91 (42.5)

26 (45.6)

65 (41.4)

0.58

Interictal epileptic activities

 Spikes or sharps

46 (21.5)

12 (21.1)

34 (21.7)

0.92

 Spike-and-wave/sharp-and-wave

14 (6.5)

2 (3.5)

12 (7.6)

0.28

Seizures

21 (9.8)

5 (8.8)

16 (10.2)

0.76

Status epilepticus

16 (7.4)

2 (3.5)

14 (8.9)

0.18

Reactivity

 Present

69 (32.2)

24 (42.1)

45 (28.7)

0.01

 Not tested

74 (34.6)

23 (40.4)

51 (32.5)

 

 Absent

71 (33.2)

10 (17.5)

61 (38.9)

 
  1. Results expressed as medians [quartiles] or numbers (%)
  2. Attenuation: periods ≥ 10 µV but < 50% of the higher voltage background
  3. Suppression: periods of lower voltage are < 10 µV of the higher voltage background
  4. mRS: modified Rankin Scale; ICU: intensive care unit; stdEEG: standard electroencephalography; GCS: Glasgow Coma Scale; CSF: cerebrospinal fluid; HSV: herpes simplex virus; MRI: magnetic resonance imaging
  5. ϕA good functional status prior to admission was defined by a Knaus score of A or B
  6. £Initial admission to hospital wards vs direct ICU admission
  7. *Other reasons included mainly respiratory failure
  8. ¤GCS was determined in 203 patients
  9. §Temperature was determined in 201 patients
  10. Data about HSV genotype was available for 183 out of 214 patients (others had unspecified HSV positivity in the CSF)
  11. $Leukocyte count was determined in 205 patients
  12. Lymphocyte count was determined in 133 patients
  13. Protein level was determined in 183 patients
  14. Glycorachia level was estimated in 165 patients
  15. Includes low voltage (i.e. 10–20 µV) and suppressed voltage (i.e. < 10 µV)
  16. Includes discontinuous (10–49% attenuated or suppressed), burst attenuation/suppression (50–99% attenuated or suppressed), suppression/attenuation (> 99% attenuated or suppressed)