General data
One hundred and sixty-four patients with anti-NMDAR encephalitis were enrolled in the study. Of them, 95 were from Peking Union Medical College Hospital and 69 were from Henan Provincial People’s Hospital. Ninety-four (57.3%) were female and 70 (42.7%) were male, yielding a female:male ratio of 1.34:1.00. The mean age was 25.85 ± 12.62 years (range 2–65 years). 18 women (19.1% of female) presented ovarian, while 1 woman thymoma, 1 man carcinoma. 43 patients (26.2% of all patients) have received immunotherapy before lumbar puncture. The median mRS score was 4 (range 1–5). The general data of the enrolled patients were presented in table 1.
Table 1: The general data of the enrolled 164 patients with anti-NMDAR encephalitis
Variable
|
Value
|
Female (No, percentage)
|
94 (57.3%)
|
Age (year, median (25th, 75th percentile))
|
23 (17, 30.75)
|
Time since symptom onset (day)
|
30(15, 60)
|
Presence of tumor (No, percentage)
|
20 (12.2%)
|
Tumor types
|
|
Ovarian teratoma (No, percentage of female)
|
18 (19.1%)
|
Thymoma (No, percentage)
|
1 (0.6%)
|
Carcinoma (No, percentage)
|
1 (0.6%)
|
First episode (No, percentage)
|
139 (84.8%)
|
Recurrence episode (No, percentage)
|
25 (15.2%)
|
Immunotherapy before lumbar puncture (No, percentage)
|
43 (26.2%)
|
mRS score (median (25th, 75th percentile))
|
4(3, 5)
|
mRS, modified Rankin Scale; NMDAR, N-methyl D-aspartate receptor
CSF cytology
All 164 patients underwent CSF cytology examination (Table 2), and lymphocytes and monocytes were detected in all samples (100%). Neutrophils were detected in 23/164 (14.0%) samples, and eosinophils were detected in 1/164 (0.6%). Activated lymphocytes were detected in 51/164 (31.1%) samples and plasma cells were detected in 16/164 (9.8%). Inflammatory reactions were evident in samples from 112/164 (68.3%) patients, of which 46 were deemed mild, 58 moderate, and 8 severe. With regard to inflammation type, 89 patients exhibited lymphocytic inflammation, 22 exhibited lymphocytic and neutrophilic mixed inflammation, and 1 exhibited lymphocytic, neutrophilic, and eosinophilic mixed inflammation. The proportion of neutrophils in the total number of leukocytes ranged from 1% to 80%. In 11 patients the proportion of neutrophils was < 10%, in 8 patients it was between 10% and 50%, and in 3 patients it exceeded 50%. In the 1 patient with lymphocytic, neutrophilic, and eosinophilic mixed inflammation there was 3% neutrophils and 2% eosinophils. Representative images of CSF cytology in patients with anti-NMDAR encephalitis are shown in Figure 1.
Table 1 The CSF results of 164 patients with anti-NMDAR encephalitis
Variables
|
Units
|
Value
|
CSF cytology (164 cases)
|
|
|
Abnormal
|
Samples
|
112/164 (68.3%)
|
Inflammation degree in CSF cytology
|
|
|
Mild inflammatory reaction
|
Samples
|
46/164 (28.0%)
|
Moderate inflammatory reaction
|
Samples
|
58/164 (35.4%)
|
Severe inflammatory reaction
|
Samples
|
8/164 (4.9%)
|
Inflammatory type
|
|
|
Lymphocytic inflammation
|
Samples
|
89/164 (54.3%)
|
Lymphocytic and neutrophilic mixed inflammation
|
Samples
|
22/164 (13.4%)
|
Lymphocytic, neutrophilic and eosinophilic mixed inflammation
|
Samples
|
1/164 (0.6%)
|
Activated lymphocyte
|
Samples
|
51/164 (31.1%)
|
Plasma cell
|
Samples
|
16/164 (9.8%)
|
NMDAR antibody titers (142 cases)
|
|
|
Mild positive
|
Samples
|
24/142 (16.9%)
|
Moderate positive
|
Samples
|
59/142 (41.5%)
|
Strong positive
|
Samples
|
54/142 (38.0%)
|
Extensive positive
|
Samples
|
5/142 (3.5%)
|
CSF routine examination (164 cases)
|
|
|
White cell counts (range)
|
Cells ×10 6/L
|
0-242
|
White cell counts (median (25th, 75th percentile))
|
Cells ×10 6/L
|
10 (2, 34)
|
White cell counts (0-5)×106/L
|
Samples
|
59/164 (36.0%)
|
White cell counts (6-10)×106/L
|
Samples
|
26/164 (15.9%)
|
White cell counts (11-100)×106/L
|
Samples
|
71/164 (43.3%)
|
White cell counts > 100×106/L
|
Samples
|
8/164 (4.9%)
|
CSF protein (164 cases)
|
|
|
CSF protein ( range)
|
g/L
|
0.083 -1.93
|
CSF protein ( median (25th, 75th percentile))
|
g/L
|
0.36 (0.26, 0.52)
|
CSF protein < 0.45g/L
|
Samples
|
110/164 (67.1%)
|
CSF protein (0.45-1)g/L
|
Samples
|
43/164 (26.2%)
|
CSF protein (1-1.5)g/L
|
Samples
|
8/164 (4.9%)
|
CSF protein > 1.5g/L
|
Samples
|
3/164 (1.8%)
|
CSF glucose (164 cases)
|
|
|
CSF glucose (range)
|
mmol/L
|
1.38-7.0
|
CSF glucose (mean±SD)
|
mmol/L
|
3.46 ± 0.88
|
CSF glucose < 2.5mmol/L
|
Samples
|
9/164 (5.5%)
|
CSF chlorine (164 cases)
|
|
|
CSF chlorine (range)
|
mmol/L
|
109 - 135
|
CSF chlorine (mean±SD)
|
mmol/L
|
123.46 ± 4.49
|
CSF chlorine <120mmol/L
|
Samples
|
23/164 (14.0%)
|
Intracranial pressure (146 cases)
|
|
|
Intracranial pressure (range)
|
mmH2O
|
20 - 350
|
Intracranial pressure (median (25th, 75th percentile))
|
mmH2O
|
160 (130, 220)
|
Intracranial pressure >180mmH2O
|
Samples
|
54/146 (37.0%)
|
OCBs (111 cases)
|
|
|
Specific OCBs positive
|
samples
|
51/111 (45.9%)
|
NMDAR, N-methyl-D-aspartate receptor; CSF, cerebrospinal fluid; OCBs, oligoclonal bands
Routine CSF examination
Intracranial pressure data were obtained from all 146 patients. High intracranial pressure was detected in 54 (37.0%), low intracranial pressure was detected in 5, and in 87 patients intracranial pressure was normal. Increased white cell counts in CSF were detected in 105/164 (64.0%) samples via routine CSF examination, with a median of 10 x 106 cells/L (range 0–242 x 106 cells). Severe pleocytosis, defined as CSF white blood cell counts ≥ 100 x 106/L, was only present in 8/164 (4.9%) samples (median 130 x 106/L, 25th and 75th percentiles 115.5 x 106/L and 210 x 106/L, range 101 x 106/L–242 x 106/L). All the above results are presented in Table 2.
CSF biochemical tests
As shown in Table 2, total protein levels in the CSF were elevated in 54/164 (32.9%) patients (range 0.46–1.93 g/L). In 43/164 (26.2%) patients elevated total protein levels of > 0.45 and < 1.0 g/L were detected, in 8/164 (4.9%) patients elevated total protein levels between 1.0 and 1.5 g/L were detected, and in 3/164 (1.8%) patients elevated total protein levels exceeded 1.5 g/L. CSF glucose levels were decreased in 9/164 (5.5%) patients (median 2.30, 25th and 75th percentiles 1.57 and 2.35 mmol/L, range 1.38–2.43 mmol/L). Chlorine was decreased in the CSF of 23/164 (14.0%) patients, with a median of 117 mmol/L (range 109–119 mmol/L).
Specific OCBs
Of the 164 patients in the study 111 underwent OCB examination, and in 51 patients specific OCBs were detected in the CSF (Table 2). The positivity rate in the 111 patients examined was 45.9%.
NMDAR antibody titers in CSF
As at the beginning of our work, some patients’ NMDAR antibody titers were not been fully evaluated, finally 142 patients’ NMDAR antibody titers in CSF were obtained, of which 24 were deemed mild positive, 59 moderate positive, 54 severe positive and 5 extensive positive (Table 2).
Correlations between mRS score and CSF parameters, and associations between plasma cells and specific OCBs
Spearman’s rank correlations between mRS score and CSF parameters showed that mRS score was significantly correlated with NMDAR antibody titer in CSF (rho = 0.357, p < 0.001); however, mRS score was not significantly correlated with white cell count determined via routine CSF examination (rho = 0.130, p = 0.096), degree of inflammation determined via routine CSF examination (rho = 0.147, p = 0.060), white cell count determined via CSF cytology (rho = 0.120, p = 0.125), or degree of inflammation determined via CSF cytology (rho = 0.101, p = 0.198)(Figure 2 and Table 3). The χ2 test was used to assess the association between plasma cells and specific OCBs (Table 4), and the two parameters were not significantly associated (χ2 = 0.831, r = 0.086, p = 0.362).
Table 3: Correlations between mRS score and CSF parameters in patients with anti-NMDAR encephalitisa
|
mRS score (n=164)
|
rho
|
p value
|
White cell count determined via routine CSF examination
|
0.130
|
0.096
|
Degree of inflammation determined via routine CSF examination
|
0.147
|
0.060
|
White cell count determined via CSF cytology
|
0.120
|
0.125
|
Degree of inflammation determined via CSF cytology
|
0.101
|
0.198
|
NMDAR antibody titer in CSF
|
0.357
|
<0.001*
|
a Spearman’s rank correlational test
*p <0.05
mRS, modified Rankin Scale; NMDAR, N-methyl D-aspartate receptor; CSF cerebrospinal fluid
Table 4: Associationa between plasma cells and specific OCBs in patients with anti-NMDAR encephalitis.
|
|
Specific OCBs
|
Value
|
|
|
Negative
|
Positive
|
Total
|
Plasma cells
|
Negative
|
55
|
44
|
99
|
χ2 = 0.831
|
Positive
|
5
|
7
|
12
|
r = 0.086
|
Total
|
60
|
51
|
111
|
p = 0.362
|
aχ2 test
*p < 0.05
OCBs, oligoclonal bands; NMDAR, N-methyl-D-aspartate receptor
Correlations and comparisons between routine CSF examination and CSF cytology
White cell count determined via routine CSF examination was significantly positively correlated with white cell count determined via cytology (rho = 0.630, p < 0.001), and degree of inflammation determined via routine CSF examination was significantly positively correlated with degree of inflammation determined via cytology (rho = 0.592, p < 0.001 )(Table 5). In comparison of the detective ability of routine CSF examination at a positivity threshold of 5 × 106 white blood cells/L with that of CSF cytology, the difference was statistically significant (p < 0.001). The associated kappa value was 0.388 (p < 0.001), thus the consistency between the two methods was poor (Table 6).
Table 5: Correlationsa between routine CSF examination and CSF cytology in patients with anti-NMDAR encephalitis.
|
White cell count determined via cytology (n=164)
|
|
Degree of inflammation determined via cytology (n=164)
|
rho
|
p value
|
|
rho
|
p value
|
White cell count determined via routine CSF examination
|
0.630
|
<0.001*
|
Degree of inflammation determined via routine CSF examination
|
0.592
|
<0.001*
|
|
|
|
|
|
|
|
aSpearman’s rank correlational analysis
*p < 0.05
CSF; cerebrospinal fluid; NMDAR N-methyl-D-aspartate receptor
Table 6: Analysis of the comparison and consistency between CSF cytology and routine examination in 164 patients with anti-NMDAR encephalitis.
|
CSF cytology
|
χ2 test
|
Kappa test
|
Positive
|
Negative
|
CSF routine examination (<=5×106/L)
|
26
|
33
|
χ2 = 24.974
|
Kappa = 0.388
|
CSF routine examination(>5×106/L)
|
86
|
19
|
p<0.001*
|
p<0.001*
|
*p < 0.05
CSF; cerebrospinal fluid; NMDAR N-methyl-D-aspartate receptor
Correlations between mRS score and CSF cytology parameters in non-pleocytosis subgroup based on routine diagnostics
Correlations between CSF cytology results and disease severity in the non-pleocytosis subgroup based on routine diagnostics were also conducted(Table 7). In the total 59 patients those presented non-pleocytosis based on CSF routine examination, 26 samples showed inflammation in CSF cytology while 33 were negative. In this subgroup, mRS score was positively correlated with white cell count and degree of inflammation determined via CSF cytology (rho = 0.259, p = 0.047; rho = 0.264, p = 0.043, respectively), and patients with CSF inflammation detected by cytology were likely to have more serious disease severity (mRS>3) ( χ2 = 5.544, p = 0.019) in comparison to patients with negative cytological findings (Figure 3).
Table 7: Correlations between mRS score and CSF cytology parameters in non-pleocytosis subgroup based on routine diagnosticsa
|
mRS score(n=59)
|
rho
|
p value
|
White cell counts determined via cytology
|
0.259
|
0.047*
|
Degree of inflammation determined via cytology
|
0.264
|
0.043*
|
a Spearman’s rank correlational analysis
* p < 0.05
mRS, modified Rankin Scale; CSF cerebrospinal fluid