An Association Between Inammation and Cerebral Venous Thrombosis: A Retrospective Study

Background: Evidence is currently accumulating for the role of inammation in cerebral venous thrombosis (CVT). Neutrophil/lymphocyte ratio (NLR), platelet/lymphocyte ratio (PLR), monocyte/high-density lipoprotein ratio (MHR), and systematic immune-inammation index (SII) are easily obtainable indicators of systemic inammations. However, there were few studies on the relationship between them and CVT. Therefore, we aimed to evaluate the connection between the occurrence of CVT and the inammatory markers described. Methods: The samples from 150 participants (including 90 CVT and 60 controls) with similar baseline characteristics were collected in this retrospective study. The NLR, PLR, MHR, SII and le records were employed to compare CVT patients with the control group. Results: The levels of NLR (3.93 [2.27, 7.87] vs. 1.65 [1.31, 2.06], P < 0.001), PLR (149.52 [98.39, 198.82] vs. 107.34 [83.31, 129.47], P < 0.001), SII (382.45 [273.51, 520.92] vs. 896.84 [559.89, 1591.87], P < 0.001) and MHR (0.51 [0.40, 0.64] vs. 0.41 [0.29, 0.53], P = 0.001) were signicantly higher in the CVT group. After multivariate logistic regression analysis, the SII degree (13.136, [5.675, 30.407], P < 0.001) and MHR degree (2.620, [1.123, 6.113], P = 0.026) were found as independent predictors of CVT. Conclusions: NLR, PLR, SII, and MHR may be able to predict the onset of CVT which conrmed that inammation played an important role in CVT.


Data collection
Following data of patients with CVT were obtained at baseline in the study: demographics; dates of onset of symptoms and admission, the features of imaging; the National Institutes of Health Stroke Score (NIHSS) and blood test results (i.e. the level of direct bilirubin (DBil), HDL, white blood cell (WBC), red cell distribution width (RDW), mean platelet volume (MPV), monocytes, neutrophils, and lymphocytes.
Demographics and blood test results were also collected in the control group.
The severity of CVT on admission was divided into ve grades according to NHISS, with 0 to 1 as degree 1, 2 to 4 as degree 2, 5 to 15 as degree 3, 16 to 20 as degree 4, and over 20 as degree 5. The time from the onset of symptoms to admission was less than 30 days that were de ned as an acute-subacute onset, while more than 30 days as a chronic onset.

Statistical analysis
All statistical analyses were performed by SPSS 20.0 for Windows (IBM, Armonk, N.Y., USA). Quantitative variables with a normal distribution were speci ed as mean ± standard deviation and with abnormal distribution were expressed as median with interquartile range (IQR). Categorical variables were speci ed with number and percentage (%) values. Student's t-test or Mann-Whitney test was used for continuous data, while the χ2 test was used for categorical data. Student's t-test or Mann-Whitney test and univariate regression analysis were used to verify factors correlated with clinical outcomes. The receiver operating characteristic (ROC) curve was used to demonstrate the sensitivity and speci city of signi cant variables and the optimal cut-off values for predicting the onset. We obtained optimal cut-off values via calculating best Youden index. Factors with P < 0.05 in the univariate analysis were entered into a forward multivariable logistic regression analysis. The correlation between in ammation and the severity of CVT was evaluated by Spearman's correlation analysis. All statistical analyses were conducted using the statistical software package SPSS 20.0 for Windows. Two-tailed P-value ≤ 0.05 was considered to indicate a signi cant difference.

Patients
A total of 90 CVT patients (mean age: 37.83 ± 15.92 years old, sex: 35 females and 55 males) and 60 controls (mean age: 39.17 ± 13.24 years old, sex: 21 females and 39 males) were included in the study. The demographic and clinical characteristics of the patients and controls were summarized in Table 1.

In ammation indicators and the onset of CVT
The ROC curves were applied to investigate whether NLR, PLR, SII, and MHR could be used to predict the onset of CVT (Fig. 1). The results showed that the predicting power of baseline serum NLR, PLR, SII, and MHR on the onset with an area under the curve value of 0.826, 0.702, 0.827, 0.657 (all P < 0.05), respectively ( Table 2). The optimal cutoff of NLR, PLR, SII and MHR is 2.14 (sensitivity 0.789, speci city 0.800), 147.11 (sensitivity 0.533, speci city 0.867), 496.07 (sensitivity 0.844, speci city 0.75), and 0.42 (sensitivity 0.711, speci city 0.600), respectively. To further estimate the baseline in ammation status on predicting the onset of CVT, the level of SII and MHR was divided into two degrees (SII < 496 and ≥ 496; MHR < 0.42 and ≥ 0.42) according to the optimal cutoff value of those indicators. The multivariate logistics analysis found that degree of SII and MHR were signi cantly associated with the onset of CVT (SII degree, adjusted OR 13.136, 95% CI 5.675-30.407, P < 0.001; MHR degree, adjusted OR 2.620, 95% CI 1.123-6.113, P = 0.026) ( Table 3). The ROC curve revealed the predicting power of the model with an area under the curve value of 0.847 (P < 0.001, 95% CI 0.779-0.916) (Fig. 2).

In ammation indicators and the severity of CVT
All 90 patients were divided into ve groups based on NHISS on admission. Correlation analysis demonstrated that the level of NLR (r = 0.369, P < 0.001), PLR (r = 0.242, P = 0.022) and SII (r = 0.329, P < 0.001) were positively associated with baseline NHISS. Correlation analysis did not re ect the correlation between the number of segments involved and the level of NLR, PLR, SII or MHR (Fig. 3).  (Fig. 4).

Discussion
In recent years, CVT has attracted more attention to the morbidity increasing [1]. It presents various neurological signs and symptoms, and its common clinical presentations (e.g., headache, seizures, focal neurological de cits, altered consciousness, and papilledema) can present in isolation or association with other symptoms [20]. Headache, the most common symptom in CVT, was present in nearly 90% of patients in the International Study on Cerebral Vein and Dural Sinus Thrombosis [21]. Similar headache frequency was reported in our study and 37.8% CVT patients presented isolated headache (Table 1). For this reason, patients with primary headaches were selected as the control group.
Due to complex and nonspeci c clinical ndings of CVT, delay in diagnosis and misdiagnosis frequently occurred. It's reported that an initial misdiagnosis of CVT could occur in 73% of patients [22] and delays in diagnosis for over 10 days could happen in 40% of patients admitted to the hospital [23]. A median delay of 7 days (mean ± SD, 18.3 ± 59.4 days) was reported [24]. Even though they received standard anticoagulation, the deterioration of neurological function was hard to be reversed or stopped [25]. Over 50% of the discharged patients complained about headache and 20-30% complained about depression, concentration problems, linguistic di culties, or cognitive impairment, which had an impact on their psychosocial functioning and employment status [26][27][28]. Therefore, nding an accurate and accessible indicator to achieve prompt diagnosis is essential and important since it might reduce the incidence of death and long-term sequelae [29].
Up to now, D-dimer is the only recognized blood index related to CVT. However, there are some shortages.
First, it was considered to help excluding CVT for its low positive predictive value [1]. Second, CVT patients with less clot burden may be particularly at risk of false-negative results [30]. Furthermore, a number of different D-dimer assays are available with variable test performance characteristics [1]. Therefore, it is expected to access a better index from routine blood work.
A close link between in ammation and thrombosis has been detected in previous studies [31,32]. Although the pathophysiology of CVT has not been de ned yet, the evidence is currently accumulating for the role of in ammation in CVT. Gu et al. [7] have demonstrated that recombinant human soluble thrombomodulin reduced infarct volume in a model of CVT, via inhibiting in ammation by blocking high mobility group box 1 (HMGB1) binding to a receptor for advanced glycation end-products. Rashad and Nagai et al. [6,33] found intense in ammatory cell in ltration on the infarct area and high level in several in ammation indicators in the early stage of CVT. Also, previous clinical studies have found in ammation indicators (e.g., MPV, RDW, CRP, ESR, and bilirubin) increasing in patients with CVT [8,34,35], potently hinting the correlation between in ammation and the severity and outcome of CVT. Consistent with the previous results, the high levels of WBC, monocyte, neutrophils, and platelets were found in CVT patients compared with the control group. Incompatibly, the MPV value was found within the normal range with a lower value in the CVT group. Several studies believed that MPV is not able to re ect in ammation properly, and that could decrease in the acute stage [36]. Based on the results of this study, it is hard to de ne whether a lower MPV level resulted from a low number of participants or the pathophysiological properties of CVT. All of these pathologic processes, well-known risk factors, and laboratory ndings of CVT were associated with an in ammatory state. Regardless of the direction of the relationship, it was believed to have a signi cant correlation between in ammation and CVT.
With the growing understanding of in ammation, NLR, PLR, SII, and MHR have been widely investigated in malignancies, in ammatory diseases, cardiovascular and cerebrovascular diseases. These indicators are more stable than individual blood parameters, which may be altered by several variables (e.g., dehydration, overhydration, and blood specimen handling) [37]. Indicating the balance of the neutrophils (the active component of the in ammation) with the lymphocytes (the regulatory and protective component), NLR was found to be a good prognostic factor in functional outcomes and mortality in patients with severe traumatic brain injury [38]. Zeng et al. [17] demonstrated that both NLR and PLR can be used to predict the diagnosis and prognosis of nasopharyngeal carcinoma [17]. Many studies revealed that DVT improves the levels of NLR and PLR [11,39]. As for SII, considering together neutrophil, platelet, and lymphocyte, it suggested the balance between host systemic in ammation and coagulation status comprehensively, thus it was used in predicting outcomes of malignancies and ischemic stroke [15-17, 40, 41]. Monocytes were reported to involve in in ammatory and pro-thrombotic pathways, while HDL interferes with the pro-in ammatory effects of monocytes by inhibiting the migration of macrophages [42][43][44][45]. Therefore, it assumed that MHR was a reliable and more comprehensive indicator of in ammation. Indeed, it has been reported that higher MHR was associated with poor outcome of cardiovascular diseases and renal dysfunction [18,19,45]. For this reason, we hypothesized the association between SII, NLR, PLR, and MHR with the onset of CVT. Our study con rmed that the levels of NLR, PLR, SII, and MHR were signi cantly higher in CVT patients. ROC curves were analyzed and showed a satisfying result. The area under the ROC curve (AUC) of NLR, PLR, SII, and MHR was 0.826, 0.702, 0.827, and 0.657, respectively, suggesting the power of SII, NLR, and PLR in predicting CVT. NLR and SII yielded a sensitivity of 0.780 and 0.844 and a speci city of 0.800 and 0.750, respectively. Basing on the multivariable regression analysis, the degrees of SII and MHR remained as independent indicators of CVT that the AUC was 0.847 representing a good predicting power. Therefore, NLR, PLR, SII, and MHR could help clinicians to suspect CVT, especially among the patients with unexplained headache and a normal plain CT, then decide which patients require MRI/MRV immediately for con rmation of the diagnosis. These would help to shorten the time from the onset of symptoms to diagnosis and reduce misdiagnosis.
Moreover, the results of this study found that the levels of SII, NLR, and PLR were positively correlated with the baseline NHISS degree, indicating the vital role of in ammation in the progression of CVT. However, there was no difference in in ammation indicators among patients with different numbers of cerebral venous sinus involved. In another word, SII, NLR, and PLR levels were not correlated with the anatomic extent of thrombosed sinuses, which enable them to better identify patients with lighting clot burden than D-dimer [30].
Furthermore, the NLR and SII levels were distinctly higher in the acute-subacute stage of CVT, which was consistent with the results of another study [34]. Wang et al. [34] demonstrated that in ammation may develop soon after CVT and gradually decrease during the course. In ammation may affect mainly during the early stage. The previous study on DVT mouse model found that neutropenic mice developed no or signi cantly smaller thrombi compared with controls [32], but it needed further research to con rm whether an early intervention of in ammation is bene ted for CVT patients.
The results of this study focused on the differences between CVT patients and primary headache patients, which might help more in clinical practice since CVT patients presenting isolated headache were more likely to be at risk of delay in diagnosis and misdiagnosis. However, there were still some limitations. First, there was not enough study population because of the low morbidity of CVT. Second, as a retrospective study, there was some missing data and only baseline values were analyzed rather than the temporal trend. Third, it cannot explain whether the milieu of increased in ammation was present before the onset of disease and caused the thrombus or it was a response to the thrombus.

Conclusion
NLR, PLR, SII, and MHR levels were remarkably higher in CVT patients, which can be utilized to predict the onset. In ammation exerts a critical role in CVT and may be a promising therapeutic target for CVT. Further prospective randomized controlled study and animal experiments are needed to verify our ndings and de ne the underlying mechanism of in ammation acting on CVT. The correlation between in ammation indicators and the severity of CVT. PLR, platelet/lymphocyte ratio; NLR, neutrophil/lymphocyte ratio; SII, systematic immune-in ammation index; MHR, monocyte/highdensity lipoprotein ratio.