General change trend of routine CSF biochemical tests
The change trend of body temperature after LCD was as follows: body temperature first decreased, increased and then decreased. Body temperature on the second day after drainage was significantly different from body temperature before drainage (P < 0.001). Body temperature began to increase on the sixth day after drainage and reached the highest point on the ninth day after drainage, after which it began to decrease (Figure 2A). The WBC count on the first day after drainage was significantly higher than WBC count before drainage (P<0.001), and then began to show an overall downward trend. By day 4, the WBC count was significantly lower than the WBC count before drainage (P=0.004<0.01) (Figure 2B). The change trend of the polykaryocyte percentage was similar to that of body temperature; it began to decrease significantly on the third day after drainage (P=0.004<0.01) (Figure 2C). The time node was synchronized with the change of WBC. Of note, protein was above the normal range during drainage (Figure 2D), the change of glucose was within the normal range during drainage (Figure 2E) and the change of chloride was essentially below the normal range during drainage (Figure 2F). These trends were overall consistent with the characteristics of meningitis.
Correlation analysis of daily CSF drainage with body temperature and WBC
Correlation analysis demonstrated a negative correlation between daily CSF drainage and body temperature (r = -0.14), and there was no statistical difference between the two trends (P=0.65 > 0.05) (Figure 3A, 3B). There was also a negative correlation between daily CSF drainage and WBC count (r = -0.56), with a statistical difference between the two trends (P=0.046 < 0.05) (Figure 3C, 3D). There was a negative correlation between daily CSF flow and polykaryocyte percentage (r = -0.29), with no statistical difference between the two trends (P=0.34 > 0.05) (Figure 3E, 3F). Lastly, there was a positive correlation between WBC count and polykaryocyte percentage (r = 0.696), and the change trend of the two was statistically different (P=0.006 < 0.01) (Figure 3G, 3H).
When the daily CSF drainage volume was 250-300 ml, the WBC change curve was most consistent with the overall WBC change curve
Based on the observed average daily CSF drainage volumes, the patients were divided into five groups: 100-150 ml/d (n=11, 21.6%), 150-200 ml/d (n=19, 37.3%), 200-250 ml/d (n=9, 17.6%), 250-300 ml/d (n=8, 15.7%) and greater than 300 ml/d (n=4, 7.8%). The WBC change curves of the five groups all increased on the first day after drainage, and then presented an overall trend of decline. Among them, the WBC of the 250-300ml/d group decreased the most significantly on the fourth day after drainage (P=0.006<0.01), and the subsequent fluctuation was smaller, which was most consistent with the overall WBC curve when compared with the other subgroups (Figure 4A). In addition, there was no significant difference in drainage time between the five groups (Figure 4B), indicating that although the WBC trend for the 200-250 ml/d group was most consistent with the overall WBC change curve, more daily flow did not shorten duration of LCD placement.
The type of antibiotic affects the WBC change curve
Patients were divided into four groups according to the types of antibiotics used during drainage, as follows: cephalosporin treatment group (more than 3 generations of cephalosporin) (n=16, 31.4%), meropenem treatment group (n=10, 19.6%), linezolid treatment group (n=7, 13.7%) and multiple antibiotic treatment group (n=18, 35.3%). The WBC count change curve of the meropenem group and the multiple antibiotic group was consistent with the overall curve, while the cephalosporin group and linezolid group showed some fluctuations. The decrease of WBC on the fourth day of drainage was the most significant in the meropenem treatment group (P=0.011<0.05) (Figure 4C). In addition, the drainage time between the meropenem treatment group and the cephalosporin treatment group was relatively short, and there was a statistical difference in the drainage time between the cephalosporin treatment group and the linezolid treatment group (P=0.012 < 0.05) and the multiple antibiotic treatment group (P=0.021 < 0.05) (Figure 4D). There was no significant statistical difference in the daily drainage volumes of the four groups (P>0.05) (Figure 4E).
Differences in body temperature and WBC curve in different surgical sites
Based on the surgical site, patients were divided into two groups: the supratentorial craniotomy group (n=23, 45.1%) and the subtentorial craniotomy group (n=28, 54.9%). A statistical difference was observed in the drainage time between the two groups (P=0.012<0.05), with a longer drainage time in the supratentorial craniotomy group, and no significant statistical difference was observed in the daily drainage volume between the two groups (P>0.05) (Figure 5A). The trends of body temperature, WBC and polykaryocyte percentage were similar in the two groups. However, according to the trend of body temperature changes of the two groups, the overall body temperature of the supratentorial surgery group was higher than that of the subtentorial surgery group. When comparing body temperature at each time point before and 5 days after drainage, there were statistically significant differences in body temperature between the two groups (Figure 5B), suggesting that symptoms of postoperative meningitis may vary in different surgical sites and that symptoms of hyperthermia are more common in the supratentorial surgery group. Overall, the differences in WBC count (Figure 5C) and polykaryocyte percentage (Figure 5D) at each time point between the two groups were not particularly significant.