Correlation of Serum S-100 Protein Level with Severity of Ischaemic Stroke

Abstract

Background: Stroke is currently the second leading cause of death worldwide and the first leading cause of death in Bangladesh. The National Institute of Health Stroke Scale is the most commonly used deficit rating scale to assess stroke severity. S-100 protein is a low molecular weight calcium-binding protein expressed mostly in glial cells like astrocytes, oligodendrocytes, and microglial cells. During the ischaemic process, S-100 protein is secreted from the glial cells into the extracellular space. After secretion, S-100 protein releases initially into the cerebrospinal fluid and then eventually into the bloodstream due to disruption of the blood-brain barrier. Aim of the study: To correlate serum S-100 protein level with the severity of ischaemic stroke. Methods: This cross-sectional study was conducted at the Department of Laboratory Medicine in collaboration with the Department of Neurology, BSMMU, Dhaka, Bangladesh from September 2018 to August 2019. A total of 70 ischaemic stroke patients were enrolled in this study. After taking proper history and neurological examination, the severity of ischemic stroke was assessed on the basis of NIHSS score. Then, serum S-100 protein levels were measured by the Electrochemiluminescence Immunoassay method. Statistical analysis was done by SPSS version 22.0. Results: According to the NIHSS scores, 35(50.0%) of the patients had moderate stroke (NIHSS score=5-15), 17(24.3%) had minor stroke (NIHSS=1-4), 12(17.1%) had moderate to severe stroke (NIHSS=16-20) and 4(5.0%) had severe stroke (NIHSS=21-42). The mean S-100 protein level was found 0.283±0.165 μg/L. Mean S-100 protein levels was assessed in different categories of severity of ischaemic stroke. Maximum Mean± SD value of serum S-100 protein was found in case of severe stroke (NIHSS score=21-42; Mean ± SD: 0.739±0.207, range: 0.523-1.019). The significance test was done by ANOVA test which was found statistically significant (p-value <0.001). Pearson’s correlation test revealed a significant strong positive correlation (r=+943, p<0.001) between serum S-100 protein level and NIHSS scores of ischaemic stroke patients. Conclusion: In the present study it was found that serum S-100 protein levels were higher in severe ischaemic stroke in relation to the ischaemic stroke of lower severity. S-100 protein level is rapidly determined by the method used in the present study. Serum S-100 protein level in this regard can be used as an important tool to predict the severity of ischaemic stroke. Further study is needed to confirm the findings of the present study.