Prognostic Value Of Short-latency Somatosensory-evoked Potentials In Patients With Acute Cerebral Infarction

Background Cerebral infarction(CI), also known as ischemic stroke, is the result of a disturbance of the cerebral blood circulation caused by various reasons, which leads ultimately to a series of clinical syndrome includinglocal brain tissueischemic and anoxic necrosis and thenrelevant neurologic impairment. The disability rate and fatality rate of cerebral infarction is very high, especially the acute severe cerebralinfarction accompanying with disturbance of consciousness, high intracranial pressure, persistent high fever and serious medical complications. The prognosis is related to infarction location and infarct size. Although there are still some area of infarction and infarct size is similar, patients on clinical prognosis is still a big difference. This is closely related to the damage and recovery degree of patients' brain function. Therefore, it is very important to take an efficient way in the early stage to evaluate the brain function, guide the medical measures, distribute the medical resources and select the treatment regimens. On clinical, the techniques used to evaluate the brain function mainly include head computed tomography (CT), transcranial doppler, electroencephalogram and so on. However, these techniques are restricted to certain conditions, for example, head CT can't be assessed beside the bed, transcranial doppler (TCD) only reflects blood flow velocity but can't reflect neurological function of patients; electroencephalogram (EEG) is greatly influenced by temperature and narcotic drugs. While short-latency somatosensory evoked potentials (SLSEP) can be assessed beside the bed and not affected by sedative drugs and state of consciousness, which is an ideal method of making brain function assessment. The acknowledged SLSEP originates fromsubcortex and its main parameters include N9, N13, P15, N20, N25 and central conduction time (CCT), etc. Of which, N9 wave, N13 wave mainly originate from the peripheral nerve while N20 wave originates from the posterior central gyrussomatosensory cortex of stimulation. CCT mainly indicates the central conduction time, these two indexes have become key points of evaluating brain damage prognosis, but these studies were mainlyclassification research based on whether N20 amplitude occurred, CCT prolonged, like the current widely used Judson grading standard, Haupt grading standard. The present study for N20 amplitude of evoked potential is less, and the majority of studies is focus on the brain damage after cardiopulmonary resuscitation and cerebral trauma, while relatively less study on brain damage caused by ischemic infarction. While N20 amplitude can directly reflect number of reservations in medial lemniscus and relative integrity of medial lemniscus is important influencing factor for cerebral infarction. Therefore, this research make an assessment to the prognosis of patients with cerebral infarction, assuming that N20 amplitude size can predict the prognosis of patients with cerebral infarction and making a comparison with Judson grading standards.Purpose Evaluate Judson grading standard of short-latency somatosensory evoked potentials (SLSEP) and predictive value of affected side N20 amplitude to prognosis of patients with acute cerebral infarction, establish ROC curve of affected side N20 amplitude and Judson grading standard in assessment of cerebral infarction.Methods 46 patients with acute cerebral infraction in the neurologydepartment of Zhongda Hospital Affiliated to Southestern China University from February 2015 to January 2016 were included in the group and they were proved to suffer from acute cerebral infraction by CT scanning or magnetic resonance imaging (MRI) scanning and they were tested by SLSEP in one week. Parameter values of SLSEP and NIHSS were recorded in 3-7 days. Three months later, Rankin score (Modified Rankin Scale) were adopted to conduct follow-up evaluation on prognosis. mRS 0-3 points were good prognosis group,4-6 points were bad prognosis group. SPSS22.0 and MedCalc15.1 software were adopted for statistical analysis.Results 1. The N20 amplitude in the affected side of short-latency somatosensory evoked potentials (SLSEP) and NIHSS score is a significant negative correlation(p< 0.05). Judson grading standard and NIHSS score is a significant positive correlation(p <0.05).2.The sensitivity, specificity and accuracy of N20 amplitude in the affected side predicting the prognosisi of patients with acute cerebral infarction are 95.45%, 75%,80.4%, and its forecast cutoff is 1.08uV. The sensitivity, specificity and accuracy of Judson grading predicting the prognosisi of patients with acute cerebral infarction are 95.45%,70.83%,87%. Prognostic value of N20 amplitude and Judson grading standard have no significant differences(p=0.54).Conclusion 1. Both of The N20 amplitude in the affected side of short-latency somatosensory evoked potentials (SLSEP)and Judson grading standard may be used for the assessment of prognosis in patients with acute cerebral infarction after 3 months, and their value of predicting prognosis have no significant differences, stilling can not explain which one is more accurate.2. The study preliminary tells us the cutoff value of N20 amplitude in the affected side which predict prognosis of patients with acute cerebral infarction is 1.08uV after 3 months.