Prognostic Value Of Somatosensory Evoked Potential In Prolonged Coma Patients With Diffuse Axonal Injury

Objective:To evaluate the prognostic value of somatosensory evoked potential (SEP) in prolonged coma patients with diffuse axonal injury and compare the prognostic accuracy of SEP with magnetic resonance imaging (MRI).Methods:43traumatic coma patients with diffuse axonal injury (DAI) received the examination of MRI at one month after injury. The patients were divided into three groups recording to the lesions in MRI (Ⅰ:the lesions between grey and white matter, Ⅱ: the lesions in/around basal ganglia and corpus callosum, Ⅲ:the lesions in brain stem). SEP was recorded in three days after the examination of MRI. The results of SEP were also divided into three groups (Ⅰ:the amplitude of N20and the central conducting time (CCT) are normal; Ⅱ:CCT prolonged or the amplitude of N20<2.0uV; Ⅲ:unbilateral of bilateral amplitude of N20<0.5uV with N13). The patients were assessed at6months after injury with Glasgow Outcome Scale (GOS). The patients with GOS1to3were unfavorable while GOS4to5were favorable. The patients with GOS1to2were non-awakening while GOS3to5were awakening.Results:The average GOS of patients with the MRI Ⅱ and Ⅲ grade were3.06±1.18and2.32±0.95respectively, which were significantly lower than patients with MRI I grade (4.00±0.71, p<0.05). The average GOS of patients with SEP Ⅲ grade were1.80±0.78, which was significantly lower than patients with SEP Ⅰ and Ⅱ grade (Ⅱ grade3.05±0.87, I grade4.14±0.69, p<0.05). The prognostic accuracy of MRI Ⅲ grade for unfavorable and non-awakening were90.9%and54.5%respectively, while SEP Ⅲ grade for unfavorable and non-awakening were100%and80%respectively. Besides, the prognostic accuracy of SEP I grade for favorable and awakening were85.7%and100%respectively.Conclusions:The outcome of DAI patients was worse as the SEP grade raised, and the outcome of patients with absent N20were all unfavorable. The prognostic value of SEP for prolonged DAI patients was better than MRI, with a higher accuracy for both favorable and unfavorable outcome. SEP also had a certain prognostic value of awakening for DAI patients in prolonged coma.