title: Predicting comatose patients with acute stroke outcome using middle-latency somatosensory evoked potentials.
abstract: OBJECTIVE
  To evaluate the prognostic value of middle-latency somatosensory evoked potential (MLSEP) in comatose patients with acute severe supratentorial stroke, considering both unfavourable outcome and death.
  
  
  METHODS
  Eighty-eight patients with acute severe supratentorial stroke underwent MLSEP, short-latency somatosensory evoked potential (SLSEP), Glasgow Coma Scale (GCS) and cerebral computed tomography (CCT) within 1 week from onset. MLSEP and SLSEP were recorded in 25 normal controls. All patients were evaluated with two criteria of outcome as unfavourable outcome (modified Rankin Scale 4-6) and death 6 months after onset. N60 of MLSEP predictive value was compared with N20 of SLSEP, GCS and CCT.
  
  
  RESULTS
  Sixty-seven patients (76.1%) suffered from cerebral infarction; and 21 patients (23.9%) suffered from intracerebral haemorrhage. Seventy-one patients (80.7%) had unfavourable outcomes and 39 patients (44.3%) died. The peak latencies of MLSEP were prolonged and some waves of MLSEP were absent in stroke patients, and the proportion of absent waves in lesion-ipsilateral MLSEP was higher than in contralateral MLSEP. By using the prognostic authenticity analysis of predictors, the lesion-ipsilateral absence of N60 showed the highest sensitivity for unfavourable outcome (97.2%, confidence interval (CI): 89.3-99.5%) and death (100%, CI: 88.8-100%), which was superior to GCS, CCT and N20. Bilateral absence of N60 showed a high specificity of 100% for unfavourable outcome, which was as good as bilateral absence of N20. However, it showed a specificity of 89.8% (CI: 77.0-96.2%) for death, not as good as bilateral absence of N20 (98%, CI: 87.8-99.9%). The false positive rate of lesion-ipsilateral absence of N60 for unfavourable outcome and death was 12.7% (CI: 6.6-22.5%) and 50.6% (CI: 39.2-62.0%), respectively, and that of bilateral absence of N60 was 0 (CI: 0-12.3%) and 14.3% (CI: 5.4-31.0%), respectively.
  
  
  CONCLUSIONS
  We confirm the high predictive value of MLSEP in severe stroke. MLSEP showed higher sensitivity than SLSEP for predicting unfavourable outcome and death. Combined MLSEP with SLSEP results produced even greater predictive value.
  
  
  CONCLUSIONS
  The combination of MLSEP and SLSEP would increase the sensitivity and maintain the high specificity not only for predicting outcome in coma after cardiopulmonary resuscitation but also after severe stroke.
authors.affiliation: Department of Neurology, Xuanwu Hospital of Capital Medical University, Beijing 100053, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhang
authors.forename: Ying Ying
authors.initials: YY
authors.lastname: Su
authors.forename: Hong
authors.initials: H
authors.lastname: Ye
authors.forename: Shu Ying
authors.initials: SY
authors.lastname: Xiao
authors.forename: Wei Bi
authors.initials: WB
authors.lastname: Chen
authors.forename: Jing Wei
authors.initials: JW
authors.lastname: Zhao
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D001288:Attention / Q000502:physiology; D003128:Coma / Q000175:diagnosis* / Q000209:etiology*; D004569:Electroencephalography; D004576:Electromyography; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D011237:Predictive Value of Tests; D011930:Reaction Time / Q000502:physiology*; D020521:Stroke / Q000150:complications*; D013997:Time Factors; D050781:Transcranial Magnetic Stimulation / Q000379:methods; D014953:Wrist / Q000294:innervation; D055815:Young Adult