Abstract W P211: Clinical Characteristics of Pseudo Negative Cases in Prehospital Triage for Stroke

Abstract

Objective: The accuracy of prehospital diagnosis for stroke by emergency medical services (EMS) is improved using instruments for symptom recognition. On the other hand, prehospital misdiagnosis for stroke and subsequent delay in presentation to a hospital with stroke expertise play a critical role in the exclusion of potential therapeutic candidates. Our study aims to investigate the clinical characteristics of pseudo-negative cases in prehospital triage for stroke/TIA by EMS. Methods: From April 2013 to April 2014, consecutive 644 acute stroke patients were transferred by EMS to our hospital. We investigated prehospital diagnosis, Cincinnati prehospital stroke scale (CPSS) by EMS, neurological symptoms and complaints of patients themselves at stroke onset. We also examined activity of daily life (ADL) and cognitive impairments before stroke onset, and stroke subtypes in final diagnoses. Results: Among 644 acute stroke patients, 36 patients (22 men, mean 72.5±4.4 years old) were pseudo-negative cases in prehospital triage for stroke and had no abnormalities in CPSS by EMS. When EMS arrived at emergency site, 12 patients (33%) had loss of consciousness. Before stroke onset, 6 patients (17%) had impaired ADL (modified Rankin Scale >2), and 5 (14%) cognitive impairment. Among the stroke subtypes, the proportion of small vessel occlusion (22.4%, p=0.0025) and transient ischemic attack (TIA) (25%, p=0.0021) was significant higher in pseudo negative cases in prehospital triage; on the other hand, intracranial hemorrage (11%, p=0.0028) was lower. In complaint of patients themselves at stroke onset, weakness in one or two extremities was reported in 20 patients (56%), abnormal speech/language in 13 (36%), however all of them were not clarified by EMS. Conclusion: This study showed that small vessel occlusion and TIA tend to be misdiagnosed in a prehospital triage by EMS. The complaint of patients themselves at stroke onset is important to prehospital diagnoses by EMS.