Abstract P307: The ALPHA Sign in the Diagnosis of Potential Stroke
Abstract
Background: Any clinical feature that may improve the early recognition of, or increase pretest probability of, acute stroke could shorten treatment times. We evaluated the sensitivity and specificity of the “Arm and Leg Positioning and self-Help Assessment” (ALPHA) sign in a predominantly stroke population. This sign was developed from the observation that some stroke patients guard the affected limb. Even mild deficits seem to have minimally supportive micro-gestures of one hand touching or lightly supporting the affected limb.
Methods: IRB approval was obtained to review available videos of 63 stroke and non-stroke patients. Observers were instructed to only watch the initial 30 seconds of each video and focus on the limbs. The remaining video, and all the audio, were withheld. Videos were independently scored for the ALPHA sign. A composite score, defined as positive if >/= 50% of examiners reported its presence, was assigned. Scores were compared to true diagnosis (stroke/ CNS lesion was positive if there was a scorable deficit and imaging positive CNS lesion). Sensitivity analyses were performed.
Results: Of the original 69 videos, 37 were from the outpatient setting (21 with stroke or other CNS lesions; 16 neurologically intact) and 26 were from the inpatient setting (20 with stroke or other CNS lesions; 6 neurologically intact). The ALPHA sign had a specificity of 86.4% and positive predictive value of 89.7%. Sensitivity was 63.4% and negative predictive value was 55.9%.
Conclusions: High specificity and positive predictive value of the ALPHA sign were found suggesting that the recognition of subtle supportive gestures may help in early identification of CNS lesions during a stroke code. As expected, the sign had a lower sensitivity as the cohort was not limited to motor-only deficits. Further assessments in other stroke types, assessing a larger cohort and more examiners of various training level, are planned.
Vish Ramesh
NIH NLM Postdoctoral Fellow
