Association of National Institues of Healt Stroke Scales Scores, acute diffusion magneic resonance imaging stroke volume, arterial occlusion and affected hemispher

Background and Purpose: The NIH Stroke Scale (NIHSS) is used to assess acute ischemic stroke severity and outcome, however, it can award more points for tests of presumed left-hemisphere function, such as language, than for tests of right-hemisphere function, such as neglect. This difference may be important if a low NIHSS score is used to exclude patients with right-hemisphere stroke from clinical trials or established treatments. High NIHSS scores are usually associated with arterial occlusion but it is unknown what the effect of side of stroke lesion to clinical evaluation in this association is. We tested the NIHSS scores as an instrument to determine arterial occlusion within 12 hours of stroke onset. The aim of this study was to investigate whether the relationship between acute NIHSS score and arteral occlusion as determined by acute MR angiography differs between right- and left-sided stroke and the other aim was to confirm the relationship between acute NIHSS score and acute stroke volume as determined by acute diffusion -weighted MRI differs between right- and left-sided stroke.Methods: This was a retrospective study of 139 patients with acute stroke seen at Florence Nightingale Stroke Center who underwent an MRI (DWI, PWI and MRA) examination and NIHSS within 12 hours of stroke onset. NIHSS score was recorded prospectively by the admitting stroke fellow at the time of acute presentation, immediately preceding imaging. Computerized volumetric analysis of the MRI lesions, intracranial MR anjiography evaluation was performed by investigators blinded to clinical data.Results: Mean (±SD) NIHSS score was 9,7 ± 6,7 Receiver operating characteristic curves showed that the validity of NIHSS in predicting arterial occlusion was smilar in patients between left and right-sided stroke. The best cut-off point in patients evaluated with left-sided stroke was an NIHSS of 8 (83 % sensitivity, specificity 84 %), while in patients evaluated after with right-sided stroke best cut-off point was 9 (sensitivity 72 %, specificity 72 %). There were significant correlations between the acute NIHSS scores and acute DWI lesion volumes (r=0.44 right, r=0.68 left). For patients with NIHSS scores of 0 to 5, the DWI volume of right cerebral lesions was greater than that of left-sided lesions (mean volume, 2,8 versus 13,2 cm3; P=0.002).Conclusions: Patients with right-sided stroke may have a low NIHSS score despite substantial DWI lesion volume. And the validity of NIHSS in predicting arterial occlusion was smilar in patients between left and right-sided (Right 9 , Left 8) stroke. An NIHSS score of 8 seems to represent the cut-off for discriminating between patients with arterial occlusion and patients without.