NIH Stroke Scale (NIHSS) Calculator
Calculate the NIH Stroke Scale to assess stroke severity, determine treatment eligibility, and predict patient outcomes.
What is the NIH Stroke Scale (NIHSS)?
The NIH Stroke Scale (NIHSS) is a standardized, validated 15-item neurological examination tool used to quantify stroke severity. Scores range from 0 (no deficit) to 42 (severe deficit). NIHSS is used to assess baseline stroke severity, guide treatment decisions (especially thrombolytic therapy eligibility), predict outcomes, and monitor neurological changes. It evaluates consciousness, vision, motor function, sensation, language, and attention across 11 domains.
How do I interpret NIHSS scores?
NIHSS interpretation: 0 = No stroke symptoms. 1-4 = Minor stroke. 5-15 = Moderate stroke. 16-20 = Moderate to severe stroke. 21-42 = Severe stroke. Higher scores indicate worse outcomes and disability. NIHSS >=10 suggests large vessel occlusion. Scores guide treatment: thrombolytic therapy typically considered for NIHSS >=4, thrombectomy for NIHSS >=6 with large vessel occlusion. Serial NIHSS tracks improvement or deterioration during hospitalization.
Who should perform the NIHSS assessment?
NIHSS should be performed by trained healthcare providers (physicians, nurses, paramedics) who have completed formal NIHSS certification. Proper training ensures reliable, reproducible assessments. The exam takes 5-10 minutes. Certification is available free online through NIH/NINDS. Consistent technique is critical for serial assessments. In emergency settings, rapid NIHSS screening identifies stroke candidates for time-sensitive interventions like thrombolysis (within 4.5 hours) or thrombectomy (within 24 hours).
What does each NIHSS component assess?
NIHSS components: 1a) Level of consciousness (LOC). 1b) LOC questions (month, age). 1c) LOC commands (open/close eyes, grip). 2) Best gaze. 3) Visual fields. 4) Facial palsy. 5a-5b) Motor arm (left/right). 6a-6b) Motor leg (left/right). 7) Limb ataxia. 8) Sensory. 9) Best language (aphasia). 10) Dysarthria. 11) Extinction/inattention (neglect). Each item scored 0-2 or 0-4 depending on severity of deficit. Sum provides total score.
Can NIHSS predict stroke outcomes?
Yes, NIHSS strongly predicts stroke outcomes. Higher baseline NIHSS correlates with worse outcomes, increased mortality, and greater disability at discharge. Studies show: NIHSS 0-5 → 60-70% excellent outcome. NIHSS 6-13 → 35-50% good outcome. NIHSS >=14 → 10-20% good outcome. NIHSS >20 → high mortality risk. NIHSS improvement of >=4 points or reaching 0-1 indicates favorable response to treatment. However, outcomes also depend on stroke type, location, time to treatment, and patient factors.