NIH Stroke Scale (NIHSS) Calculator
Important Instructions
- Score what you see, not what you think - assess actual patient responses
- Score the first response - except for Item 9 (Best Language)
- Don't coach the patient - avoid influencing their responses
- For patients with prior deficits, intubation, or language barriers, consult the official NIH Stroke Scale protocol
1a. Level of Consciousness
Assess the patient's alertness and responsiveness to stimuli.
1b. LOC Questions
Ask the patient the month and their age. Score based on correct answers.
1c. LOC Commands
Ask patient to open/close eyes and grip/release non-paretic hand.
2. Best Gaze
Test horizontal eye movements. Only assess horizontal eye movements.
3. Visual
Test visual fields by confrontation using finger counting.
4. Facial Palsy
Ask patient to show teeth, raise eyebrows, and close eyes tightly.
5. Motor Arm (Left)
Test left arm by holding at 90° if sitting or 45° if supine for 10 seconds.
5. Motor Arm (Right)
Test right arm by holding at 90° if sitting or 45° if supine for 10 seconds.
6. Motor Leg (Left)
Test left leg by holding at 30° for 5 seconds (always test supine).
6. Motor Leg (Right)
Test right leg by holding at 30° for 5 seconds (always test supine).
7. Limb Ataxia
Test finger-nose-finger and heel-shin for ataxia on both sides.
8. Sensory
Test pinprick sensation on face, arm, trunk, and leg compared to non-affected side.
9. Best Language
Assess naming, reading, and describing a picture. Score the BEST response.
10. Dysarthria
Assess speech clarity by having patient read or repeat words.
11. Extinction & Inattention
Test for sensory or visual extinction or inattention to one side of space.
Results & Interpretation
NIH STROKE SCALE SCORE
Complete all assessment items to calculate total score
Stroke Severity Scale
Clinical Interpretation
Complete the assessment to see detailed interpretation based on NIHSS score.
Medical Management & Advice
Immediate Consultation
Consult Neurology immediately for all patients presenting with ischemic stroke symptoms. Time is critical for stroke management.
Thrombolysis Assessment
Evaluate whether the patient is a potential candidate to receive intravenous thrombolysis (tPA). Consider contraindications and time since symptom onset.
Imaging Requirements
Obtain urgent neuroimaging including non-contrast head CT to rule out hemorrhage. Consider CT angiography and MRI/MRA for further evaluation.
Stroke Center Transfer
Whenever possible, transfer acute stroke patients to a comprehensive stroke center for specialized care and better outcomes.
Stroke Mimics
Always consider stroke mimics in differential diagnosis: recrudescence of old stroke, Todd's paralysis, complex migraine, conversion disorder, metabolic encephalopathy.
Educational Resources
How to Use This Tool
The NIH Stroke Scale (NIHSS) calculator is designed to standardize the assessment of stroke severity. Follow these steps:
- Examine the patient using the standard NIH Stroke Scale protocol
- Select appropriate scores for each of the 11 assessment items
- Click "Calculate Total Score" to get the NIHSS score
- Review the results including stroke severity classification and management recommendations
- Download the PDF report for medical documentation
This tool is for healthcare professionals trained in NIHSS administration. Always consult official protocols for complex cases.
Clinical Significance
The NIH Stroke Scale is a critical tool in stroke management with several important applications:
- Quantifies stroke severity - provides objective measurement of neurological deficit
- Predicts clinical outcomes - higher scores correlate with worse prognosis
- Guides treatment decisions - helps determine eligibility for thrombolysis and thrombectomy
- Monitors patient progress - tracks neurological changes over time
- Facilitates communication - standardizes assessment between healthcare providers
Scores <4 typically indicate mild stroke with good prognosis, while scores >20 suggest severe stroke with higher mortality risk.
Stroke Mimics & Differential
Always consider stroke mimics in the differential diagnosis, especially with atypical features:
- Recrudescence of old stroke from metabolic or infectious stress
- Todd's paralysis following seizure activity
- Complex migraine with neurological symptoms
- Functional disorders such as conversion disorder or pseudoseizure
- Metabolic encephalopathy from electrolyte imbalances
- Brain tumor or other space-occupying lesions
- Peripheral vestibular disorders mimicking stroke symptoms
Neuroimaging and thorough history are essential to distinguish stroke from mimics.
Frequently Asked Questions
The NIH Stroke Scale (NIHSS) is a standardized neurological examination tool used to quantify the severity of ischemic stroke. It consists of 11 items that evaluate level of consciousness, gaze, visual fields, facial palsy, motor strength, ataxia, sensation, language, dysarthria, and extinction/inattention. Scores range from 0 (no stroke symptoms) to 42 (severe stroke).
The NIHSS is broadly predictive of clinical outcomes. Patients with scores <4 have a high likelihood of good clinical outcomes, while scores >20 are associated with higher mortality and poorer functional outcomes. However, individual cases vary, and the scale should be used as part of a comprehensive clinical assessment rather than as the sole predictor of outcome.
The NIHSS has several limitations: it may underestimate posterior circulation strokes, has limited sensitivity for right hemisphere strokes, and can be challenging to administer in patients with pre-existing neurological deficits, language barriers, or intubation. For complex cases, clinicians should consult the official NIH Stroke Scale training materials and protocol.
Consult the official NIH Stroke Scale protocol when assessing patients with: prior known neurologic deficits (weakness, blindness, etc.), intubation or inability to cooperate, language barriers, suspected stroke mimics, or when there is uncertainty about scoring specific items. This calculator is a helpful tool but does not replace official certification or protocol for complex cases.
Intravenous thrombolysis (tPA) is typically administered within 4.5 hours of symptom onset for eligible patients with ischemic stroke. Some patients may be candidates for extended windows up to 9 hours with advanced imaging selection. Mechanical thrombectomy may be considered up to 24 hours in selected cases. The NIHSS score helps determine treatment eligibility, with higher scores often indicating potential benefit from more aggressive interventions.