How to Perform the NIH Stroke Scale (NIHSS)
The NIH Stroke Scale is a standardized, validated instrument that assesses severity of neurological impairment after stroke with an administration time of 5-10 minutes, and should be performed by trained and certified professionals to ensure accurate assessment of stroke severity. 1
Purpose and Importance
- The NIHSS provides valuable prognostic information and has been correlated with infarct volume, with scores >16 forecasting high probability of death or severe disability, whereas scores <6 forecast good recovery 1
- The scale is used to guide decisions concerning acute stroke therapy, including the use of thrombolytic therapy 1
- Initial NIHSS scores strongly predict the likelihood of patient recovery after stroke 1
Preparation for Assessment
- Ensure the examiner is trained and certified in NIHSS administration (certification involves watching training videos and passing an examination) 1
- Any healthcare professional can become certified (physician, nurse, therapist, or social worker) 1
- Have standardized testing materials ready (picture, naming objects, sentences for reading) 2
Steps to Perform the NIHSS
1. Level of Consciousness Assessment
- Assess alertness by observing patient response to stimulation 1, 3
- Test orientation by asking month and age 1
- Test ability to follow commands by asking patient to open/close eyes and grip/release hand 1
2. Gaze Assessment
- Observe horizontal eye movements by having patient follow your finger or face 3, 2
- Note any abnormal gaze or partial gaze palsy 3
3. Visual Field Testing
4. Facial Palsy Assessment
- Ask patient to show teeth, raise eyebrows, and close eyes 1, 2
- Observe for symmetry or asymmetry of facial movements 1
5. Motor Arm Function
- Have patient extend arms palm down at 90 degrees (if sitting) or 45 degrees (if supine) and hold for 10 seconds 3
- Score each arm separately using the following criteria:
- 0 = No drift (arm holds position for full 10 seconds)
- 1 = Drift (arm drifts down before full 10 seconds)
- 2 = Some effort against gravity (cannot maintain position but has some effort)
- 3 = No effort against gravity (arm falls)
- 4 = No movement at all 3
6. Motor Leg Function
- Have patient hold leg at 30 degrees for 5 seconds 1
- Score each leg separately using similar criteria as for arms 1
7. Limb Ataxia
- Perform finger-nose-finger and heel-shin tests 1
- Note presence of ataxia in upper and/or lower extremities 1
8. Sensory Testing
9. Language Assessment
- Ask patient to describe a standardized picture 2
- Have patient name objects 2
- Ask patient to read sentences 2
- Score based on fluency and comprehension:
10. Dysarthria
11. Extinction and Inattention
- Test for neglect using double simultaneous stimulation 1
- Note any extinction to bilateral simultaneous stimulation 1
Additional Assessment
- Test finger extension (often added to NIHSS but not contributing to total score) 1
Frequency of Assessment
- Perform NIHSS at time of presentation/hospital admission, or at least within first 24 hours 1
- For patients treated with thrombolysis, a complete NIHSS should be performed on admission to intensive care unit 1
- An abbreviated version can be performed with more frequent assessments during monitoring 1
- Complete NIHSS should be done if there is evidence of neurological decline 1
- Reassess using NIHSS at time of acute care discharge 1
Common Pitfalls to Avoid
- Do not confuse inability to speak due to decreased consciousness with aphasia 2
- Distinguish between language function (aphasia) and articulation (dysarthria) 4
- Do not mistake mild word-finding difficulties for normal language 4
- Ensure proper positioning for motor testing to accurately assess drift 3
- Do not confuse a score of 3 (no effort against gravity but some movement) with a score of 4 (no movement at all) in motor assessment 3