NIH Stroke Scale Administration and Interpretation

Purpose and Importance

The American Heart Association recommends using the NIH Stroke Scale to assess severity of neurological impairment after stroke, with scores >16 forecasting high probability of death or severe disability, whereas scores <6 forecast good recovery 1, 2
Initial NIHSS scores strongly predict the likelihood of patient recovery after stroke, and are used to guide decisions concerning acute stroke therapy, including the use of thrombolytic therapy 1

The American Academy of Neurology recommends that examiners be trained and certified in NIHSS administration, which involves watching training videos and passing an examination, to ensure accurate assessment of stroke severity 1

Assess level of consciousness by observing patient response to stimulation, testing orientation, and ability to follow commands, with a focus on alertness, language, and motor function 1
Perform motor arm function assessment by having patient extend arms palm down at 90 degrees and hold for 10 seconds, scoring each arm separately based on drift, effort against gravity, and movement 3
Assess language function by asking patient to describe a standardized picture, name objects, and read sentences, scoring based on fluency and comprehension 4

The American Heart Association recommends performing NIHSS at time of presentation/hospital admission, or at least within first 24 hours, and reassessing using NIHSS at time of acute care discharge 1, 2

The NIHSS assesses various domains, including visual fields, gaze, facial palsy, sensory, dysarthria, and extinction/inattention, through 11 core items, with the American Heart Association recommending its use for stroke assessment 5
The scale evaluates sensation to pinprick, with the American Stroke Association noting its importance in stroke diagnosis 6

The NIHSS determines eligibility for thrombolytic therapy, with the American College of Cardiology recommending its use in acute stroke management decisions 5
A 4-point improvement or worsening on the NIHSS may alter treatment eligibility, according to the American Heart Association 5

The NIHSS may underestimate posterior circulation stroke severity because symptoms like vertigo and dysphagia are not included, as noted by the American Stroke Association 5
Distal motor function and balance/gait disorders are not adequately covered by the standard scale, with the American Academy of Neurology recommending additional assessments 6
Two items (facial palsy and dysarthria) have demonstrated lower inter-rater reliability compared to other components, according to the American Heart Association 6

The American Heart Association recommends rearranging the NIHSS order to reduce camera manipulations, performing close-up items before zoomed-out views, for telemedicine assessments 7
The items of visual fields and gaze have excellent reliability in both bedside and telemedicine assessments, according to the American Stroke Association 7
The item of limb ataxia demonstrates lower inter-rater reliability, particularly in telemedicine assessments, as noted by the American Academy of Neurology 7
Items with lowest reliability, such as facial palsy, ataxia, and dysarthria, require extra attention during assessment, as stated by the American Heart Association 7

The NIHSS includes assessment of visual field deficits and gaze abnormalities as part of its visual function domain. 8
Language and speech are evaluated through picture description, object naming, sentence reading (aphasia) and dysarthria assessment. 8
Motor function is examined by testing facial palsy and bilateral arm/leg strength; strength is graded by having the patient hold the arms at 90° for 10 seconds and scoring drift and effort against gravity. 9

Items that assess distal upper‑extremity weakness and balance/gait are considered inadequately evaluated, contributing to lower overall reliability of the scale. 8
The facial palsy and dysarthria items demonstrate lower inter‑rater reliability compared with other NIHSS components. 8
Limb ataxia shows poor reliability, especially when the assessment is performed via telemedicine. 8

The NIHSS can be administered remotely with high‑quality video conferencing, yielding a strong correlation with bedside scores (Pearson r = 0.97). 8
Remote assessments take slightly longer on average (mean 9.7 minutes) than in‑person examinations (mean 6.55 minutes), yet maintain scoring accuracy. 8

A change of ±4 points from the baseline NIHSS score may modify a patient’s eligibility for thrombolytic therapy and should trigger a reassessment before proceeding with treatment. 9