NIH Stroke Scale

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Objective[edit | edit source]

The National Institutes of Health Stroke Scale (NIHSS) is a systematic, quantitative assessment tool to measure stroke-related neurological deficit[1]. In clinical practice it can be used to evaluate and document neurological status in acute stroke patients, determine appropriate treatment and assist in standardizing communication between healthcare practitioners[2]. The NIHSS has been shown to be a predictor of both short and long term outcomes of stroke patients[3][4].

The NIHSS is designed to be a simple tool that can be administered in less than 10 minutes by physicians, nurses or therapists[1].

Intended Population[edit | edit source]

Acute stroke patients[2].

Method of Use[edit | edit source]

The NIHSS is a 15-item neurological examination stroke scale used to evaluate the effect of acute cerebral infarction on the levels of consciousness, language, neglect, visual-field loss, extraocular movement, motor strength, ataxia, dysarthria, and sensory loss[1]. A trained observer rates the patent’s ability to answer questions and perform activities, without coaching and without making assumptions about what the patient can do[5].

Ratings for each item are scored on a 3- to 5-point scale, with 0 as normal, and there is an allowance for untestable items. Scores range from 0 to 42, with higher scores indicating greater severity.

Stroke severity may be stratified on the basis of NIHSS scores as follows:[6]

  • Very Severe: >25
  • Severe: 15 – 24
  • Mild to Moderately Severe: 5 – 14
  • Mild: 1 – 5'

Evidence[edit | edit source]

Reliability[edit | edit source]

Inter-rater reliability for individual elements of the NIHSS has been shown to be generally good[7].  However, overall scoring can be inconsistent, so proper training is required to use the NIHSS accurately[8][9][10]. A simpler, modified version of the NIHSS has been found to have greater inter-rater reliability with equivalent clinical performance[11].

  • A study of 4 patients assessed by 30 physicians and 29 study coordinators, with a space of 3 months between assessments, found that the NIHSS has excellent interrater (ICC = 0.95) and test-retest reliability (ICC = 0.93)[12]
  • A study of 20 patients rated by 4 clinicians, with each patient subsequently evaluated by 2 independent observers found Adequate to Excellent inter-rater agreement for 9 of the 13 items on the NIHSS (Kappa = 0.32 to 0.79); lowest levels of agreement were found for the Facial palsy (Kappa = 0.22) and limb ataxia (Kappa = -0.16) items[13].
  • 4 items have poorly reliability or are redundant (level of consciousness, facial weakness, ataxia, and dysarthria[14].

Validity[edit | edit source]

Outcomes related to NIHSS scores at admission[15][16]:

  • Scores of <5; 80% of stroke survivors will be discharged to home.
  • Score between 6 and 13 typically require acute inpatient rehabilitation.
  • Scores of >14 frequently require long-term skilled care.


The validity of the NIHSS is reduced if there is a language barrier, if the patient previously had a neurological deficit or if they are intubated[17]. Moreover, there was found to be differences between the average NIHSS of patients with a good functional outcome between posterior circulation stroke and anterior circulation stroke[18].

Responsiveness[edit | edit source]

NIHSS scores were compared to infarction size (measured by computed tomography) on 65 patients at 1 week post stroke. 10 items demonstrated an average of 25% change over 7 days. However, changes in limb ataxia and best gaze may have been overstated[6].

Links[edit | edit source]

NIH Stroke Assessment Tool PDF

References[edit | edit source]

  1. ↑ 1.0 1.1 1.2 NIH Stroke Scale. Approach to Human Subject Protection and Patient Safety. Available from: https://www.nihstrokescale.org/ (Accessed 12/07/2022)
  2. ↑ 2.0 2.1 Spilker J, Kongable G, Barch C, Braimah J, Brattina P, Daley S, Donnarumma R, Rapp K, Sailor S. Using the NIH Stroke Scale to assess stroke patients. The NINDS rt-PA Stroke Study Group. J Neurosci Nurs. 1997 Dec;29(6):384-92.
  3. ↑ H.P. Adams Jr., P.H. Davis, E.C. Leira, K.-C. Chang, B.H. Bendixen, W.R. Clarke, R.F. Woolson, Hansen, MS. Baseline NIH Stroke Scale score strongly predicts outcome after stroke: A report of the Trial of Org 10172 in Acute Stroke Treatment (TOAST). Neurology July 1, 1999 vol. 53 no. 1 126
  4. ↑ Runde D. Calculated Decisions: NIH stroke scale/score (NIHSS). Emerg Med Pract. 2020 Jul 15;22(7):CD6-CD7.
  5. ↑ Know Stroke. NIH Stroke Scale. Available from https://www.stroke.nih.gov/resources/scale.htm (Accessed 12/07/2022)
  6. ↑ 6.0 6.1 Brott T, Adams HP Jr, Olinger CP, Marler JR, Barsan WG, Biller J, et al. Measurements of acute cerebral infarction: a clinical examination scale. 1989. Stroke 20(7): 864-870.
  7. ↑ Josephson SA1, Hills NK, Johnston SC.. NIH Stroke Scale reliability in ratings from a large sample of clinicians. Cerebrovasc Dis. 2006;22(5-6):389-95.
  8. ↑ André C. The NIH Stroke Scale is unreliable in untrained hands. J Stroke Cerebrovasc Dis. 2002 Jan-Feb;11(1):43-6.
  9. ↑ Lyden P1, Raman R, Liu L, Emr M, Warren M, Marler J. National Institutes of Health Stroke Scale certification is reliable across multiple venues. Stroke. 2009 Jul;40(7):2507-11.
  10. ↑ Lyden P, Raman R, Liu L, Grotta J, Broderick J, Olson S, Shaw S, Spilker J, Meyer B, Emr M, Warren M, Marler J. NIHSS training and certification using a new digital video disk is reliable. Stroke. 2005 Nov;36(11):2446-9.
  11. ↑ EB Medicine. Current Topics in Acute Stroke Care. Available from https://www.ebmedicine.net/topics/stroke/stroke-imaging-modalities-CRAO/calculators (Accessed 12/07/2022)
  12. ↑ Goldstein LB, Samsa GP. Reliability of the National Institutes of Health Stroke Scale Extension to Non-Neurologists in the Context of a Clinical Trial. Stroke. 1997;28:307–310
  13. ↑ Goldstein LB, Bertels C, Davis JN. Interrater reliability of the NIH stroke scale. Arch Neurol. 1989 Jun;46(6):660-2.
  14. ↑ Kasner SE. Clinical interpretation and use of stroke scales. Lancet Neurol. 2006 Jul;5(7):603-12.
  15. ↑ Schlegel D, Kolb SJ, Luciano JM, Tovar JM, Cucchiara BL, Liebeskind DS, Kasner SE. Utility of the NIH Stroke Scale as a predictor of hospital disposition. Stroke. 2003 Jan;34(1):134-7
  16. ↑ Rundek T, Mast H, Hartmann A, Boden-Albala B, Lennihan L, Lin IF, et al. Predictors of resource use after acute hospitalization: the Northern Manhattan Stroke Study. Neurology. 2000 Oct 24;55(8):1180-7
  17. ↑ MD Calc. NIH Stroke Scale/Score (NIHSS). Available from: https://www.mdcalc.com/calc/715/nih-stroke-scale-score-nihss (Accessed 12/07/2022)
  18. ↑ Kazi SA, Siddiqui M, Majid S. Stroke Outcome Prediction Using Admission Nihss In Anterior And Posterior Circulation Stroke. J Ayub Med Coll Abbottabad. 2021 Apr-Jun;33(2):274-278


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