“Using the NIHSS:
What Are Its
Benefits and
Pitfalls?”
Ashley S. Bean, MD, MA, FACEP, FAAEM, FAWM
University of Arkansas for Medical Sciences
Disclosures
• I have no financial disclosures.
Objectives
• Define the National Institute of Health (NIH)
Stroke Scale and give a brief overview of the
scoring system
• Highlight benefits of the stroke scale
• Discuss some of the pitfalls of the NIH
Stroke Scale
• Discuss the relevance of the NIH Stroke
Scale to clinical practice
NIH Stroke Scale
• 15-item graded neurologic examination
stroke scale
– Provides a quantitative measure of strokerelated neurologic impairment
• It is not a measure of disability
– Time efficient and standardized
• Evaluates effect of acute cerebral infarction
by assigning points to different categories
– 0 = normal
– Higher numbers = worse impairment
• Points totaled to determine level of severity
NIH Stroke Scale
• Developed as a communication tool and for
use in research settings to assess
differences in clinical trial interventions
• Has since been validated for clinical practice
– Used to determine whether degree of
disability merits use of thrombolytic therapy
– Helps determine if change in exam has
occurred
– Can predict patient outcome
• Online training takes 2 – 3 hours
www.nihstrokescale.org
NIH Stroke Scale
Category
Cranial Nerves
Motor
Level of Consciousness
Language
Ataxia
Sensory
Inattention
Possible Points
Points
8
16
7
5
2
2
2
42
Stroke Severity
NIH Stoke Scale
Stroke Severity
0
No Stroke (?)
1–4
Minor Stroke
5 – 15
Moderate Stroke
15 – 20
Moderate to Severe
Stroke
Severe Stroke
21 – 42
NIH Stroke Scale Structure
Left Cortical
Right Cortical
Right Motor
Left Motor
Level of
Horizontal Eye
Consciousness
Movement
Questions
Right Arm
Motor
Left Arm Motor
Level of
Consciousness
Commands
Visual Fields
Right Leg
Left Leg
Language
Extinction and
Inattention
Dysarthria
Sensory
Practical Suggestions
• Work rapidly but methodically
– Exam should take 5 - 8 minutes
• Each item must be scored
• Score the first effort
• Score only observed performance, not what
you think the patient can do
• Do not go back and change the score
• Do not “coach” the patient
• Include deficits from previous strokes in the
score
NIH STROKE SCALE
CATEGORIES
Level of Consciousness
Category
Points
LOC overall
LOC questions
LOC commands
0-3
0-2
0-2
Possible Points
7
Level of Consciousness
Category
Points
LOC overall
0–3
•
•
•
•
Alert
Awaken with mild stimuli
Awaken with painful stimuli
Posturing or unresponsive
LOC questions
• Both questions correct
• 1 question correct
• 0 questions correct
LOC commands
• Follows both commands
• Follows one command
• Follows neither command
Possible Points
0
1
2
3
0–2
0
1
2
0–2
0
1
2
7
Level of Consciousness
Category
Points
LOC overall
0–3
•
•
•
•
Alert
Awaken with mild stimuli
Awaken with painful stimuli
Posturing or unresponsive
LOC questions
• Both questions correct
• 1 question correct
• 0 questions correct
LOC commands
• Follows both commands
• Follows one command
• Follows neither command
Possible Points
0
1
2
3
0–2
0
1
2
0–2
0
1
2
7
Higher
numbers
indicate more
severe
impairment
Cranial Nerves
Category
Points
Gaze palsy
Visual field deficit
Facial motor
0-2
0-3
0-3
Possible Points
8
Harrison's principles of internal medicine.
Vol. 2. New York: McGraw-Hill Medical,
2008.
womens-healthadvice.com/assets/images/strokesymptoms.jpg
Motor
Category
Points
Each Arm
Each Leg
Possible Points
0-4
0-4
16
10 second
test of
motor drift
preservation-uni.com
Cerebellar
Category
Points
Limb ataxia
Possible Points
0-2
2
emj.bmj.com/content/22/2/128/F11.large.jpg
informatics.med.nyu.edu/modules/pub/neurosur
gery/heelshin.jpg
Sensory
Category
Points
Pain, noxious stimuli
Possible Points
0-2
2
Obtunded
Patient: test
withdrawal from
noxious stimulus
Tests series of pinpricks
Language
Category
Points
Aphasia
Dysarthria
Possible Points
0-3
0-2
5
“Describe
the scene”
“Read the
Sentences”
“Name the
objects”
Inattention
Category
Points
Inattention
Possible Points
0-2
2
Tests visual,
tactile, auditory,
spatial, and
personal
inattention
SCORING THE EXAM
Worksheet
• www.ninds.nih.gov/doctors/NIH_Stroke_Scale.pdf
Internet Calculator
• www.mdcalc.com/nih-stroke-scale-score-nihss/
Free Smartphone app
“StatCoder”
StatCoder App
WHAT ARE THE BENEFITS OF
THE NIH STROKE SCALE?
Literature: Benefits
Author
Year Results
Adams
1999 Initial NIH Stroke Scale correlates
with 7 day and 3 month outcome
Lyden
1994 Reliability improves after video training
Lyden
2005 DVD training is reliable among
neurologist, emergency medicine
physicians and nurses
Goldstein
1997 Reliable among variety of physician
investigators and nurse study
coordinators
Tong
1998 NIH Stroke Scale correlates with lesion
size on MRI
Literature: Benefits
Author
Year Results
Kasner
1999 NIHSS can be abstracted from medical
records with high degree of reliability and
validity
Nilanont
2010 Thai version of NIHSS is valid for assessing
acute stroke severity and is reliable when
administered in a Thai-speaking setting by
trained healthcare professionals
Schwamm
2009 NIHSS-telestroke examination,
administered by a stroke specialist using
“high-quality video-teleconferencing”, is
comparable to NIHSS-bedside
assessment
Demaerschalk 2012 NIH Stroke Scale is reliable via
smartphone video teleconferencing
Correlates with Outcome
at 7 Days
• Effect of baseline
NIH Stroke Scale
score on
outcome at 7
days
• Patients'
outcomes are
rated as
excellent, good,
poor, or dead
Adams, H. P., et al. "Baseline NIH Stroke Scale score strongly predicts outcome
after stroke A report of the Trial of Org 10172 in Acute Stroke Treatment
(TOAST)." Neurology 53.1 (1999): 126-126.
3
Correlates with Outcome
at 3 Months
• Effect of baseline
NIH Stroke Scale
score on
outcome at 3
months
• Patients'
outcomes are
rated as
excellent, good,
poor, or dead
Adams, H. P., et al. "Baseline NIH Stroke Scale score strongly predicts outcome
after stroke A report of the Trial of Org 10172 in Acute Stroke Treatment
(TOAST)." Neurology 53.1 (1999): 126-126.
4
Correlates with Outcome
• Score < 12-14: 80% good or excellent
outcome
• Score > 20-26: 20% good or excellent
outcome
• Lacunar infarct patients had the best
outcomes
Adams, H. P., et al. "Baseline NIH Stroke Scale score strongly predicts outcome
after stroke A report of the Trial of Org 10172 in Acute Stroke Treatment
(TOAST)." Neurology 53.1 (1999): 126-126.
Reliable via Telemedicine
• Evidence-based review of the scientific data
evaluating the use of telemedicine for stroke
care
“The NIHSS-telestroke examination, when
administered by a stroke specialist using HQVTC, is recommended when an NIHSS-bedside
assessment by a stroke specialist is not
immediately available for patients in the acute
stroke setting, and this assessment is
comparable to an NIHSS-bedside assessment
(Class I, Level of Evidence A).”
Schwamm, Lee H., et al. "A review of the evidence for the use of telemedicine
within stroke systems of care. A scientific statement from the American Heart
Association/American Stroke Association." Stroke 40.7 (2009): 2616-2634.
Figure 2. Representative still images from telestroke consultations.
Schwamm L H et al. Stroke. 2009;40:2616-2634
Copyright © American Heart Association, Inc. All rights reserved.
Reliable via Smartphone
• 100 patients admitted suspected acute
stroke assessed at bedside using iPhone 4
– Each examination was directed remotely via
teleconferencing software
– Both physician performing the bedside exam
and remote physician calculated NIH Stroke
Scale score for each patient
• Each physician was blinded to other’s NIH
Stroke Scale score
• Mean time to complete exam = 8.9 minutes
Demaerschalk, Bart M., et al. "Reliability of real-time video smartphone for assessing
National Institutes of Health Stroke Scale scores in acute stroke patients." Stroke
43.12 (2012): 3271-3277.
Reliable via Smartphone
• NIH Stroke Scale scores
ranged from 0 to 37
• Interrater reliability assessed
– Excellent agreement in 8 items
– Moderate agreement in 6
items: LOC (consciousness),
best gaze, facial palsy,
sensory, dysarthria, and
extinction/inattention
– Poor agreement in 1 item:
ataxia
Demaerschalk, Bart M., et al. "Reliability of real-time video smartphone for assessing
National Institutes of Health Stroke Scale scores in acute stroke patients." Stroke
43.12 (2012): 3271-3277.
Reliable via Smartphone
Total NIH Stroke Scale
scores obtained
remotely and at
bedside showed an
excellent level of
agreement (correlation
coefficient, 0.95)
Smartphone high-quality video
teleconferencing is reliable, easy to use,
and affordable for telestroke NIH Stroke
Scale administration
WHAT ARE THE PITFALLS OF
THE NIH STROKE SCALE?
NIH Stroke Scale Pitfalls
•
•
•
•
•
Zero does not equal “No Stroke”
Contains items with poor reliability
May be unreliable in untrained hands
Criticized for its redundancy and complexity
Emphasis on language and following
commands may result in higher value for
dominant hemisphere strokes
• Lessened weighting for posterior circulation
strokes
• It is a measurement of impairment not
disability
Zero does not equal
“No Stroke”
• 20 patients with NIH Stroke Scale Score = 0
from 2618 patients with acute ischemic
stroke admitted to the hospital had an acute
infarction by magnetic resonance imaging
– 58% had posterior circulation infarcts
– 42% had anterior circulation infarcts
• The most common presenting symptoms
were headache, vertigo, nausea and ataxia
Ischemic stroke may cause symptoms that
are associated with no deficits on the NIH
Stroke Scale Score
Martin-Schild, Sheryl, et al. "Zero on the NIHSS does not equal the absence of
stroke." Annals of emergency medicine 57.1 (2011): 42-45.
Items with Poor Reliability
• Overall reliability is good
– Shown to be reliable in multiple languages
(English, Spanish, Italian, Chinese, Thai)
• Certain items have repeatedly shown
poorer reliability (among 15,000 people
who took online certification)
• Level of
Consciousness
• Gaze
• Facial Palsy
• Ataxia
• Dysarthria
Meyer, Brett C., and Patrick D. Lyden. "The modified National Institutes of Health
Stroke Scale: its time has come." International Journal of Stroke 4.4 (2009): 267-273.
Unreliable in Untrained Hands
• Evaluated last-year medical students without
previous NIH Stroke Scale training
• The scale was presented in 2 lectures
• Case presented from NIH training video
• 13 items scored by 42 students
• 36% scored all items correctly
• 48% gave results at least 2 points different
thanmagnitude
correct
The
of mistakes is enough to
inappropriately include or exclude patients
from thrombolytic therapy
André, Charles. "The NIH Stroke Scale is unreliable in untrained hands." Journal
of Stroke and Cerebrovascular Diseases 11.1 (2002): 43-46.
For a given NIH
Stroke Scale score,
the median volume of
right hemisphere
strokes is larger than
that of left hemisphere
strokes
Cube-root Lesion Volume
Higher Value for Dominant
Hemisphere Strokes
Baseline NIH Stroke Scale
Difference reflects the weighting of
language function (dominant hemisphere)
versus hemineglect (non-dominant)
Woo, Daniel, et al. "Does the National Institutes of Health Stroke Scale favor left
hemisphere strokes?." Stroke 30.11 (1999): 2355-2359.
Posterior Circulation
• Some items related to posterior circulation
can be scored (level of consciousness,
visual fields, facial palsy, sensory, motor,
dysarthria and ataxia)
– Among most unreliable categories
• Diplopia, dysphagia, gait instability, hearing,
and nystagmus receive no score
• Patients with low scores may still have
disabling strokes in cerebellum or brainstem
• Other scales better assess posterior stroke
symptoms
Posterior Circulation
• Prospective study of 310 patients
hospitalized within 3 days after onset of an
ischemic stroke
– 101 patients with posterior circulation stroke
– 209 patients with anterior circulation stroke
• Infarcts identified using magnetic resonance
imaging
• Favorable outcome defined as modified
Rankin Scale score of ≤ 2 at 3 months
– Measure of disability
Sato, S., et al. "Baseline NIH Stroke Scale Score predicting outcome in anterior
and posterior circulation strokes." Neurology 70.24 Part 2 (2008): 2371-2377.
Posterior Circulation
• Optimal cutoff scores of the baseline NIH
Stroke Scale for favorable outcome
– ≤ 5 for patients with posterior circulation
stroke
– ≤ 8 for patients with anterior circulation stroke
• Cutoff score of baseline NIH Stroke Scale for
a favorable chronic outcome was lower in
patients with posterior circulation strokes
compared to patients with anterior circulation
strokes
Sato, S., et al. "Baseline NIH Stroke Scale Score predicting outcome in anterior
and posterior circulation strokes." Neurology 70.24 Part 2 (2008): 2371-2377.
IS THE NIH STROKE SCALE
RELEVANT?
Vietnam Stroke Characteristics
Tirschwell, David L., Thanh GN
Ton, Kiet A. Ly, Quang Van Ngo,
Tung T. Vo, Chien Hung Pham,
William T. Longstreth, and Annette
L. Fitzpatrick. "A prospective
cohort study of stroke
characteristics, care, and
mortality in a hospital stroke
registry in Vietnam." BMC
neurology 12, no. 1 (2012): 150.
50% of strokes admitted
to hospital are
hemorrhagic
Cong, Nguyen Huu. "Stroke care
in Vietnam." International Journal
of Stroke 2, no. 4 (2007): 279-280.
Only 40-50% of people
with stroke present for
medical care
Only 28% of people with
ischemic stroke present
within 3 hours
Evaluation for Thrombolytic
Therapy
• A main use of NIH Stroke Scale is to
determine if thrombolytic therapy is
appropriate
• Thrombolytics should not be utilized if
hemorrhagic stroke or mass lesion can not be
excluded
• Thrombolytics are contraindicated if no brain
imaging can be performed
– CT or MRI imaging is only reliable means of
differentiating hemorrhagic vs. ischemic stroke
– History, physical and laboratory test do not
reliably differentiate types of strokes
Vietnam Stroke Characteristics
• If ….
– Only 40% of people with strokes present to
the hospital and
– 50% of people have hemorrhagic strokes and
– Only 30% of patients with an ischemic stroke
present within the window for thrombolytic
therapy and
– As of 2007, only 2% of 382 patients presenting
to a stroke center with ischemic stroke
received thrombolytic therapy
(Lien Nguyen Thi Kim: Hoa.t Xoˆ. ng cu’ a Xo’n vi.Xoˆ. t quy. Beˆ. nh vieˆ. n 115 tu`’
tha´ng 1/2004 to´’i tha´ng 8/2006)
Is the NIH Stroke Scale relevant in Vietnam?
NIH Stroke Scale Relevance
• Provide consistency of communication
between nurses and other health care
professionals
• Clearly document neurologic outcomes
• Provides a tool for serial monitoring
• Predicts risk of autonomic dysfunction
• Predictive of long-term care needs
Neurologic Monitoring
• 347 patients presenting within 48 hours of
onset of stroke symptoms
• 1/3 of acute ischemic stroke patients had
neurologic decline ≥ 2 NIH Stroke Scale
points
– Decline associated with increased modified
Rankin Scale Score
– Decline associated with 3-fold risk of death
• NIH Stroke Scale score is a highly sensitive
predictor for poor functional outcome and inhospital mortality
Siegler, James E., et al. "What change in the national institutes of health stroke
scale should define neurologic deterioration in acute ischemic stroke?." Journal of
Stroke and Cerebrovascular Diseases 22.5 (2013): 675-682.
Neurologic Monitoring
• More than half of patients who experienced
neurologic deterioration were discovered
upon work-up to have had a reversible
etiology
An increase in NIH stroke scale score by 2
points over a 24-hour period is clinically
meaningful and warrants clinical
investigation and intervention
which might minimize disability
Siegler, James E., et al. "What change in the national institutes of health stroke
scale should define neurologic deterioration in acute ischemic stroke?." Journal of
Stroke and Cerebrovascular Diseases 22.5 (2013): 675-682.
NIH Stroke Scale Predicts
Autonomic Dysfunction
• Autonomic changes put patients with more
severe stroke at increasing risk of
cardiovascular complications and poor
outcome
• 50 patients with middle cerebral infarcts
– Assessed NIH Stroke Scale scores and
parameters of autonomic cardiovascular
modulation within 24 hours after stroke onset
• 28 left-hemispheric strokes
• 22 right-hemispheric strokes
– Compared with 32 healthy controls
Hilz, Max Josef, et al. "High NIHSS values predict impairment of cardiovascular
autonomic control." Stroke 42.6 (2011): 1528-1533.
NIH Stroke Scale Predicts
Autonomic Dysfunction
• Increasing NIH Stroke Scale
score associated with
progressive loss of overall
autonomic modulation
– Increased blood pressure
and respiratory rate
– Decreased R-R interval
NIH Stroke Scale scores can predict risk of
autonomic dysregulation and can be used
as premonitory signs of autonomic failure
Hilz, Max Josef, et al. "High NIHSS values predict impairment of cardiovascular
autonomic control." Stroke 42.6 (2011): 1528-1533.
NIH Stroke Scale Predicts
Long-term Needs
• 80% of patients
with score ≤ 5 are
discharged home
• Those with scores 6
▬ 13 usually require
acute rehabilitation
• Patients with scores
≥ 14 frequently
need long-term
care
Home
Rehab
Schlegel, Daniel, et al. "Utility of the NIH Stroke Scale as a predictor of
hospital disposition." Stroke 34.1 (2003): 134-137.
Nursing
Facility
Conclusions
• The NIH Stroke Scale is an efficient and
standardized brief neurological examination
which correlates with chronic functional
outcome, hospital disposition after stroke,
and infarct volume
• Overall reliability supported by literature in
different settings: telemedicine, medical
record abstraction, in multiple languages and
by different types of health care
professionals
• Reliability can improve with personal and
video tape training
Conclusions
• Pitfalls include:
–
–
–
–
Stroke exclusion with a score of zero
Lack of reliability of a few items
Lack of reliability in untrained hands
Skewed weighting for anterior and dominant
hemisphere strokes
– It measures impairment not disability
• Main relevance is as a research tool and in
the selection of patients with ischemic stroke
who are eligible for thrombolytic therapy
Conclusions
• NIH Stroke Scale score can also be used to:
– Monitor neurologic status
– Document neurologic outcomes
– Communicate between health care
professionals
– Predict in-hospital as well as long-term care
needs
The NIH Stroke Scale, while imperfect, still
imparts information relevant to clinical
practice
FREE training
secure.trainingcampus.net/uas/modules/trees/windex.a
spx?rx=nihss-english.trainingcampus.net
FREE Online Resources
• NIH Stoke Scale Training on YouTube
– https://www.youtube.com/watch?v=x4bjXqtfn
6k
• NIHSS Worksheet
– www.ninds.nih.gov/doctors/NIH_Stroke_Scale
.pdf
• NIHSS Calculator
– www.mdcalc.com/nih-stroke-scale-scorenihss/
References
• Charles, A. N. "The NIH stroke scale is unreliable in untrained
hands." Stroke Cerebrovascular Dis 11.1 (2002): 423-446.
• Meyer, Brett C., and Patrick D. Lyden. "The modified National
Institutes of Health Stroke Scale: its time has come."
International Journal of Stroke 4.4 (2009): 267-273.
• Nicks, Bret, et al. "Neurologic emergencies in resource-limited
settings: Stroke care considerations." African Journal of
Emergency Medicine (2014).
• Martin-Schild, Sheryl, et al. "Zero on the NIHSS does not equal
the absence of stroke." Annals of emergency medicine 57.1
(2011): 42-45.
• Woo, Daniel, et al. "Does the National Institutes of Health
Stroke Scale favor left hemisphere strokes?." Stroke 30.11
(1999): 2355-2359.
• Schlegel, Daniel, et al. "Utility of the NIH Stroke Scale as a
predictor of hospital disposition." Stroke 34.1 (2003): 134-137.
References
• Siegler, James E., et al. "What change in the national institutes
of health stroke scale should define neurologic deterioration in
acute ischemic stroke?." Journal of Stroke and
Cerebrovascular Diseases 22.5 (2013): 675-682.
• Sato, S., et al. "Baseline NIH Stroke Scale Score predicting
outcome in anterior and posterior circulation strokes."
Neurology 70.24 Part 2 (2008): 2371-2377.
• Lyden, P., et al. "Improved reliability of the NIH Stroke Scale
using video training. NINDS TPA Stroke Study Group." Stroke
25.11 (1994): 2220-2226.
• Tong, D. C., et al. "Correlation of perfusion-and diffusionweighted MRI with NIHSS score in acute (< 6.5 hour) ischemic
stroke." Neurology 50.4 (1998): 864-869.
• Demaerschalk, Bart M., et al. "Reliability of real-time video
smartphone for assessing National Institutes of Health Stroke
Scale scores in acute stroke patients." Stroke 43.12 (2012):
3271-3277.
References
• Goldstein, Larry B., and Gregory P. Samsa. "Reliability of the
National Institutes of Health Stroke Scale Extension to nonneurologists in the context of a clinical trial." Stroke 28.2
(1997): 307-310.
• Schwamm, Lee H., et al. "A review of the evidence for the use
of telemedicine within stroke systems of care. A scientific
statement from the American Heart Association/American
Stroke Association." Stroke 40.7 (2009): 2616-2634.
• Tirschwell, David L., et al. "A prospective cohort study of stroke
characteristics, care, and mortality in a hospital stroke registry
in Vietnam." BMC neurology 12.1 (2012): 150.
• Kasner, Scott E., et al. "Reliability and validity of estimating the
NIH stroke scale score from medical records." Stroke 30.8
(1999): 1534-1537.
References
• Nilanont, Yongchai, et al. "Establishment of the Thai version of
National Institute of Health Stroke Scale (NIHSS) and a
validation study." Journal of the Medical Association of
Thailand= Chotmaihet thangphaet 93 (2010): S171.
• Hilz, Max Josef, Sebastian Moeller, Aynur Akhundova, Harald
Marthol, Elisabeth Pauli, Philipp De Fina, and Stefan Schwab.
"High NIHSS values predict impairment of cardiovascular
autonomic control." Stroke 42, no. 6 (2011): 1528-1533.
• Lyden, Patrick, Rema Raman, Lin Liu, James Grotta, Joseph
Broderick, Scott Olson, Sandi Shaw et al. "NIHSS training and
certification using a new digital video disk is reliable." Stroke
36, no. 11 (2005): 2446-2449.
• Cong, Nguyen Huu. "Stroke care in Vietnam." International
Journal of Stroke 2, no. 4 (2007): 279-280.