NIH Stroke Scale (NIHSS)

David Goldemund M.D.
Updated on 14/03/2024, published on 27/09/2022
  • NIHSS is a standardized neurological scale developed to help physicians objectively quantify stroke severity
  • scoring range: 0-42 (with higher scores indicating more severe stroke symptoms)
  • scoring rules must be strictly followed to ensure reproducibility
  • variants of the NIHSS have been introduced:
    • modified NIHSS
      • some items are easier to score; data indicate higher reproducibility compared to the original NIHSS
      • however, it has not been widely adopted
    • NIHSS-8

Different classifications and tresholds have been reported

(Kimura, 2022)

  • NIHSS < 8  (mild stroke)
  • NIHSS 8-15 (moderate stroke)
  • NIHSS ≥ 16 (severe stroke)

(Kogan, 2020)

  • NIHSS ≤ 4 (minor stroke)
    • even patients with NIHSS 0 may have stroke and not TIA
  • NIHSS 5-15 (moderate stroke)
  • NIHSS 16-20 (moderate to severe stroke)
  • NIHSS 21-42 (severe stroke)

(Koton, 2022)

  • NIHSS ≤ 5 (minor)
  • NIHSS 6–10 (mild)
  • NIHSS 11–15 (moderate)
  • NIHSS 16–20 (severe)
  • NIHSS > 20 (very severe)
  • administer the items in the order listed, and do not go back to change scores
  • follow the instructions provided for each item
  • score based on what the patient actually does, not on what the clinician believes they could or should do
  • always assess the first response, not the best one (except for item 9 – Best Language)
    • for example, if a patient initially gives an incorrect answer about their age and later corrects themself, the answer should be scored as incorrect
    • this is crucial because otherwise, it is not possible to ensure reproducibility
  • never assist or coach the patient during the examination (unless the instructions explicitly allow this)
  • some items are scored only if present
    • for example, ataxia is scored as absent in a plegic patient
  • older deficits are also scored, except for sensory impairments
  • NIHSS is NOT a guide to select  tPA-suitable patients – tPA should be used regardless of severity  → see IVT contraindication
  • NIHSS indicates stroke severity and has been shown to correlate with infarct size and risk of hemorrhage
    • NIHSS of >20 was associated with a 17% rate of intracranial hemorrhage when treated with tPA, compared to a 3% rate in patients with a score of <10 (The NINDS t-PA Stroke Study Group 1997).
  • NIHSS may also predict large vessel occlusion (LVO)
    • higher NIHSS indicates a higher probability of LVO; although a low NIHSS score does not necessarily exclude it
    • some cut-off values for predicting LVO have been reported
      • NIHSS scores ≥ 9 within 3 hours after symptom onset and NIHSS scores ≥ 7 within >3 to 6 hours (Heldner, 2013)
  • baseline NIHSS may predict clinical outcome
    • a retrospective review of 1281 ischemic stroke patients found that each 1-point increase in NIHSS reduced the odds of an excellent outcome by 24% at 7 days and 17% at 3 months  (Adams 1999).
    • patients with moderate (6-13 points) or severe (>14 points) NIHSS scores were 3 times more likely to be placed in a nursing home after discharge and 8 times more likely to require rehabilitation therapy (Rundek 2000).
    • patients with a score of ≤ 4 are highly likely to have favorable clinical outcome irrespective of treatment
National Institute of Health Stroke Scale (NIHSS)
1a. Level of Consciousness
  • the investigator must choose a response if a complete evaluation is prevented by such obstacles as an endotracheal tube, language barrier, orotracheal trauma, or bandages
  • a 3 is scored only if the patient does not move (other than reflexive posturing) in response to noxious stimulation
0 – alert; keenly responsive
1 – not alert;  arousable verbally or by minor stimulation to obey, answer, or respond
2 – not alert; requires repeated or strong/painful stimulation to make at least escape movements
3 – coma, reflex postures (reflex), totally unresponsive and areflexic
1b. LOC – Answers
  • the patient is asked about the current month and their age
  • the answer must be correct – there is no partial credit for being close
  • aphasic and stuporous patients who do not comprehend the questions will score 2
  • patients unable to speak because of endotracheal intubation, orotracheal trauma, severe dysarthria from any cause, language barrier, or any other problem not secondary to aphasia are given a 1
  • only the initial answer is scored; no verbal or nonverbal cues are allowed
0 – answers both questions correctly
1 – answers 1 question correctly or severe dysarthria/mechanical or language barrier
2 = answers neither question correctly, aphasia, coma
1c. LOC – Tasks
  • the patient is asked to open and close the eyes and then to grip and release the non-paretic hand (or other tasks)
  • credit is given if a clear attempt is made but not completed due to weakness
  • if the patient does not respond to the command, the task should be demonstrated (pantomime), and the result scored (i.e., follows none, one, or two commands)
  • patients with trauma, amputation, or other physical disabilities should be given appropriate one-step commands
  • only the first attempt is scored
0 – performs both tasks correctly
1 – performs one task correctly
2 = performs neither task correctly, coma
2. Best gaze
  • only horizontal eye movements are tested
  • voluntary or reflexive (oculocephalic) eye movements are scored, not caloric testing
  • patients with an isolated peripheral nerve paresis (CN III, IV, or VI) score  1
  • patients with ocular trauma, coma, bandages, pre-existing blindness, or other disorders of visual acuity or fields should be tested with reflexive movements
0 – normal
1 – isolated peripheral paresis or partial gaze palsy in one or both eyes; can be overcome by the oculocephalic maneuver, no forced deviation
or total gaze paresis
2 – forced deviation or total gaze paresis, cannot be overcome by the oculocephalic maneuver
3. Visual fields
  • test by side confrontation, use finger counting or visual threat (blink reflex)
  • include double simultaneous stimulation; if there is extinction, the patient receives a 1, and the results are used for item 11
  • with unilateral blindness, visual fields in the fellow eye are scored
  • score 1 only if there is a clear-cut asymmetry, including quadrantanopia
  • if the patient is blind from any cause, score 3
0 – normal
1 – partial hemianopia or extinction
2 – complete hemianopia
3 – bilateral hemianopia or blindness (including cortical blindness)
4. Facial palsy
  • ask or use pantomime to encourage the patient to show teeth or raise eyebrows and close eyes
  • assess the symmetry of the grimace in response to noxious stimuli in the poorly responsive or noncomprehending patient
  • if facial trauma/bandages, orotracheal tube, tape, or other physical barriers obscure the face, these should be removed to the extent possible
0 – normal
1 – minor paralysis (flattened nasolabial fold, asymmetry on smiling)
2 – partial paralysis (total or near-total paralysis of the lower face)
3 –  complete uni- or bilateral paralysis  (absence of facial movement in the upper and lower face), coma
5. Motor arm

  • extend the arms (palms down) 90 degrees (if sitting) or 45 degrees (if supine)
  • drift is scored if the arm falls before 10 seconds
  • the aphasic patient is encouraged to use urgency in the voice and pantomime but not noxious stimulation
  • start with the non-paretic arm
  • in the case of amputation or shoulder fusion, the examiner should record the score as untestable (UN) and clearly write the explanation for this choice
0  – no drift; limb holds 90 (or 45) degrees for 10 seconds
1 –  limb drifts down before 10 seconds; does not hit the bed or other support
2 – some effort against gravity; limb fails to reach or maintain (if cued) 90 (or 45) degrees, drifts down to bed
3 – no effort against gravity;  arm falls to the bed
4 – no movement
UN = amputation or joint fusion, explain
6. Motor leg

  • hold the leg at 30 degrees (tested supine). Drift is scored if the leg falls before 5 seconds
  • the aphasic patient is encouraged using urgency in the voice and pantomime but not noxious stimulation
  • start with the non-paretic leg
  • in the case of amputation or hip fusion, the examiner should record the score as untestable (UN) and write the explanation for this choice
0 – no drift; leg holds 30-degree position for whole 5 seconds
1 – drift by the end of 5 seconds, but the leg does not hit the bed
2 – some effort against gravity; leg falls to bed by 5 seconds but has some effort against gravity
3 – no effort against gravity; the leg falls to bed immediately, with some movement on the bed

4 – no movement
UN = amputation or joint fusion, explain
7. Limb ataxia
  • test with eyes open
  • the finger-nose-finger and heel-shin tests are performed on both sides
  • ataxia is scored only if present out of proportion to the weakness
  • ataxia is scored as 0 in a patient who cannot understand, is paralyzed, or is in a coma
  • ensure testing is done in an intact visual field
  • in case of blindness, test by having the patient touch the nose from the extended arm position
  • only in the case of amputation or joint fusion the examiner should record the score as untestable (UN) and clearly write the explanation for this choice
0 – absent or paralyzed/does not understand/coma
1 – present in one limb
2 – present in two limbs
UN = Amputation or joint fusion, explain
8. Sensory
  • a sensation or grimace to pinprick or withdrawal from the noxious stimulus in the obtunded or aphasic patient
  • the examiner should test as many body areas (arms [not hands], legs, trunk, face) as needed to accurately check for hemisensory loss
  • only sensory loss attributed to stroke is scored as abnormal
  • a score of 2 should only be given when a severe or total loss of sensation can be clearly demonstrated; stuporous and aphasic patients will probably score 1 or 0
  • bilateral loss of sensation due to brainstem stroke is scored 2
  • if the patient is unresponsive, quadriplegic, or in a coma, give a 2 on this item
0 – normal
1 – mild-to-moderate sensory loss; pinprick is less sharp/duller, or there is a loss of superficial pain with a pinprick, but the patient is aware of being touched
2 – severe or total sensory loss; the patient is unaware of being touched; coma/unresponsive
9. Best Langauge
  • a great deal of information about comprehension will be obtained during the preceding sections; understanding is judged from responses here, as well as to all of the commands in the preceding general neurological exam
  • the patient is asked to name the items on the attached naming sheet and to read from the attached list of sentences
  • the patient is asked to describe the attached picture
  • if visual loss interferes with the tests, ask the patient to identify objects placed in the hand, repeat, and produce speech
  • the intubated patient is asked to write
  • the patient in a coma (item 1a=3) will automatically score 3
  • the examiner must choose a score for the patient with a stupor or limited cooperation, but a score of 3 should be used only if the patient is mute and follows no one-step commands
0 – no aphasia
1 – mild-to-moderate aphasia; loss of fluency or ability to understand without significant limitation
2 – severe aphasia with fragmentary expression; the great need for inference, questioning, and guessing by the listener; the listener carries the burden of communication
3 – mute, global aphasia – no usable speech or auditory comprehension, coma/unresponsive

10. Dysarthria

  • an adequate speech sample must be obtained 
  • if the patient has severe aphasia, the clarity of articulation of spontaneous speech can be rated
  • if the patient is intubated or has other physical barriers to speech, the examiner should record the score as untestable (UN) and write the explanation
  • do not tell the patient why they are being tested
0 – normal
1 – mild-to-moderate dysarthria; patient slurs at least some words, can be understood with some difficulty
2 – severe dysarthria (unintelligible slurring out of proportion to dysphasia), anarthria, mutism, coma
UN – intubated / other physical barriers – explain
11. Extinction and Inattention (formerly neglect)
  • sufficient information to identify neglect may be obtained during the prior testing
  • test simultaneous sensitivity and visual field, search for anosognosia
  • if the patient has severe vision loss preventing visual double simultaneous stimulation, and the cutaneous stimuli are normal, the score is normal
  • if the patient has aphasia but does appear to attend to both sides, the score is normal
  • abnormality is scored only if present, so the item is never untestable
0 – no abnormality
1 – neglects 1 modality – visual, tactile, auditory, spatial, or personal inattention or extinction to
simultaneous bilateral stimulation in one of the sensory modalities
2 – neglects >1 modality, profound hemi-inattention or extinction (fails to recognize own hand or orients to only one side of space), coma
Scoring patients in a coma (item 1a = 3)
 1a  Level of consciousness
 1b  LOQ questions (answers)
 1c  LOC questions (tasks)
   2  Best gaze
   3   Visual fields
   4   Facial palsy
 5-6  Arm and leg motor drift (left and right)
   7   Limb Ataxia
   8   Sensory
   9   Best language (aphasia)
 10   Dysarthria
 11   Extinction and Inattention (neglect)

test oculocephalic maneuver
test blink reflex

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NIH Stroke Scale