NIH Stroke Scale (NIHSS): how the 15 Brott 1989 items add up to a score from 0 to 37

The NIH Stroke Scale (NIHSS), in the form Brott and colleagues published in 1989, adds the points from 15 neurologic examination items. Each item is scored from 0 up to its own maximum, and the total runs from 0 to 37.

Not a medical device. Not a diagnosis or dosing recommendation.

Use this calculator via API

Neurology calculators
Brott T et al. · 1989
The NIHSS formula
Worked examples
Frequently asked questions

What is the NIH Stroke Scale?

Brott and colleagues described the scale in Stroke in 1989. Their abstract calls it a 15-item neurologic examination stroke scale, designed for use in trials in acute stroke.

Magent's calculator follows that 1989 form. It includes pupillary response and plantar reflex, and it scores one motor arm and one motor leg, the weaker limb, instead of left and right separately. That makes it different from the later NINDS form with 11 categories, which dropped the pupil item and split motor scoring into left and right.

The person using the calculator assigns every item. The calculator adds them and returns the total and the top of 37. The 1989 paper didn't publish mild, moderate or severe bands for the total, so the calculator doesn't return any.

This page explains the items and the sum. It doesn't say what a score means for a particular person.

The NIHSS formula

NIHSS = level of consciousness (0–3)
      + LOC questions (0–2) + LOC commands (0–2)
      + pupillary response (0–2)
      + gaze (0–2) + visual (0–2)
      + facial palsy (0–3)
      + motor arm, weaker limb (0–4) + motor leg, weaker limb (0–3)
      + plantar reflex (0–3)
      + limb ataxia (0–2) + sensory (0–2) + neglect (0–2)
      + dysarthria (0–2) + language (0–3)
total 0–37; no severity bands

Exact expression the calculator uses:

NIHSS = loc (0-3) + loc_questions (0-2) + loc_commands (0-2) + pupillary_response (0-2) + best_gaze (0-2) + best_visual (0-2) + facial_palsy (0-3) + best_motor_arm (0-4) + best_motor_leg (0-3) + plantar_reflex (0-3) + limb_ataxia (0-2) + sensory (0-2) + neglect (0-2) + dysarthria (0-2) + best_language (0-3); Brott 1989 15-item neurologic examination scale (weaker-limb motor; includes pupillary response and plantar reflex); total = sum; max 37; no published total-score severity bands

The 15 items

Input	Meaning	Accepted range
`loc`	Level of consciousness: 0 alert, 1 drowsy, 2 stuporous, 3 coma	0 to 3
`loc_questions`	LOC questions: 0 answers both correctly, 1 answers one correctly, 2 incorrect	0 to 2
`loc_commands`	LOC commands: 0 obeys both correctly, 1 obeys one correctly, 2 incorrect	0 to 2
`pupillary_response`	Pupillary response: 0 both reactive, 1 one reactive, 2 neither reactive	0 to 2
`best_gaze`	Gaze: 0 normal, 1 partial gaze palsy, 2 forced deviation	0 to 2
`best_visual`	Visual: 0 no visual loss, 1 partial hemianopia, 2 complete hemianopia	0 to 2
`facial_palsy`	Facial palsy: 0 normal, 1 minor, 2 partial, 3 complete	0 to 3
`best_motor_arm`	Motor arm, weaker limb: 0 no drift, 1 drift, 2 cannot resist gravity, 3 no effort, 4 no movement	0 to 4
`best_motor_leg`	Motor leg, weaker limb: 0 no drift, 1 drift, 2 cannot resist gravity, 3 no effort	0 to 3
`plantar_reflex`	Plantar reflex: 0 normal, 1 equivocal, 2 extensor, 3 bilateral extensor	0 to 3
`limb_ataxia`	Limb ataxia: 0 absent, 1 present in upper or lower, 2 present in both	0 to 2
`sensory`	Sensory: 0 normal, 1 partial loss, 2 dense loss	0 to 2
`neglect`	Neglect: 0 no neglect, 1 partial neglect, 2 complete neglect	0 to 2
`dysarthria`	Dysarthria: 0 normal articulation, 1 mild to moderate, 2 near unintelligible or worse	0 to 2
`best_language`	Language: 0 no aphasia, 1 mild to moderate, 2 severe aphasia, 3 mute	0 to 3

How the score works

Score each item. The person using the calculator picks a whole number for each of the 15 items, from 0 up to that item's maximum.
Add the 15 numbers. The total is 0 to 37.
Read the total as a count of points. The calculator doesn't attach a severity label to it.

0 on every item gives 0. Every item at its maximum gives 37. Motor arm has the widest range, 0 to 4.

Inputs come from the user

Every item is set by the person using the calculator. Magent's calculator doesn't examine the patient. All 15 items are required, and an item that's missing, isn't a whole number or falls outside its range is rejected with an error. The calculator returns the total, the top of 37 and the points for each item.

Worked examples

These use Magent's own expected values for the calculator. Any item not named is 0.

Example 1: every item 0

Score: 0 out of 37.

Example 2: level of consciousness 3

loc 3, all other items 0.
Score: 3 out of 37.

Example 3: motor arm 4

Motor arm 4, all other items 0.
Score: 4 out of 37.

Example 4: pupillary response 2

Pupillary response 2, all other items 0.
Score: 2 out of 37.

Example 5: five items scored

Pupillary response 2 + gaze 2 + facial palsy 1 + motor arm 4 + motor leg 3.
Score: 12 out of 37. No severity label is returned.

Example 6: every item at its maximum

3 + 2 + 2 + 2 + 2 + 2 + 3 + 4 + 3 + 3 + 2 + 2 + 2 + 2 + 3, in the order of the table above.
Score: 37, the maximum.

History of the NIH Stroke Scale

The scale comes from Brott T, Adams HP Jr, Olinger CP and colleagues, Measurements of acute cerebral infarction: a clinical examination scale, Stroke, 1989 (volume 20, issue 7, pages 864–870). The abstract reports high agreement between raters and on repeat testing, and compares scale scores with infarct size on CT and with clinical outcome. It notes that pupillary response was the item raters agreed on most but had low validity, while less consistent items, such as arm or leg motor function, were more valid.

When it's used

The 1989 paper designed the scale for trials in acute stroke, scored from a neurologic examination.

Where it's used

The 1989 paper tested the scale with raters from neurology and the emergency department: a neurologist, a neurology house officer, a neurology nurse and an emergency department nurse.

Who uses it

In the 1989 paper, repeat-testing agreement didn't differ significantly among those four kinds of raters. With the calculator, the person who did the examination enters the 15 item scores, and the calculator adds them.

Limits of the calculation

You score each item. The calculator doesn't examine the patient.
It's the 1989 form with 15 items, a pupil item, a plantar reflex item and weaker-limb motor scoring. It isn't the later NINDS form with 11 categories, and it isn't the modified NIHSS (mNIHSS).
It returns a total out of 37. It doesn't apply mild, moderate or severe bands from later sources.
This page doesn't say what to do with a score.

Clinical decisions belong to a qualified clinician who knows the patient.

Modified NIHSS (mNIHSS) sums 11 NINDS-style items, with left and right motor scored separately.
Pediatric NIHSS sums 15 NINDS-form items with left and right motor arm and leg.
LAMS adds three motor items: facial droop, arm drift and grip.
RACE scale adds facial palsy, arm and leg motor, head and gaze deviation, and cortical signs.
Glasgow Coma Scale adds eye, verbal and motor responses.

Glossary

LOC: level of consciousness.
Weaker limb: in this form, one motor arm score and one motor leg score, for the weaker side.
NINDS form: the later version of the scale with 11 categories, no pupil item and left and right motor scoring.
Cerebral infarction: the condition in the 1989 paper's title; the paper compared scale scores with infarct size on CT.

Common mistakes

Using the wrong version. This calculator is the 1989 form. Scores from the later NINDS form, with left and right motor items, don't go in here.
Scoring both arms or both legs. The 1989 form scores the weaker arm and the weaker leg once each.
Leaving out the pupil or plantar reflex item. Both are part of the 1989 form.
Going past an item's range. Motor arm stops at 4, and most items stop at 2 or 3.
Expecting a severity label. The calculator returns the total and nothing more.

Source

Brott T, Adams HP Jr, Olinger CP, et al. Measurements of acute cerebral infarction: a clinical examination scale. Stroke. 1989;20(7):864-870. DOI: 10.1161/01.STR.20.7.864. PMID: 2749846

Frequently asked questions

How do you calculate the NIHSS?

Score each of the 15 items from 0 up to its maximum and add them. The total is 0 to 37.

What is a normal NIHSS score?

0 on every item gives a total of 0. The 1989 paper didn't publish bands for the total, and the calculator doesn't apply any.

What is the highest NIHSS score?

37 in the 1989 form, with every item at its maximum.

Why does this NIHSS include pupillary response?

The 1989 form has a pupil item, scored 0 to 2. The later NINDS form dropped it.

Are both arms scored?

No. The 1989 form scores one motor arm and one motor leg, the weaker limb.