There are a variety of stroke scales that doctors can use. However, the National Institutes of Health Stroke Scale (NIHSS) is the most popular neurological examination tool to assess and quantify the severity of stroke symptoms.
It consists of 11 items that evaluate different aspects of neurological function, including a person’s level of consciousness, language, motor function, sensory function, and visual fields.
Doctors commonly use the NIHSS in clinical trials and in the management of those who have experienced an acute stroke to guide treatment decisions and predict outcomes.
This article examines what the NIHSS is and its purpose. It also looks at the benefits and drawbacks of the scale.
The NIHSS is a standardized neurological examination tool to assess and quantify the severity of stroke symptoms, taking less than 10 minutes.
The purpose of the NIHSS is to provide an
Doctors developed the NIHSS to provide a consistent and reliable way to evaluate those who have had a stroke and to help them make treatment decisions and predict a person’s outlook.
The NIHSS can also help with monitoring people during rehabilitation and assessing the impact of stroke on daily life activities.
The NIHSS evaluates the
| Item | Examination | Score |
|---|---|---|
| 1 | 1a. Level of consciousness (LOC) | 0: Alert 1: Not alert, arousable 2: Not alert, and has a reduced level of consciousness or alertness 3: Unresponsive |
| 1b. LOC questions | 0: Answers both correctly 1: Answers one correctly 2: Incorrect | |
| 1c. LOC commands | 0: Obeys both correctly 1: Obeys one correctly 2: Incorrect | |
| 2 | Best gaze | 0: Normal 1: Partial gaze palsy 2: Forced deviation |
| 3 | Visual fields | 0: No visual loss 1: Partial hemianopsia 2: Complete hemianopsia 3: Bilateral hemianopsia Hemianopsia refers to the loss of one half of person’s vertical visual field. |
| 4 | Facial palsy | 0: Normal 1: Minor paralysis 2: Partial paralysis 3: Complete paralysis |
| 5 | Motor arm | 0: No drift 1: Drift before 10 seconds 2: Falls before 10 seconds 3: No effort against gravity 4: No movement |
| 6 | Motor leg | 0: No drift 1: Drift before 10 seconds 2: Falls before 10 seconds 3: No effort against gravity 4: No movement |
| 7 | Limb ataxia | 0: Absent 1: One limb 2: Two limbs |
| 8 | Sensory | 0: Normal 1: Mild loss 2: Severe loss |
| 9 | Best language | 0: Normal 1: Mild aphasia 2: Severe aphasia 3: Mute or global aphasia Aphasia refers to a person’s difficulty with speech and language. |
| 10 | Dysarthria — when a person has difficulty speaking due to weakness in the muscles used for speech | 0: Normal 1: Mild 2: Severe |
| 11 | Extinction and inattention | 0: Normal 1: Mild 2: Severe |
The NIHSS is a valuable tool for assessing stroke severity and guiding treatment decisions in those with acute stroke.
Healthcare professionals with training in stroke care, such as emergency medicine physicians, neurologists, and stroke nurses, typically use this scale.
A 2017 article in the
Doctors should perform the NIHSS as soon as possible after a person arrives at the hospital with stroke symptoms. This is because it provides important information that can guide treatment decisions and predict outcomes.
The NIHSS can help identify those who are most likely to benefit from time-sensitive treatments, such as intravenous thrombolysis or endovascular therapy. It can also help to determine the appropriate level of care, including admission to a specialized stroke unit.
Doctors can also use the NIHSS to monitor the person’s condition over time and to assess the impact of stroke on daily life activities.
A doctor typically performs the scale at regular intervals during the acute phase of stroke care and during rehabilitation to assess progress and help them decide on treatment.
The NIHSS has several benefits and has widespread validation as a reliable and valid tool for assessing stroke severity.
Some key benefits and validity of the NIHSS include:
- Standardization: The NIHSS provides a standardized and objective assessment of stroke severity. This allows healthcare professionals to compare scores over time, which can help guide treatment decisions and monitor a person’s progress.
- Predictive value: It is a
strong predictor of stroke outcomes, including mortality, functional outcomes, and recovery. This can help healthcare professionals identify those most likely to benefit from time-sensitive treatments and guide post-stroke management. - Inter-rater reliability: The NIHSS has high inter-rater reliability, which means that different healthcare professionals can obtain similar scores when assessing the same person who experienced a stroke. This is important for ensuring consistency in stroke care and comparing scores across different settings.
- Validity: It has received validation as a reliable and valid tool for assessing stroke severity in different patient populations, including those with ischemic and hemorrhagic stroke, and in different healthcare settings, including emergency departments, stroke units, and rehabilitation centers.
- Versatility: The NIHSS is useful in clinical trials, research studies, and routine clinical practice to assess stroke severity, monitor a person’s progress, and guide treatment decisions. Doctors can also use it in telestroke settings to assess people remotely and provide timely treatment recommendations.
There are also some potential limitations of the NIHSS:
- Floor and ceiling effects: The NIHSS may not capture the full range of stroke severity, particularly in those with very mild or severe symptoms. This can result in floor or ceiling effects, where a person scores the minimum or maximum score on some or all items, which limits the ability of the NIHSS to capture change over time.
- Limited assessment of cognitive function: It
does not assess cognitive function in detail, which may be a limitation in those with cognitive deficits, such as dementia. - Limited assessment of posterior circulation strokes: Doctors primarily designed the NIHSS to assess anterior circulation strokes, and it
may not fully capture the symptoms of posterior circulation strokes. - Lack of sensitivity to subtle deficits: The NIHSS
may not be sensitive enough to detect subtle neurological deficits that can impact a person’s daily life activities. - Limited assessment of upper limb function: Its motor items only assess proximal upper limb function and do not capture fine motor or hand function, which may be important for some people.
Doctors should be aware of these potential limitations when using the NIHSS and consider additional assessments and information when making treatment decisions for individual people.
Overall, the NIHSS is a valuable tool for assessing stroke severity and guiding treatment decisions in those with acute stroke.
Healthcare professionals should use it in conjunction with additional assessments and information when making treatment decisions for a person.