The NIH Stroke Scale (NIHSS)

NIH Stroke Scale and Stroke Evaluation

Doctor consulting with a nurse
Getty Images/ David Sacks

The NIH Stroke Scale (NIHSS) is a standardized scoring tool used by physicians and other healthcare professionals to measure and record the level of impairment caused by a stroke. If you have overheard your stroke team discussing your NIHSS or the NIHSS of your loved one, you might have some questions about the meaning behind your score.

What Is a Stroke?

A stroke is a disease that affects the arteries leading to and within the brain. It is the No. 5 cause of death and a leading cause of disability in the United States. A stroke occurs when a blood vessel that carries oxygen and nutrients to the brain is either blocked by a blood clot or bursts (or ruptures). When that happens, the affected region of the brain cannot get the blood (and oxygen) it needs, so the brain tissue becomes impaired, resulting in a physical or cognitive handicap, which is a stroke.

Effects of Stroke

The brain is an extremely complex organ that controls various body functions. If a stroke occurs and blood flow can't reach the region that controls a particular body function, that part of the body may not function as it should. Stroke effects can include physical weakness, loss of balance, decreased sensation, trouble speaking and a number of other problems.

Because there are so many different stroke effects, depending on the affected region of the brain, not all strokes are of equivalent severity. The NIHSS is a tool by which stroke severity can be compared over time to determine whether a stroke is mild or severe and whether the effects are improving or worsening.

What Does the NIHSS Measure?

The NIH Stroke Scale measures several aspects of brain function, including consciousness, vision, sensation, movement, speech, and language.A certain number of pointsare given for each of these physical and cognitive functions during a focused neurological examination. A maximal score of 42 represents the most severe and devastating stroke.

The level of stroke severity as measured by the NIH stroke scale scoring system:

  • 0 = no stroke
  • 1-4 = minor stroke
  • 5-15 = moderate stroke
  • 15-20 = moderate/severe stroke
  • 21-42 = severe stroke

NIH Stroke Scale Use

Decision Making in Stroke Treatment

The NIH Stroke Scale serves several purposes, but its main use in clinical medicine is during the assessment of whether or not the degree of disability caused by a given stroke is suitable for treatment with tPA. This medication is a powerful blood thinner that can improve stroke outcome but can only be used in limited situations. The medical team uses the NIHSS, along with careful clinical decision making, to determine whether or not you are a candidate for emergency treatment with tPA.

Research Tool

Another important use of the NIHSS is in research, where it allows for the objective comparison of efficacy across different stroke treatments and rehabilitation interventions. This can help researchers determine, with uniform criteria, whether a medical treatment is effective in the treatment of stroke.

Consistent Communication Among Health Care Providers

In general, neurologists and other health care providers who take care of you during and after your stroke use detailed clinical records to communicate about your condition. The NIHSS stroke scale is a number that can covey the severity of your stroke but is not the main point that your doctors look at when assessing your condition and making treatment decisions.

However, the uniformity of the scale can help your health care providers get a picture of how much your stroke has improved or worsened over time.

A Word From Verywell

Your healthcare team may use specialized ways to assess and record your medical condition so that everyone on the team will understand how your illness is improving or worsening over time. The NIH stroke scale is one of the tools that your stroke care team uses to communicate in a consistent manner, particularly because there are many different people on your stroke care team who are involved in caring for you as you recover from your stroke. 

The NIH stroke scale is not the only tool used to evaluate and record your condition if you have had a stroke, but you can follow the numbers that your health care providers use when they record your NIH stroke severity so that you can get a general idea about your overall progress over time.

Aside from the NIHSS, there is also a post stroke checklist that may be used to asses your recovery after a stroke.

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Article Sources
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  2. Lui SK, Nguyen MH. Elderly stroke rehabilitation: overcoming the complications and its associated challenges. Curr Gerontol Geriatr Res. 2018;2018:9853837. doi:10.1155/2018/9853837

  3. Harrison JK, Mcarthur KS, Quinn TJ. Assessment scales in stroke: clinimetric and clinical considerations. Clin Interv Aging. 2013;8:201-11. doi:10.2147/CIA.S32405

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