The NIH Stroke Scale (NIHSS)

NIH Stroke Scale and Stroke Evaluation

Doctor looking at CT Scan
Morsa Images/Digital Vision/Getty Images

The NIH Stroke Scale (NIHSS) is a standardized tool used by physicians and other healthcare professionals to measure the level of impairment caused by a stroke.

What is Stroke?

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 clot or bursts (or ruptures).

When that happens, part of the brain cannot get the blood (and oxygen) it needs, so it and brain cells die.

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 won't work as it should. 

Risk Factors of Stroke

  • Age — The chance of having a stroke approximately doubles for each decade of life after age 55. While stroke is common among the elderly, a lot of people under 65 also have strokes.
  • Heredity (family history) — Your stroke risk may be greater if a parent, grandparent, sister or brother has had a stroke. 
  • Race — African-Americans have a much higher risk of death from a stroke than Caucasians do. This is partly because blacks have higher risks of high blood pressure, diabetes and obesity.
  • Sex (gender) — Each year, women have more strokes than men, and stroke kills more women than men. Use of birth control pills, pregnancy, history of preeclampsia/eclampsia or gestational diabetes, oral contraceptive use, and smoking, and post-menopausal hormone therapy may pose special stroke risks for women. 
  • Prior stroke, TIA or heart attack — The risk of stroke for someone who has already had one is many times that of a person who has not. Transient ischemic attacks are "warning strokes" that produce stroke-like symptoms but no lasting damage. TIAs are strong predictors of stroke. A person who's had one or more TIAs is almost 10 times more likely to have a stroke than someone of the same age and sex who hasn't. Recognizing and treating TIAs can reduce your risk of a major stroke. TIA should be considered a medical emergency and followed up immediately with a healthcare professional. If you've had a heart attack, you're at higher risk of having a stroke, too.

    NIH Stroke Scale

    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 merits treatment with tPA. 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.

    The NIH Stroke Scale measures several aspects of brain function, including consciousness, vision, sensation, movement, speech, and language. A certain number of points are given for each impairment uncovered during a focused neurological examination. A maximal score of 42 represents the most severe and devastating stroke. Guidelines as of 2008 allow strokes with scores greater than 4 points to be treated with tPA.

    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

    References:

    American Stroke Association. http://www.strokeassociation.org/STROKEORG/AboutStroke

    Bradley G Walter, Daroff B Robert, Fenichel M Gerald, Jancovic, Joseph; Neurology in clinical practice, principles of diagnosis and management. Philadelphia Elsevier, 2004.

    Continue Reading