From the Guidelines
The NIH Stroke Scale (NIHSS) is a crucial assessment tool for evaluating stroke severity, consisting of 11 components that measure key neurological functions, with a total score ranging from 0 to 42, and is essential for guiding treatment decisions and predicting patient outcomes. The scale assesses level of consciousness, horizontal eye movement, visual field testing, facial palsy, motor arm and leg function, limb ataxia, sensory function, language, dysarthria, and extinction/inattention, with each component scored based on severity 1. The NIHSS has significant implications for clinical practice, as it helps determine stroke severity, guides treatment decisions, including eligibility for thrombolytic therapy with tPA, and serves as a predictor of patient outcomes 1.
Key components of the NIHSS include:
- Level of consciousness, which assesses alertness, orientation, and ability to follow commands
- Motor function, which evaluates arm and leg strength and coordination
- Sensory function, which assesses touch and pain perception
- Language and dysarthria, which evaluate speech and communication abilities
- Extinction/inattention, which assesses the patient's ability to focus and respond to stimuli
The NIHSS score is highly correlated with outcome, with higher scores indicating worse prognoses and a higher likelihood of death or severe disability 1. A score of greater than 16 forecasts a high probability of death or severe disability, whereas a score of less than 6 forecasts a good recovery. Proper training in administering the NIHSS is essential to ensure consistent and accurate scoring, as treatment decisions and clinical pathways often depend on these assessments. Serial NIHSS assessments are also useful for monitoring stroke progression or improvement over time, allowing healthcare providers to adjust treatment plans accordingly 1.
From the Research
Overview of the National Institutes of Health (NIH) Stroke Scale
The NIH Stroke Scale is a widely used assessment tool to determine the severity of stroke and guide treatment decisions. It consists of 15 items that evaluate various aspects of neurological function, including level of consciousness, language, visual fields, and motor strength.
Components of the NIH Stroke Scale
The components of the NIH Stroke Scale include:
- Level of consciousness
- Language
- Visual fields
- Extraocular movement
- Motor strength
- Ataxia
- Dysarthria
- Sensation
Implications of the NIH Stroke Scale
The NIH Stroke Scale has significant implications for assessing stroke severity and guiding treatment decisions. A study published in 2020 found that the baseline NIHSS score has a profound association with mortality after acute stroke 2. Another study published in 2002 found that a shortened version of the NIHSS, consisting of 8 items, can be used to measure stroke severity and predict outcomes in the prehospital setting 3.
Modified Versions of the NIH Stroke Scale
There are modified versions of the NIH Stroke Scale, including the modified NIHSS (mNIHSS), which minimizes redundancy and eliminates poorly reliable items 4. The mNIHSS has shown greater reliability in multiple settings and cohorts, including scores abstracted from records, when used via telemedicine, and when used in clinical trials.
Retrospective Assessment of Initial Stroke Severity
The NIH Stroke Scale can be used for retrospective assessment of initial stroke severity, with an algorithm developed for retrospective NIHSS scoring showing near-perfect interrater reliability and excellent agreement between prospective and retrospective NIHSS scores 5.
Percent Change on the NIH Stroke Scale
Percent change on the NIH Stroke Scale can be a useful acute stroke outcome measure, with a study published in 2009 finding that percent NIHSS score change predicted functional outcomes very well, with areas under the curve of 0.90 or greater 6.
Key Findings
Key findings from the studies include:
- The NIH Stroke Scale is a valid assessment tool for determining stroke severity and guiding treatment decisions.
- The baseline NIHSS score has a profound association with mortality after acute stroke.
- Modified versions of the NIH Stroke Scale, such as the mNIHSS, can improve reliability and minimize redundancy.
- The NIH Stroke Scale can be used for retrospective assessment of initial stroke severity.
- Percent change on the NIH Stroke Scale can be a useful acute stroke outcome measure.