NIH Stroke Scale: What is it and how does it work?

NeuroRehab Team
Friday, January 22nd, 2021

National Institutes of Health Stroke Scale (NIHSS) is a clinical tool that measures stroke-related neurologic deficits. This measure can be quantified. NIHSS is used in modern neurology for three main objectives;

• to evaluate the violence of stroke to its patients and document the neurological status of the patients.
• To determine the treatment to be administered to patients by planning the appropriate patient care and act as a common language for the exchange of information understood by healthcare providers.
• To predict the outcome of the patient from the illness, both long and short term outcomes. It can also indicate a lesion size and be a measure of stroke severity.

Background and Development

NIHSS was initially intended for research purposes. It was designed as a research tool in clinical trials for acute strokes to measure baseline data. It was used to assess the severity of ischemic stroke in controlled clinical studies.

NIHSS can be termed as a composite scale because it was derived from four other scales. The Toronto Stroke Scale, the Edinburgh-2 Coma Scale, Oxbury Initial Severity Scale and the Cincinnati Stroke Scale. It is designed to be a simple tool that can be used at the bedside consistently by healthcare providers like nurses, therapists and physicians.

Since this stroke scale is widely used, not only the caregivers of stroke patients must be informed about its works. The patients and their families should also be aware of how the scale works and how to read it.

How NIHSS Works?

NIHSS is a 15 item neurological tool, although some may say it has 11 elements because the first element is divided into three sub-elements 1a, 1b and 1c, while the fifth and sixth have two sub-elements each. These elements evaluate the effects of cerebral infarction. Each item’s ratings are scored on a point scale of three to five points with 0 being normal. Additionally, there is an allowance for things that are not testable. The score ranges from 0 to 42, with 42 being the highest possible score. When it comes to the NIHSS, the higher the score, the greater the severity of stroke. Therefore, a patient with a score of 35 has a higher severity risk compared to one with a score of 13.

An observer rates a patient depending on their ability to answer questions and perform some activities. This assessment per patient does not require a lot of time; usually, it takes less than ten minutes to be complete.

Scoring

NIHSS scores may be used to stratify stroke severity as follows (Brott et al., 1989);

• Very severe: above 25
• Severe: 15-24
• Mild to moderately severe: 5-14
• Mild: 1-5

There are also outcomes related to NIHSS scores at admission, acute stroke (Schlegel et al., 2003; Rundek et al., 2000)

• For scores below 5, 80% of stroke survivors will be released to go home.
• Scores between 6-13, the patients require acute in-patient rehabilitation.
• For scores above 14, the patients require long term skilled care.

At times, the patients might seem to be struggling with the assessments, and all you want to do as a caregiver, a family member or an examiner is to help them get through this by assisting them or coaching them for the assessment. Your attempt to help, however genuine, does no good to the patient because then, the scores reflected on the evaluation are not entirely the patient’s effort. Therefore, the clinicians are not in a position to accurately tell the severity of the stroke. They might end up discharging a patient who needs in-patient rehabilitation. Therefore, it would be best if the patients were neither aided nor coached by anyone for their assessments. This way, the results would be accurate.

Elements of the Scale

Here are the elements of the National Institutes of Health Stroke Scale;

• The first one is the level of consciousness, which is subdivided into two other elements: consciousness questions and the level of consciousness commands. This element evaluates the responsiveness and alertness of a patient through simple questions and commands. For the questions like the current date, month or even age, the patient must be exact.
• The second element is the best gaze which evaluates the patient’s ability to move their eyes naturally through moving an object horizontally and asking the patient to follow it.
• Visual element tests the patient’s ability to see things that are not directly before them.
• Facial palsy tests how well a patient can move their facial muscles. It may involve activities like raising eyebrows while closing their eyes. It may include observing facial expression after introducing a noxious stimulus if the patient is not responsive.
• The motor arm is divided into the right motor arm element and left motor arm. Both the right and left arms test whether a patient can hold up their arms for a specific time.
• Motor leg, just like the motor arm, is divided into right and left motor leg elements where each leg is held up for 30 seconds.
• Limb ataxia tests whether there is damage to the cerebellum through the heel-shin and finger-nose-finger tests.
• Sensory test which tests the patient’s sensory abilities and looking at the responses to certain stimuli.
• Best language to test whether the stroke affected the patient’s ability to communicate fluently or clearly.
• Dysarthria tests for a slur in speech.
• Extinction and inattention, also known as neglect, test the patient’s level of attention to their surroundings.

Click to See Scale

Instructions

The National Institutes of Health Stroke Scale requires observers to be adequately trained to use it accurately and effectively. A certified clinician should perform an assessment of a patient; a nurse, physician or therapist. The evaluation should be completed within twelve hours of admission, during the initial assessment before a t-PA decision. The stroke severity assessment majorly depends on the accuracy and consistency of the patient’s evaluation by an observer. It is, therefore, necessary to have adequate training.

To learn more about other important stroke-related scales and evaluations, visit www.neurorehabdirectory.com for more information.