The National Institutes of Health Stroke Scale, or NIH Stroke Scale (NIHSS), is a tool used by healthcare providers to objectively quantify the impairment caused by a stroke and aid planning post-acute care disposition, though was intended to assess differences in interventions in clinical trials. The NIHSS was designed for the National Institute of Neurological Disorders and Stroke (NINDS) Recombinant Tissue Plasminogen Activator (rt-PA) for Acute Stroke Trial and was first published by neurologist Dr. Patrick Lyden and colleagues in 2001. Prior to the NIHSS, during the late 1980s, several stroke-deficit rating scales were in use (e.g., University of Cincinnati scale, Canadian neurological scale, the Edinburgh-2 coma scale, and the Oxbury initial severity scale).
The NIHSS is composed of 11 items, each of which scores a specific ability between a 0 and 4. For each item, a score of 0 typically indicates normal function in that specific ability, while a higher score is indicative of some level of impairment.National Institutes of Health, National Institute of Neurological Disorders and Stroke. Stroke Scale. https://www.ninds.nih.gov/sites/default/files/documents/NIH-Stroke-Scale_updatedFeb2024_508.pdf.
The individual scores from each item are summed in order to calculate a patient's total NIHSS score. The maximum possible score is 42, with the minimum score being a 0.NIH Stroke Scale Training, Part 2. Basic Instruction. Department of Health and Human Services, National Institute of Neurological Disorders and Stroke. The National Institute of Neurological Disorders and Stroke (NINDS) Version 2.0
Score Stroke severity 0No stroke symptoms1–4Minor stroke5–15Moderate stroke16–20Moderate to severe stroke21–42Severe stroke
Performing the scale While administering the NIHSS, it is important that the examiner does not coach or help with the assigned task. The examiner may demonstrate the commands to patients that are unable to comprehend verbal instructions; however, the score should reflect the patient's own ability. It is acceptable for the examiner to physically help the patient get into position to begin the test, but the examiner must not provide further assistance while the patient is attempting to complete the task.
For each item, the examiner should score the patient's first effort, and repeated attempts should not affect the patient's score. An exception to this rule exist in the language assessment (Item 9), in which the patient's best effort should be scored.
Some of the items contain "Default Coma Scores". These scores are automatically assigned to patients that scored a 3 in Item 1a. Note that the NIHSS may fluctuate depending on the time.
1. Level of consciousness (LOC) Level of consciousness (LOC) testing is divided into three sections. The first LOC items test for the patient's responsiveness. The second LOC item is based on the patient's ability to answer questions that are verbally presented by the examiner. The final LOC sub-section is based on the patient's ability to follow verbal commands to perform simple task.
Although this item is broken into three parts, each sub-section is added to the final score as if it is its own item.
A) LOC responsiveness Scores for this item are assigned by a medical practitioner based on the stimuli required to arouse patient. The examiner should first assess if the patient is fully alert to their surroundings. If the patient is not completely alert, the examiner should attempt a verbal stimulus to arouse the patient. Failure of verbal stimuli indicates an attempt to arouse the patient via repeated physical stimuli. If none of these stimuli are successful in eliciting a response, the patient can be considered totally unresponsive.
Score Test results0Alert; Responsive1Not alert; Verbally arousable or aroused by minor stimulation to obey, answer, or respond.2Not alert; Only responsive to repeated or strong and painful stimuli3Totally unresponsive; Responds only with reflexes or is areflexic
Notes If patients scores a 3 in this factor, the default coma scores should be used when applicable
B) LOC questions Patient is verbally asked their age and for the name of the current month.
Score Test results0Correctly answers both questions1Correctly answers one question2Does not correctly answer either question
Notes Default Coma Score: 2 The patient must answer each question 100% correct without help to get credit Patients unable to speak are allowed to write the answer Aphasic patients or patients in a stuporous state who are unable to understand the commands receive a score of 2 Patients that are unable to talk due to trauma, dysarthria, language barrier, or intubation are given a score of 1
C) LOC commands The patient is instructed to first open and close their eyes and then grip and release their hand.
Score Test results0Correctly performs both tasks1Correctly performs 1 task2Does not correctly perform either task
Notes Commands can only be repeated once. The hand grip command can be replaced with any other simple one step command if the patient cannot use their hands. A patient's attempt is regarded as successful if an attempt is made but is incomplete due to weakness. If the patient does not understand the command, the command can be visually demonstrated to them without an impact on their score. Patients with trauma, amputations, or other physical impediments can be given other simple one-step commands if these commands are not appropriate.
2. Horizontal eye movement Assesses ability for patient to track a pen or finger from side to side only using their eyes. This is designed to assess motor ability to gaze towards the hemisphere opposite of injury. This item is tested because conjugated eye deviation (CED) is present in approximately 20% of stroke cases. CED is more common in right hemispheric strokes and typically in lesions affecting the basal ganglia and temporoparietal cortex. Damage to these areas can result in decreased spatial attention and reduced control of eye movements.
Score Test results0Normal; Able to follow pen or finger to both sides1 Partial gaze palsy; gaze is abnormal in one or both eyes, but gaze is not totally paralyzed. Patient can gaze towards hemisphere of infarct, but cannot go past midline2Total gaze paresis; gaze is fixed to one side
Notes If patient is unable to follow the command to track an object, the investigator can make eye contact with the patient and then move side to side. The patient's gaze palsy can then be assessed by their ability to maintain eye contact. If patient is unable to follow any commands, assess the horizontal eye movement via the oculocephalic maneuver. This is done by manually turning the patient's head from midline to one side and assessing the eye's reflex to return to a midline position. If the patient has isolated peripheral nerve paresis assign a score of 1.
3. Visual field test Assess the patient's vision in each visual fields. Each eye is tested individually, by covering one eye and then the other. Each upper and lower quadrant is tested by asking the patient to indicate how many fingers the investigator is presenting in each quadrant. The investigator should instruct the patient to maintain eye contact throughout this test, and not allow the patient to realign focus towards each stimulus. With the first eye covered, place a random number of fingers in each quadrant and ask the patient how many fingers are being presented. Repeat this testing for the opposite eye.
Score Test results0No vision loss1Partial hemianopia or complete quadrantanopia; patient recognizes no visual stimulus in one specific quadrant2Complete hemianopia; patient recognizes no visual stimulus in one half of the visual field3Bilateral blindness, including blindness from any cause
Notes If patient is non-verbal, they can be allowed to respond by holding up the number of fingers the investigator is presenting. If patient is not responsive the visual fields can be tested by visual threat (the investigator moving an object towards the eye and observing the patient's response, being careful not to trigger the corneal reflex with air movement).
4. Facial palsy Facial palsy is partial or complete paralysis of portions of the face. Typically this paralysis is most pronounced in the lower half of one facial side. However, depending on lesion location the paralysis may be present in other facial regions. While inspecting the symmetry of each facial expression the examiner should first instruct patient to show their teeth (or gums). Second, the patient should be asked to squeeze their eyes closed as hard as possible. After reopening their eyes, the patient is then instructed to raise their eyebrows.Schimmel M, Leemann B, Christou P, Kiliaridis S, Herrmann F, Muller F. Quantitative assessment of facial muscle impairment in patients with hemispheric stroke. Journal of Oral Rehabilitation [serial online]. n.d.;NOV, 2011, 38.11, p800-p809, 10p.
Score Test results0Normal and symmetrical movement1Minor paralysis; function is less than clearly normal, such as flattened nasolabial fold or minor asymmetry in smile2Partial paralysis; particularly paralysis in lower face3Complete facial Hemiparesis, total paralysis in upper and lower portions of one face side
Notes If the patient is unable to understand verbal commands, the instructions should be demonstrated to the patient. Patients incapable of comprehending any commands may be tested by applying a noxious stimulus and observing for any paralysis in the resulting grimace.
5. Motor arm With palm facing downwards, have the patient extend one arm 90 degrees out in front if the patient is sitting, and 45 degrees out in front if the patient is lying down. If necessary, help the patient get into the correct position. As soon as the patient's arm is in position the investigator should begin verbally counting down from 10 while simultaneously counting down on their fingers in full view of the patient. Observe to detect any downward arm drift prior to the end of the 10 seconds. Downward movement that occurs directly after the investigator places the patient's arm in position should not be considered downward drift. Repeat this test for the opposite arm. This item should be scored for the right and left arm individually, denoted as item 5a and 5b.
Score Test results0 No arm drift; the arm remains in the initial position for the full 10 seconds1Drift; the arm drifts to an intermediate position prior to the end of the full 10 seconds, but not at any point relies on a support2Limited effort against gravity; the arm is able to obtain the starting position, but drifts down from the initial position to a physical support prior to the end of the 10 seconds3No effort against gravity; the arm falls immediately after being helped to the initial position, however the patient is able to move the arm in some form (e.g. shoulder shrug)4No movement; patient has no ability to enact voluntary movement in this arm
Notes Default coma score: 8 Test the non paralyzed arm first if applicable Score should be recorded for each arm separately, resulting in a maximum potential score of 8. Motor Arm assessment should be skipped in the case of an amputee, however a note should be made in the scoring of the amputation. If patient is unable to understand commands, the investigator should deliver the instructions via demonstration
6. Motor leg