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. [1]
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. [2] [3]
Score [3] | Stroke severity |
---|---|
0 | No stroke symptoms |
1–4 | Minor stroke |
5–15 | Moderate stroke |
16–20 | Moderate to severe stroke |
21–42 | Severe stroke |
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. [1]
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. [4]
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. [3]
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 his or her 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. [3]
Score | Test results |
---|---|
0 | Alert; Responsive |
1 | Not alert; Verbally arousable or aroused by minor stimulation to obey, answer, or respond. |
2 | Not alert; Only responsive to repeated or strong and painful stimuli |
3 | Totally unresponsive; Responds only with reflexes or is areflexic |
Notes
Patient is verbally asked his or her age and for the name of the current month. [3]
Score | Test results |
---|---|
0 | Correctly answers both questions |
1 | Correctly answers one question |
2 | Does not correctly answer either question |
Notes
The patient is instructed to first open and close his or her eyes and then grip and release his or her hand. [3]
Score | Test results |
---|---|
0 | Correctly performs both tasks |
1 | Correctly performs 1 task |
2 | Does not correctly perform either task |
Notes
Assesses ability for patient to track a pen or finger from side to side only using his or her 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. [5]
Score | Test results |
---|---|
0 | Normal; Able to follow pen or finger to both sides |
1 | 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 midline |
2 | Total gaze paresis; gaze is fixed to one side |
Notes
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. [3]
Score | Test results |
---|---|
0 | No vision loss |
1 | Partial hemianopia or complete quadrantanopia; patient recognizes no visual stimulus in one specific quadrant |
2 | Complete hemianopia; patient recognizes no visual stimulus in one half of the visual field |
3 | Bilateral blindness, including blindness from any cause |
Notes
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 his or her teeth (or gums). Second, the patient should be asked to squeeze his or her eyes closed as hard as possible. After reopening his or her eyes, the patient is then instructed to raise his or her eyebrows. [6]
Score | Test results |
---|---|
0 | Normal and symmetrical movement |
1 | Minor paralysis; function is less than clearly normal, such as flattened nasolabial fold or minor asymmetry in smile |
2 | Partial paralysis; particularly paralysis in lower face |
3 | Complete facial Hemiparesis, total paralysis in upper and lower portions of one face side |
Notes
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 his or her 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. [3]
Score | Test results |
---|---|
0 | No arm drift; the arm remains in the initial position for the full 10 seconds |
1 | Drift; the arm drifts to an intermediate position prior to the end of the full 10 seconds, but not at any point relies on a support |
2 | Limited 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 seconds |
3 | No 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) |
4 | No movement; patient has no ability to enact voluntary movement in this arm |
Notes
With the patient in the supine position, one leg is placed 30 degrees above horizontal. As soon as the patient's leg is in position the investigator should begin verbally counting down from 5 while simultaneously counting down on his or her fingers in full view of the patient. Observe any downward leg drift prior to the end of the 5 seconds. Downward movement that occurs directly after the investigator places the patient's leg in position should not be considered downward drift. Repeat this test for the opposite leg. Scores for this section should be recorded separately as 6a and 6b for the left and right legs respectively. [3]
Score | Test results |
---|---|
0 | No leg drift; the leg remains in the initial position for the full 5 seconds |
1 | Drift; the leg drifts to an intermediate position prior to the end of the full 5 seconds, but at no point touches the bed for support |
2 | Limited effort against gravity; the leg is able to obtain the starting position, but drifts down from the initial position to physical support prior to the end of the 5 seconds |
3 | No effort against gravity; the leg falls immediately after being helped to the initial position, however, the patient is able to move the leg in some form (e.g. hip flex) |
4 | No movement; patient has no ability to enact voluntary movement in this leg |
Notes
This test for the presence of a unilateral cerebellar lesion, and distinguishes a difference between general weakness and incoordination. The patient should be instructed to first touch his or her finger to the examiner's finger then move that finger back to his or her nose, repeat this movement 3-4 times for each hand. Next the patient should be instructed to move his or her heel up and down the shin of his or her opposite leg. This test should be repeated for the other leg as well. [3]
Score | Test results |
---|---|
0 | Normal coordination; smooth and accurate movement |
1 | Ataxia present in 1 limb; rigid and inaccurate movement in one limb |
2 | Ataxia present in 2 or more limbs: rigid and inaccurate movement in both limbs on one side |
Notes
Sensory testing is performed via pinpricks in the proximal portion of all four limbs. While applying pinpricks, the investigator should ask whether or not the patient feels the pricks, and if he or she feels the pricks differently on one side when compared to the other side. [3]
Score | Test results |
---|---|
0 | No evidence of sensory loss |
1 | Mild-to-Moderate sensory loss; patient feels the pinprick, however he or she feels as if it is duller on one side |
2 | Severe to total sensory loss on one side; patient is not aware he or she is being touched in all unilateral extremities |
Notes
This item measures the patient's language skills. After completing items 1-8, it is likely the investigator has gained an approximation of the patient's language skills; however, it is important to confirm this measurement at this time. The stroke scale includes a picture of a scenario, a list of simple sentences, a figure of assorted random objects, and a list of words. The patient should be asked to explain the scenario depicted in the first figure.
Next, the patient should read the list of sentences and name each of the objects depicted in the next figure. The scoring for this item should be based on both the results from the test performed in this item in addition to the language skills demonstrated up to this point in the stroke scale. [3]
Score | Test results |
---|---|
0 | Normal; no obvious speech deficit |
1 | Mild-to-moderate aphasia; detectable loss in fluency, however, the examiner should still be able to extract information from patient's speech |
2 | Severe aphasia; all speech is fragmented, and examiner is unable to extract the figure's content from the patients speech. |
3 | Unable to speak or understand speech |
Notes
Dysarthria is the lack of motor skills required to produce understandable speech. Dysarthria is strictly a motor problem, and is not related to the patient's ability to comprehend speech. Strokes that cause dysarthria typically affect areas such as the anterior opercular, medial prefrontal and premotor, and anterior cingulate regions. These brain regions are vital in coordinating motor control of the tongue, throat, lips, and lungs. [7] To perform this item the patient is asked to read from the list of words provided with the stroke scale while the examiner observes the patient's articulation and clarity of speech. [3]
Score | Test results |
---|---|
0 | Normal; clear and smooth speech |
1 | Mild-to-moderate dysarthria; some slurring of speech, however the patient can be understood |
2 | Severe dysarthria; speech is so slurred that he or she cannot be understood, or patients that cannot produce any speech |
Notes
Sufficient information regarding this item may have been obtained by the examiner in items 1–10 to properly score the patient. However, if any ambiguity exist the examiner should test this item via a technique referred to as "double simultaneous stimulation".
Double simultaneous stimulation is performed by having the patient close his or her eyes and asking him or her to identify the side on which they are being touched by the examiner. During this time, the examiner is alternating between touching the patient on the right and left side. Next, the examiner touches the patient on both sides at the same time. This should be repeated on the patients face, arms, and legs.
To test extinction in vision, the examiner should hold up one finger in front of each of the patient's eyes and ask the patient to determine which finger is wiggling or if both are wiggling. The examiner should then alternate between wiggling each finger and wiggling both fingers at the same time. [3]
Score | Test results |
---|---|
0 | Normal; patient correctly answers all questions |
1 | Inattention on one side in one modality; visual, tactile, auditory, or spatial |
2 | Hemi-inattention; does not recognize stimuli in more than one modality on the same side. |
Notes
The NIHSS was designed to be a standardized and repeatable assessment of stroke patients utilized by large multi-center clinical trials. [8] Clinical researchers have widely accepted this scale due to its high scoring consistency, which has been demonstrated in inter-examiner and in test-retest scenarios. [9] Clinical research use of the NIHSS typically involves obtaining a baseline NIHSS score as soon as possible after onset of stroke symptoms [10] [11] The NIHSS is then repeated at regular intervals or after significant changes in patient condition. This history of scores can then be utilized to monitor the effectiveness of treatment methods and quantify a patient's improvement or decline. [12] [13] The NIHSS has also been used in a prospective observational study, to predict 3 month outcomes of patients with undernutrition during hospital stays directly after a stroke. [14]
NIHSS has gained popularity as a clinical tool utilized in treatment planning. Tissue plasminogen activator (tPA), a type of thrombolysis, is one of the main options for treatment of acute ischemic strokes (the type of stroke caused by blood clots that are preventing blood flow within a cerebral artery).
The effectiveness and risk of tPA is strongly correlated with the delay between stroke onset and tPA delivery ("door-to-needle time"). Current standards recommend for tPA to be delivered within 4,5 hours of onset, while best results occur when treatment is delivered within 90 minutes of onset. [15]
Since the NIHSS has been established as a quick and consistent quantifier of stroke severity, many physicians have looked to NIHSS scores as indicators for tPA treatment. [16] This rapid assessment of stroke severity is targeted to reduce delay of tPA treatment. While some clinical trials have used minimum and maximum NIHSS scores to determine eligibility for acute treatment such as tPA, [10] [11] guidelines such as those from the American Heart Association / American Stroke Association urge against NIHSS scores being used as the sole reason for declaring a patient as ineligible for tPA treatment. [17]
In an effort to produce a complete neurological assessment the NIHSS was developed after extensive research and multiple iterations. The goal of the NIHSS was to accurately measure holistic neurological function by individually testing specific abilities. NIHSS total score is based on the summation of 4 factors. These factors are left and right motor function and left and right cortical function. The NIHSS assesses each of these specific functions by the stroke scale item listed in the chart below. [18]
Left cortical | Right cortical | Right motor | Left motor |
---|---|---|---|
LOC questions | Horizontal eye movement | Right arm motor | Left arm motor |
LOC commands | Visual fields | Right leg | Left leg |
Language | Extinction and inattention | Dysarthria | |
Sensory |
The Modified NIH Stroke Scale (mNIHSS) is a shortened, validated version of the mNIHSS. It has been shown to be equally, if not more, accurate than the longer, older NIHSS. It removes questions 1A, 4, and 7. This makes the mNIHSS shorter and easier to use.
The mNIHSS predicts patients at high risk of hemorrhage if given tissue plasminogen activator (tPA) and which patients are likely to have good clinical outcomes. [19] The mNIHSS has also recently been shown to be taken without seeing the patient, and only using medical records. This potentially improves care while in the emergency room and the hospital, but also facilitates retrospective research. [20]
The National Institutes of Health Stroke Scale has been repeatedly validated as a tool for assessing stroke severity and as an excellent predictor for patient outcomes. [21] [22] [23] Severity of a stroke is heavily correlated with the volume of brain affected by the stroke; strokes affecting larger portions of the brain tend to have more detrimental effects. [24] NIHSS scores have been found to be reliable predictors of damaged brain volume, with a smaller NIHSS score indicating a smaller lesion volume. [25]
The NIHSS places 7 of the possible 42 points on abilities that require verbal skills; 2 points from the LOC questions, 2 points from LOC commands, and 3 points from the Language item. The NIHSS only awards 2 points for extinction and inattention. [26] Approximately 98% of humans have verbal processing take place in the left hemisphere, indicating that the NIHSS places more value on deficits in the left hemisphere. This results in lesions receiving a higher (worse) score when occurring in the left hemisphere, compared to lesions of equal size in the right hemisphere. Due to this emphasis, the NIHSS is a better predictor of lesion volume in the strokes occurring within the left cerebral hemisphere. [17]
The NIHSS has been found to be an excellent predictor of patient outcomes. A baseline NIHSS score greater than 16 indicates a strong probability of patient death, while a baseline NIHSS score less than 6 indicates a strong probability of a good recovery. On average, an increase of 1 point in a patient's NIHSS score decreases the likelihood of an excellent outcome by 17%. [27] However, correlation between functional recovery and NIHSS scores was weaker when the stroke was isolated to the cortex. [25]
Hemiparesis, also called unilateral paresis, is the weakness of one entire side of the body. Hemiplegia, in its most severe form, is the complete paralysis of one entire side of the body. Either hemiparesis or hemiplegia can result from a variety of medical causes, including congenital conditions, trauma, tumors, traumatic brain injury and stroke.
A transient ischemic attack (TIA), commonly known as a mini-stroke, is a minor stroke whose noticeable symptoms usually end in less than an hour. A TIA causes the same symptoms associated with a stroke, such as weakness or numbness on one side of the body, sudden dimming or loss of vision, difficulty speaking or understanding language, slurred speech, or confusion.
Apraxia is a motor disorder caused by damage to the brain, which causes difficulty with motor planning to perform tasks or movements. The nature of the damage determines the disorder's severity, and the absence of sensory loss or paralysis helps to explain the level of difficulty. Children may be born with apraxia; its cause is unknown, and symptoms are usually noticed in the early stages of development. Apraxia occurring later in life, known as acquired apraxia, is typically caused by traumatic brain injury, stroke, dementia, Alzheimer's disease, brain tumor, or other neurodegenerative disorders. The multiple types of apraxia are categorized by the specific ability and/or body part affected.
The Glasgow Coma Scale (GCS) is a clinical scale used to reliably measure a person's level of consciousness after a brain injury.
Cerebrovascular disease includes a variety of medical conditions that affect the blood vessels of the brain and the cerebral circulation. Arteries supplying oxygen and nutrients to the brain are often damaged or deformed in these disorders. The most common presentation of cerebrovascular disease is an ischemic stroke or mini-stroke and sometimes a hemorrhagic stroke. Hypertension is the most important contributing risk factor for stroke and cerebrovascular diseases as it can change the structure of blood vessels and result in atherosclerosis. Atherosclerosis narrows blood vessels in the brain, resulting in decreased cerebral perfusion. Other risk factors that contribute to stroke include smoking and diabetes. Narrowed cerebral arteries can lead to ischemic stroke, but continually elevated blood pressure can also cause tearing of vessels, leading to a hemorrhagic stroke.
Stroke is a medical condition in which poor blood flow to the brain causes cell death. There are two main types of stroke:
Desmoteplase is a novel, highly fibrin-specific "clot-busting" (thrombolytic) drug in development that reached phase III clinical trials. The Danish pharmaceutical company, Lundbeck, owns the worldwide rights to Desmoteplase. In 2009, two large trials were started to test it as a safe and effective treatment for patients with acute ischaemic stroke. After disappointing results in DIAS-3, DIAS-4 was terminated, and in December 2014 Lundbeck announced that they would stop the development of desmoteplase.
Intracerebral hemorrhage (ICH), also known as hemorrhagic stroke, is a sudden bleeding into the tissues of the brain, into its ventricles, or into both. An ICH is a type of bleeding within the skull and one kind of stroke. Symptoms can vary dramatically depending on the severity, acuity, and location (anatomically) but can include headache, one-sided weakness, numbness, tingling, or paralysis, speech problems, vision or hearing problems, memory loss, attention problems, coordination problems, balance problems, dizziness or lightheadedness or vertigo, nausea/vomiting, seizures, decreased level of consciousness or total loss of consciousness, neck stiffness, and fever.
Cerebral infarction, also known as an ischemic stroke, is the pathologic process that results in an area of necrotic tissue in the brain. In mid to high income countries, a stroke is the main reason for disability among people and the 2nd cause of death. It is caused by disrupted blood supply (ischemia) and restricted oxygen supply (hypoxia). This is most commonly due to a thrombotic occlusion, or an embolic occlusion of major vessels which leads to a cerebral infarct. In response to ischemia, the brain degenerates by the process of liquefactive necrosis.
A neurological examination is the assessment of sensory neuron and motor responses, especially reflexes, to determine whether the nervous system is impaired. This typically includes a physical examination and a review of the patient's medical history, but not deeper investigation such as neuroimaging. It can be used both as a screening tool and as an investigative tool, the former of which when examining the patient when there is no expected neurological deficit and the latter of which when examining a patient where you do expect to find abnormalities. If a problem is found either in an investigative or screening process, then further tests can be carried out to focus on a particular aspect of the nervous system.
The Cincinnati Prehospital Stroke Scale is a system used to diagnose a potential stroke in a prehospital setting. It tests three signs for abnormal findings which may indicate that the patient is having a stroke. If any one of the three tests shows abnormal findings, the patient may be having a stroke and should be transported to a hospital as soon as possible. The CPSS was derived from the National Institutes of Health Stroke Scale developed in 1997 at the University of Cincinnati Medical Center for prehospital use.
The Barthel scale is an ordinal scale used to measure performance in activities of daily living (ADL). Each performance item is rated on this scale with a given number of points assigned to each level or ranking. It uses ten variables describing ADL and mobility. A higher number is associated with a greater likelihood of being able to live at home with a degree of independence following discharge from a hospital. The amount of time and physical assistance required to perform each item are used in determining the assigned value of each item. External factors within the environment affect the score of each item. If adaptations outside the standard home environment are met during assessment, the participant's score will be lower if these conditions are not available. If adaptations to the environment are made, they should be described in detail and attached to the Barthel index.
Cerebellar stroke syndrome is a condition in which the circulation to the cerebellum is impaired due to a lesion of the superior cerebellar artery, anterior inferior cerebellar artery or the posterior inferior cerebellar artery.
A silent stroke is a stroke that does not have any outward symptoms associated with stroke, and the patient is typically unaware they have suffered a stroke. Despite not causing identifiable symptoms, a silent stroke still causes damage to the brain and places the patient at increased risk for both transient ischemic attack and major stroke in the future. In a broad study in 1998, more than 11 million people were estimated to have experienced a stroke in the United States. Approximately 770,000 of these strokes were symptomatic and 11 million were first-ever silent MRI infarcts or hemorrhages. Silent strokes typically cause lesions which are detected via the use of neuroimaging such as MRI. The risk of silent stroke increases with age but may also affect younger adults. Women appear to be at increased risk for silent stroke, with hypertension and current cigarette smoking being amongst the predisposing factors.
Gavestinel (GV-150,526) was an investigational drug developed by GlaxoSmithKline for acute intracerebral hemorrhage, which in 2001 failed to show an effect in what was at the time, the largest clinical trial in stroke that had been conducted.
Grinker's myelinopathy, also known as anoxic leukoencephalopathy, is a rare disease of the central nervous system. The disease is characterized by a delayed leukoencephalopathy after a hypoxic episode. It is typically, though not necessarily, related to carbon monoxide poisoning or heroin overdose. It occurs in roughly 2.8% of those who experience an acute hypoxic/anoxic episode. Because of the wide range of symptoms and the delay in onset, it is often misdiagnosed as other neuropathologies. Grinker's myelinopathy was originally characterized by Roy R. Grinker in 1925 or 1926, depending on the source.
Pupillometry, the measurement of pupil size and reactivity, is a key part of the clinical neurological exam for patients with a wide variety of neurological injuries. It is also used in psychology.
Fugl-Meyer Assessment (FMA) scale is an index to assess the sensorimotor impairment in individuals who have had stroke. This scale was first proposed by Axel Fugl-Meyer and his colleagues as a standardized assessment test for post-stroke recovery in their paper titled The post-stroke hemiplegic patient: A method for evaluation of physical performance. It is now widely used for clinical assessment of motor function. The Fugl-Meyer Assessment score has been tested several times, and is found to have excellent consistency, responsivity and good accuracy. The maximum possible score in Fugl-Meyer scale is 226, which corresponds to full sensory-motor recovery. The minimal clinically important difference of Fugl-Meyer assessment scale is 6 for lower limb in chronic stroke and 9-10 for upper limb in sub-acute stroke.
Embolic stroke of undetermined source (ESUS) is an embolic stroke, a type of ischemic stroke, with an unknown origin, defined as a non-lacunar brain infarct without proximal arterial stenosis or cardioembolic sources. As such, it forms a subset of cryptogenic stroke, which is part of the TOAST-classification. The following diagnostic criteria define an ESUS:
Stephan A. Mayer is an American neurologist and critical care physician who currently serves as Director of Neurocritical Care and Emergency Neurology Services for the Westchester Medical Center Health System. Mayer is most noted for his research in subarachnoid and intracerebral hemorrhage, acute ischemic stroke, cardiac arrest, coma, status epilepticus, brain multimodality monitoring, therapeutic temperature modulation, and outcomes after severe brain injury. He has gained media attention for popularizing the concept that physicians have historically underestimated the brain’s resilience and capacity for recovery. He has authored over 400 original research publications, 200 chapters and review articles, and 370 abstracts.
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