National Institutes of Health Stroke Scale
出典(authority):フリー百科事典『ウィキペディア(Wikipedia)』「2015/11/28 18:02:02」(JST)
NIHSS(National Institute of Health Stroke Scale)は脳卒中重症度評価スケールのひとつである。1989年にBrottらによってその有効性が報告されて以来臨床現場、臨床研究でよく用いられている。判定表などはインターネット上で入手することができる。各項目ともに点数が高いほど重症度も高くなり最大で42点となるように設定されている。
脳梗塞の治療法であるrt-PA静注療法ではrt-PA静注中の1時間は15分ごと、その後は投与開始から7時間(投与後6時間)は30分ごと、その後24時間までは1時間ごとにNIHSSを施行するように管理指針が出ている。
リスト順に行うこと、逆に行ったり評点を変えるようなことはしない、実際に患者がなしえた点数をつける。医師が推察した点数をつけない。診察しながら点数を記載する。特別な誘導を行わない。
脳神経項目が少ないため後方循環系の障害は評価が不十分となることがある。
失語症が存在すると点数が高くなる傾向があり、同範囲の脳障害でも左半球障害では右半球障害よりも高い点数となる。
同じ点数でもADLの程度が全く異なる場合がある。
くぼみ手徴候などのような軽微な麻痺所見はカウントされない。
JCSⅢ-300の場合は意識レベル、顔面神経麻痺、上下肢麻痺、感覚障害、言語、消去や不注意の項目は自動的に最高点となり失調が0点となる。そのため最低で35点ということになる。
意識水準、質問、命令の順に評価する。痛み刺激への反応しか認められない場合は麻痺、感覚障害、言語、消去や不注意の項目も最高点となるため注意が必要である。質問の答えは近似した内容であっても正解でなければ不正解として評価する。
前頭眼野、側頭、頭頂葉から脳幹への眼球運動経路の障害では核上性眼球運動障害による水平性注視麻痺が起こるため、水平性眼球運動のみで評価する。随意眼球運動障害が見られない場合、または共同偏視が認められる場合は眼球頭反射の有無で評価する。眼球頭反射が消失していれば重症である。
対座法でどちらの指が動いたのかで評価する。意識障害がある場合はvisual threatによる閉眼や指が動いた方を注視するのかで評価する。
鼻唇溝の平坦などでは1点、口角下垂や兎目など顔面下半分の完全またはほぼ完全な麻痺では2点となる。なお末梢性顔面神経麻痺のように顔面の上側でも麻痺が認められると3点となる。
あくまで指示、パントマイムなどで判定する。痛み刺激を用いて判定はしてはいけない。くぼみ手徴候やバレ徴候の回内など軽度の麻痺は0点で評価される。痛み刺激の反応などでは4点で評価する。
1肢毎の評価となるため片側上下肢の失調では2点となる。運動失調は筋力低下の影響を割引いても存在する場合にありとする。完全麻痺や理解力がなかったり、意識障害では0点とする。
意識障害や失語が認められる場合は逃避反応や表情で評価する。前腕、下肢、体幹、顔面の4点ほどで評価することが多い。無反応の四肢麻痺や昏睡では2点とする。
流腸性、理解力で判断する。文章カードや絵カードをもちいることもある。
言語の明瞭性を評価する。
棒の真ん中を指すように命じ、半側空間無視を調べる。その他の病態失認などが認められると2点、昏睡患者も2点で評価する。
点数がADL障害を十分に反映しないことからmodified rankin scale(mRS)、stroke impairment assessment set(SIAS)などを併用することがある。
mRS | 程度 | 内容 |
---|---|---|
0 | 全く症候がない | 自覚、他覚所見なし |
1 | 症候はあっても明らかな障害はない | 日常の務めや活動は行える |
2 | 軽度の障害 | 発症以前の活動を全て行えるわけではないが身の回りのことは自立 |
3 | 中等度の障害 | 何らかの介助を必要とするが歩行や食事は自立している。 |
4 | 中等度から重度の障害 | 歩行、着衣、食事に介助は必要であるが持続的な介助は必要ではない |
5 | 重度の障害 | 常に誰かの介助が必要である |
6 | 死亡 |
発症時のBrunnstrom StageがⅣ以上ならば6ヶ月以内にほぼ完全に回復に達するとされ、発症後2週間の時点でStageがⅣ以上に回復する例は8割の患者でStageⅥまで回復するとされている。上肢、指、下肢でそれぞれStageを決める。
stage | 内容 |
---|---|
Ⅰ | 反射的に随意的にも、筋の収縮や運動がみられない(弛緩状態) |
Ⅱ | 連合反応または随意的筋収縮がわずかに認められる(痙性が出始める) |
Ⅲ | 随意的に共同運動として関節の運動が可能になる(痙性が著明になる) |
Ⅳ | 分離運動が部分的に可能となる(痙性がやや弱まる) |
Ⅴ | さらに分離運動進展した状態になる(痙性が軽減する) |
Ⅵ | 分離運動が自由に、速く、協調性をもって行えるようになる(痙性が消失あるいは目立たなくなる) |
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. 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 |
Throughout 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.
Level of consciousness 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 is present in approximately 20% of stroke cases. CED is more commons in right hemispheric strokes and typically in lesions effecting the basal ganglia and temporoparietal cortex. Damage to these areas can result in decreased spatial attention and reduced control of eye movements.[4]
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 can't 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.[5]
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 a 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 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, he or she 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 effect 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.[6] To perform this item the patient is be asked to read from the list of words provided with the stroke scale while the examiner observes the patients 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". This 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.[7] Clinical researchers have widely accepted this scale due to high levels of score consistency. Consistency of NIHSS scores has been demonstrated in inter-examiner and in test-retest scenarios.[8] Clinical research use of the NIHSS typically involves obtaining a baseline NIHSS score as soon as possible after onset of stroke symptoms [9][10] 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.[11][12] 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.[13]
NIHSS has gained popularity as a clinical tool utilized in treatment planning. Minimum and maximum NIHSS scores have been set for multiple treatment options in order to assist physicians in choosing an appropriate treatment plan.[9][10]Tissue plasminogen activator (tPA), a type of Thrombolysis is currently the only proven treatment for acute ischemic strokes. Ischemic strokes are the result of blood clots that are preventing blood flow within a cerebral blood vessel. The goal of tPA treatment is to break up the clots that are occluding the vessel, and restore cerebral blood flow. Treatment with tPA has been shown to improve patient outcome in some studies and to be harmful in others. The effectiveness and risk of tPA is strongly correlated with the delay between stroke onset and tPA delivery. Current standards recommend for tPA to be delivered within 3 hours of onset, while best results occur when treatment is delivered within 90 minutes of onset.[14] 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.[15] This rapid assessment of stroke severity is targeted to reduce delay of tPA treatment. Some hospitals use an NIHSS of less than 5 to exclude patients from tPA treatment, however the American Heart Association urges against NIHSS scores being used as the sole reason for declaring a patient as ineligible for tPA treatment.[16]
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.[17]
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.[18] 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.[19]
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.[20][21][22] Severity of a stroke is heavily correlated with the volume of brain affected by the stroke, strokes effecting larger portions of the brain tend to have more detrimental effects.[23] NIHSS scores have been found to be reliable predictors of damaged brain volume, with a smaller NIHSS score indicating a smaller lesion volume[24]
Due to the NIHSS’s focus on cortical function, patients suffering from a cortical stroke tend to have higher (worse) baseline scores. 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.[25] 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.[16]
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%.[26] However, correlation between functional recovery and NIHSS scores was weaker when the stroke was isolated to the cortex.[24]
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