Nihss Stroke Scale Answer Key

Decoding the NIHSS Stroke Scale: A Comprehensive Guide

The National Institutes of Health Stroke Scale (NIHSS) is a standardized neurological examination used to evaluate stroke severity. Understanding the NIHSS score is crucial for healthcare professionals in making critical decisions about treatment, prognosis, and patient management. This comprehensive guide will delve into the individual components of the NIHSS, providing detailed explanations and examples to help you understand how the scale works and what the scores mean. We will also address frequently asked questions to demystify this vital assessment tool.

Understanding the NIHSS Structure and Scoring

The NIHSS comprises eleven items, each assessing a specific neurological function. Each item is scored from 0 (normal) to a maximum score that varies depending on the item. The total score ranges from 0 to 42, with higher scores indicating greater stroke severity. The scoring system is not linear; a score of 10 doesn't necessarily mean twice the severity of a score of 5. Instead, it represents a cumulative impact of neurological deficits across different domains. It's essential to remember that the NIHSS assesses the acute neurological deficits at a specific point in time and doesn't predict long-term outcomes.

Here's a breakdown of each item within the NIHSS, along with examples of scoring:

1. Level of Consciousness (LOC):

Score 0: Alert and conversant.
Score 1: Not alert; but arousable by minor stimulation to answer questions with command followed.
Score 2: Not alert; requires repeated stimulation to achieve a response.
Score 3: Responds only with reflex motor or autonomic effects, or totally unresponsive, or only to noxious stimuli.

Example: A patient who is awake and responds appropriately to questions would receive a score of 0. A patient who is drowsy but can be roused to answer questions receives a score of 1. A patient who only groans in response to painful stimuli would receive a score of 3.

2. Horizontal Gaze Palsy (HGP):

Score 0: Full horizontal gaze.
Score 1: Partial gaze palsy (at least one eye with impaired horizontal gaze).
Score 2: Forced deviation (no horizontal movement).

Example: If a patient can move their eyes fully to both the left and right, the score is 0. If one eye shows limitation in its horizontal movement, it receives a score of 1. If the patient's eyes are fixed in one direction and cannot move horizontally, the score is 2.

3. Vertical Gaze Palsy (VGP):

Score 0: Full vertical gaze.
Score 1: Partial gaze palsy (at least one eye with impaired vertical gaze).
Score 2: Forced deviation (no vertical movement).

Example: Similar to horizontal gaze palsy, a score of 0 indicates full vertical eye movement. Limited vertical gaze in one or both eyes results in a score of 1, while the inability to move the eyes vertically receives a score of 2.

4. Facial Palsy (FP):

Score 0: Normal symmetrical movements.
Score 1: Minor paralysis (e.g., asymmetry on smiling).
Score 2: Partial paralysis (e.g., flat affect, but able to raise eyebrows).
Score 3: Complete paralysis (e.g., cannot raise eyebrows or frown).

Example: A patient with normal symmetrical facial movements during smiling and frowning receives a 0. A subtle asymmetry when smiling would get a 1. Inability to fully raise one eyebrow but capable of other facial expressions would score a 2. Complete inability to move the facial muscles would result in a score of 3.

5. Motor Arm (MA):

This section assesses motor strength in both arms, scored separately and then the higher score is used. Each arm is scored as follows:

Score 0: No drift.
Score 1: Drift (minimal weakness).
Score 2: Some effort against gravity.
Score 3: No effort against gravity.
Score 4: No movement.

Example: If a patient can hold their arms outstretched without drift, the score is 0. Slight drift would score 1. If the arm falls quickly but demonstrates some effort against gravity, the score is 2. Complete inability to lift the arm against gravity gets a 3, and no movement is a 4. The higher score from both arms is used for the final NIHSS score.

6. Motor Leg (ML):

Similar to motor arm, this assesses leg strength. Scoring is identical:

Score 0: No drift.
Score 1: Drift.
Score 2: Some effort against gravity.
Score 3: No effort against gravity.
Score 4: No movement.

Example: The same principles as motor arm apply to motor leg. The higher score from both legs is used.

7. Limb Ataxia (LA):

Score 0: Absent.
Score 1: Present in one limb.
Score 2: Present in two limbs.

Example: Ataxia is assessed by observing the patient's ability to perform finger-to-nose or heel-to-shin tests. The absence of ataxia is 0, ataxia in one limb is 1, and ataxia in two limbs is 2.

8. Sensory (SE):

Score 0: Normal.
Score 1: Mild-to-moderate sensory loss.
Score 2: Severe sensory loss or total anesthesia.

Example: This assesses sensory function in the limbs. Normal sensation is 0. Reduced sensation is 1. Complete loss of sensation is 2.

9. Best Language (BL):

Score 0: No aphasia.
Score 1: Mild aphasia.
Score 2: Severe aphasia.
Score 3: Mute.

Example: The examiner assesses the patient's ability to understand and express language. Normal language skills score 0. Minor difficulties in expression or comprehension score 1. Significant difficulties score 2. Complete inability to speak scores 3.

10. Dysarthria (DY):

Score 0: Normal articulation.
Score 1: Mild to moderate dysarthria.
Score 2: Severe dysarthria.

Example: This assesses the clarity of speech. Clear speech is 0. Slurred speech is 1. Unintelligible speech is 2.

11. Extinction and Inattention (EI):

Score 0: No extinction or inattention.
Score 1: Extinction to bilateral simultaneous stimulation.
Score 2: Extinction and inattention.

Example: The examiner simultaneously stimulates both sides of the body and observes if the patient can identify both stimuli. If both stimuli are identified, the score is 0. If only one stimulus is identified (extinction), the score is 1. If the patient neglects one side, the score is 2.

Interpreting NIHSS Scores: Clinical Implications

The NIHSS score provides a snapshot of stroke severity and helps clinicians guide treatment decisions. While there are no universally accepted cut-offs, certain score ranges are often associated with particular prognoses and treatment approaches:

NIHSS score of 0-4: Suggests a milder stroke.
NIHSS score of 5-15: Indicates moderate stroke severity.
NIHSS score of 16-20: Suggests severe stroke.
NIHSS score of >20: Indicates very severe stroke.

These ranges are guidelines and should be interpreted in conjunction with other clinical information such as the patient's age, medical history, and overall clinical presentation.

Limitations of the NIHSS

It's crucial to acknowledge the limitations of the NIHSS:

Inter-rater reliability: While the scale aims for objectivity, variations in examiner skill and interpretation can affect scores. Proper training is essential.
Doesn't predict long-term outcomes: The NIHSS assesses acute deficits; it doesn't predict the patient's long-term recovery or functional status.
Doesn't capture all aspects of stroke: The scale primarily focuses on neurological deficits. It doesn't directly assess cognitive changes, mood disorders, or other potential consequences of stroke.
Specific to ischemic stroke: The NIHSS is primarily designed for ischemic strokes. Its applicability to hemorrhagic stroke is limited.

Frequently Asked Questions (FAQ)

Q: Who administers the NIHSS?

A: The NIHSS is primarily administered by trained healthcare professionals, including neurologists, physicians, and nurses specializing in stroke care.

Q: How often is the NIHSS administered?

A: The frequency of administration depends on the patient's clinical status. It's typically performed shortly after stroke onset and may be repeated at intervals to monitor changes in neurological function.

Q: Can the NIHSS score change over time?

A: Yes, the NIHSS score can change over time as the patient recovers or deteriorates. Serial assessments are valuable for tracking progress and guiding treatment adjustments.

Q: Is there a "pass" or "fail" on the NIHSS?

A: There's no pass/fail. The NIHSS provides a quantifiable measure of neurological impairment, guiding clinical decision-making related to treatment and prognosis.

Q: What if the patient is unable to cooperate with the exam?

A: If a patient is unable to cooperate due to altered consciousness or other reasons, the examiner should document this limitation and score the items as best as possible based on observable signs.

Q: What treatments are influenced by NIHSS score?

A: The NIHSS score plays a role in determining eligibility for thrombolytic therapy (tPA), a crucial treatment for ischemic stroke. Higher scores may indicate a greater risk of hemorrhagic transformation and influence the decision-making process regarding tPA administration.

Conclusion

The NIHSS is a powerful tool for assessing stroke severity, guiding treatment strategies, and monitoring patient progress. While it's essential to understand its limitations, the NIHSS remains a cornerstone of stroke care, providing valuable objective data that contributes to improved patient outcomes. This comprehensive overview provides a solid foundation for understanding the scale's individual components, scoring system, and clinical interpretations. However, remember that this information is for educational purposes and should not be used to diagnose or treat any medical condition. Always consult with a healthcare professional for any health concerns. The accurate and consistent application of the NIHSS requires proper training and experience.