The NIH Stroke Scale, also known as NIHSS, is a critical tool developed to quantify the level of impairment caused by a stroke. Designed initially for clinical trials, specifically the National Institute of Neurological Disorders and Stroke (NINDS) rt-PA Acute Stroke Trial, it's now widely utilized to assist in post-acute care planning. The scale helps standardize the assessment of stroke effects, aiding healthcare providers in making informed decisions regarding patient care and evaluating the efficacy of interventions.

Structure and Scoring

The NIHSS consists of 11 items, each scoring abilities between 0 (normal function) and 4 (severe impairment), with a total score ranging from 0 to 42. The scoring is as follows:

0: No stroke symptoms

1-4: Minor stroke

5-15: Moderate stroke

16-20: Moderate to severe stroke

21-42: Severe stroke

Administering the Scale

Key principles include non-assistance in task execution and scoring the patient's initial attempt without influence from repeated efforts. Physical assistance is limited to positioning for the test initiation. Notably, the language assessment permits scoring based on the best effort.

Specific Test Items

Level of Consciousness (LOC): Divided into responsiveness, questions (patient's age and current month), and commands (eye opening, hand grip). Each subsection contributes to the total score.

Horizontal Eye Movement: Evaluates the patient's ability to track an object, assessing gaze towards the hemisphere opposite of injury.

Visual Field Test: Tests each eye's vision in all quadrants to identify any loss of vision.

Facial Palsy: Assesses symmetry in facial movements through various expressions.

Motor Arm: Observes for any arm drift when extended.

Motor Leg: Checks for leg drift when positioned at an angle.

Limb Ataxia: Evaluates coordination through finger-to-nose and heel-to-shin tests.

Sensory: Sensory loss is assessed via pinprick in all limbs.

Language: Measures language skills through description, reading, and naming tasks.

Speech: Assesses speech clarity and articulation.

Extinction and Inattention (Neglect): Tests for unawareness of stimuli on one side.

Usage and Importance

While initially intended for clinical research to ensure uniformity in stroke assessment, NIHSS has found broader clinical application, notably in determining eligibility for treatments like tPA (tissue plasminogen activator). It's a predictor of outcomes, guiding treatment timelines and assessing stroke severity.

Modified NIH Stroke Scale (mNIHSS)

The mNIHSS, a streamlined version of the NIHSS, excludes certain items for efficiency without compromising accuracy, proving particularly useful in both acute care settings and research.

Accuracy and Predictive Value

The NIHSS has been validated as a reliable tool for assessing stroke severity and predicting patient outcomes, with scores correlating to the extent of brain damage. However, it has been noted that the scale may favor left hemisphere strokes in scoring due to the emphasis on verbal abilities.

Conclusion

The NIH Stroke Scale is an indispensable tool in the stroke treatment and research arsenal, enabling precise assessment of stroke impact and guiding clinical decisions. Its development and adoption reflect the ongoing efforts to improve stroke care and outcomes through standardized evaluation methodologies.