About the NIH Stroke Scale
The NIH Stroke Scale (NIHSS) is a standardized bedside neurological examination used to quantify the severity of a stroke. Developed for the NINDS clinical trials in the late 1980s, it is now one of the most widely used stroke assessment tools in emergency medicine and neurology. The exam has 15 items covering consciousness, eye movement, vision, facial movement, limb strength, coordination, sensation, language, speech, and inattention, and it produces a single score from 0 to 42 that rises with the severity of neurological impairment.
How the score is built
Each item is scored independently on its own point scale (most run 0-2, 0-3, or 0-4), based on what the patient actually does during the exam rather than what the examiner believes they could do. The item scores are:
- Consciousness (items 1a-1c): level of alertness, and whether the patient can answer simple orientation questions and follow simple commands.
- Eyes and vision (items 2-3): horizontal gaze and visual field testing in each quadrant.
- Face and limbs (items 4-6b): facial symmetry, and arm and leg strength tested separately on the left and right.
- Coordination and sensation (items 7-8): limb ataxia (finger-to-nose, heel-to-shin) and pinprick sensory testing.
- Language and speech (items 9-10): aphasia testing and articulation (dysarthria).
- Inattention (item 11): extinction or neglect to simultaneous bilateral stimulation.
Adding all 15 item scores together gives the total NIHSS score, from 0 (no deficit) to a maximum of 42.
Interpreting the result
Higher totals indicate a more severe neurological deficit. As a general clinical guide, a score of 0 means no stroke symptoms are present, 1-4 is usually described as a minor stroke, 5-15 as a moderate stroke, 16-20 as moderate-to-severe, and 21-42 as a severe stroke. These bands are widely used rules of thumb, not fixed diagnostic cutoffs, and the same total can arise from very different combinations of items.
When to consult a professional
This tool performs the standard NIHSS point addition for education and record-keeping. Reliable scoring requires a trained examiner following the official exam instructions, and the result does not replace brain imaging, a full neurological exam, or the judgment of the treating clinical team. Any decision about stroke treatment should be made by qualified healthcare professionals using the complete clinical picture.