NIH Stroke Scale Score for Complete Left Hemianopia Without Blink to Visual Threat
The NIH Stroke Scale score for a patient with complete hemianopia on the left side who does not blink to visual threat is 2 points for item 3 (Visual Fields). 1, 2
Understanding the Visual Field Assessment in NIHSS
The NIH Stroke Scale scores visual fields on a 0-3 scale: 1, 2
- 0 = No visual field defect
- 1 = Partial hemianopia, quadrantanopia, or extinction
- 2 = Complete hemianopia
- 3 = Bilateral hemianopia or blindness (including cortical blindness)
A negative visual threat test (no blink response) on the left side indicates a complete hemianopia, which corresponds to a score of 2 on the NIHSS item 3. 2
The visual threat test is specifically used when patients cannot cooperate with formal visual field testing due to aphasia, confusion, or decreased level of consciousness. 2
Visual Threat Testing Technique
The examiner brings their finger toward the patient's eye from the periphery on each side to perform the visual threat test. 2
A normal response is for the patient to blink when the finger approaches from either side. 2, 3
If the patient consistently fails to blink when the finger approaches from the left side, this indicates a complete hemianopia on that side. 2, 3
Clinical Significance and Implications
Complete hemianopia indicates damage to the visual pathway, often from occipital lobe stroke or other posterior circulation lesions. 2, 3
The blink-to-threat reflex is cortically mediated and requires intact primary visual cortex as well as higher-order mechanisms for visual attention mediated in the inferior parietal lobule and frontal eye fields. 3
Approximately 68% of acute stroke patients experience acquired vision deficits, and surprisingly, 44% of these patients may be unaware of their field loss. 4
The presence of complete hemianopia contributes to the overall NIHSS score, which is a strong predictor of stroke outcomes. 1, 2
Common Pitfalls in Assessment
Do not confuse hemianopia with visual neglect, as they are distinct neurological deficits that require different rehabilitation approaches. 2
Be aware that patients may be unaware of their visual field defect, which can delay diagnosis and appropriate management. 2, 4
Ensure that the patient's inability to blink to threat is not due to facial weakness, which would be scored separately under item 4 (Facial Palsy) of the NIHSS. 1
When assessing visual fields using the threat response, ensure the stimulus is presented from the periphery and not directly in front of the patient. 2