NIHSS Scoring for Homonymous Hemianopsia
A complete homonymous hemianopsia does not have a dedicated item on the NIH Stroke Scale and therefore scores 0 points as an isolated visual field defect. However, if the patient demonstrates associated extinction or inattention to bilateral simultaneous stimulation, this would score 1-2 points on NIHSS item 11.
Understanding NIHSS Visual Assessment
The NIHSS is an 11-part standardized assessment tool with scores ranging from 0 to 42, where higher scores indicate more severe strokes 1, 2. Importantly, the NIHSS does not have a specific item that directly scores homonymous hemianopsia as a visual field defect 1.
Item 11: Extinction and Inattention (Neglect)
The only NIHSS item that may capture visual field-related deficits is item 11, which evaluates extinction and inattention using the following criteria 1:
- 0 points = No abnormality 1
- 1 point = Visual, tactile, auditory, spatial, or personal inattention or extinction to bilateral simultaneous stimulation in one sensory modality 1
- 2 points = Profound hemi-inattention or extinction to more than one modality 1
Clinical Distinction: Hemianopsia vs. Neglect
Homonymous hemianopsia and unilateral neglect are distinct entities 1:
- Hemianopsia is a pure visual field defect affecting the right or left halves of the visual fields in both eyes 3
- Neglect is the lack of awareness of a specific body part or external environment contralateral to the brain lesion, usually occurring with right (nondominant) cortical strokes 1
A patient with isolated homonymous hemianopsia who is fully aware of their deficit and responds appropriately to bilateral simultaneous stimulation would score 0 points on item 11 1.
Common Clinical Pitfall
Do not confuse a visual field defect with neglect. A patient with homonymous hemianopsia may have full awareness and attention to the affected side despite the field cut, whereas a patient with neglect demonstrates inattention or extinction even when stimuli are presented 1. The NIHSS item 11 specifically assesses for extinction and inattention, not the presence of a visual field defect itself 1.
Clinical Significance
Homonymous hemianopsia is most commonly caused by stroke (69.6%), trauma (13.6%), and tumors (11.3%), with lesions typically located in the occipital lobes (45%) or optic radiations (32.2%) 4. Complete homonymous hemianopsia is associated with adverse prognosis, with 28-day mortality of 49% compared to 11% for partial hemianopsia 5.