What do the visual field results on the National Institutes of Health (NIH) stroke scale indicate?

From the Guidelines

The visual field results on the National Institutes of Health (NIH) stroke scale indicate the presence and severity of visual field defects, which are important indicators of neurological damage from stroke, with scores ranging from 0 to 3, where 0 indicates no visual field loss, 1 indicates partial hemianopia, 2 indicates complete hemianopia, and 3 indicates bilateral hemianopia including cortical blindness 1.

Visual Field Assessment

The visual field assessment is a crucial component of the NIH stroke scale, as it helps clinicians evaluate the extent of brain injury, particularly in the visual pathways and occipital cortex.

• The assessment is performed by testing visual fields by confrontation in all four quadrants for each eye.
• Visual field defects often correlate with specific stroke territories, such as a right-sided stroke affecting the posterior cerebral artery, which may cause a left homonymous hemianopia.
• The results of the visual field assessment provide valuable information about stroke severity and potential functional impairments that might affect the patient's recovery and rehabilitation needs.

Clinical Implications

The visual field results on the NIH stroke scale have significant clinical implications, as they can influence decisions regarding acute treatment, such as thrombolytic therapy 1.

• A score of greater than 16 on the NIHSS forecasts a high probability of death or severe disability, whereas a score of less than 6 forecasts a good recovery.
• The NIHSS score strongly predicts the likelihood of the patient's recovery after stroke.
• The visual field assessment is an essential component of the NIHSS, as it provides critical information about the severity of stroke and prognostic information.

Rehabilitation and Recovery

The visual field results on the NIH stroke scale also have implications for rehabilitation and recovery, as visual field defects can affect a patient's quality of life, motivation, and social behaviors 1.

• The most common visual impairment after stroke is visual field loss, affecting approximately 30% of stroke survivors.
• Some degree of spontaneous restoration of visual fields generally occurs after stroke, but the percentage of patients who achieve significant recovery is uncertain.
• Compensatory scanning training may be effective at improving scanning and reading outcomes, but there is insufficient evidence to reach conclusions about the effectiveness of interventions for patients with visual field defects after stroke 1.

From the Research

Visual Field Results on the NIH Stroke Scale

The National Institutes of Health (NIH) stroke scale is a systematic assessment tool that provides a quantitative measure of stroke-related neurologic deficit. The visual field results on this scale indicate the presence and extent of visual field defects in patients with stroke.

• Visual Field Defects: Studies have shown that visual field defects are estimated to affect 20% to 57% of people who have had a stroke 2, 3. These defects can affect functional ability in activities of daily living, quality of life, and ability to participate in rehabilitation.
• Types of Visual Field Defects: The types of visual field defects that can occur after a stroke include homonymous hemianopia, quadrantanopia, and blind spots 4.
• Assessment and Rehabilitation: Assessment of visual field defects is crucial for targeted treatment and rehabilitation. Treatment options include visual search training, visual awareness, typoscopes, substitutive prisms, low vision aids, refraction, and occlusive patches 4.
• Impact on Mortality: Visual field defects after ischemic stroke have been associated with increased mortality, with a hazard ratio of 1.30 (CI 1.07-1.56, P = 0.007) after adjusting for age, sex, and other factors 5.
• NIH Stroke Scale Scores: Patients with visual field defects tend to have higher NIH Stroke Scale scores, indicating more severe neurologic deficits 6, 5. For example, one study found that patients with visual field defects had a mean NIH Stroke Scale score of 12.7, compared to 3.5 for patients with normal visual fields 5.

Rehabilitation and Outcome

The outcome of visual field defects after stroke can vary, with some patients experiencing full recovery, improvement, or no recovery. One study found that 15 patients (7.5%) had full recovery, 78 (39%) had improvement, and 104 (52%) had no recovery 4. The quality of life scores for patients with visual field loss were also lower than those for stroke patients without visual impairment 4.

Limitations and Future Directions

While there is evidence on the visual field results on the NIH stroke scale, there are limitations to the current research. For example, there is a lack of high-quality evidence on the effectiveness of interventions for visual field defects after stroke 2, 3. Further research is needed to fully understand the impact of visual field defects on stroke patients and to develop effective rehabilitation strategies.