Unveiling the Riddoch phenomenon: a regression analysis of stroke-induced homonymous hemianopia

Area of Science:

• Neuroscience
• Ophthalmology
• Neurology

Background:

• The Riddoch phenomenon describes motion perception in the blind visual field of patients with homonymous hemianopia.
• Predictors of this phenomenon are not well understood, hindering insights into visual recovery after stroke.

Purpose of the Study:

• To identify clinical and neuroanatomical predictors of the Riddoch phenomenon in stroke patients.
• To investigate the role of specific visual processing areas and systemic health factors in residual motion perception.

Main Methods:

• Retrospective analysis of 32 stroke patients with homonymous hemianopia.
• Quantification of the Riddoch phenomenon using Rama Motion Perimetry (RMP) and Humphrey Visual Field Index (VFI) (RMP-VFI).
• Assessment of lesions in visual processing regions (V1, V5, LGN, splenium) via MRI and statistical modeling (regression analysis).

Main Results:

• Spared V5 was associated with significantly higher RMP-VFI scores compared to lesioned V5 (24.1 vs. 1.8, p=0.033).
• Diabetes mellitus emerged as a significant negative predictor of RMP-VFI (β=-24.6, p=0.017).
• The model explained 30% of the variance in RMP-VFI, with spared V5 showing a positive trend (p=0.071).

Conclusions:

• Integrity of motion-sensitive area V5 is crucial for the Riddoch phenomenon.
• Diabetes mellitus is a novel negative clinical predictor of residual motion perception after stroke, potentially affecting neural plasticity.
• Findings deepen the understanding of visual recovery mechanisms post-stroke, considering both neuroanatomical and systemic factors.