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

Changing stroke rehab and research worldwide now.Time is Brain! trillions and trillions of neurons that DIE each day because there are NO effective hyperacute therapies besides tPA(only 12% effective). I have 523 posts on hyperacute therapy, enough for researchers to spend decades proving them out. These are my personal ideas and blog on stroke rehabilitation and stroke research. Do not attempt any of these without checking with your medical provider. Unless you join me in agitating, when you need these therapies they won't be there.

What this blog is for:

My blog is not to help survivors recover, it is to have the 10 million yearly stroke survivors light fires underneath their doctors, stroke hospitals and stroke researchers to get stroke solved. 100% recovery. The stroke medical world is completely failing at that goal, they don't even have it as a goal. Shortly after getting out of the hospital and getting NO information on the process or protocols of stroke rehabilitation and recovery I started searching on the internet and found that no other survivor received useful information. This is an attempt to cover all stroke rehabilitation information that should be readily available to survivors so they can talk with informed knowledge to their medical staff. It lays out what needs to be done to get stroke survivors closer to 100% recovery. It's quite disgusting that this information is not available from every stroke association and doctors group.

Monday, September 1, 2025

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

No clue, ask your doctor.

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

¹Department of Diagnostic and Therapeutic Radiology, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
²Division of Neurology, Department of Medicine, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
³Biostatistics Department of Clinical Epidemiology and Biostatistics, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
⁴Department of Brain Repair and Rehabilitation, University College London, London, United Kingdom

Introduction: A subset of patients with homonymous hemianopia can consciously perceive motion within their blind visual fields—a phenomenon known as the Riddoch phenomenon. However, the factors predicting this residual motion perception remain poorly understood. This study aims to identify clinical and neuroanatomical predictors of the Riddoch phenomenon in stroke patients.

Methods: We retrospectively analyzed 32 adult patients (mean age 60.41 years, 34.4% female) with stroke-induced homonymous hemianopia treated at a single center between 2020 and 2023. Clinical data, brain MRI, and visual field assessments were reviewed. The Riddoch phenomenon was quantified as the difference between kinetic motion perception measured by Rama Motion Perimetry (RMP) and static visual perception assessed by Humphrey Visual Field Index (VFI), termed RMP-VFI. Lesions in key visual processing regions—primary visual cortex (V1), motion-sensitive area V5, lateral geniculate nucleus (LGN), and splenium of the corpus callosum—were identified on MRI. Univariate and multiple linear regression models were applied to evaluate predictors of RMP-VFI.

Results: Mean RMP-VFI scores were significantly higher in patients with spared V5 compared to those with lesioned V5 (24.1 vs. 1.8, p = 0.033), while no significant differences were observed for other regions. Multiple linear regression revealed diabetes mellitus as a significant negative predictor of RMP-VFI (β = −24.6, 95% CI: −44.47, −4.75; p = 0.017), with spared V5 showing a positive but marginally non-significant association (β = 17.5, 95% CI: −1.61, 36.66; p = 0.071). The model explained 30% of the variance in RMP-VFI (adjusted R² = 0.25).

Discussion: Integrity of area V5 plays a key role in the Riddoch phenomenon by preserving motion perception despite cortical damage. For the first time, diabetes mellitus is identified as a significant clinical factor negatively influencing residual motion perception, possibly by impairing neural plasticity. These findings enhance understanding of the neural and systemic factors modulating visual recovery after stroke.