Researchers Identify Visual System Changes that May Signal Parkinson’s Disease

Changes in the visual systems of newly diagnosed Parkinson’s disease (PD) patients may provide important biomarkers for the early detection and monitoring of the disease, according to a new study in Radiology.

Non-motor symptoms, such as the inability to perceive colors, a change in visual acuity and a decrease in blinking, are common in PD, according to lead author Alessandro Arrigo, MD, ophthalmology resident at the University Vita-Salute San Raffaele in Milan. However, these symptoms can preceded the appearance of the more commonly recognized motor symptoms by more than a decade. If patients are unaware of the link between these non-motor symptoms and PD, their disease may go undiagnosed and under-treated.

The multi-disciplinary team of ophthalmology, neurology and neuroradiology researchers at the University of Messina, Italy, studied 20 newly diagnosed PD patients and 20 age- and gender-matched controls. MRI was performed on both the healthy controls and the patients, who underwent imaging within four weeks of their diagnosis. Researchers used diffusion-weighted imaging to assess the white matter changes and voxel-based morphometry to investigate concentration changes in the brain. Study participants also received an ophthalmologic exam.

The researchers found significant abnormalities within the visual system brain structures of the PD patients, including alterations of optic radiations, a reduction of white matter concentration and a reduction of optic chiasm volume. Further studies are needed to better understand the timing of the degeneration along visual pathways, as well as the specific changes.

“The in-depth study of visual symptoms may provide sensitive markers of Parkinson’s disease,” Dr. Arrigo said. “Visual processing metrics may also prove helpful in differentiating other Parkinsonism disorders, following disease progression and monitoring patient response to drug treatment.”

Web Extras

• Access the study, “Visual System Involvement in Patients with Newly Diagnosed Parkinson Disease,” at http://pubs.rsna.org/doi/abs/10.1148/radiol.2017161732