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Imaging predicts early postural instability in Parkinson’s disease



– Diffusion-weighted MRI and the presence of at least five of seven clinical features may prove useful for determining which newly diagnosed patients with Parkinson’s disease are likely to have rapidly progressive disease, Frank M. Skidmore, MD, reported at the annual meeting of the American Academy of Neurology.

Patients with gray matter and axonal disease on initial imaging were found to have more aggressive disease associated with early gait dysfunction than were patients with primarily white matter and axonal disease, said Dr. Skidmore, associate professor of neurology at the University of Alabama, Birmingham.

Diffusion-weighted imaging provides a way to assess cellular fluid partitioning and directional information in gray and white matter. Thus, it has the potential to identify brainstem pathology that is associated with disease progression, he said. “Our approach provides a pathway towards using MR to detect early, prognostic, neurodegenerative changes in diseases of the brain.”

Dr. Skidmore and colleagues performed diffusion-weighted imaging on 101 patients with newly diagnosed Parkinson’s disease and 56 healthy controls. They found that Parkinson’s disease was associated with altered radial diffusion in white matter. Changes were observed mainly in the striatonigral tract and the substantia nigra. The investigators also noted atrophy in the cerebellar peduncle among patients with Parkinson’s disease.

At baseline, the patients who went on to have subsequent development of early postural instability and gait dysfunction had decreased intracellular fluid partitioning in the substantia nigra and the mesencephalic locomotor region, which are predominantly gray matter regions. These participants had a lower orientation diffusion index (ODI) and a lower estimate of cellularity, Dr. Skidmore said.

The researchers defined early gait dysfunction as the achievement of a Hoehn and Yahr score of 3 at least once while on medication during the first 5 years after Parkinson’s disease diagnosis. Follow-up was at least 5 years in 79 of the patients.

To identify clinical features associated with early postural instability and gait difficulty, the investigators examined data for 301 patients. In this population, Dr. Skidmore and colleagues identified 218 patients whose Hoehn and Yahr scores never exceeded 2 and 83 patients with at least one Hoehn and Yahr score of 3 or more. Using Bonferroni correction, they examined Unified Parkinson’s Disease Rating Scale (UPDRS) data for all patients to identify significant differences between these two groups. Seven items distinguished patients who developed early postural instability and gait difficulty. They included lightheadedness, fatigue, difficulty walking, ability to rise from a chair, and postural problems. The seven-item scale was superior to the Unified Parkinson’s Disease Rating Scale (UPDRS) at predicting which newly diagnosed patients would develop early postural and gait difficulties

SOURCE: Skidmore F et al. AANN 2019, Abstract S41.004.

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