Walking with Parkinson’s

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New imaging approach reveals brain region responsible for impaired walking in Parkinson's.
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Lesion network mapping is a relatively new technique that has been used to identify brain regions implicated in pain, hallucinations and impaired decision making.
Imagine that while walking to the corner store, you freeze in mid-step and are unable to move your leg forward. This is something that nine out of ten people living with advanced Parkinson disease experience—a condition that is known as freezing of gait (FOG). Although FOG is a common cause of falls and severely compromises quality of life, the underlying disease mechanisms remain unclear.

To gain further insight into the causes of FOG, Krembil Clinician Investigator Dr. Alfonso Fasano co-led a new study examining the brains of 14 people who developed FOG as a consequence of various types of localized brain damage. The study was the result of international collaborations between UHN, the Berenson-Allen Center for Noninvasive Brain Stimulation, Harvard Medical School and Beth Israel Deaconess Medical Center.
The approach used by the researchers, known as ‘lesion network mapping’, was developed by Dr. Fasano’s collaborators. He comments, “When the brain is damaged, due to stroke or cancer, scarring can develop in specific regions. Lesion network mapping works by pinpointing these scars, which are known as lesions, using magnetic resonance imaging to provide insight into brain function based on what symptoms are observed.”
The researchers superimposed the locations of the lesions, as well as the connected brain regions (ie, brain networks), onto reference brains. By identifying the regions where most of the lesions and their networks overlapped, they discovered that 13 of the 14 lesions were connected to a specific region of the cerebellum—a part of the brain needed for producing precise and coordinated movements.
Dr. Fasano explains, “Our findings move us one step closer to helping those with the most severe forms of FOG in Parkinson disease—an achievement that is partly due to the patient population that we chose to focus on. By selecting 14 patients with medication-resistant FOG that did not have Parkinson disease, we were able to avoid other confounding symptoms that are often observed in patients with advanced Parkinson disease. Our next focus will be on defining the ideal target for deep brain stimulation as a potential therapeutic approach to help these patients.”
This work was supported by the Sidney R Baer Jr Foundation, the National Institutes of Health, the Dystonia Medical Research Foundation and the National Parkinson Foundation, the National Center for Research Resources: Harvard Clinical and Translational Science Center and the Toronto General & Western Hospital Foundation.​
Fasano A, Laganiere SE, Lam S, Fox MD. Lesions causing freezing of gait localize to a cerebellar functional network. Ann Neurol. 2017 Jan. doi: 10.1002/ana.24845.