Common Medication Provides Insight into Brain Abnormalities in Dystonia

June 23, 2016
Berlin

A common medication used for the symptomatic treatment of dystonias has been shown to target brain abnormalities in the cerebral cortex in patients with cervical dystonia (CD), according to a study released today at the 20th International Congress of Parkinson’s Disease and Movement Disorders.

A common medication used for the symptomatic treatment of dystonia has been shown to target brain abnormalities in the cerebral cortex in patients with cervical dystonia (CD), according to a study released today at the 20th International Congress of Parkinson’s Disease and Movement Disorders. 

Roxana Burciu and a team of researchers at the University of Florida Gainesville, aimed to assess task-related brain activity in patients with CD using functional magnetic resonance imaging (fMRI) with and without a single-dose administration of trihexyphenidyl, an anti-cholinergic medication. For decades, anti-cholinergic medications have been commonly prescribed for patients with varying types of dystonia, but the reason they are so widely used has not been determined. Although it was previously thought that anti-cholinergics primarily affect the basal ganglia, the results of this study are evidence that they are effective in other areas of the brain, particularly in the cerebral cortex. 

Sixteen patients with idiopathic CD were compared using a 3T MRIscanner with 16 age- and gender-matched healthy individuals. Subjects were scanned twice, both off-medication and on average two hours after a single dose of trihexyphenidyl. While off medication, the CD patients had reduced motor activity compared to the healthy subjects. After administration of trihexyphenidyl, there was an increase in motor-related activity in middle frontal gyrus and primary somatosensory cortex. The results suggest that somatosensory processing in CD can be acutely changed through trihexyphenidyl administration. 

Hyder A. Jinnah, Professor of Neurosurgery, Human Genetics & Pediatrics at Emory University School of Medicine, states,

“The study by Burciu and colleagues is the first attempt to determine what part of the brain is influenced by anti-cholinergic drugs in dystonia. Before treatment, the patients with cervical dystonia showed abnormal activity in multiple brain regions. After treatment, the abnormal brain activity was at least partly corrected in two regions. Both of these regions were in the cerebral cortex, not the basal ganglia. This study provides clues towards which regions of the brain might be abnormal, and how trihexyphenidyl might correct these abnormalities.”

Jinnah adds, 

“Like any good study, the findings from this study lead to many more questions than answers. Do the brain abnormalities found reflect a cause for dystonia, or a consequence of it? Does the result mean that these medications work in the cortex, not the basal ganglia, as previously believed? Why do patients with cervical dystonia have brain abnormalities that show up when they use their hands, which are not affected? Does the drug affect the brains of normal people who do not have dystonia in the same way? How can we exploit this new information to improve the value of anti-cholinergics for patients with dystonia?”

About the 20th International Congress of Parkinson's Disease and Movement Disorders: Meeting attendees gather to learn the latest research findings and state-of-the-art treatment options in Movement Disorders, including Parkinson's disease. Over 5,000 physicians and medical professionals from more than 86 countries will be able to view over 2,200 scientific abstracts submitted by clinicians from around the world.

About the International Parkinson and Movement Disorder Society: The International Parkinson and Movement Disorder Society (MDS), an international society of over 5,000 clinicians, scientists, and other healthcare professionals, is dedicated to improving patient care through education and research. For more information about MDS, visit http://www.movementdisorders.org.

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