Cerebral palsy impacts approximately one in 345 youngsters in the U.S., with over half encountering an issue known as dystonia — involuntary and frequently distressing muscle contractions, predominantly in the legs, which result in atypical movements and postures, complicating everyday tasks like walking. Historically, medical professionals have depended on subjective evaluations for diagnosing dystonia, which can lead to inconsistencies and postponed treatment. For children with cerebral palsy, such delays may exacerbate their condition, making it increasingly challenging to address.
Currently, an interdisciplinary research group spearheaded by Bhooma Aravamuthan, MD, DPhil, an assistant professor of neurology at Washington University School of Medicine in St. Louis, has discovered an objective technique for assessing leg dystonia in children with cerebral palsy. Their approach analyzes leg movement variability — particularly, how much a child’s legs adduct, or shift toward the body’s center, while seated. Utilizing this clear-cut method, doctors can swiftly and accurately gauge the severity of dystonia in their patients and customize treatments accordingly.
To better comprehend the origins of dystonia, the researchers also identified in mice the circumstances and brain area associated with leg movement variability, implying that early medical interventions aimed at pertinent brain processes could effectively manage or even avert this prevalent complication.
The findings were published online on July 3 in Annals of Neurology.
“A primary objective of this research is to standardize dystonia evaluation by quantifying diagnoses previously reliant on physicians’ intuition,” stated Aravamuthan, who embarked on this project while being guided in the lab of co-senior author Jordan McCall, PhD, an associate professor of anesthesiology at WashU Medicine. “These findings can be promptly integrated into clinical practice to assist in making treatment decisions for children with cerebral palsy and ultimately enhance patient outcomes.”
Utilizing technology to assess movement
Although dystonia is a prevalent characteristic of cerebral palsy, earlier studies have struggled to define it due to its symptom variability, which may be subtle and arise only during specific tasks or when a child experiences stress. Motivated by her experiences with pediatric neurology patients, Aravamuthan and her team aimed to both quantify the clinical presentation of leg dystonia and decipher its underlying mechanisms in the brain, aspiring to make standardized evaluation and treatment swiftly accessible to patients.
Aravamuthan’s investigation comprised two main components. Initially, a group of eight pediatric movement disorder specialists from various institutions across the U.S. reviewed videos of 193 children aged 3 and up with cerebral palsy engaging in a seated task with their hands. They discovered that the variability in the child’s leg movements correlated strongly with the severity of their dystonia as assessed from the videos, suggesting that this variability — which can be objectively and quantitatively evaluated in a clinical setting regarding the angle and position of the child’s legs as they move toward the body’s midline — might serve as a dependable indicator of the condition.
“We established definitive guidelines that practitioners can utilize today to evaluate dystonia in patients with cerebral palsy more accurately,” Aravamuthan remarked. “This will enhance treatment for our patients as well as facilitate drug development and future research that can depend on this consistent and reproducible assessment method.”
In the second segment of the study, Aravamuthan’s team sought to determine if stimulating specific brain cells in the area related to motor control could elicit similar leg movement variability in mice as observed in humans. These cells, known as striatal cholinergic interneurons (ChIs), play a crucial role in coordinating muscle movements and ensuring fluid and intentional actions, making them a valuable target for developing dystonia treatments.
Researchers at Aravamuthan’s lab selectively stimulated these neurons in mice over a 14-day period. They noted that mice with chronic ChI stimulation exhibited increased leg movement variability compared to those without ChI stimulation, imitating the dystonia observed in individuals with cerebral palsy. This was not the case with short-term stimulation, indicating that sustained activity in these neurons is essential for manifesting the dystonia. This implies that medications targeting overactive striatal ChIs may present a promising strategy for addressing dystonia.
“We understand from clinical observations that it can take weeks, months, or sometimes even years after brain injury for an individual to develop dystonia,” Aravamuthan noted. “There are existing medications aimed at diminishing the excitability of these neurons, but they’re often administered after dystonia has been established for some time, which may explain their inconsistent effectiveness. Our research in mice suggests that providing these medications early on and preventing chronic activation of these neurons could avert the onset of dystonia.”
Aravamuthan emphasized that further experiments and drug trials will be necessary before such interventions can be implemented clinically.
Gemperli K, Lu X, Chintalapati K, Rust A, Bajpai R, Suh N, Blackburn J, Gelineau-Morel R, Kruer MC, Mingbunjerdsuk D, O’Malley J, Tochen L, Waugh JL, Wu S, Feyma T, Perlmutter J, Mennerick S, McCall JG, Aravamuthan BR. Chronic striatal cholinergic interneuron excitation causes cerebral palsy-related dystonic behavior in mice. Annals of Neurology. Online July 3, 2025. DOI: https://onlinelibrary.wiley.com/doi/10.1002/ana.27299
This research was supported by the National Institute of Neurological Disorders and Stroke (K08NS117850, R01NS117899, R01NS106298), the Pediatric Epilepsy Research Foundation, the Rita Allen Foundation and the National Institute of Mental Health (R01MH123748). The content reflects solely the views of the authors and does not necessarily represent the official perspectives of the NIH.
About Washington University School of Medicine
WashU Medicine is a prominent leader in academic medicine, encompassing biomedical research, patient care, and educational programs with a faculty of 2,900. Its National Institutes of Health (NIH) research funding portfolio ranks second among U.S. medical schools and has increased by 83% since 2016. Alongside institutional investment, WashU Medicine allocates over $1 billion annually to innovative basic and clinical research and training. Its faculty practice consistently ranks among the top five in the country, featuring more than 1,900 faculty physicians practicing at 130 locations. WashU Medicine physicians exclusively staff Barnes-Jewish and St. Louis Children’s hospitals — the academic hospitals of BJC HealthCare — and provide care to patients at BJC’s community hospitals throughout the region. WashU Medicine has a distinguished history in MD/PhD training, recently dedicating $100 million to scholarships and curriculum reform for medical students, and hosts premier training programs in every medical subspecialty along with physical therapy, occupational therapy, and audiology and communication sciences.
Originally published on the WashU Medicine website
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