Classification of Functional Movement Disorders with Resting State fMRI, 2022, Hallett, Horovitz et al

Abstract

Introduction: Functional movement disorder (FMD) is a type of functional neurological disorder (FND) characterized by abnormal movements that patients do not perceive as self-generated. Prior imaging studies show a complex pattern of altered activity, linking regions of the brain involved in emotional responses, motor control, and agency. This study aimed to better characterize these relationships by building a classifier via support vector machine (SVM) to accurately distinguish between 61 FMD patients and 59 healthy controls using features derived from resting state functional MRI (rs-fMRI).

Methods: First, we selected 66 seed regions based on prior related studies, then calculated the full correlation matrix between them, before performing recursive feature elimination to winnow the feature set to the most predictive features and building the classifier.

Results: We identified 29 features of interest that were highly predictive of FMD condition, classifying patients from controls with 80% accuracy. Several key features included regions in the right sensorimotor cortex, the left dorsolateral prefrontal cortex (dlPFC), the left cerebellum and the left posterior insula.

Conclusion: The features selected by the model highlight the importance of the interconnected relationship between areas associated with emotion, reward and sensorimotor integration, potentially mediating communication between regions associated with motor function, attention, and executive function. Exploratory machine learning was able to identify this distinctive, abnormal pattern, suggesting that alterations in functional linkages between these regions may be a consistent feature of the condition in many FMD patients.

Paywall, https://www.liebertpub.com/doi/10.1089/brain.2022.0001

 

Maybe the emotional regions are activated by the embarrassment of having your arms wave about randomly in public so everyone turns to look at you. Not to mention anger that they say it is functional!

Then there is the humour of the situation when little kids wave back

 

1. Take n people who have been told they have FND and n people who have not
2. Note that 'FND' is shorthand for YBAIYDIEIYSII (you're barmy and it's you doing it even if you say it isn't.)
3. Look for activity in brain regions expected in people who have been told they have YBAIYDIEIYSII
4. Which will be thinking about motor control and agency with a load of emotion thrown in.

5. Find it and prove you told these people they had YBAIYDIEIYSII

A more useful approach would be to look for differences between the two groups that you had not at all expected. That might tell you something new about the problem.

 

Jo, this is an incisive analysis. The only problem is the FND folks skip #2 in the public presentation of their ideas.