4 Frequently Asked Questions About Functional Movement Disorder
4 frequently asked questions about functional movement disorder Functional movement disorder (FMD) is a type of movement disorder that causes abnormal and involuntary body movements such as jerks, tics, and tremors in the limbs or head. Although FMD causes similar symptoms as most movement disorders, the cause of FMD is not the same as of other movement disorders, which is damage to the brain or neurons.