Carine W. Maurer

The “Whack-a-Mole” Sign in Functional Movement Disorders

Making the diagnosis of functional movement disorders can be challenging. Identifying positive physical signs and diagnostic maneuvers is critical to this process. Distractibility, entrainability, and variability are examples of classic physical findings in these patients. In this case series, we identify and characterize another phenomenon observed in some of these patients. In this phenomenon, movement suppression of one body part is followed by immediate reemergence of movement in another. We propose that this phenomenon be referred to as the “whack‐a‐mole” sign. This name is derived from the arcade game whack‐a‐mole, in which a mole, when hit into its original hole, re‐emerges elsewhere. We present a case series of 4 patients with functional movement disorders who exhibit this sign.

Impaired sense of agency in functional movement disorders: An fMRI study

The sense of agency (SA) is an established framework that refers to our ability to exert and perceive control over our own actions. Having an intact SA provides the basis for the human perception of voluntariness, while impairments in SA are hypothesized to lead to the perception of movements being involuntary that may be seen many neurological or psychiatric disorders. Individuals with functional movement disorders (FMD) experience a lack of control over their movements, yet these movements appear voluntary by physiology. We used fMRI to explore whether alterations in SA in an FMD population could explain why these patients feel their movements are involuntary. We compared the FMD group to a control group that was previously collected using an ecologically valid, virtual-reality movement paradigm that could modulate SA. We found selective dysfunction of the SA neural network, whereby the dorsolateral prefrontal cortex and pre-supplementary motor area on the right did not respond differentially to the loss of movement control. These findings provide some of the strongest evidence to date for a physiological basis underlying these disabling disorders.