Academic journal article Mental Health Aspects of Developmental Disabilities

Movement Disorders: Things That Do Go Bump in the Night

Academic journal article Mental Health Aspects of Developmental Disabilities

Movement Disorders: Things That Do Go Bump in the Night

Article excerpt

Movement disorders are complex phenomena that frequently create confusion among mental health clinicians working in the field of dual diagnosis. Some of the confusion arises from uncertainty about whether movements are voluntary or involuntary. Because abnormal movements are exacerbated by stress or other anxiety provoking situations, wax and wane in severity and are associated with other disruptive behaviors, they are frequently confused with other repetitive behaviors as well as primary psychiatric disorders. This first segment of a series of Ask the Doctor provides a basic overview of the neuropsychiatry and behavioral pharmacology of abnormal movements.

Keywords: tics, pharmacotherapy, psychiatric, Tourette's disorder, involuntary, side-effects, intellectual disability

Q. Dr. Barnhill, many individuals with intellectual disability have abnormal movements, such as finger flicking or tics. Can you describe what these are and how they are identified?

A. We will be talking about involuntary abnormal movements. But first what do we know about movement in general and how do involuntary ones differ from voluntary ones?

At first blush this seems like an easy question to answer. But if we take a little time to think about it, things quickly get a bit blurred. Observable, volitional movements are the tip of an iceberg. Any voluntary movement is the culmination of hierarchical sequenced, highly regulated neurological activity. Even a simple voluntary movement like pointing at a bird requires the integration and coordination of sensory data such as target perception and selection; planning of specific actions; a fluid visual-spatial guidance system that gets the hand to where it should be; proprioceptive and kinesthetic feedback to make rapid adaptation to distance and motion factors; sequential alternating activation-inhibition of multiple muscle groups and coordination of signals that the action is complete, then stopping that act and getting ready for the next. It is also apparent that even pointing begins with global planning in the premotor cortex followed by a rapid progression through increasingly finely tuned visual, kinesthetic, and refined motor activity. All this occurs in milliseconds and is infinitely more complicated than a reflex movement away from a hot stove.

Consider a more complex task such as playing Rachmaninoff's Third Piano Concerto. Obviously to even consider this piece requires enormous skill and talent as well as years of practice. Functional brain imaging would reveal basic different patterns of brain activity during the early phases of practicing and learning this intricate piece than once it is mastered. By the time it is mastered by the pianist, most of the millions of different hand and finger movements are largely automatic. In short, those adjustments and variations of motor sequences are outside direct conscious awareness, allowing the concert pianist to rapidly merge technical skill with the expression of the intense emotion and power of this music.

For most of us, learning a new skill requires a different level of brain function than performing a well practiced one. Just think of how you feel when faced with the ominous label "some assembly required" on a child's toy. It is readily apparent to those of us who are "mechanically-challenged" and tremble in fear at this warning that learning new motor skills the night before or as is the case for real pros, intuiting how things fit together, is one challenge. Accomplishing the sequence of actions to complete the task under time pressure is another and reinforces this concept. Disorders of motor coordination, dyspraxias and movement disorders impact these cognitive-to-motor action transformations.

Q. So what happens during an abnormal movement?

A. Now imagine that somewhere in this complex process a short circuit occurs. Depending on where the error appears, different parts of the performance are affected. …

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