Section 29. Disorders of the Nervous System >
Part 5. Paroxysmal Disorders >
Chapter 566. Movement Disorders, Tics, and Tourette SyndromeDiana Apetauerova
Topics Discussed: movement disorders; neurology; tic disorder; tourette syndrome.
Sections: Approach to the Patient, Hyperkinetic Movement Disorders, Hypokinetic Movement Disorders, References.
Excerpt:"Movement disorders are defined as either a loss or poverty (akinesia)
or slowness (bradykinesia) of movement that is not associated with
weakness or an excess of abnormal involuntary movements. Based on
this, movement disorders are classified as either hypokinetic (Parkinsonism) or
hyperkinetic (tremor, dystonia, chorea, tics, myoclonus). Movement
disorders are generally caused by abnormalities in basal ganglia
and their connections. The basal ganglia are that group of gray
matter nuclei lying deep within the cerebral hemispheres (caudate,
putamen, and pallidum), the diencephalon (subthalamic nucleus),
and the mesencephalon (substantia nigra). The causes of many movement
disorders remain unknown, in others various causes have been identified
ranging from environmental toxins, genetic causes, medications,
metabolic disorders, structural lesions, neurodegenerative causes,
infectious, postinfectious causes, and autoimmune and psychogenic
causes. More recent genetic, biochemical, and functional imagine
advances have provided additional information about the pathophysiology
and etiology of some movement disorders. Many diseases have now
been localized to a specific gene (PD, dystonia, ataxia, paroxysmal
dyskinesia, etc); several inherited movement disorders are due to
expanded repeats of the trinucleotide cytosine-adenosine-quanosine
(CAG) such as Huntington disease, some spinocerebellar ataxias (SCAs),
and Dentatorubral and Pallidoluysian Atrophy (DRPLA). ..."
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