Hyperkinetic movement disorders

The relationship between movement disorders and substance abuse can be examined from two approaches: first, assessment of the movements which occur secondary to substance abuse, and second, review of the movement disorders that might increase the propensity for substance abuse. This chapter will first address the myriad of hyperkinetic movements that can be seen in drug abusers, followed by a discussion of alcohol and two movement disorders (myoclonus-dystonia and essential tremor) in which patients may be at increased risk of alcohol abuse and dependence due to self-treatment of the disorders with alcohol. Hyperkinetic movement disorders include tremor, myoclonus, dystonia, chorea, athetosis, tics, akathisia, and stereotypies. Amphetamines have been associated with dystonia, chorea, tics, and tremors, and may exacerbate underlying movement disorders. In addition to worsening pre-existing movements, cocaine may cause tics, dystonia, chorea, myoclonus, and tremor. Movements associated with opioid use usually occur in the setting of medically ill patients, and include myoclonus and chorea. Alcohol, in contrast, may dampen some hyperkinetic movement disorders, and people with essential tremor and myoclonus-dystonia may use alcohol to self-treat symptoms. In some situations this has led to abuse which has been more damaging to the lives of the affected individuals than the underlying movement disorders.