Hyperkinetic movement disorders are conditions defined by excessive involuntary movement, the counterpart to parkinsonian hypokinesia (too little movement, as in Parkinson disease). Here the brake on motor output is released, so extra movements intrude.
Two habits help before naming a cause: describe the movement precisely (speed, rhythm, distribution, relation to rest and action, sleep behavior) and review the medication list early, since drug-induced causes are taught in the satellites.
One bedside behavior helps across the whole family. Hyperkinetic movements typically fade or disappear in sleep, so a movement reported as continuing unchanged through sleep should prompt reconsideration, including seizure activity or another non-hyperkinetic cause, usually with EEG (electroencephalography, the recording of brain electrical activity) input. The rule is a strong discriminator rather than an absolute law: some tremors persist into light sleep, and a few rare myoclonus forms (myoclonus means brief, shock-like jerks) behave atypically, so exceptions are investigated rather than ignored.
Choose a route through the topic
Three satellites divide the topic, each explaining one part of it.
- Hyperkinetic Movement Disorders Classification: understand the predictability-based framework for describing an unclear movement before naming it: /notes/neurology/hyperkinetic-movement-disorders-classification/
- Chorea, Ballismus, and Athetosis: understand one basal ganglia continuum from flowing chorea to violent proximal ballismus, with Huntington disease as the genetic prototype: /notes/neurology/hyperkinetic-movement-disorders-chorea-ballismus/
- Tremor Classification and Clinical Approach: understand the most common phenotype organized by when it appears, separating Parkinson disease, essential, and cerebellar patterns: /notes/neurology/hyperkinetic-movement-disorders-tremor/
Start with classification when the movement type is still unclear, then read the chorea spectrum and tremor notes in either order.