Involuntary movements: tremor, chorea, dystonia, myoclonus and tics
- Syndrome
How to name the movements a patient cannot control, because the name points to the cause.
See it in 3D: Caudate nucleus · Putamen · Globus pallidus · Substantia nigra · Thalamus · Cerebellum
What it is
Involuntary movements are first named by watching them: are they rhythmic (tremor), flowing and random (chorea), twisting and sustained (dystonia), brief shock-like jerks (myoclonus) or repetitive actions preceded by an urge (tics)? Most come from the basal ganglia and their circuits, some from the cerebellum, the brainstem or the cortex. Hyperkinetic disorders add movement; parkinsonism, the hypokinetic disorder, takes it away.
Key findings
- Watch the patient at rest, with the arms outstretched, during finger–nose testing, while writing and while walking.
- Rest tremor: present with the limb supported and relaxed, it fades with movement; typical of Parkinson disease.
- Postural and action tremor: present when holding a posture or moving; typical of essential tremor and enhanced physiological tremor.
- Intention tremor: grows as the finger approaches the target; cerebellar.
- Tics can be held back for a short time and are preceded by an urge; chorea cannot be suppressed.
Pathophysiology
- The basal ganglia (caudate, putamen, globus pallidus, subthalamic nucleus and substantia nigra) form loops with the thalamus and cortex that select wanted movements and suppress unwanted ones.
- Loss of dopamine from the substantia nigra slows movement (parkinsonism); loss of caudate neurons, as in Huntington disease, releases movement (chorea).
- A lesion of the subthalamic nucleus causes violent flinging of the opposite limbs (hemiballismus).
- The cerebellum adjusts movement as it happens; its damage produces intention tremor and ataxia rather than extra movements.
Naming the movement
| Movement | What it looks like | Typical causes |
|---|---|---|
| Tremor | Rhythmic back-and-forth oscillation; at rest, in posture or with action | Parkinson disease (rest), essential tremor (posture and action), cerebellar lesions (intention), hyperthyroidism, drugs and withdrawal |
| Chorea and athetosis | Brief, flowing, random movements that move from one body part to another; athetosis is slower and writhing | Huntington disease, Sydenham chorea after rheumatic fever, pregnancy, levodopa, stroke of the striatum |
| Ballismus | Large, violent flinging of a whole limb, usually one side | Stroke of the opposite subthalamic nucleus |
| Dystonia | Sustained contractions causing twisting or abnormal postures, often triggered by a specific action | Primary dystonias, Wilson disease, dopamine-blocking drugs (acute dystonia) |
| Myoclonus | Sudden, very brief shock-like jerks; asterixis is a brief loss of tone | Metabolic encephalopathy (liver, kidney), hypoxic brain injury, prion disease, epilepsy |
| Tics | Repetitive, stereotyped movements or sounds preceded by an urge and briefly suppressible | Tourette syndrome and other tic disorders, stimulants |
| Tardive dyskinesia | Repetitive chewing, lip-smacking and tongue movements | Long-term use of dopamine-blocking drugs |
Common causes
- Essential tremor: symmetric postural tremor of the hands, sometimes the head and voice, often with a family history and improvement with alcohol.
- Parkinson disease: asymmetric rest tremor with slowness and rigidity.
- Huntington disease: chorea with behavioral change and dementia, inherited dominantly.
- Wilson disease: tremor, dystonia or parkinsonism in a young person, with liver disease and Kayser–Fleischer rings.
- Drugs such as antipsychotics and metoclopramide cause acute dystonia, parkinsonism and tardive dyskinesia.
Tests that confirm it
- The diagnosis is mostly clinical; a video of the movements helps.
- Thyroid function in new tremor; copper studies and an eye exam for Kayser–Fleischer rings in anyone young with a movement disorder.
- Brain MRI for sudden, one-sided or atypical movements; genetic testing for Huntington disease when suspected.
Test yourself
Think of the answer, then tap the question to see it.
How is the rest tremor of Parkinson disease told apart from essential tremor?
Parkinson tremor appears with the limb at rest and fades with movement; essential tremor appears when holding a posture or moving.
What separates tics from chorea?
Tics are stereotyped, preceded by an urge and can be briefly suppressed; chorea is random, flowing and cannot be suppressed.
Which lesion causes hemiballismus?
A lesion, usually a stroke, of the subthalamic nucleus on the opposite side.
Which disease must be ruled out in a young person with tremor or dystonia?
Wilson disease, a treatable disorder of copper metabolism.
Connections
See it in 3D6
The structures of Durgical's 3D anatomy where it is found.
Educational content on the clinical exam; it is learned and practised under supervision. It does not replace assessment by a health professional and is not for self-diagnosis.
Sources: Overview of Movement and Cerebellar Disorders (MSD Manual Professional Edition, 2024); Tremor (MSD Manual Professional Edition, 2024).
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Representative model, for educational purposes only.