Abnormal Involuntary Movements

oPatientPlus articles are written by UK doctors and are based on research evidence, UK and European Guidelines. They are designed for health professionals to use, so you may find the language more technical than the condition leaflets.

Abnormal involuntary movements (AIMs) are also known as 'dyskinesias'.

There are several varieties of dyskinesia which have different clinical appearances, underlying causes and treatments. Tremor, chorea, dystonia and myoclonus are examples of types of dyskinesia which have different mechanisms and modalities of treatment.

Tics and stereotypies may also be considered to be related, but some experts call these 'unvoluntary' because there is an element of voluntary control.


Sinuous writhing movement of the fingers and hands.

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Continuous jerky movements in which each movement is sudden and the resulting posture is held for a few seconds. This usually affects the head, face or limbs. The focus may move from one part of the body to another at random.

Adverse effects of drug treatments, especially those for Parkinson's disease, epilepsy and schizophrenia, are a common cause of chorea:

  • Huntington's chorea - autosomal dominant inheritance, usually presents in middle age with chorea and dementia. Insidious onset with motor, cognitive and psychiatric abnormalities. There is no treatment.
  • Sydenham's chorea - also known as St Vitus' dance. Mainly associated with acute rheumatic fever. It is now rare. It usually presents in children aged 7-12 years, initially with psychological symptoms of behavioural disturbance followed by generalised chorea; it usually recovers in 1-3 months. Penicillin for rheumatic fever and diazepam, haloperidol or tetrabenazine for chorea.


A dystonia is a sustained muscle contraction, frequently causing repetitive twisting movements or abnormal postures.[1] It is a dynamic condition that often changes in severity depending on the posture assumed and on voluntary activity of the area of the body involved. The diagnosis is clinical and there are no specific tests available; therefore, expert opinion should be sought.

They can be classified according to aetiology (primary pure, primary plus or primary paroxysmal, secondary, etc.), age at onset (early or late) or distribution (eg focal, segmental etc.).

Primary pure dystonia is inherited in a mainly autosomal dominant pattern.[2] Two genes have been identified: DYT1 and DYT6. It usually presents in children, with dystonic spasms of the legs on walking, and occasionally of the arms, trunk or neck. It is normally progressive and spreading to the whole body, causing severe disability within about ten years. A levodopa trial should be offered to patients with early-onset dystonia without an alternative diagnosis.[3]

Blepharospasm and writer's cramp are both focal dystonias. Blepharospasm involves recurrent spasms of eye closure. Writer's cramp is the inability to write or use any manual instrument due to abnormal posture of the hand and arm.[4] See also separate Writer's Cramp article. Botulinum toxin injection is the first-line treatment for most types of focal dystonia. Hemidystonia involves half of the body and is usually secondary to a structural lesion in the contralateral basal ganglia.

Dystonias may be secondary to a neurological condition such as a focal brain lesion, exposure to drugs or chemicals, or as part of Parkinson's disease. Intrathecal baclofen can be indicated in patients where secondary dystonia is combined with spasticity.

Deep brain stimulation (long-term electrical stimulation of the globus pallidus internus) is an effective treatment for primary generalised or segmental forms, and for those patients who do not achieve sufficient relief with a more conservative approach.[1] Dystonia may lead to permanent contractions, by causing tendons to shorten.[5]


These are wild flinging/throwing movements of one arm or leg, usually occurring as a result of a cerebrovascular event. They can vary in intensity from mild to severe and may even cause injury. They usually subside over a period of 3-6 months, but can be treated with a phenothiazine, haloperidol or tetrabenazine. They may require neurosurgery, to be adequately controlled.


These are rapid muscle jerks, that are frequently repetitive. They appear as:

  • Benign essential myoclonus; affects much of body, repeated as many as 50 times per minute. Presents in childhood or adolescence with mild disability. Helped by alcohol and beta-blockers.
  • Progressive myoclonic encephalopathies; appear as part of a range of other neurological disorders.
  • Static myoclonic encephalopathies; Lance-Adams syndrome after cerebral anoxia.

Myoclonic epilepsies, eg focal myoclonus - restricted to one part of the body, eg hemifacial spasm occurring in 1 per 100,000, mainly affecting older women. Myoclonus usually requires a combination of drugs (in large doses). [6] Anti-epileptic drugs, eg valproate, levetiracetam and piracetam, are effective in cortical myoclonus, but less so in others. Clonazepam may be helpful with all types of myoclonus.

Spasmodic torticollis

This usually presents in middle age or in the elderly, with torticollis or sometimes retrocollis or antecollis. It can be repetitive, causing tremulous torticollis. There is often a compensatory lordosis. 20% of patients may remit for a year or more, but it is mostly a lifelong condition. The condition is worsened by stress, but the patient often finds some manual activity to control the torticollis, eg touching the jaw with a forefinger. Identification of overactive muscle and injection of botulinum toxin often help. In intractable conditions, local denervation may be needed.

Tardive dyskinesia

This usually occurs following at least six months' treatment with neuroleptics. The risk of new cases is around 5% per year of cumulative drug exposure, with age and early occurring extrapyramidal side-effects being two important risk factors.[7] In elderly individuals receiving antipsychotic medications for the first time, the incidence was generally fivefold higher. It occurs in 20% of those on chronic therapy and persists in 40% of cases after discontinuation of therapy. It is characterised by orofacial mouthing with lip-smacking and tongue protrusion, body rocking and distal chorea. In younger patients it may cause axial and cranial dystonia.


These are repetitive stereotyped movements. The patient can initiate them voluntarily and can also intentionally suppress them for a short time.

  • Simple tic - sudden rapid twitch always occurring at the same site. Occurs in a quarter of all children and resolves within a year. May persist into adulthood; rarely treated.
  • Complex multiple tics - more extensive and severe. When occurring with the patient speaking, particularly swearing, they may represent Gilles de la Tourette's syndrome. They may also appear as a symptom of encephalitis lethargica, neuroacanthocytosis and can also be drug-induced.


This is a rhythmic movement of part of the body. There are three types of pathological tremor:

  • Static - occurs in a relaxed limb when fully supported at rest. Causes include Parkinson's disease, Parkinsonism, other extrapyramidal diseases, multiple sclerosis.
  • Postural - occurs if a limb is static (can also remain during movement). Types include physiological tremor, exaggerated physiological tremor, eg in thyrotoxicosis, anxiety states, alcohol abuse, drugs (eg sympathomimetics, antidepressants, valproate, lithium), heavy metal poisoning ('hatter's shakes' from mercury). Neurological disease, eg severe cerebellar lesions, Wilson's disease, neurosyphilis, peripheral neuropathies, benign essential (familial) tremor, task-specific tremors, eg primary writing tremor.
  • Kinetic or action tremor - occurs during voluntary active movement of an upper body part. Intention tremor is one that occurs when a tremor worsens as a goal-directed hand movement nears its intended target. Brain stem or cerebellar disease including multiple sclerosis, spinocerebellar degenerations, vascular disease, tumours.

There are also psychogenic tremors.

Tremors and dystonias that are not secondary to Parkinson's disease may be effectively treated with deep brain electrical stimulation.[1][8] Benign essential tremor is treated with alcohol in moderation. Beta-blockers or primidone are also used.

Dystonia may be assessed using a validated rating scale such as the Burke-Fahn-Marsden Dystonia Rating Scale or the Unified Dystonia Rating Scale.[9] They are most useful for measuring the effectiveness of certain treatments such as deep brain stimulation. The Abnormal Involuntary Movement Scale is used to assess tardive dyskinesias and other AIMs.[10] This can be useful to monitor progress and response to treatment.

Further reading & references

  1. Guidelines on diagnosis and treatment of primary dystonias, European Federation of Neurological Societies (2010)
  2. Dystonia 1, Torsion, Autosomal Dominant; DYT1, Online Mendelian Inheritance in Man (OMIM)
  3. Albanese A, Barnes MP, Bhatia KP, et al; A systematic review on the diagnosis and treatment of primary (idiopathic) Eur J Neurol. 2006 May;13(5):433-44.
  4. Zeuner KE, Peller M, Knutzen A, et al; How to assess motor impairment in writer's cramp. Mov Disord. 2007 Jun 15;22(8):1102-9.
  5. Dystonia, National Institute of Neurological Disorders and Stroke
  6. Kojovic M, Cordivari C, Bhatia K; Myoclonic disorders: a practical approach for diagnosis and treatment. Ther Adv Neurol Disord. 2011 Jan;4(1):47-62.
  7. Kane JM, Correll CU; Pharmacologic treatment of schizophrenia. Dialogues Clin Neurosci. 2010;12(3):345-57.
  8. Deep brain stimulation for tremor and dystonia (excluding Parkinson's disease), NICE (2006)
  9. Susatia F, Malaty IA, Foote KD, et al; An evaluation of rating scales utilized for deep brain stimulation for dystonia. J Neurol. 2010 Jan;257(1):44-58. Epub 2009 Jul 29.
  10. Munetz MR, Benjamin S; How to examine patients using the Abnormal Involuntary Movement Scale. Hosp Community Psychiatry. 1988 Nov;39(11):1172-7.

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.

Original Author:
Dr Hayley Willacy
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Peer Reviewer:
Dr Adrian Bonsall
Document ID:
1741 (v24)
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