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

There are several different 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.

Classification

Athetosis

Sinuous writhing movement of the fingers and hands.

Chorea

Continuous jerky movements in which each movement is sudden and the resulting posture is held for a few seconds. Usually affects head, face or limbs. The focus may move from one part of the body to another at random.
Common cause of chorea is adverse effects of drug treatments especially those for Parkinson's disease, epilepsy and schizophrenia.

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

Dystonias

Many abnormal involuntary movements occur because of disorders in the basal ganglia.

• Dystonias - muscle spasms contracting the neck, limbs and trunk into typical postures:
  • In the neck - torticollis (twisted), anticollis (flexed) and retrocollis (extended). Cervical dystonia may be treated with selective peripheral denervation¹
  • In the back - scoliosis (twisted) or lordosis (arched)
  • Also the hyperpronated arm and the plantar-flexed inverted foot
  Spasm occurs with intentional movement and may be intermittent and repetitive, so giving a rhythmic appearance to the movement or may be persistent, to give a fixed posture.
• Idiopathic torsion dystonia; condition inherited in autosomal dominant pattern.² Usually presents in children, with dystonic spasms of the legs on walking, occasionally of the arms, trunk or neck. Normally progressive and spreading to the whole body, causing severe disability within about ten years. Trial of levodopa as may have dopa-responsive dystonia-Parkinsonism (Segawa's syndrome); otherwise high doses of benzodiazepines and anticholinergics, e.g. benzhexol.

In adults the condition is not usually inherited and presents with a focal dystonia:

• Blepharospasm - recurrent spasms of eye closure; treated with botulinum toxin injection into the orbicularis oculi muscle.
• Oromandibular dystonia - recurrent spasm affecting the mouth and jaw, larynx and pharynx. No effective treatment.
• Writer's cramp - inability to write or use any manual instrument due to abnormal posture of hand and arm.³ Ask patient to use other hand, injection of botulinum toxin into forearm may help. See Writer's Cramp article.

Hemiballism

Wild flinging/throwing movements of one arm or leg, usually occurring as result of a cerebrovascular event. Can vary in intensity from mild to severe and may even cause injury. Usually subsides over 3-6 months but can be treated with a phenothiazine, haloperidol or tetrabenazine. May require neurosurgery.

Myoclonus

Rapid muscle jerks, frequently repetitive. Appears 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, e.g. focal myoclonus - restricted to one part of the body, e.g. spinal affecting extremities, and hemifacial spasm occurring in 1 per 100,000, mainly affecting older women.

Spasmodic torticollis

This usually presents in middle age or elderly with torticollis or sometimes retrocollis or anticollis. Can be repetitive causing tremulous torticollis. Often has a compensatory lordosis. In one fifth of patients, may remit for a year or more but mostly life-long condition. Condition worsened by stress but patient often finds some manual activity to control the torticollis, e.g. touching jaw with forefinger. Identification of overactive muscle and injection of botulinum toxin often helps. May need local denervation in intractable conditions.

Tardive dyskinesia

Usually occurs following at least six months' treatment with neuroleptics; more frequent in older patients; occurs in 20% of those on chronic therapy and persists in 40% of cases after discontinuation of therapy. Characterised by orofacial mouthing with lip-smacking and tongue protrusion, body rocking and distal chorea. In younger patients may cause axial and cranial dystonia.⁴

Tics

Repetitive stereotyped movements. Patient can initiate voluntarily and can also intentionally suppress 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.⁵ May persist into adulthood; rarely treated.
• Complex multiple tics - more extensive and severe. When occurring with patient speaking, particularly swearing, maybe represent Gilles de la Tourette syndrome. May also appear as symptom of encephalitis lethargica, neuroacanthocytosis and be drug induced.

Tremor

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, e.g. in thyrotoxicosis, anxiety states, alcohol abuse, drugs (e.g. sympathomimetics, antidepressants, valproate, lithium), heavy metal poisoning ('hatter's shakes' from mercury). Neurological disease, e.g. severe cerebellar lesions, Wilson's disease, neurosyphilis, peripheral neuropathies, benign essential (familial) tremor, task-specific tremors, e.g. primary writing tremor.
• Kinetic or action tremor - occurs during voluntary active movement of 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 MS, spinocerebellar degenerations, vascular disease, tumours.

Tremors and dystonias that are not secondary to Parkinson's disease may be effectively treated with deep brain electrical stimulation.⁶
There are also psychogenic tremors.
Benign essential tremor is treated with alcohol in moderation. Beta-blockers or primidone are also used.

Assessment of AIMs

The Abnormal Involuntary Movement scale is used to assess tardive dyskinesias and other AIMs.^7,8 This can be useful to monitor progress and response to treatment.

Document references

1. Selective peripheral denervation of cervical dystonia, NICE (2004)
2. Early-onset Torsion Dystonia (DYT1), Online Mendelian Inheritance in Man (OMIM).
3. Gordon NS; Focal dystonia, with special reference to writer's cramp. Int J Clin Pract. 2005 Sep;59(9):1088-90. [abstract]
4. Kulkarni SK, Naidu PS; Pathophysiology and drug therapy of tardive dyskinesia: current concepts and future perspectives. Drugs Today (Barc). 2003 Jan;39(1):19-49. [abstract]
5. Snider LA, Sachdev V, MaCkaronis JE, et al; Echocardiographic findings in the PANDAS subgroup. Pediatrics. 2004 Dec;114(6):e748-51. Epub 2004 Nov 15. [abstract]
6. Deep brain stimulation for tremor and dystonia (excluding Parkinson's disease), NICE (2006)
7. Munetz MR, Benjamin S; How to examine patients using the Abnormal Involuntary Movement Scale. Hosp Community Psychiatry. 1988 Nov;39(11):1172-7. [abstract]
8. Dr Bob. Abnormal Involuntary Movement scale. Virtual En-psych-lopedia

Internet and further reading

• Dystonia, National Institute of Neurological Disorders and Stroke
• A systematic review on the diagnosis and treatment of primary (idiopathic) dystonia and dystonia plus syndromes: report of an EFNS/MDS-ES Task Force European. Journal of Neurology 2006, 13: 433–444
• The Dystonia Society

Acknowledgements