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.
Cerebrovascular diseases are a common cause of secondary movement disorders. Post-stroke movement disorders include Parkinsonism and a wide range of hyperkinetic movement disorders, including chorea, ballism, athetosis, dystonia, tremor, myoclonus, stereotypies and akathisia.
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This is a rhythmic movement of part of the body. Essential tremor and Parkinsonian tremor are the most common forms of tremor 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. Brainstem 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. Benign essential tremor is treated with alcohol in moderation. Beta-blockers or primidone are also used.
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 Tourette’s syndrome. They may also appear as a symptom of encephalitis lethargica and of neuroacanthocytosis; they can also be drug-induced.
Sinuous, slow, involuntary writhing movements affecting the fingers, hands, toes and feet. The arms, legs, neck and tongue may also be affected. Causes include asphyxia, neonatal jaundice, Huntington’s chorea, cerebrovascular disease and trauma. Management can be difficult but treatment options include medications (eg, diazepam, haloperidol, tetrabenazine), surgery and retraining techniques.
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.
Chorea may be caused by adverse effects of drug treatments, especially medications for Parkinson’s disease, epilepsy and schizophrenia.
A dystonia is a sustained muscle contraction, frequently causing repetitive twisting movements or abnormal postures. 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. Dystonias may be primary or secondary.
Treatments available for dystonia include oral medications, botulinum toxin and surgical procedures. Oral medications are generally used for generalised and segmental dystonia. Botulinum toxin is the mainstay of treatment for focal dystonia. Surgical procedures are available for medication-refractory dystonia, markedly affecting quality of life.
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 and cause significant disability. 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, mainly affecting older women).
Myoclonus usually requires a combination of drugs (in large doses). 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. Botulinum toxin may be useful for segmental myoclonus.
Torticollis is a twisting of the head and neck caused by a shortened sternocleidomastoid muscle, tipping the head toward the shortened muscle, while rotating the chin in the opposite direction. Torticollis may occur in all ages, from newborns to adults.See also the separate article on Neck Pain (Cervicalgia) and Torticollis.
This usually occurs following at least six months of 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.
In elderly individuals receiving antipsychotic medications for the first time, the incidence is generally five-fold higher. It occurs in approximately 20% of those on chronic therapy and persists in about 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.