Dystonia

What dystonia is

Normal movement depends on the brain switching muscles on and off in a precise balance. In dystonia that control is disrupted, mainly in circuits that link the basal ganglia, cerebellum and cortex. Opposing muscles contract at the same time, producing twisting, pulling or tremor-like movements.

Typical features help neurologists recognize it:

• the abnormal movement or posture is patterned, repeating in the same direction each time
• it is often task-specific at first, appearing only when writing, playing an instrument or walking forward
• a sensory trick (geste antagoniste) can ease it, such as lightly touching the chin to straighten the neck
• it worsens with stress and fatigue and disappears during sleep

Dystonia symptoms by body part

Many people also have a tremor, pain from constantly contracting muscles, fatigue, and anxiety or low mood.

Types of dystonia

Doctors classify dystonia in two ways.

By distribution:

• Focal: one body part. This is the most common form in adults.
• Segmental: two or more adjacent parts, such as neck and arm.
• Multifocal: two or more non-adjacent parts.
• Generalized: the trunk plus at least two other areas.
• Hemidystonia: one side of the body, usually after a stroke or brain injury.

By cause:

• Isolated (primary) dystonia: dystonia is the only feature, apart from tremor. Many cases are idiopathic (no cause found); some are genetic, such as DYT1 (TOR1A) early-onset generalized dystonia.
• Combined dystonia: dystonia plus another movement disorder, such as parkinsonism or myoclonus. One example is dopa-responsive dystonia, a childhood form that improves dramatically with levodopa.
• Acquired (secondary) dystonia: caused by an identifiable condition or exposure.

Causes and risk factors

• Genetics: more than 25 genes are linked to dystonia. A family history raises suspicion, especially when it begins before age 26.
• Medicines: antipsychotics and anti-nausea drugs such as metoclopramide can cause sudden acute dystonia or late-onset tardive dyskinesia and tardive dystonia. Too much levodopa can cause dystonia in Parkinson's disease.
• Brain conditions: stroke, head injury, brain tumors, cerebral palsy, encephalitis and lack of oxygen at birth.
• Neurodegenerative diseases: Parkinson's disease, Huntington's disease and multiple system atrophy.
• Metabolic disorders: Wilson disease, where copper builds up in the liver and brain, is treatable and must not be missed in anyone under 50.
• Overuse: intensive repetitive fine movements trigger task-specific dystonia in musicians, writers and athletes (the "yips" in golfers can be a form of dystonia).

Focal dystonias in adults typically start between ages 40 and 60 and are more common in women.

How dystonia is diagnosed

There is no single test. A neurologist, ideally a movement disorder specialist, makes the diagnosis by watching the movements at rest and during tasks. They will ask when it started, whether it is task-specific, family history and all medicines taken, including anti-sickness drugs.

Tests depend on age and pattern:

• Blood and urine tests for copper and ceruloplasmin, and an eye exam for copper rings, to exclude Wilson disease in younger people
• MRI of the brain if there is hemidystonia, sudden onset or other neurological signs
• Genetic testing for early-onset or familial cases
• A trial of levodopa in children and young people, to identify dopa-responsive dystonia

Dystonia is sometimes mistaken for essential tremor, stress, arthritis or a "stiff neck", and diagnosis is often delayed for years.

Dystonia treatment

Treatment is tailored to which body parts are affected. There is no cure for most forms, but symptoms can usually be reduced substantially.

Botulinum toxin injections

The first-line treatment for most focal dystonias. Small doses injected into the overactive muscles weaken them for about 3 months, after which injections are repeated. They work well for cervical dystonia and blepharospasm. Side effects depend on the site, such as temporary neck weakness, droopy eyelid or trouble swallowing.

Oral medicines

• Anticholinergics such as trihexyphenidyl, mainly in younger people with generalized dystonia
• Levodopa for dopa-responsive dystonia, often with remarkable results
• Muscle relaxants such as baclofen, and benzodiazepines such as clonazepam
• Antidotes for acute drug-induced dystonia, such as diphenhydramine or benztropine given in the ER, which usually work within minutes

Deep brain stimulation (DBS)

Electrodes implanted in the globus pallidus deliver continuous stimulation. DBS is effective for severe generalized dystonia, especially genetic DYT1 dystonia, and for cervical dystonia that does not respond to injections. Improvement builds over weeks to months.

Physical, occupational and speech therapy

Stretching, posture training, sensory-trick techniques, ergonomic tools such as thicker pens, and voice therapy all help. Stress management and treating anxiety or depression also reduce symptom severity.

Living with dystonia

Focal adult dystonia usually stays limited to one or two areas, and life expectancy is normal. About 1 in 10 people with cervical dystonia have a spontaneous remission, although it often returns. Childhood-onset generalized dystonia is more likely to spread and cause disability, but DBS has changed the outlook for many. Pain, fatigue and social anxiety are common and worth raising with your doctor.

Frequently asked questions

What is the main cause of dystonia?

In most adults with focal dystonia no single cause is found. It is thought to stem from abnormal signaling in brain circuits that control movement, sometimes with a genetic predisposition. Other cases are caused by medicines, stroke, brain injury, Parkinson's disease or Wilson disease.

Is dystonia a serious condition?

Most adult-onset dystonia affects one body part and does not shorten life, but it can cause pain and affect work and social life. Generalized dystonia in children can be disabling. Acute drug-induced dystonia and dystonic storm are medical emergencies.

Does dystonia get worse over time?

Focal dystonia often worsens over the first few years, then stabilizes. Dystonia that starts in childhood, particularly in a leg, is more likely to spread to other body parts. Dystonia caused by a progressive disease follows the course of that disease.

Can stress cause dystonia?

Stress does not cause dystonia, but it commonly makes symptoms worse, and the movements typically ease when relaxed and stop during sleep. Managing stress, anxiety and fatigue is a useful part of treatment alongside injections or medicines.

What is the difference between dystonia and a tremor?

A tremor is a rhythmic, regular shaking. Dystonia causes sustained or patterned twisting contractions and abnormal postures. The two can occur together: dystonic tremor is often jerky and irregular and may stop when the person lets the body part move into its preferred posture.