Dystonia – Causes, Symptoms, Diagnosis, Treatment

In dystonia, muscles contract involuntarily — causing an uncontrollable twisting of the affected body part. Symptoms can be mild or severe, and often interfere with the performance of many day-to-day tasks.

Doctors divide dystonia into two broad categories, depending on the age of onset. If your symptoms begin in your youth, you could have a type of dystonia that’s inherited and the symptoms may eventually affect the entire body.

Most cases of dystonia, however, occur in older individuals and tend to affect only one body part — often the neck, face or hand.

Dystonia is an uncommon disorder. The highest estimates place the proportion of people affected at less than 1 percent. Women seem to be more likely to develop dystonia than men are.

Causes

Doctors don’t know what causes most cases of dystonia, but it has been linked to communication problems between nerve cells located in the basal ganglia — an area of the brain involved in initiating muscle contractions.

While many cases of dystonia have no obvious cause, the disorder sometimes results from an underlying neurological problem, such as:

  • Traumatic brain injury
  • Stroke
  • Brain tumor
  • Oxygen deprivation
  • Infections, such as tuberculosis or encephalitis
  • Reactions to certain drugs
  • Heavy metal or carbon monoxide poisoning

Symptoms

Dystonia symptoms typically:

  • Begin in a single region, such as your foot or hand.
  • Occur with a specific action. For example, you may experience involuntary contractions in one leg when walking forward, but not when running forward or walking backward.
  • Worsen with stress, fatigue or anxiety.
  • Plateau within a few years.

The impact of dystonia on a person’s quality of life varies depending on the part of the body affected and the severity of contractions:

  • Eyelids. Rapid blinking or squinting (blepharospasm) can be so severe as to make a person functionally blind.
  • Neck. Cervical dystonia may cause the head to twist and turn painfully to one side, or to pull forward or backwards.
  • Jaw and tongue. Oromandibular dystonia may cause slurred speech or difficulty eating or swallowing.
  • Hand and forearm. Writer’s cramp or musician’s cramp causes pain during a single repetitive motion, such as writing or playing an instrument.

Diagnosis

A diagnostic work-up will include a thorough assessment of your symptoms, usually by a neurologist. Your doctor will also take a complete medical history to identify dystonia in the family, previous head injury or stroke, exposure to toxins or drugs, or evidence of other potential secondary causes. Blood or urine tests may reveal the presence of toxins, and MRI may be used to identify tumors, lesions or evidence of stroke.

Treatment

Dystonia treatment has improved in recent years, due to successes with botulinum toxin injections. For more disabling cases, deep brain stimulation is now being considered.

Oral medications

Some forms of early-onset dystonia respond to levodopa — a medication that increases the effect of dopamine, a neurotransmitter involved with muscle movement. Dystonia prescriptions that act on other neurotransmitters include:

  • Procyclidine hydrochloride (Kemadrin)
  • Diazepam (Valium)
  • Lorazepam (Ativan)
  • Clonazepam (Klonopin)
  • Baclofen (Kemstro)

Sensory trick
A common phenomenon associated with dystonia is called a sensory trick. Touching an affected or adjacent body part can sometimes significantly reduce contractions. For example, placing a hand on the chin, side of the face or back of the head may reduce neck muscle contractions.

People with dystonia typically discover and use this trick to reduce their own dystonic contractions. Some physical therapists have developed head or neck braces, hand splints or other devices that mimic the sensory trick.

Botulinum toxin
Botulinum toxin (Botox, Myobloc) blocks the release of a chemical messenger that triggers muscle contractions. When your doctor injects the toxin into a muscle, it causes that muscle to temporarily weaken, which may reduce or eliminate dystonia contractions. The effect wears off, and injections need to be repeated about every three months.

Deep brain stimulation
This technique involves implanting an electrode in the brain and a stimulating device, connected to the electrode, in the chest. The stimulator generates electrical pulses, transmitted via the electrode implanted into a specific brain region that reduces the abnormal muscle contractions. To modulate the effect of the treatment, your doctor can adjust the frequency and intensity of electrical pulses.

Surgery
Surgery is considered only in severe cases of dystonia, when nothing else has worked. Surgeons can sever or remove the nerves controlling the contracted muscle, although there is a risk of disfigurement. In cases where dystonia affects a large percentage of the body, it may help to surgically destroy a portion of the thalamus — a part of the brain that helps control movement.

Complications

Dystonia may affect your mobility and your scope of daily activities. People with more widespread dystonia may be stigmatized because many people believe mental illness or mental retardation is the cause of disordered movement. All of these factors may lead to feelings of frustration, depression or anxiety.

The constant contraction of muscles is somewhat like a sustained workout, so dystonia can be both exhausting and painful. Fatigue, in turn, exacerbates the symptoms.