Dystonia

Dystonia is a medical term that describes a range of movement disorders that cause muscle spasms and contractions.

Introduction

Dystonia is a medical term that describes a range of movement disorders that cause muscle spasms and contractions.

The spasms and contractions may either be sustained or may come and go.

Movements are often repetitive and cause unusual, awkward and sometimes painful postures. Tremor (shaking) can also be a characteristic of some types of dystonia.

Dystonia is thought to be a neurological condition (caused by underlying problems with the brain and nervous system). However, in most cases brain functions such as intelligence, memory and language remain unaffected.

Types of dystonia

Dystonia can affect only one muscle or a group of muscles. There are five main types of dystonia. They are:

  • Focal dystonia - where a single region, such as the hand or eyes, is affected. Cervical dystonia, blepharospasm (abnormal twitch of the eyelid), laryngeal dystonia and writer's cramp are all examples of focal dystonia.
  • Segmental dystonia - where two or more connected regions of the body are affected. Cranial dystonia (blepharospasm affecting the lower face and jaw or tongue) is an example.
  • Multifocal dystonia - where two or more regions of the body that aren't connected to each other, such as the left arm and left leg, are affected.
  • Generalised dystonia - where the trunk and at least two other parts of the body are affected. The legs may or may not be affected.
  • Hemidystonia - where one entire side of the body is affected.

About 90% of all cases are either cervical dystonia (which affects the neck muscles) or blepharospasm (which affects the eyelids). These are both focal dystonias that tend to develop later in life. They don’t usually get any worse and no other muscles are affected.

Read more about the symptoms of dystonia.

Causes of dystonia

Exactly how dystonia develops remains uncertain, but it's thought to be caused by a problem with the part of the brain that controls muscle movement (the basal ganglia).

If there's no identifiable cause of dystonia, or if the cause is genetic, it's described as primary dystonia.

Secondary dystonia is where dystonia occurs as a symptom of an underlying condition or injury. Common causes include stroke, brain injury, encephalitis (infection of the brain) and Parkinson’s disease.

Read more about the causes of dystonia.

Diagnosing dystonia

Diagnosing dystonia is a complicated process that involves identifying the precise nature and specific features of a person’s movement disorders, and then seeing which type of dystonia classification they fit into.

When diagnosing dystonia, it's important to confirm whether you have primary or secondary dystonia because this will determine the type of treatment you need.

If you have typical signs of late-onset focal dystonia, specific investigations may not be required. However, tests may be needed to confirm whether you have primary or secondary dystonia. These may include brain scans, urine or blood tests and genetic testing.

Read more about how dystonia is diagnosed.

Treating dystonia

There's no cure for dystonia, but the condition can usually be effectively managed.

Treatment will vary depending on the type of dystonia you have and the precise nature of your symptoms. However, the four main types of treatment are:

  • [botulinum toxin] - widely used to treat neurological conditions that involve abnormal muscle contractions, such as dystonia; it's injected into the affected muscles to temporarily weaken them and reduce spasms
  • medication - such as anticholinergics, Baclofen and muscle relaxants
  • physiotherapy - where exercises are used to improve range of motion and posture and prevent muscle weakness
  • surgery - if other treatments are unsuccessful, the nerve endings that are causing spasms can be cut (selective peripheral denervation), or electrodes can be implanted within the brain which are connected to a small device that's similar to a pacemaker (deep brain stimulation)

Read more about how dystonia is treated.

Outlook

Dystonia is an unpredictable condition. It tends to progress slowly and the severity of a person's symptoms can vary from one day to another.

Focal dystonia usually progresses gradually over a period of about five years and then doesn't get any worse.

Sometimes, a person's symptoms will improve or disappear completely. This is known as total remission and it's thought to occur in around 5-10% of people.

Total remission is more likely in cases of secondary dystonia, such as dystonia that occurs after a stroke. If someone has another underlying condition, such as Parkinson’s disease, the symptoms of dystonia are more likely to last for the rest of their lives.

Symptoms

The symptoms of dystonia can vary depending on the type of dystonia and when it develops.

In early-onset dystonia, the symptoms begin during childhood or early adulthood. Symptoms usually start in the legs or arms before spreading to other limbs and sometimes the upper part of the body.

Dystonia that starts in later life (late-onset) usually affects people over 40 years of age. The symptoms usually begin in the head, neck or one of the arms, and don't get any worse.

Early-onset dystonia

Generalised dystonia

Generalised dystonia often begins around the time a child reaches puberty. The symptoms usually begin in one of the limbs before spreading to other parts of the body.

Symptoms of generalised dystonia can include:

  • muscle spasms
  • having an abnormal, twisted posture
  • a foot, leg or arm turning inwards
  • body parts jerking rapidly

Dopa-responsive dystonia

Dopa-responsive dystonia is a type of generalised dystonia.

The symptoms of this type of dystonia usually begin during childhood, between the ages of 6 and 16 years. The most common symptom is an abnormal, stiff way of walking. The sole of the foot can bend upwards or the foot may turn outwards at the ankle.

Some people with dopa-responsive dystonia may also have muscle stiffness and spasms in their arms and torso.

Late-onset dystonia

Cervical dystonia

Cervical dystonia, also known as torticollis, is the most common form of dystonia. It's a type of focal dystonia (where only one body part is affected) that affects the neck muscles.

Involuntary contractions and spasms in the neck muscles can range from mild to severe and cause your head and neck to twist or be pulled forwards, backwards or from side to side.

Muscle spasms and contractions can lead to the additional symptoms of neck pain and stiffness.

The symptoms of cervical dystonia can often be relieved by touching your chin, neck or the back of your head. The reasons for this are unclear.

Blepharospasm

Blepharospasm is a type of focal dystonia that causes the muscles around your eyes to spasm involuntarily.

Uncontrollable eye closure is a common characteristic of blepharospasm. In the most severe cases, a person may be unable to open their eyes for several minutes, effectively making them blind for short periods of time.

Frequent blinking, eye irritation and sensitivity to light (photophobia) are also possible characteristics of blepharospasm.

If you have blepharospasm, the pattern of your symptoms can change throughout the day. For example, you may have few or no symptoms when you wake up in the morning, but they may start to appear or get worse when you're tired or stressed.

Hemifacial spasm

Although it isn't considered to be a dystonia, hemifacial spasm can cause similar symptoms, with repetitive twitching of the muscles on one side of the face, usually around the eyes and mouth. It can respond well to botulinum toxin injections.

Laryngeal dystonia

Laryngeal dystonia is a type of focal dystonia that causes the muscles of the voice box (larynx) to spasm. Your voice can either sound ‘strangled’ or very quiet and ‘breathy’, depending on whether the muscles of your larynx spasm outwards or inwards.

Writer’s cramp

Writer’s cramp, also known as task-specific dystonia, is a type of focal dystonia that causes involuntary cramps and movements in the muscles of the arm and wrist.

As the name suggests, writer’s cramp usually affects people who do a lot of writing. Other less well-known types of task-specific dystonia include:

  • musician’s cramp
  • golfer’s cramp
  • typist’s cramp

As in other types of late-onset dystonias, tremor (shaking) may also be a prominent feature.

Myoclonus dystonia

Myoclonus dystonia is a rare type of segmental dystonia that affects the muscles in the arms, neck and torso.

Segmental dystonia affects two or more connected parts of the body. It causes sudden 'jerk-like' spasms that are similar to the spasms that someone has when they get an electric shock.

Oromandibular dystonia

Oromandibular dystonia is a type of segmental dystonia that affects the lower facial muscles, tongue or jaw.

It can cause a number of different facial distortions, including grimacing and lip pursing. The jaw can repeatedly open and close or pull outwards and upwards. Tongue movements can be continuous or occur intermittently.

In some cases, the symptoms of oromandibular dystonia only occur when your mouth is being used, such as while eating or talking. In other cases, the symptoms may be improved by talking or chewing.

If you have oromandibular dystonia, you may also have difficulty swallowing (dysphagia).

Paroxysmal dystonia

Paroxysmal dystonia is a rare type of dystonia where muscle spasms and unusual body movements only occur at certain times. The sudden onset of symptoms is known as an attack.

The symptoms of paroxysmal dystonia can be similar to the symptoms of an epileptic fit. However, during an attack, only your muscles will be affected. Unlike epilepsy, you won't lose consciousness and you'll remain fully aware of your surroundings. Attacks can last from a few minutes to several hours.

Certain situations or substances can trigger an attack of paroxysmal dystonia including:

  • stress
  • [fatigue]
  • alcohol
  • coffee
  • sudden movement

Causes

Dystonia can be primary or secondary depending on whether it's been passed down through the family or caused by another underlying condition.

Primary dystonia

Most cases of primary dystonia are thought to be caused by problems with a part of the brain called the basal ganglia.

The basal ganglia is a collection of brain cells deep within the brain which influences other parts of the brain that control muscles. This is done by using special messenger-chemicals called neurotransmitters.

There are currently at least 12 types (or sub-types) of dystonia that are linked to genetic mutations, including generalised dystonia, dopa-responsive dystonia and paroxysmal dystonia.

Read more about the different types of dystonia.

The genes responsible for these types of dystonia are passed down through families in a pattern that's known as autosomal dominant. This means that if you have one of these abnormal genes, there's a 1 in 2 chance that your children will inherit that gene and develop dystonia.

Late-onset primary dystonia is poorly understood and its cause (or causes) are unknown.

Secondary dystonia

Secondary dystonia, also known as acquired dystonia, can have a wide range of causes including:

  • Parkinson’s disease - a neurological condition caused by the lack of a neurotransmitter called dopamine
  • Huntington’s disease - an inherited condition caused by a lack of cholesterol in the brain
  • Wilson’s disease - a genetic condition that leads to a build-up of copper in the body’s tissues
  • multiple sclerosis - a condition caused by damage to the nervous system
  • cerebral palsy - a condition caused by brain damage that occurs before or soon after birth
  • certain medications - such as those used to treat epilepsy, can cause dystonia as a side effect in a small number of people
  • infections - such as HIV or encephalitis (a brain infection)
  • injury - to the skull or spine
  • brain tumours
  • stroke -a serious medical condition where the blood supply to part of the brain is cut off
  • poisoning - such as carbon monoxide poisoning

Diagnosis

Diagnosing dystonia isn't straightforward. It involves using a stepwise approach that starts by identifying the precise nature and specific features of your movement disorders.

The specialist will then try to identify which type of dystonia classification your movement disorders fall into, taking into consideration a number of factors including:

  • how old you were when your symptoms started
  • the order in which your symptoms developed
  • the speed at which the condition is progressing
  • the results of initial tests and investigations

It's important to confirm whether you have primary or secondary dystonia to help determine the type of treatment you need.

In primary dystonia, muscle spasms are the only symptom and there's no other associated condition. Secondary dystonia is caused by an underlying health condition, injury or some other type of damage.

If you have the typical signs of late-onset focal dystonia, you may not need to have specific investigations. However, you may need to have a series of tests and examinations to confirm whether you have primary or secondary dystonia. These tests are described below.

  • Your recent medical and family history will be discussed - for example, whether you've recently had a head injury, or whether you have a relative with dystonia.
  • Urine and blood tests - to check how well your organs, such as your liver, are functioning and whether you have an infection or high levels of toxins in your body.
  • Genetic testing - a DNA sample can be taken from your blood and checked for the abnormal genes associated with some types of dystonia; genetic testing can also confirm whether or not your dystonia is caused by a genetic condition, such as Huntington's disease.
  • A magnetic resonance imaging (MRI) scan - can check whether there's any damage to your brain, or whether you have a condition that's affecting your brain, such as a tumour.

If you have early-onset dystonia, you may also be given a course of medication called [levodopa]. If your symptoms suddenly improve after taking levodopa, a confident diagnosis of dopa-responsive dystonia can be made.

Treatment

There are a number of treatment techniques that can help control the involuntary movements and spasms of dystonia, including physical therapy, medication, and in some cases, surgery.

The aim is to provide relief from the abnormal movements and postures of dystonia, plus any associated pain and discomfort.

In some cases, other conditions that arise due to dystonia, such as depression, may also need to be treated.

Treatment for dystonia should be based on the individual and their specific needs. As different people respond differently to different treatments, it may be necessary to try several options to find out which one works best.

There are four main types of treatment for dystonia. They are:

  • botulinum toxin
  • medication
  • physiotherapy
  • surgery, including deep brain stimulation (DBS)

Wherever possible, physiotherapy, medication or botulinum medication will be used to treat dystonia rather than surgery, particularly in the case of children and young people.

Each type of treatment is discussed in more detail below.

Botulinum toxin

Since being introduced into clinical practice in the late 1980s, botulinum toxin has become an effective and widely used form of treatment for a number of different neurological conditions that involve abnormal muscle contractions, such as dystonia.

It's given by injection directly into the affected muscles and works by blocking the neurotransmitters responsible for muscle spasms reaching the affected muscles.

The effects of the injection usually last three months, after which time you'll need another injection. The site of the injection may feel painful for a few days, but this should soon pass.

Other side effects of botulinum toxin will depend on which part of your body is injected. For example, injections:

  • in the neck area may cause swallowing difficulties (dysphagia)
  • around the eyes may lead to drooping of the eyes and double vision
  • in the vocal cord may cause your voice to become soft and ‘breathy’

These types of side effects should pass after about a week.

Medication

There are a number of different medications that can be used to treat dystonia.

Anticholinergics

Anticholinergics are a type of medication that can be used to effectively treat all types of dystonia.

However, they're mainly used to treat generalised dystonia because botulinum toxin now tends to be used to treat focal dystonia and segmental dystonia (see below).

Anticholinergics work by blocking the release of a neurotransmitter called acetylcholine, known to cause muscle spasms in some cases of dystonia. Trihexyphenidyl and procyclidine are two examples of anticholinergics.

Side effects of anticholinergics include:

  • dry mouth
  • constipation
  • difficulties urinating
  • blurred vision
  • memory problems
  • confusion

Baclofen

Baclofen is a medication that's sometimes used to treat spasticity (excessive muscular tension) caused by stroke or multiple sclerosis. However, it’s also helps in treating people with dystonia.

In particular, daily doses of baclofen are effective in treating people with segmental and generalised dystonia as well as those with oromandibular dystonia.

Common side effects of Baclofen include:

  • kidney problems - seek medical advice if you develop symptoms such as sleepiness or lethargy (lack of energy)
  • nausea - this may be reduced by taking Baclofen with food or milk
  • drowsinesss
  • balance and co-ordinaton problems
  • confusion

Read more about the potential side effects of Baclofen.

Muscle relaxants

Muscle relaxants are sometimes used to treat cases of dystonia that fail to respond to other types of medication. They work by increasing the levels of a neurotransmitter called gamma-aminobutyric acid (GABA), which helps relax affected muscles.

Diazepam, lorazepam and clonazepam are all types of muscle relaxants which may be used to treat dystonia.

Depending on the pattern of your symptoms, muscle relaxants can be given by injection (intravenously) or in tablet form (orally). Side effects of muscle relaxants include:

  • drowsiness
  • tiredness
  • muscle weakness
  • dizziness
  • impaired co-ordination

These side effects should be temporary and disappear once your body gets used to the medication. If you have symptoms of dizziness, avoid driving and operating heavy machinery.

Don't suddenly stop taking muscle relaxants. If you do, you'll experience withdrawal symptoms such as \anxiety], sweating or [tremors (shaking).

If your care team decides you should stop taking muscle relaxants, your dose will gradually be reduced.

Physiotherapy

Physiotherapy uses specific exercises to help you maintain a full range of motion, improve your posture and prevent the shortening or weakening of affected muscles.

However, there's not much in the way of good quality evidence to show physiotherapy is effective for dystonia.

Some people with dystonia find their symptoms improve by simply touching the affected body part or a nearby area. This is known as a 'sensory trick' or 'geste antagoniste'.

For example, people with cervical dystonia (where the neck muscles spasm and tighten) often find their symptoms improve by touching the back of their head or the side of their face.

Read more about physiotherapy.

Surgery

Surgery may be recommended if your dystonia symptoms don't respond to botulinum toxin, medication or physiotherapy.

Deep brain stimulation (DBS)

Deep brain stimulation (DBS) is a type of brain surgery used to treat dystonia. During surgery, two small holes will be drilled into your skull.

The surgeon will pass electrodes through each hole and position them in a part of the basal ganglia called the globus pallidus. The basal ganglia is part of the brain that affects muscle movement.

The electrodes will be connected to a small pulse generator that's similar to a pacemaker. It will be implanted under your skin, usually on your chest or lower abdomen.

The pulse generator sends signals to the globus pallidus. This alters nerve impulses produced by the basal ganglia and improves the symptoms of dystonia.

The most common complication of DBS is that either the pulse generator stops working or the electrodes become displaced, which may require further surgery to correct.

DBS is a relatively new technique so there's little information regarding its long-term safety or effectiveness. Therefore, before deciding to have DBS you should discuss the risks and benefits of the treatment with your surgical team.

If you have DBS, you're likely to need a series of follow-up appointments. This is because in most cases the signals produced by the pulse generator need to be adjusted to ensure that your symptoms are being properly controlled.

It may be several weeks or months before you begin to feel the benefit of DBS. The benefit should continue to increase for a few years following surgery.

Selective peripheral denervation

Selective peripheral denervation is a type of surgery used to treat cervical dystonia. However, these days it only tends to be used in a few, select cases.

During the procedure, the surgeon will make an incision in your neck before cutting some of the nerve endings connected to muscles prone to spams.

The surgery will be carried out under general anaesthetic, which means you'll be unconscious throughout the procedure and unable to feel pain or discomfort.

After the procedure, you'll lose some feeling in your neck because the nerves have been disconnected.

Selective peripheral denervation is generally a safe type of surgery and complications are rare. However, possible complications include:

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