Dystonia

Dystonia is a neurological condition characterised by involuntary muscle contractions that cause repetitive movements and painful twisting into abnormal positions. It can interfere with everyday tasks such as walking, speaking, and being able to independently eat and take care of personal hygiene. Because it is a rare disease with a multitude of genetic causes, it can be difficult to accurately diagnose and treat.

Description

Dystonia that is detected in childhood can quickly progress and interfere in a child’s language development and mobility. It can cause a physical disability that will affect them for the rest of their life.

Symptoms

Childhood dystonia can appear as an isolated problem or it can be associated with other neurological and developmental problems.

When it presents as an isolated issue, this is called primary dystonia, and it frequently has a genetic cause. Children with this form of the disease do not usually have other health problems, and their neurological development is normal. At first, it manifests during activities like walking, running, or writing, and it later spreads to other parts of the body, producing generalised dystonia.

Myoclonus-dystonia is one of the most common types of hereditary dystonia in children.It is characterised by the presence of sudden muscle jerks (myoclonus) and psychiatric disorders such as anxiety, depression, and obsessive-compulsive traits. The first symptoms appear in childhood and affect the lower limbs of children, who have difficulty walking, running, and engaging in sporting activities. This disease also affects these children’s social relationships, as they have problems speaking in public and eating or drinking with friends.

Dystonia can also be associated with other neurological problems, like spasticity, ataxia, muscle weakness, delayed neurological development, and intellectual disability. This is what we call secondary dystonia, and neurometabolic and neurodegenerative causes must be ruled out in these cases.

Currently, there are more than 200 known genetic defects that have been associated with childhood dystonia.

Who does it affect?

Children and adults of all ages.

Diagnosis

Since it is a rare disease that isn’t the same in everyone, it can be difficult to accurately diagnose and treat. It is important to distinguish hereditary dystonia from cerebral palsy, which is caused by brain damage at birth. This diagnosis has very important implications in how the child will be treated.

A genetic diagnosis decreases the need to carry out more diagnostic tests, allows a prognosis to be made, and helps provide guidance to parents to avoid future ill children. It also has a very positive psychosocial impact, both for the patient and for the family.

Standard treatment

Childhood dystonia is progressive and debilitating, but it can be prevented with an early diagnosis and the use of specific therapies that target the genetic defect identified.

Treatments

Levodopa is the treatment of choice for dopa-responsive dystonia, which is caused by defective dopamine synthesis. Botulinum toxin is used to control facial dystonia. For generalised dystonia, different drugs are administered to reduce the tremors, muscle tone, and painful spasms. In addition, in some cases of paroxysmal dystonia, which is characterised by brief, repetitive involuntary movements at night, anti-epileptics are prescribed.

Surgical alternatives

The intrathecal baclofen pump, which administers liquid medication through a device placed under the skin, is used to treat generalised secondary dystonia. It reduces pain, muscle tone, and spasms.

Deep brain stimulation or pallidal stimulation, in which two electrodes are placed in the pallidal nuclei of the brain using a stereotactic procedure, is the treatment of choice for primary dystonia, especially if it is generalised or does not respond to conventional medication. In these cases, children can regain function in the area affected by dystonia and see an improvement in their quality of life. It can also be useful in some specific cases of secondary dystonia, although it is less effective than in primary dystonia.

Standard tests

First, an extensive metabolic, neurophysiological, and neuroimaging study is carried out in order to classify the type of dystonia, before performing the genetic studies.

For patients with myoclonus-dystonia, first Sanger sequencing is carried out. For other kinds of dystonia, whole-exome sequencing (on the parents and the patient) or sequencing for the index case (the patient) is done first, depending on the DNA samples available.