Deep brain stimulation (DBS) and lesioning for dystonia

Dystonia is a disorder of the brain which causes abnormal, uncontrollable muscle spasms. It happens when there is a chemical imbalance in a deep part of the brain called the basal ganglia.

Every individual with dystonia is affected in different ways.

Dystonia has many different causes. It can be inherited and caused by mutations in specific genes. Or it can be acquired - through a brain injury, metabolic disorder or as a symptom of another neurological disease.

Sometimes, we can diagnose the dystonia but are unable to identify the cause.

We may recommend neurosurgical treatment if your child has already tried other options, such as medication or botulinum toxin muscle injections, and these have not improved their symptoms.

At GOSH, we offer two possible neurosurgical treatments for dystonia:

• Deep brain stimulation (DBS)
• Stereotactic lesioning

We will recommend the treatment that we think is most likely to help your child.

Both treatments, including their risks and benefits, are explained below. Your medical team will discuss the options with you in more detail and answer any questions.

What is DBS? 

During DBS, two fine wires called electrodes are placed into an area of the brain called the Globus Pallidus internus (GPi), one on each side. The GPi is part of the area of the brain termed the basal ganglia.

The electrodes are connected under the skin to a battery, usually placed in the chest. The battery sends small electrical pulses to the electrodes to help change brain activity and reduce dystonia symptoms. Much like a pacemaker, the whole system sits under the skin and is not externally visible.

MRI images showing the GPi in green, and the Globus Pallidus externus (GPe) in blue. The GPi is the most common target in DBS for dystonia.

What ongoing care is needed with DBS?

DBS requires ongoing programming and maintenance. The settings will need to be adjusted by your child’s doctors to get the maximum benefit.

There are choices between batteries for DBS:

• Rechargeable battery:
• Needs to be charged via a wireless charger for a few hours a week.
• Needs to be replaced after 20 to 25 years.
• Non-rechargeable battery:
• Doesn’t need to be charged.
• Needs to be replaced every three to five years.

Each battery replacement requires a short operation.

How effective is DBS? 

DBS is a proven, effective treatment for dystonia and can reduce the severity of the symptoms.

• It is important to remember that effectiveness varies from person to person.
• Four out of five people who have DBS have a significant improvement in their symptoms.
• It usually takes a few months to see benefit from the treatment.

DBS is not a cure for dystonia. If your child’s dystonia is likely to progress, DBS will not prevent the progression.

What are the risks of DBS?

As with any procedure, there are risks. The risks of DBS include the risk of the anaesthetic, infection, bleeding, causing damage to the brain (resulting in stroke or seizures), leak of brain fluid and the treatment not working.

Over time, the DBS system may cause problems, or the wires may break, requiring revision of components and, if infected, may require removal.

The risk of serious complications is about 1% and the risk of infection is about 3%.

Once stimulation is started, the electrical currents can cause muscle spasm, involuntary movements, strange sensations, visual changes and balance problems. These are reversible – they go away once the stimulation is turned off. We aim to minimise these side effects by adjusting the stimulation settings. If this is not possible, we may consider resiting the electrodes to get them into a better position.

How does DBS affect lifestyle? 

People with DBS should avoid strong magnetic fields.

This includes airport scanners, which can be set off by the devices, and interfere with DBS settings. We can provide a letter to show at airport security.

If you need to have an MRI scan, you must let the MRI team know about the DBS system. It is possible to have an MRI, but the system must be in MRI mode.

We advise against contact sports because of the risk of damage to the implant. If there are specific activities that your child is keen to pursue after DBS then please ask us about any restrictions.

Other than this, having a DBS implant shouldn’t impact your lifestyle.

What is stereotactic lesioning? 

In stereotactic lesioning, a radiofrequency current is passed through a fine wire into the brain. This wire heats the brain and stops that area from functioning. We usually target deep areas of the brain such as the GPi or the pallidothalamic tract (PTT).

It is usually performed only on one side of the brain to treat problems on the other side of the body. It can be done on both sides if needed.

What ongoing care is needed with stereotactic lesioning?

Stereotactic lesioning is a one-off procedure. It does not require regular programming or maintenance. However, it is not reversible – once the lesion is made, it cannot be reversed.

How effective is stereotactic lesioning? 

Lesioning is an alternative, but effective, treatment and works in a similar way to DBS.

There is less of a risk of infection than DBS. This may make it a more suitable option than DBS for some children with dystonia.

What are the risks of stereotactic lesioning? 

As with any procedure, there are risks. The risks of stereotactic lesioning include the risk of the anaesthetic, infection, bleeding, causing damage to the brain (resulting in stroke or seizures), leak of brain fluid and the treatment not working.

The risk of serious complications, including stroke, is about three percent.

About 10% of children may experience temporary problems with walking, balance or speech. We would expect these to improve over a period of a few weeks. 

There are several important pre-operative assessments we’ll need your child to have before DBS or stereotactic lesioning. These include:

• A detailed assessment of the dystonia and its impact.
• A detailed magnetic resonance imaging (MRI) scan of the brain. This helps us to accurately identify the best target for the treatment. Your child will need to have this MRI under a general anaesthetic (asleep) to ensure there is minimal movement and we get the best images.
• A neuropsychological assessment. This involves a number of questionnaires to assess your child’s development and its impact on them and the family.
• A pre-operative assessment including blood tests. This is to make sure your child is safe to have the operation and the anaesthetic.

Only after these tests have been completed, will your child will be scheduled for the surgical procedure.

It is important that your child does take any medication that thins the blood for two weeks before and two weeks after the procedure. This includes (but is not limited to):

• Medication like aspirin, clopidogrel, warfarin, rivaroxaban, apixaban, dabigatran.
• Non-steroidal pain killers such as ibuprofen and diclofenac.

If your child is on any of these medications, please let the team know as soon as possible.

Your child will be admitted on the morning of the surgery to one of our wards.

Your child will be put under a general anaesthetic for the procedure.

• The DBS procedure takes about four hours.
• Stereotactic lesioning takes about three hours.

What happens during the procedure? 

We will:

• Attach a frame to your child’s head and take some scans (X-ray, CT or MRI scans). This allows us to find the area to target with the best accuracy.
• Perform the operation, with the assistance of a robot – this increases the accuracy.
• Take another scan to ensure the electrodes/lesion is in the right place. If they are not in the right place, we will attempt to place it again under the same anaesthetic.
• Remove the frame.

What happens after the operation? 

The anaesthetist will then ensure your child wakes up safely from the anaesthetic. You will be called to the recovery area to meet your child after the operation.

After a few hours in the recovery area, your child will be transferred to our ward for routine care.

Your child should be ready for discharge one to three days after the operation.

If you child has had a DBS procedure, we will discuss with you and your child about switching on the DBS device. This may either happen during their inpatient stay, or we may ask you to come back in for this a few days later.

Before we discharge you, we will give you clear instructions about how to look after the surgical wounds and how to contact us should there be any concerns or problems.

It is important your child attends all follow-up appointments to ensure your child gets maximum benefit from the procedure.

Appointments will include:

One week after surgery: 

A review with the neurosurgical team to ensure the wounds are healing well and the treatment is generally being well tolerated.

First months after surgery: 

Monthly visits to the neurology clinic to allow adjustment of the stimulation settings and medication. Further visits will depend on your child’s response to the system and will vary from child to child.

One year after surgery:

An outcome assessment where we will repeat many of the pre-operative assessments to find out how much your child has benefitted from the treatment.

More information about dystonia can be found on the Dystonia UK website.

You can contact Functional Neurosurgery:

Telephone: 0207 405 9200 ext. 8862

Email: functionalneurosurgery@gosh.nhs.uk