Lesioning is when small areas of damage (lesions) are made in your brain. These lesions target cells that control movement and are used to treat movement disorders, such as essential tremor, Parkinson’s disease, and dystonia.
In the 1950s and 1960s, lesioning was a common treatment for these disorders. However, it had mixed results and, with the discovery of other treatments, was rarely used by the 1980s.
Now, lesioning is considered an option for people with movement disorders that don’t respond well to other treatments.
Although lesioning is not a commonly used treatment, it has better results than it used to. This is because doctors now have a better understanding of the causes of movement disorders, as well as more accurate mapping of the brain and superior surgical tools.
People who may benefit from lesioning
Lesioning is best for people who have severe movement disorders and don’t respond to medications, can’t tolerate the side effects from medication, or don’t want or aren’t good candidates for deep brain stimulation (DBS).
You might have lesioning to treat Parkinson’s disease if you have:
- severe tremors (especially on one side), stiffness, or movement difficulties that are no longer controlled with medication
- serious motor problems from long-term use of levodopa (L-dopa)
In those with essential tremor, propranolol and primidone are frontline treatments that reduce tremors for 50 to 60 percent of people. Lesioning might be an option if these medications don’t work, or the side effects are too severe.
Doctors usually prefer to do DBS instead of lesioning. However, some people aren’t good candidates for DBS, or might not be able to handle the frequent battery changes it requires. They might also not want to have a visible pulse generator. In some of these cases, a doctor might recommend lesioning instead.
What to expect before and during surgery
Before surgery, your doctor will use an MRI or CAT scan to create a 3-D model of your brain. This allows them to see exactly what area of the brain to target. Your doctor might also use a procedure called microelectrode recording to detect to how the cells in your brain fire. This helps them narrow down the target even more.
There are several different types of lesioning surgery. These include:
- Pallidotomy. In this procedure, surgeons make a lesion in the Globus pallidus, a part of the brain that’s overactive in Parkinson’s disease. This surgery is not a good option for people with Parkinson’s disease who don’t respond well to L-dopa.
- Thalamotomy. This procedure is mostly used for dystonia that affects one side of the body, or Parkinson’s tremors on one side of the body. It targets the thalamus, a part of the brain that helps control motor responses. Thalamotomy is not used for bradykinesia, speech problems, or walking problems.
- Subthalmotomy. This procedure targets the subthalamus, a small area of the brain that plays a role in motor control. It’s the rarest type of lesioning.
Each of these procedures can be done using one of the following techniques:
- Radiofrequency. Radiofrequency is a type of high-frequency radio wave that can be used to create a lesion. The waves are passed through a probe in the brain that’s used to target the correct tissue.
- Radiosurgery. Radiosurgery uses targeted radiation to lesion brain tissue. It’s most commonly used for thalamotomies.
- Ultrasound. Ultrasound lesioning is done through the skull. Ultrasound waves are high-frequency sound waves that are aimed at the target area. Your surgeon will measure the temperature of the sound waves to make sure they’re hot enough to damage the targeted tissue.
- Liquid nitrogen. Liquid nitrogen is an extremely cold substance that’s injected into a hollow probe. The cold probe is then put into the brain and used to create a lesion.
In every type of surgery, you’ll be awake and your scalp will be numbed with local anesthesia. This lets your surgical team interact with you, to make sure everything is going the way it should.
For procedures that use radiofrequency or liquid nitrogen, your doctor will drill a small hole in your skull to insert the probe and carry out the procedure. Ultrasound therapy and radiosurgery can be done through the skull.
After a lesioning procedure, you’ll probably spend two or three days in the hospital. Full recovery usually takes about six weeks, but it’s different for everyone. You should avoid any strenuous activity during those six weeks or until your doctor advises you that it’s alright to do so.
If you had an open surgery, it’s important that you don’t touch your stitches. Your doctor will tell you when they can be removed.
Benefits of lesioning
Lesioning can’t cure movement disorders, but in some cases, it can help ease your symptoms.
Studies of lesioning have found varying results, which is one reason these procedures are rarely performed. However, some research has shown success for people whose symptoms are not well-controlled by medicine.
One study found that ultrasound thalamotomy significantly reduced hand tremors and improved quality of life for people with essential tremor. Another review found that a pallidotomy on one side of the brain is as successful as DBS on one side of the brain for dystonia and Parkinson’s disease. However, DBS on both sides of the brain was the most effective treatment.
Risks of lesioning
Lesioning destroys brain tissue, which can have negative effects even with today’s targeted procedures. The most common risks are speech and other cognitive problems, especially when the procedure is done on both sides of the brain.
Other risks include:
- gait problems
- vision problems
- stroke or hemorrhage during the mapping process, which occurs in 1 to 2 percent of patients
Lesioning isn’t a common treatment. However, for people with movement disorders who don’t respond to or can’t have other treatments, it can be a good option. If your movement disorder isn’t well-controlled with medicine, you have negative side effects or long-term effects from medication, or you aren’t a candidate for DBS, lesioning might reduce your symptoms.