Deep brain stimulation for multiple sclerosis
Fact-checked by Deep brain stimulation is a surgical procedure that is sometimes used to manage severe tremors in people with multiple sclerosis (MS) when other interventions have not been effective.
MS is a neurological condition in which the immune system attacks healthy parts of the central nervous system, which is composed of the brain and spinal cord. Damage to the neural pathways that control movement can lead to tremors, an involuntary shaking or trembling that may affect various parts of the body. The most common type is intention tremor, which occurs during purposeful movements.
MS tremors can significantly interfere with daily life and can be difficult to treat. Patients may first try approaches such as physical therapy, occupational therapy, and medications. When these medical treatments fail, and tremors are severe, DBS, a neuromodulation approach, may be considered.
Who is eligible for DBS?
In the U.S., DBS is not formally approved for the treatment of MS. Instead, approved indications include other conditions such as Parkinson’s disease, essential tremor, the movement disorder dystonia, epilepsy, and obsessive-compulsive disorder.
Still, DBS is sometimes used off-label in MS patients to manage severe tremors that have not responded well to less invasive options.
Eligibility for this therapeutic option is determined by medical professionals on a case-by-case basis, following a thorough clinical assessment of each patient. Ideal candidates are MS patients who:
- Have severe and disabling tremors that significantly interfere with daily activities
- Are generally healthy enough to undergo neurosurgery
DBS is only used for the management of tremors. It does not treat other MS symptoms or alter the long-term progression of the disease. People with severe MS disability caused by issues other than tremor are not good candidates for DBS.
How deep brain stimulation works
MS tremor arises due to nerve damage in brain regions involved in controlling movement, causing nerve cells to send abnormal signals to muscles.
DBS delivers electrical pulses to the brain, usually to an area called the thalamus, which serves as a key relay center for these faulty signals. This is known as thalamic deep brain stimulation, and it aims to disrupt the abnormal signals causing tremors, although the exact mechanisms are not yet fully understood.
Thalamic DBS systems have three main components:
- Electrode: A thin, insulated wire that is inserted into the thalamus, where it delivers the electrical impulses. The target is typically the ventral intermediate nucleus.
- Neurostimulator: A small, battery-operated device placed under the skin in the chest. It controls the frequency and intensity of the stimulation.
- Extension wire: An insulated wire that runs under the skin and connects the electrode to the neurostimulator.
The DBS surgery
Before surgery, detailed scans are collected to generate a precise map of the brain. This allows the surgeon to identify the exact place that needs to be targeted for tremor control.
The thalamic DBS procedure is then done in two separate surgeries, spaced about a few days to weeks apart:
- During the first procedure, a surgeon drills a small hole in the skull through which the electrode is inserted into the brain. The patient may be kept awake during the procedure to ensure the stimulation is working.
- In the second procedure, the surgeon makes a small cut in the skin under the collarbone and implants the neurostimulator. The extension wire is run under the skin to connect it to the electrode. This is generally done under general anesthesia.
After the initial surgery, most patients will need to stay in the hospital for one day, while the second surgery generally allows for same-day discharge.
For the next few weeks, they will receive instructions on how to care for the wound sites on their scalp and chest. Heavy lifting and strenuous exercise should be avoided.
Device programming and long-term follow-up
During the initial recovery period, the DBS device is turned off. After the swelling has subsided and the incisions have healed, a neurologist will activate the device and program it.
The neurologist will determine the frequency and intensity of the electrical stimuli required to achieve the best possible tremor control without side effects. It may take multiple visits over several months to find the optimal settings.
In the long term, patients will meet regularly with their neurologist to make sure the stimulator is working optimally and adjust the settings as needed. The battery in some neurostimulators needs to be replaced periodically, which involves a short outpatient procedure.
Risks, side effects, and lack of response
While the DBS surgery is generally safe, it is still an invasive procedure that carries certain risks and potential side effects, including:
- bleeding in the brain
- infection
- seizures
- pain and swelling at the implantation site
- incorrect placement of the electrodes or device malfunction, which may require additional surgery
After surgery, if the DBS settings are slightly off their intended target, it could cause side effects, including:
- speech or vision problems
- numbness or tingling in the limbs and face
- muscle pulling or tightness
- balance issues
- mood changes
- lightheadedness
These DBS-related side effects are typically temporary and can usually be reversed by adjusting the stimulation settings.
Limitations of DBS
While DBS for MS can be effective in controlling tremors, success is not guaranteed, and a poor outcome is possible.
MS-associated tremors are complex, and predicting the clinical response is difficult. In general, success rates for DBS are lower in MS-related tremor than in other types of tremor.
Long-term DBS efficacy also varies. For some individuals, DBS may provide initial relief from tremors, but its benefits can wane over time. When DBS does not deliver meaningful results after an appropriate trial period, the device may be turned off or removed.
Multiple Sclerosis News Today is strictly a news and information website about the disease. It does not provide medical advice, diagnosis, or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.
