Deep brain stimulation (DBS) involves implanting stimulating electrodes into targets in the brain.
DBS is a neurosurgical treatment approach that is being used to treat a greater number and variety of dystonias than ever before. The techniques and technology of DBS are constantly evolving as dystonia research progresses. The movement disorders field now has a decade of experience and data in the medical literature about the long-term safety and efficacy of DBS.
What is Deep Brain Stimulation ?
Deep brain stimulation (DBS) is a surgical procedure used to treat a variety of neurological disorders, including movement dystonias such as dystonia. A battery-powered stimulator essentially a brain pacemaker is surgically implanted and delivers electrical stimulation to the areas of the brain associated with dystonia. The stimulator is implanted into the chest or abdomen, and extension wires connect the stimulator to leads deep in the brain. The stimulation is adjusted by remote control to achieve the best settings for each individual patient. The procedure is completed in several phases: pre-surgical assessment and work-up, implanting the leads, implanting the stimulator, activating the stimulator, and programming the stimulation settings.
After a patient is determined to be a candidate and cleared for surgery, hardware is surgically implanted in the brain and body. Adult patients are typically awake during the process of implanting the leads and participate in the placement by responding to questions and instructions from the surgical team. The simulators and wires are implanted under general anaesthesia. After a brief period of healing, the simulator settings are activated and adjusted over a series of appointments. It can take weeks or months for individuals to achieve full benefit. The stimulators must be periodically replaced by outpatient surgery and additional programming adjustments may be needed.
How does DBS treat dystonia?
Although DBS has proven to be a safe and effective treatment for a variety of disorders, the exact mechanism of action is not fully understood; doctors know it works, they just can’t exactly explain why. Dystonia symptoms result when excessive signalling from the brain causes involuntary muscle contractions and movements. The stimulation delivered to the brain by the DBS stimulator suppresses these excessive signals, thereby lessening the dystonia symptoms.
How do I know if I am a candidate for DBS?
DBS is not appropriate for all individuals with dystonia, and not all patients who undergo the procedure will experience the same results. Based on the research to date, individuals who have isolated (primary) dystonia are likely but not guaranteed to have the best outcomes from DBS, and perhaps those who are younger, test positive for the DYT1 dystonia gene mutation, and are treated relatively early on in the dystonia progression. Individuals with severe cervical dystonia or dystonia acquired by drug exposure (tardive dystonia) may also be good candidates for DBS. Individuals with other forms of acquired (secondary) dystonia should be evaluated on a case by case basis. There are also promising data on the use of DBS to treat myoclonus dystonia and focal dystonias, include cranial dystonias such as blepharospasm and oromandibular dystonia.
Ultimately, DBS may be considered if medications and other treatments have failed, and if the symptoms negatively affect quality of life to the extent that the surgical risks are justified. The first step in the evaluation process for DBS is to meet with a DBS-trained movement disorders neurologist.
Is DBS safe? What are the Risks?
Overall serious effects from DBS are rare, but no invasive surgical procedure is without risk. The main risk in DBS is bleeding in the brain during the lead implantation, resulting in stroke. However, approximately 99% of patients do not have significant bleeding. Infection occurs in approximately 5% of patients. Infection can be serious and warrant the removal of the hardware. (If this happens, it may be possible to re-implant the hardware once the infection is treated). Hardware failure is also a concern, for example wire disconnection or stimulator battery failure. Most complications that occur in DBS for dystonia can be resolved without removing the hardware.
What are the benefits?
One of the challenges of treating DBS with dystonia is that it is difficult to predict which patients will benefit and to what degree. From the 10+ years of research data available, improvements of 50-60% are generally observed overall, with some patients experiencing a90% reduction in symptoms. Even an improvement rating of 30%, however, can have a significant impact on a person’s ability to function. It is not in uncommon for DBS patients to rate their improvement higher than the numerical result of the rating scales that doctors use.
DBS for dystonia is a highly specialised procedure that should be performed by a multidisciplinary team with extensive training and experience. The first step in the evaluation process for DBS is to meet and talk with your movement disorder neurologist.
How long do the batteries last?
The expected life span of a stimulator battery at a typical voltage is about four years. At a very high voltage, the battery may need to be replaced after a year; at a very low voltage, perhaps up to seven years. Replacing a battery can be done under general or local anaesthetic as an out patient procedure. Rechargeable batteries are now available, and DBS technology is evolving quickly with a focus on innovations to strengthen battery performance and reduce the need for battery replacements.
What long-term maintenance is involved in DBS?
Having DBS is a life-long commitment that requires ongoing management. Maintenance may include battery changes (which consist of out-patient surgery) and ongoing programming adjustments. Hardware problems may occur. Rarely, individuals develop new movement disorder symptoms associated with the stimulation. Individuals with DBS must be mindful of situations that can interfere with the functioning of the DBS hardware, such as exposure to magnetic fields this includes certain medical MRI imaging (magnetic resonance imaging) methods. There may be restrictions in terms of certain activities, such as extreme or contact sports that could damage the implanted hardware.
How do I get referred for DBS?
Firstly, you must discuss this procedure with your neurologist that specialises in movement disorders. If your neurologist thinks that you are a suitable candidate for surgery you will be referred onto a hospital in the UK, as DBS surgery is not available in Ireland. You will have to travel to the chosen hospital for an assessment. If you are a suitable candidate for DBS you will be informed of a date for surgery while you are there or you will receive written notification when you return home. When you receive your date for surgery you will travel back to the hospital again for the procedure.
The DBS surgery is covered under the E112 Form Treatment Abroad Scheme (read more about the scheme here)
If you are considering DBS, or have had the procedure done and wish to make contact with others who have also undergone DBS surgery Dystonia Ireland can provide further information.