Deep Brain Stimulation
Deep brain stimulation (DBS) involves implanting stimulating electrodes into targets in the brain.
Deep brain stimulation surgery is available in Ireland providing a surgical treatment that uses an implanted medical device to treat dystonia and other neurological disorders.
The first DBS procedure in Ireland was performed in November 2021 in Beaumont Hospital, Dublin by Ms Catherine Moran, Consultant Neurosurgeon. Ms Moran specialises in Functional Neurosurgery (including DBS), Complex Spine Surgery, Robotic Neurosurgery, and General Neurosurgery.
- Beaumont Hospital: Performs DBS surgeries
- The Mater University Hospital: Manages pre-operative and post- operative care.
What is Deep Brain Stimulation ?
DBS is a neuromodulation technique that involves implanting a medical device to deliver targeted electrical stimulation to specific areas of the brain. Originally reserved for severe cases of generalised dystonia, DBS is now being used to treat a broader range of patients as research and clinical experience evolve. This form of neuromodulation—modifying brain activity to study and treat neurological conditions—has opened new doors in managing complex movement disorders.
Deep brain stimulation (DBS) is a surgical procedure used to treat a variety of neurological disorders. A battery powered stimulator essentially a brain pacemaker is surgically implanted in the body and delivers electrical stimulation to the brain responsible for causing dystonia symptoms. The stimulator is implanted into the chest, and extension wires connect the stimulator to leads (electrodes) deep in the brain. In most cases both sides of the brain are treated. The stimulation to the brain is adjusted by remote control to achieve the appropriate settings for each individual patient.
The DBS procedure is completed in several phases:
- Pre-surgical assessment and work-up
- Implanting the leads deep in the brain
- Turning on the stimulator
- Adjusting the stimulation settings
The pre-surgical work-up includes a detailed neurological examination with a movement disorder neurologist. A brain MRI (magnetic resonance imaging) scan may be required.
Additional testing may include a neuropsychological evaluation and routine screening to make sure an individual is healthy enough for anaesthesia and surgery.
Adult patients are typically awake during the process of implanting the leads, which involves making tiny holes in the skull, and threading the leads deep into the brain. During this process, patients may be asked to respond to questions and instructions from the surgical team. More recently leads can also be implanted inside an MRI scanner with the patient fully asleep. The stimulators and wires are implanted under general anaesthesia. After a brief period of healing, the stimulator settings are activated and adjusted over a series of appointments. It can take months for individuals to achieve full benefit. The stimulator batteries must be periodically replaced by outpatient surgery . Additional programming adjustments may be needed. There are different technologies available to precisely map where in the brain the leads are placed. There are several models of stimulator batteries, for example non-rechargeable and rechargeable.
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 treatment is not appropriate for everyone with dystonia. Not all patients who undergo the procedure will experience the same results. Based on the research to date, individuals who have isolated (primary) dystonia which means dystonia is the only present neurological disorder, are likely but not guaranteed to have the best outcomes from DBS. Patients who are younger, test positive for the DYT1 dystonia gene mutation, and are treated relatively early after symptoms appear may also be more likely to have a good response to treatment. Individuals with 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 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 side effects from DBS are rare, but no invasive surgical procedure is without risk. DBS involves making small holes in the skull to implant the leads and surgical incisions to implant the stimulators under the skin near the collarbone. The main risk in DBS is bleeding in the brain during the lead implantation, resulting in stroke. This occurs in 1% of patients. 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 DBS devices. (If this happens, it may be possible to re-implant the devices once the infection is treated). Device 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 DBS device.
Once the stimulator is turned on, side effects from the stimulation to the brain may include light-headedness, tingling sensations, speech problems, balance problems, muscle tightness or pain, and new involuntary movements or slowness of movement. Side effects from stimulation can often be lessened or eliminated by adjusting stimulation settings.
What are the benefits?
One of the challenges of treating dystonia with deep brain stimulation (DBS) is that it is difficult to predict which patients will benefit and to what degree. Unlike essential Tremor or Parkinson’s disease the effects of DBS for dystonia are rarely immediate. It can take weeks, months, or even a year to experience the full therapeutic benefit.
From the years of research data available, improvements of 50-60% are generally observed overall, with some patients experiencing a 90% reduction in symptoms and disability. Depending on the individual patient, however, even an improvement rating of 30%, can have a significant positive impact on a person’s ability to function. It is not uncommon for DBS patients to rate their improvement higher than the numerical rating scales that doctors use to measure symptom severity and disability.
In a review of DBS in children (under21 years), outcomes from DBS were compared among different types of dystonia. The review reported that children with inherited dystonias without any structural damage to the brain experience a median 76% improvement of movement symptoms and disability. Changes with inherited dystonia disorders associated with structural changes to the brain experienced a median improvement of 27%. Children with dystonia and cerebral palsy or other acquired dystonias demonstrated 10% improvement. Children with isolated (primary) dystonia and of unknown causes (i.e. no identified genetic mutation) experienced a median improvement of 50%.
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 deep brain stimulator (DBS) 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 anaesthesia as an outpatient 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 with DBS?
Having deep brain stimulation (DBS) is a life-long commitment that requires ongoing management. Maintenance may include battery changes (which consist of outpatient surgery) and ongoing adjustments to the stimulator settings. Device problems may occur. The most common device problem is lead breakage which is reported in 4% of cases, but this occurs less frequently with newer devices. Rarely, individuals develop new movement disorder symptoms associated with the neurostimulation. Individuals with DBS must be mindful of situations that can interfere with the functioning of the DBS devices. This includes certain medical MRI imaging (magnetic resonance imaging), diathermy therapies (shortwave, microwave, and ultrasound) security metal detectors and security wands. There may be restrictions on certain activities, such as contact sports that could damage the implanted medical device. Individuals with DBS carry a medical device card that indicates they have an implanted medical device and provides safety information from the manufacturer and doctor contact information.
What is a Neuropsychological Evaluation?
Individuals who may be candidates for deep brain stimulation (DBS) undergo careful examination to ensure the procedure is appropriate for them. This includes an extensive neurological evaluation. A neuropsychological evaluation is needed to observe how the brain is functioning cognitively, mentally and emotionally. A neuropsychological assessment will identify any problems that could prevent DBS from being an appropriate choice for that patient. For example, certain conditions, such as dementia or severe depression, may prevent someone from being a good candidate for DBS. The neuropsychological assessment also provides a baseline before surgery, so that any changes in cognitive or mental functioning that may occur after surgery can be readily identified and investigated.
The neurological evaluation is not a test that a patient “ passes” or ” fails”. It is a series of exercises to understand how the brain is functioning. The evaluation is typically conducted one-on-one with a neuropsychologist and can take some hours to complete. The examination includes an interview and written or typed questionnaires.
How do I get referred for DBS?
Firstly, you must discuss this procedure with your attending neurologist. If your neurologist determines that you may be a suitable candidate, you will be referred to the National DBS Service Ireland, which operates through Beaumont Hospital and the Mater University Hospital in Dublin. This service supports a diverse group of patients with various neurological conditions who may benefit from DBS.
Following referral, you will undergo a thorough assessment conducted by a multidisciplinary team. This comprehensive assessment includes a review of your diagnosis, co-existing medical conditions, cognitive function, and psychological wellbeing. The results are then discussed at a multidisciplinary team meeting, and if you are deemed an appropriate candidate, you will be referred to a neurosurgeon and anaesthesiologist for pre-operative planning.
Careful patient selection is crucial for the success of DBS surgery. The evaluation of a patient’s suitability for surgery encompasses not only patient-specific medical conditions which may increase the surgical risk, but also considers different factors that may limit the therapeutic benefits from DBS.
The establishment of the national deep brain simulation (DBS) service in Ireland represents a pivotal advancement in the treatment of complex neurological disorders. While patient selection and peri-operative planning present ongoing challenges, DBS surgery continues to demonstrate remarkable benefits and has a transformative impact on those with movement disorders unresponsive to conventional therapies.
Patient Experiences: Patients previously had to travel to travel to the UK for DBS surgery, which involved multiple trips for assessments and follow-ups. The introduction of DBS in Ireland has significantly improved access for patients allowing them to receive treatment closer to home.
Some patients will travel to the UK for surgery especially when covered by private health insurance as the waiting times can be significantly shorter.
If you are a candidate for DBS:
- Inquire about the Irish Service: Ask your neurologist about the national DBS service in Ireland and your eligibility,
- Explore Travel Options: If there are long waiting lists, inquire about the possibility of being referred to a specialist centre abroad through the HSE’s Treatment Abroad Scheme (TAS)
If you are considering Deep Brain Stimulation (DBS) surgery or have already had the procedure and would like to make contact with others who have experienced (DBS) surgery, Dystonia Ireland can offer additional support and information.