What is DBS?
Deep brain stimulation (DBS) is a procedure where wires are implanted by a neurosurgical team in specific deep brain structures. These wires are routed under the skin to an implanted battery, placed in the chest or abdominal wall. The battery produces a continuous impulse to the brain and provide a 24 hour therapy to alleviate symptoms.
Deep Brain Stimulation is utilized in a variety of conditions which cause disorders of human movement when satisfactory improvement is not achieved with oral medications. There is strong evidence confirming efficacy of DBS in the treatment of tremor, dystonia, Tourette’s syndrome and Parkinson’s disease. The Sydney DBS team has extensive experience in treatment of these conditions.
DBS for Parkinson’s Disease
The most common indication for DBS is Parkinson’s disease.
In the early stages of PD, patients experience substantial benefit with medication therapy, usually achieving 60-80% improvement of physical symptoms with consistent control through the day. This has been termed the ‘Honeymoon phase’ (see below figure)
Over years however, symptom control can become inconsistent and sometimes accompanied by periods of excessive movement termed ‘dyskinesia’. Medication adjustments can be effective in ironing out these variations in physical performance and dyskinesia, but over time some patients find that irrespective of the alterations made to their medications, consistent symptom control cannot be achieved. It is usually at this point that patients consider advanced therapy interventions for their Parkinson’s disease including DBS.
In this situation, DBS achieves significant improvements in consistency of physical performance over and above that achieved by medication. DBS reduces dyskinesia by more than 75% and generally achieves substantially improved tremor control.
Some patients with Parkinson’s disease find medication is ineffective for their tremor from the beginning. Because of the significant impact of DBS on tremor, patient with severe medication refractory tremor may consider DBS in the first few years after diagnosis.
Occasional patients simply do not tolerate medication treatment of their PD. Whilst there may be a variety of causes for this, DBS can be effective in this population also.
Possible risks and complications
Like all surgery, DBS is not without risk. After performing surgery in over 460 patients Sydney DBS has a lifelong infection rate of 2.9% – all peripheral, with no brain infection and easily treated successfully with antibiotics etc, nil deaths and 0.24% peri-operative stroke (as at November 2017).
Risks depend on a variety of factors including the nature of Parkinson’s symptoms and the presence of other medical problems. Individual risk / benefit analysis is important in determination as to whether surgery is appropriate in each person’s case. These risks can be minimised with experience and a team based approach to peri-operative and long term care.
The surgical work up is determined on a case by case basis.
Generally, initial assessment is undertaken by Dr Paul Silberstein, Movement disorder and DBS Neurologist after referral from the usual treating Neurologist or GP.
If you wish to proceed to further assessment after this initial meeting, an MRI Brain and formal medication challenge are arranged. The MRI Brain is performed to assist in evaluating whether there is any structural abnormality that might preclude surgery. The medication challenge gives important predictive information as to the likely individual benefit of DBS. The medication challenge may be undertaken during a brief inpatient stay or as an outpatient at Dr Silberstein’s rooms.
All patients undergo a formal Neuropsychiatric and cognitive assessment with Dr Linton Meagher. This is generally performed as an outpatient at Dr Meagher’s rooms and is an important part of determining potential risks of surgery on an individual basis.
Dependent on your background medical history, you may be requested to attend for further medical evaluation with another physician (a Cardiologist for example).
Subsequent to the above investigations, you will meet again with Dr Silberstein to confirm whether your symptom profile is likely to be responsive to surgical intervention and the potential benefits and risks of surgery in your case. If the Neurologic and Neuropsychiatric assessments are favourable and you wish to proceed to surgery, a referral for consultation to Dr Raymond Cook will be made.
If the risk/benefit ratio of surgery is considered favourable and you wish to proceed, a date for DBS is planned.
DBS involves keyhole brain Neurosurgery. After a burr hole, about the size of the 5c piece is drilled in the skull, a tiny incision is made in the lining of the brain to allow implantation of the stimulating electrode. The actual surgical target generally lies 7-8 cm into the brain, and is not seen directly by the Neurosurgeon.
Accordingly, DBS surgery is like landing a plane at night in a dense fog. The runway can’t be seen and the landing must be managed through the use of computational instruments. Modern DBS utilises a variety of computational instruments to achieve surgical accuracy including sophisticated neurosurgical equipment and navigation software, intraoperative devices for recording from and stimulating the brain and intra-operative x-ray.
Surgery is generally performed in 3 stages:
Stage 1: Stereotactic frame application
Stage 2: Electrode implantation
Disclaimer: Information provided is of a general nature only. Treatment recommendations can only be made on a considered assessment of an individual’s specific medical circumstances.