Deep Brain Stimulation
Deep brain stimulation is a surgical intervention used to treat movement disorders such as dystonia, essential tremor and Parkinson’s disease when the regimen of existing medications and the various rehabilitation strategies become less effective in managing symptoms. This is a relatively new surgical procedure that received approval from the Food and Drug Administration to treat essential tremor and tremor in Parkinson’s disease in July 1997 and for advanced motor symptoms of Parkinson's disease in January 2002. It is currently approved for the treatment of dystonia through a humanitarian device exemption.
How does DBS work?
The subthalamic nucleus (STN), the globus pallidus (GPi) and the thalamus are three locations in the brain that are targeted in the deep brain stimulation (DBS) procedure for the treatment of movement disorders. DBS administers a well-controlled electrical current into the target area(s). This electrical current functions as an "off switch" by disrupting abnormal brain signals responsible for the abnormal physical movement. This disruption helps restore more normal activity in the brain, enabling more controlled movement.DBS does not involve destruction of brain tissue, and its effects are reversible and adjustable. It is not preferred over the thalamotomy or pallidotomy, two surgical techniques that involve the actual destruction of the brain cells that are "misfiring." Electrical impulses which are generated from an implanted battery, pass through the lead and into the target area. This entire system is implanted under the skin.Effectiveness
The effectiveness of the DBS procedure depends on accurate placement of the brain lead(s) or wire(s) and therefore requires special expertise. The evaluation and surgical procedure are conducted at VCU using a team approach involving neurosurgery, neurology, neuropsychology and a trained nursing staff. The target areas or nuclei are quite small and special imaging techniques and guidance devices are used to help position the leads. The patient is awake during portions of the surgery and becomes an important member of the team. The patient also helps in determining whether beneficial effects occur when the stimulation is applied during surgery.DBS can be an effective treatment in those hard-to-treat patients who meet specific criteria. Unfortunately, there is a 1-3% risk that the brain will be injured during the DBS procedure. As a result of this damage, patients may experience loss of speech, paralysis, coma or even death - usually caused by bleeding in the brain. There is an additional 5% risk of infection usually requiring the removal of the device.DBS surgery can be time consuming, usually lasting three to four hours per side of the brain being operated on. The most common complaints from patients include back and neck pain and fatigue.Deep Brain Stimulation Surgery at VCU
If the patient wishes to proceed with surgery, and is determined to be a good candidate based on review of evaluation findings by the neurosurgeon, surgery will be scheduled.
The patient who elects to undergo deep brain stimulation surgery after carefully reviewing information about the surgery and an initial informational appointment will begin the evaluation process.
Clinical notes are obtained from the referring neurologist and primary care provider. If a patient has not been seen by a neurologist, an appointment with a movement disorders specialist will be scheduled to confirm that the patient is a good candidate for surgery.
Steps of the evaluation process:
- Evaluation of diagnosis, stage of disease, evaluation of the patient’s general health, and discussion of surgery
- For patients with PD, an off PD medication/on PD medication motor examination is performed. The degree of impairment that patients experience when their medicines are not working or “off” time can be assessed by performing an examination of the patient after s/he has been off all PD medications for approximately 8 hours (“off score”). This is compared to the benefit that the patient gets when his/her medications are working or “on score” assessed after taking the PD medications.
- Neuropsychological testing - This testing is used to look for signs of memory problems, depression or anxiety. It is important to identify these problems prior to surgery. Significant dementia rules out certain types of surgery. Depression and anxiety should be under treatment prior to surgery and may affect which nucleus is chosen for stimulation.
- MRI for intraoperative guidance
- Final decision on eligibility and desire for surgery
The surgical technique used by the VCU team utilizes frameless stereotaxy, microelectrode recording, and test stimulation to place the deep brain stimulator lead in the best possible location within the brain.
Frameless stereotaxy uses six small screws or fiducials to replace the bulky metal frame used in Frame stereotaxy. These are placed during surgery while the patient is sedated and removed at the end of surgery. The patient is able adjust his/her position to get comfortable during the surgery.
All Parkinson's and Essential Tremor medications are stopped at midnight the night before surgery.
The nurse will review where to report and what time the morning of surgery.
On the day of surgery, the patient is positioned comfortably in the operating room with his/her head and neck resting on a cervical support which is attached to the table. The front of the collar is used to secure the patient while asleep but is removed once fully awake and conscious.
The patient is sedated while six small bone screws or fiducials; skin incision(s) and a burr hole or dime-size hole in the skull; is made. The patient is awakened and recording begins. The device used to hold and advance the microelectrode is attached directly to the burr hole allowing the patient to adjust his/her head position if needed to be more comfortable.
Once the microelectrode recording is completed, test stimulation is performed to determine efficacy and side effects. The microelectrode may need to be moved if there is little improvement or if there are troubling side effects. Moving the electrode is done through the same burr hole. Once an optimal location is found, the actual DBS lead is inserted and secured into place. This process is repeated for the other side of the brain for those patients undergoing bilateral stimulator placement.
The battery and extensions are placed several days later in a separate procedure, under general anesthesia after the patient has fully recovered from the intracranial surgery. Unilateral lead placement surgery is shorter and less tiring, and the battery and extension are generally placed on the same day as the DBS lead.
Most patients with unilateral stimulators are discharged from the hospital the day after surgery. Patients who have bilateral leads placed may require a longer hospital stay (one to five days). Patients who are in poor health before surgery will recover more slowly and may require a prolonged stay in the hospital or rehabilitation facility.
Patients who have an elevated blood pressure in the recovery room or other surgical complications will be admitted to the ICU. All others will go to a regular room.
Additional therapeutics
Focused Ultrasound
Focused ultrasound is a non-invasive treatment for patients with movement disorders such as Parkinson’s disease and essential tremor.
Infusions strategies
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