Patients describe the surgery as demanding and exhausting but not painful. The hospital stay, including preoperative tests, implant surgery, and recovery, usually lasts only a few days. Many people report that after the implant they do not feel the stimulation. Some people may feel a brief tingling sensation when the unit is first turned on but the sensation often disappears with time. Deep brain stimulation can be adjusted to meet the patient's needs for symptom control over time. The patient's neurologist adjusts the control unit using a programmer that communicates with the neurostimulator through radiofrequencies. This process is completely noninvasive. The deep brain stimulation unit can also be removed permanently if desired. In other words, the operation is considered reversible, unlike thalamotomy or pallidotomy. Almost 25,000 people worldwide have received deep brain stimulation units since the device was first introduced.
Who is a Good Candidate for Deep Brain Stimulation?
1. Patients whose diagnosis of idiopathic Parkinson's disease is certain. Some Parkinson's disease variants, such as progressive supranuclear palsy (PSP); multiple system atrophy (MSA); Shy-Drager syndrome; striatonigral degeneration (SND); dementia with Lewy bodies; or parkinsonism due to toxins, infections, or strokes, are not responsive to deep brain stimulation. [2]
2. Patients with a robust response to carbidopa/levodopa (Sinemet) that is a 25-30% improvement in mobility with carbidopa/levodopa (Sinemet) when comparing "on" and "off" responses. The best candidates are patients who fluctuate between "on" and "off" periods throughout the day. Typically, the surgery improves the amount of "on" time rather than improving "on" time functionality
3. Patients whose symptoms are not controlled adequately by drug therapy, such as individuals on maximally tolerated doses of dopamine agonists (Mirapex, Permax, Requip), carbidopa/levodopa (Sinemet) at appropriate intervals, trials of COMT inhibitor (Comtan), and potentially use of amantadine for dyskinesias.
4. Patients who are cognitively normal. Patients with dementia or significant memory disturbance that is not a medication side effect are not good candidates. In fact, surgery can permanently worsen cognition in these patients. Neuropsychological testing may be needed to determine whether patients are good candidates.
5. Patients who are otherwise healthy, that is, who do not have serious cardiac, pulmonary, or other chronic illness.
6. Patients who are less than 75 years old. However, patients over 80 years old who are very healthy and who exhibit good function in the "on" state may still be considered.
7. Patients with satisfactory brain imaging. Severe atrophy or vascular disease on the brain MRI suggests poor tolerance of the surgery.
8. Patients who can remain calm during surgery. Deep brain stimulation is done while the patient is awake and under mild sedation. Some cooperation with the surgery is required.
9. Patients with realistic expectations. The surgery requires frequent monitoring and doctor visits (at least initially). Typically, Parkinson's disease medications are still required although perhaps at lower doses. In addition, the stimulator is bulky and can be felt and seen under the skin. Patients should not expect a miracle "cure."
Patients should discuss these factors with their treating neurologists. They should discuss which symptoms will respond to deep brain stimulation and stabilize, which symptoms will not respond to deep brain stimulation and will worsen with time, and which symptoms may worsen as a result of deep brain stimulation. Furthermore, it is very important for patients to meet with the physician team who will program the stimulator before surgery.
Potential Risks of Surgery [1]
Surgical risks include risks associated with any brain surgery such as hemorrhage, infection, and stroke, but the incidence of such complications is very low. Patients should ask about their neurosurgeon's experience with deep brain stimulation. The following are good questions to ask a potential neurosurgeon:
1. How many deep brain stimulation implants have you done?
2. How many were successful?
3. What are the typical complications and their incidence in your hands? How does this compare with other surgeons?
4. What is the recovery rate from such complications?
At Barrow Neurological Institute, Dr. Andrew Shetter and Dr. Kris Smith have performed more than 300 deep brain stimulation procedures with minimal complications -- well within the accepted rates for this type of brain surgery.
REFERENCES
1. Medtronic ACTIVA Parkinson's Control Therapy literature; Information about deep brain stimulation; 2004
2. Krack, Paul, M.D. et al; Five Year Follow-up of Bilateral Stimulation of the Subthalamic Nucleus in Advanced Parkinson's Disease; New England Journal of Medicine; Vol 349, No. 20, pp. 1925-1934.
