The surgical procedure is associated with complications like bleeding inside the brain and infection of the implants, in a small minority of cases.
Bleeding serious enough to cause paralysis and other neurologic problems are rare and occur in only around 1.5% of patients undergoing surgery.
Infections in the implants (which may necessitate explantation and discarding of the DBS system) have been reported to occur in around 2-3% of the patients undergoing DBS all over the world.
Problems with the DBS hardware (the equipment and the wires), like errors in positioning, fracture of the electrodes etc could also occur in a similar minority.
The second part (implantation of the stimulator) of the surgery is done under general anesthesia and carries all the risks of anesthesia as in any other surgery.
Minor complications like epileptic fits during/ immediately after the procedure, transient mental changes like confused behavior, urinary incontinence etc are more common in the post-operative period and can be managed fairly easily.
Minor behavioral and cognitive problems (like reduced fluency of speech, reduced initiative to do activities, changes in mood etc) can occur in some patients as a result of stimulation and can be corrected / minimized by programming, as discussed above.
Some patients show a tendency for increased appetite, resulting in weight gain. Overweight can result in worsening mobility and should be controlled with appropriate dietary adjustments / exercises.
The risk of surgical complications could vary from patient to patient depending on factors like age, presence of other illnesses (eg: high blood pressure increases the risk of bleeding during surgery; cardiac problems may predispose to complications during anesthesia; diabetes may increase the risk of infections) etc
There is no simple, one-word answer to this question. As discussed above, deep brain stimulation surgery is a symptom-relieving measure offered to patients with PD.
DBS has not so far been shown to have any ability to retard the progression of Parkinson’s disease or to prevent or delay the problems of very advanced stage Parkinson’s disease, like memory and intellectual dysfunction, psychiatric problems etc.
Some of the symptoms of PD show very good improvement with DBS (eg: tremor/ stiffness of limbs); certain others may not improve that much (eg: freezing while walking; other sorts of disturbances in walking) ; a third group of symptoms may even worsen slightly following DBS (eg Clarity of speech, fluency).
The profile and severity of the symptoms and the rate at which the disabilities progress in Parkinson’s disease vary widely from person to person. For example, some patients are severely disabled by tremor in spite of relatively preserved walking capabilities while some others never experience any tremors; slowness and walking difficulties predominate in them.
Some patients have severe symptoms interfering with daily activities 6 or 7 years into the illness, while certain others remain active and independent with medications alone even after living for 12 -15 years with PD.
The degree of handicap caused by the symptoms also depends on ones professional and social status. For example, the implications of the disease in a manual laborer who is the sole bread-winner of a family, and another, who is leading a retired life will be totally different, even if the severity of the symptoms is identical – the former would desire for a better control of symptoms even at the risks of a major surgery while the latter may not accept this risk.
The decision regarding when to go for Deep Brain Stimulation surgery has to be individualized, taking into consideration various factors like the nature of symptoms and severity, expected improvement (which vary depending on the profile of symptoms in individual patient), expectations of the patient and family, employment status, surgical risks, family / social support (as the patient needs to be under the regular follow-up of the specialized team for life-long, after undergoing DBS) etc.
The average duration of Parkinson’s disease, for a patient undergoing DBS surgery has been typically 11-13 years; however, there has been recent studies which showed that doing DBS earlier (before the disabilities become sufficient enough to warrant DBS as per conventional guidelines) in carefully selected patients may improve the overall quality of life of the patients.
The expected benefits of DBS (improvement of symptoms, improved ability to perform daily activities, likelihood of resuming employment, better quality of life) in the individual patient has to be weighed against the potential risks and disadvantages(the small, but definite surgical risks elaborated above, need for a subsequent life-long specialized care, cost etc).
The simplest answer to the question is that “DBS should be considered when the needs and expected benefits in the individual patient outweigh the estimated risks and disadvantages of the surgery in him/her”.
For example, a patient with no illnesses other than Parkinson’s disease (thus, the risks of surgery are relatively low) and in need of continuing employment (being the sole breadwinner of the family) may choose to do DBS ‘relatively early’, even when the disability resulting from PD is only moderate.
On the contrary, the wise decision in another patient retired from employment and also having other illnesses like high blood pressure or heart disease (implying a higher surgical risk), will be to wait till the disability becomes sufficient enough to justify taking the higher risks of surgery.
Summarizing, patient with Parkinson’s disease can be considered for DBS, if the following general guidelines are met:
(1) The duration of disease is sufficiently long enough – minimum of 4 years is generally recommended- so that the doctors have had a sufficiently long period of observation and follow-up to make a confident diagnosis of PD
(2) The patient has an excellent (even though persisting only for a brief “on” period) response to medications like Levodopa
(3) The “motor fluctuations” and “dyskinesias” are judged by the patient to be disturbing and needing better control than what is possible with optimum drugs
(4) There are no major memory or other intellectual dysfunction, or depression or other psychiatric disturbances resulting from PD
(5) There are no other major illnesses increasing the risks of surgery / other illnesses present are well controlled and taking the increased surgical risk due to them is justified by the severity of the motor fluctuations and dyskinesias in the judgment of the patient, family members and the team of doctors.
(6) The patient and family have understood well the pros and cons of DBS and the expectations are realistic
(7) The patient has adequate social support to maintain a constant access to the specialized care which he / she will require throughout the rest of his / her life.
The team of doctors will assess the patient and explain in detail the expected risks and benefits in the individual patient; the final decision should come from the patient and family.
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