A long time internet acquaintance of mine, "Mary", returned home from having the DBS procedure of the STN done at the New York University Medical Center. She tolerated the procedure rather well. The procedure was performed by neurosurgeon Dr. Pat Kelly, one of our first advisory members of the Parkinsn list.
"Multi-disciplinary" is the buzz-word of moment when it comes to treating disorders nowdays. This is a holistic approach of treating the mind body and spirit of those afflicted. Since nothing is free of cost, there must be mechanisms in place to fund such practices. Medicare in the US will pay for the procedure.
"Mary" had received a bilateral pallidotomy about 5 years ago at NYU. At that time, the procedure appeared to offer long term benefits but since it in essense kills discordant neurons it is not repeatable. "Mary", over time, developed dyskinesias that were to the point of putting her joints at risk at some point in every one of her medication cycles.
http://mcns10.med.nyu.edu/CMD/stn_main.html
History:
About six years ago, one of our listmembers, Don Sandstrom was the first American to have DBS by Dr. Alim Benabid (ben uh beed)at Grenoble France. Don's procedure was bilateral and the area of the brain targeted was the ventralis intermedius (VIM). Shortly after Don returned to the US, I asked him about the procedure and his answers are at:
http://parkinsons-information-exchange-network-online.com/archive/087.html
Recently I touched base with Don again, 5 1/2 years later. According to Don, he is still doing well and while the device battery life was a big question mark, one of his failed after 5 1/2 years of 24 hour a day usage. The devices seem to be working well. By reading his comments, you can see how debilitated Don was before the procedure and his elation afterwards. The only problem Don has encountered is finding someone willing to perform the programming for the devices which is necessary as Parkinson's progresses and the condition of the implant site changes. Don said the last tuning he had was an all-day affair at the doctor's office.
Stimulation of the STN:
The implanted probe is about an inch long with 4 bands of metal which administer the electrical charge to the thalamic structures surrounding where they are placed. While the FDA has only approved the implant to be used in the thalamus, "fuzzy localization" is used by many to insert the probe slightly deeper into the Sub-Thalamic Nucleus (STN). Stimulation of the STN has been associated with additional benefits to the Parkinson's patient, such as levodopa reduction. Medicare still pays because the target is the VIM. :)
Target Localization:
Most of the teaching hospitals around the world use microelectrode recording to find the right spot. Several experienced surgeons have moved away from that practice as the "art" of finding the right spot evolved. Healing consists of art and science and skill. With new surgeons, microelectrode recording tends to overcome the lack of skill level. The downside of microelectrode recording is the increased risk of bleeding and the time a patient has to be on the operating table.
Lack of proper target localization can lead to irreversible complications. Neurosurgeons tend to remember patients who have had procedures done by famous doctors which don't turn out well. Horror stories abound when it comes to neurosurgery done improperly.
There is an alternative to microelectrode recording available now. While it is too early to say that this will be the "gold standard" of the future, it offers the promises of shorter procedure time on the operating table and fewer complications than microelectrode recording. Dr. Francel's article outlines the new alternative at:
http://parkinsons-information-exchange-network-online.com/archive/109a.html
Fruits of DBS:
After the DBS procedure, it takes a while for the brain to heal. Some practices begin the tuning process as soon as 2 weeks after implant, but others wait at least 6 weeks. The reasoning behind the waiting for the initial tuning is based on experience. Some tell me that early tuning only produces transitory results. Tuning that works in the office doesn't necessarily work when the patient goes home. Allowing sufficient time for the brain to stabilize and then starting programming is most fruitful.
Tuning involves changing the parameters of the device and requires a programming machine to do that so be prepared for frequent trips to the office for tweaking. Effectiveness of DBS is so dramatic for essential tremor (ET) that some neurosurgeons go so far as to say that it is a cure for ET. That statement brings back the memory of Dr. Iacono proclaiming that pallidotomy was a cure for PD and we have come to know the folly of such proclamations.
The first Medtronic devices implanted, contained two memories so that the patient could switch between the programs. Devices implanted today only contain one memory. Technicians who talk to me, say that it is more time consuming for the patient, since the programmer only has one shot at a time to get the tuning right. They hope that Medtronic will recondition the early devices and reissue them as they are returned for new batteries.
Studies:
Most programs use neuropsychological testing before and after the DBS procedure to test effectiveness over a large number of patients. These studies use tests to quantitativly measure your long and short term memory, you ability to put words together and strength. They are repeated at approximately three months following the procedure and the results are tracked over the number of people in the study, giving an idea as to the efficacy and risk profile of DBS.
Outcomes:
Most programs will agree that those with tremor will benefit the greatest from DBS. It is yet to be determined if mixing PD patients with those of other tremor disorders will have a tendency to skew or enhance the results.
Patients with essential tremor (ET) improve dramatically, both subjectively from the patients assessment and from the impirical data gathered by the neuropsychological testing. The selection of this group of patients who tend to be drug resistant, generally insures good results. PD patients who have "inner tremor" should do well also.
I was told by a programmer that they had one ET patient who was implanted and waited for 9 months before returning to have the devices turned on and programmed. They credited a phenomenom called micro-thalamotomy effect with this result. With tremor, it sometimes is enough to just implant the probe and the slight damage of this process disables the cause of a particular tremor.
Parkinson's is a progressive condition so therefore it is one leg of the proverbial "stool". Those diagnosed before the age of 60 tend to evolve more slowly than those diagnosed after 60. Medication is the second leg of the "stool". As the condition evolves more medication is required to maintain a balance until undesired side-effects start to occur. DBS to the subthalamic nucleus, introduces a third leg of the "stool" which when properly programmed should allow reduction in medication and the associated undesirable side-effects. Recent studies have indicated this.
Levodopa Withdrawal After Bilateral Subthalamic Nucleus Stimulation in Advanced Parkinson Disease. Molinuevo JL; Valldeoriola F; Tolosa E; Rumia J; Valls-Sole J; Roldan H; Ferrer E
http://parkinsons-information-exchange-network-online.com/archive/thalamot.html
While it would be desirable for programming technicians to know where to start, the state of the art for programming is mainly trial and error. There are hundreds or thousands of voltages, pulse widths, frequencies and polarities possible. Before you are properly tuned, you will get very acquainted with your technician.
I expect to have bilateral DBS surgery before the end of the year.
[log in to unmask]
Search the parkinsn archive online at:
http://james.parkinsons.org.uk
Catch the Parkinsn's List Online messages at:
http://parkinsons-information-exchange-network-online.com
Click the link for Parkinsn's List Online
John Cottingham
