Challenging Conventional Deep Brain Stimulation
Since first being proven effective in the early 1990s at treating essential tremor as well as disabling tremor in patients with Parkinson disease (PD), deep brain stimulation (DBS) has become a widely used surgery when medical treatment becomes ineffective in these and other indications, such as dystonia. Yet, patients' embrace of the surgery was undoubtedly hindered by the fact that conventional DBS requires them to remain awake for 4 to 6 hours while electrodes are placed in their brain.
A recent analysis from the Oregon Health & Science University (OHSU) in Portland, however, may change this dynamic. Researchers compared two different modalities for performing DBS in patients with PD: intraoperative CT imaging–guided implantation in which patients are asleep versus conventional surgery in which they remained awake during microelectrode recording–guided implantation. Their results indicate that the surgeries were not significantly different and in some cases favored asleep DBS.
To better understand what these results might mean for DBS going forward, Medscape spoke with the study's lead author, Matthew Brodsky, MD, associate professor of neurology at OHSU School of Medicine and medical director of OHSU's DBS program, and coauthor Kim Burchiel, MD, past chair and professor of neurosurgery at OHSU School of Medicine. Dr Burchiel is also the first surgeon to perform DBS in the United States.
An Eye-Opening Comparison
Medscape: What are the different surgical requirements for asleep and awake DBS?
Dr Brodsky: The surgical requirements do not really differ, aside from patients who might have a lot of difficulty being "off" their levodopa medication during the day of surgery while they are awake in the operating room and having clinical assessments during the course of the DBS implantation. This step is not necessary in the asleep procedure to verify target placement.
Also, there are some DBS patient candidates who have difficulty facing the prospect of being awake in the operating room, often for many hours, while the surgeon is placing the DBS leads, which is a requirement for an awake DBS procedure.
Medscape: What were the key take-away lessons from your study?
Dr Brodsky: For candidates with PD, improvement in motor function, such as tremor, mobility, and muscle rigidity, is as good with asleep DBS as it is with awake DBS, with similar improvements in "on" time during the day and reduction of dyskinesias. And, importantly, speech outcomes and some aspects of quality of life were superior with asleep DBS compared with awake DBS.
Medscape: You were particularly interested in tracking those postsurgical improvements in speech. Why was that such an important outcome?
Dr Brodsky: When we carefully reviewed adverse effects from DBS that were most common and significant in the literature from the larger, well-executed DBS trials (excluding significant procedure-related severe adverse events such as stroke or infection), speech fluency consistently has been reported.
There is some evidence that suggests that speech fluency can worsen due to the implantation of the DBS electrodes themselves and is not a stimulation-related adverse effect. This was our working hypothesis, and we set out to look at this outcome of special interest.
DBS's Path From Experimental to Accepted Treatment
Medscape: Dr Burchiel, you have a unique history with performing DBS surgery. Can you tell us a little about that?
Dr Burchiel: I was the first US surgeon to perform DBS for movement disorders (ie, PD, essential tremor), starting in 1991. My first experience with DBS was actually related to its use in treating refractory pain.
DBS was introduced in the 1970s for the treatment of certain types of pains, prior to the US Food and Drug Administration (FDA) taking regulatory control of implantable devices in 1976. In the early 1980s, the efficacy of DBS for pain treatment did not meet the developing standard for evidence-based medicine. When an improved technology for DBS for pain came along at that time, enthusiasm for this mode of treatment was already waning. As a consequence, FDA approval for this new device for DBS for pain was never granted.
In the mid-1980s, my colleagues in Europe continued to use DBS for pain. At that time, Prof Alim Benabid in Grenoble, France, was developing high-frequency DBS for tremor and later for the symptomatic treatment of PD. Given my prior interest in DBS for pain, I was intrigued with the prospect that DBS could alleviate a movement disorder.
In 1989 I was fortunate to communicate with Prof Benabid, and he freely shared his work and findings with me. This led, in 1991, to the first FDA-approved trial of DBS for tremor, and later PD. In 1999, our group went on to conduct the first randomized controlled trial of DBS for movement disorders in the United States, and a decade later we participated in the National Institutes of Health/Veterans Affairs trial of DBS versus best medical therapy for PD.
Medscape: In the more than 25 years since you performed that first operation, how have you seen DBS grow in terms of its acceptance?
Dr Burcheil: DBS has become the dominant surgical procedure for the symptomatic treatment of medically intractable PD, essential tremor, and certain types of dystonia. The procedure is now widely accepted as a prudent alternative when a patient becomes intractable to conventional medical therapy.
Despite this success over the past 25 years, many of us in the movement disorders field feel that it is still an underutilized therapy. DBS procedures have an excellent safety record, and I believe that as the costs of the procedures and devices fall, it will be an increasingly attractive alternative in the medically refractory patient.
Pioneering Asleep DBS
Medscape: Besides obvious patient discomfort, what are the other potential risks posed by awake DBS that may be circumvented by moving to asleep DBS?
Dr Brodsky: One significant potential risk with an awake DBS procedure is a brain hemorrhage, given that microelectrodes, which have sharp tips, are passed into the brain to take recordings to assist with targeting the placement of the stimulating electrodes, which are put in after the microelectrodes have been taken out. If suboptimal recordings are obtained with the "first pass" of the microelectrodes, there may be additional "passes" into the brain, further compounding this risk.
At some DBS surgical centers, the microelectrode device that is used actually contains five electrodes in one configuration, with one at the center and four surrounding it, also further compounding this potential risk.
Medscape: OHSU stopped performing awake DBS in January 2011. Dr Burcheil, what made you feel on solid ground to make such a shift?
Dr Burcheil: My decision to take DBS in another direction was based on about 20 years of experience with this surgery.
Given that multiple microelectrode recordings were performed during DBS surgery, there was a small added, but substantial, risk to the procedures based on that.
Furthermore, MRI imaging of the brain has advanced dramatically over the past 25 years, to the point that we could now directly visualize our targets for DBS. We no longer had to be reliant on indirect localization of DBS targets based on their physiologic output as recorded by microelectrode recording.
Concurrently, intraoperative imaging had advanced to the point that high-resolution CT scanning could be performed during surgery to locate target sites for DBS, and to confirm accurate location of the DBS electrodes within these targets prior to concluding the implant procedure.
We felt confident that these two advancements in MRI and intraoperative CT imaging could give us the information necessary to accurately place DBS electrodes, and to confirm electrode placement prior to completing the procedure and leaving the operating room.
Medscape: What was your experience of patients' reactions and recovery after the switch to asleep DBS? Do you remember there being a clear point of differentiation, or was it more subtle than that?
Dr Burcheil: Despite DBS being a highly effective procedure, many patients were intimidated by the prospect of brain surgery while they were awake on the operating table for several hours.
Our experience with asleep DBS was that the numbers of patients willing to undergo the surgery doubled almost immediately. This meant that a substantial number of additional patients who could otherwise benefit from the procedure were now willing to undergo it if they could be under anesthesia for the entire operation.
In my opinion, this is a matter of providing better patient access to a procedure that has been proven effective.
The Future of Asleep DBS
Medscape: How common is asleep DBS now, and do you see that changing in the years to come?
Dr Burcheil: While there will be a continuing role for awake DBS procedures as a means to investigate—under institutional review board protocols—the conditions for which DBS is being employed, I believe that asleep DBS will become the dominant method for the routine implantation of DBS systems in the future.
Asleep DBS appears to have no disadvantages over the more traditional microelectrode recording-based technique under local anesthesia, and in fact, based on our work, it appears to have substantial advantages in regard to speech, cognitive performance, and quality-of-life measures. I believe that as patients become more knowledgeable about surgical alternatives for DBS, they will migrate toward centers that perform asleep DBS procedures.
Dr Brodsky: Asleep DBS is currently not the way this procedure is done at a majority of surgical centers around the United States, and indeed around the world. I do predict that this will change in the years to come, as there is acceptance of the evidence that has been provided by our group and others, and as DBS training sites adapt this technique and teach future generations of clinicians involved in this specialty.
Medscape: Are you planning any specific follow-up studies on this topic?
Dr Brodsky: Because of the success that we have had with the asleep DBS approach, we are unlikely to carry out a prospective, randomized trial comparing awake versus asleep DBS. In fact, at this point, given the outcomes we found, I would have a hard time recommending awake DBS with microelectrode recording to candidates for such a study.
Our group is turning to exploring other recent innovations in DBS, including closed-loop DBS systems and potential advantages of newly available segmented stimulating electrodes that offer the ability to "steer" the current in the brain, and pulse generators that allow greater flexibility in targeted activation of neural elements and variable current delivery.
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Any views expressed above are the author's own and do not necessarily reflect the views of WebMD or Medscape.
Cite this: Rest Easy: Asleep Deep Brain Stimulation as Effective as Awake - Medscape - Feb 05, 2018.