Mark down October 30 and November 20, 2013, as medical mileposts.
On Oct. 30, a Stanford surgical team led by neurosurgeon Jaimie Henderson, MD, implanted a next-generation deep-brain-stimulation (or DBS) device into a Parkinson’s disease patient’s brain. On the order of 100,000 nearly but not quite identical procedures have been performed worldwide in the past decade or so, to relieve symptoms of not only Parkinson’s but epilepsy, chronic pain and more. Making what took place just over a month ago unique wasn’t the surgery itself but, rather, the nature of the device that was implanted – the first time ever in the United States. (In August, a patient in Germany received such a next-generation DBS device, although for a different indication.)
With current DBS technology, a fine, insulated wire is threaded into the brain so that its lead, containing four electrodes, impinges on the relevant brain area. (In Parkinson’s, for instance, the targeted area would be key brain regions that participate in the generation of spontaneous involuntary tremors characteristic of that disease). In a second procedure, a pacemaker-like device called a neurostimulator is placed under the skin, typically near the collarbone. The neurotransmitter transmits signals – at frequencies, amplitudes and durations programmed by a neurologist – to the leads, which accordingly fire electrical impulses counteracting the aberrant brain signals producing the physical symptoms in question. Over time, the neurostimulator’s impulse-transmission pattern is optimized via a trial-and-error process involving extensive patient-neurologist interaction.
Stanford neurologist and Parkinson’s specialist Helen Bronte-Stewart, MD, routinely sees patients a few weeks after their DBS devices have been implanted. They come in having not taken their medications for a while, so she can observe their symptoms and watch how they respond to different DBS frequencies and intensities.
But the new device, manufactured by the same company (Medtronic, Inc.) that makes the existing one, has an additional capability. It can not only transmit signals to the brain but, in addition, monitor and record the brain region of interest’s electrical output.
This will let Bronte-Stewart remotely capture vast amounts of information about a particular patient’s brain-firing patterns to discern that patient’s “neural signature” – and ultimately, it is hoped, be able to develop algorithms for automating the device’s signaling program so that it changes in response to changes in brain activity. (The goal, in engineering vocabulary, is a “real-time negative-feedback loop.”)
On Nov. 20, after recovering from the surgery, the patient and Bronte-Stewart, a noted expert in movement disorders, embarked on the first of a series of groundbreaking sessions during which Bronte-Stewart will download data from the implanted device for thorough analysis. While brain-activity data has been downloaded from Parkinson’s patients while they’re lying still on the operating table after the initial electronic-lead implantation, the recorded data has by necessity reflected only activity in the brain while the patient is at rest. Now Bronte-Stewart will be able to identify the neural signatures of not only the resting state but also voluntary movement, task performance and the tremor itself, and to see how those neural signatures change in response to her manipulations of DBS frequency and voltage output.
Stanford has received 10 of the new “two-way” DBS devices from Medtronic, and is recruiting Parkinson’s patients who, while they may not benefit directly from the ongoing study, wish to make a difference in how this disease’s symptoms are treated.
Previously: Revealed: The likely role of Parkinson’s protein in the healthy brain, Mind-reading in real life: Study shows it can be done (but they’ll have to catch you first), Positive results for deep-brain stimulation trial for epilepsy and Stanford neurologist discusses advances in research on movement disorders
Photo courtesy of Jaimie Henderson