Thursday, November 20, 2008

Deep Brain Stimulation

This is a topic near and dear to my heart. DBS surgery is essentially what drew my interest to neurosurgery in the first place, years ago. It’s not exactly a new technique. In fact, it’s been FDA-approved in the US for nearly a decade.

In DBS, a small wire about a millimeter thick (the “lead” or “electrode”) with four different possible stimulation points (the “contacts”) is placed in a very specific spot in the brain. How that spot is determined are for another post on another day, and varies somewhat from situation to situation. Usually the process involves some form of stereotactic targeting and physiologic confirmation. The implanted wire is then pulled under the skin (“tunneled”) to a place where a pacemaker-like device (the “implantable pulse generator” or IPC, also often informally called the “battery”) is implanted, most commonly just under the collar bone (“subclavicular”).

DBS has wide-ranging applications, and is FDA-approved for Parkinson’s disease and Essential Tremor.

There are numerous other movement disorders for which it has been reported to be effective, and it has been used in the past for some complex pain problems. Most recently, it has received considerable attention for certain psychiatric indications, and most experts in the field expect FDA approval for obsessive compulsive disorder (OCD) and major depression in the next several years.

Tuesday, November 4, 2008

New Research in Thinking Problems in Parkinson's

I had a great meeting today with a particularly bright research psychologist from Tulane about a new project that we will try to launch at LSU to look at some early aspects of dementia in Parkinson's disease.

In broad terms, it helps to think of the typical progression of Parkinson's disease as two processes, creating three broad phases of the disease. The processes are movement deterioration, and more diffuse cortical deterioration. The classical movement deterioration is more related to the kinds of things you usually see in textbooks about loss of dopamine in the substantia nigra. Roughly, it is more evident in the beginning, and is usually controlled well by medication, as least for a while. This is the first, mild, phase of the disease. In the second, moderate, phase, the movement deterioration becomes more severe, and the amount of medication required to try to control it becomes problematic. This is the phase where we look at surgery, as a treatment that doesn't require more medications. This is where the first cortical problems start to show up as well, but they are usually very mild. In the third phase, the cortex is becomming the main problem, and we see dementia, and deterioration of the reflexes that help to keep us from falling. At this point, surgery is too late.

But, the interesting thing, is that if we could look at the dementia process very early on, we might be able to understand it better and even do something about it. Interestingly, when we do the surgery, we decide where to put the electrode by 'mapping' the subthalamic nucleus with tiny electrodes to listen to the cells, and stimulating them in different places. It turns out, this is an area where we can differentially affect some of the loops in the brain thought to be involved in this mental deterioration. It's not something we normally look at while we are there, but in the next few months, for any patients at LSU that will let us listen in on those processes while we are there anyway, we'll start trying to unravel this mystery with the help of our Tulane colleague.

Here's to teamwork!

Monday, November 3, 2008

Kinds of Surgery for Parkinson's Disease

Frequently, people come to the clinic to inquire about surgery. Sometimes they've seen a program on the news, more often a family member suggested they look into it, and perhaps they looked it up on the internet. There are some professionally produced educational materials circulating, and some people have friends who have had procedures done and been pleased with the results, and passed on the educational materials they reviewed before surgery.

What people commonly don't realize is the complexity of the answers they have come seeking. There are a number of surgeries performed for PD, and it helps to draw some distinctions. In broad categories, there are surgeries in which brain cells are destroyed ("ablation" or "lesion" surgery), and surgeries in which an electrode is implanted and connected to a device similar to a pacemaker, often called the pulse generator (IPG, "implantable pulse generator"). Often, the IPG is casually called the "battery." Stimulators can be implanted in any number of ways at a variety of locations, but one method is FDA approved for PD, and it usually goes by the name "Deep Brain Stimulation," abbreviated DBS.

There are other, experimental surgeries as well, such as laying grids of electrodes over the surface of the brain, injecting gene therapies, transplant surgeries, or implanted pumps with nerve growth factors, but none of these appears particularly close to becoming a major clinical breakthrough.

With the rise of DBS surgery, very few lesion surgeries are now performed in the United States, although there may still be times, such as in infections, where they are the best choice.

Sunday, November 2, 2008

LSU Establishes Multidisciplinary Parkinson's Services

Prior to hurricane Katrina, there was a Parkinson's Center at LSUHSC in New Orleans. In fact, the website is still up. Unfortunately, none of those doctors still work at LSU. The Department of Neurology is still trying to recruit someone to fill the endowed chair in movement disorders, but the multidisciplinary team has already largely formed. With enthsiastic involvement from the Department of Neurosurgery, which has the majority of it's faculty at West Jefferson Medical Center, a team including physical and occupational therapy, speech therapy, social work, nursing, neurology, neurosurgery, psychology and psychiatry has come together to provide a comprehensive approach to patients with PD.

It's early in the process, but close cooperation with the Culicchia Neurological Clinic, and neurologist Charles Fiore has been key.