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Healthcare: Neurology

Techniques

Master
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How DBS Surgery is Performed

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Baylor Medicine is fortunate to have the latest surgical technologies to allow the most customized and precise DBS surgery experience. Through our affiliated hospitals, we can perform surgery using intraoperative CT, intraoperative MRI, advanced electrophysiological techniques, and frameless DBS. Below we will describe the technique for awake DBS surgery, but please speak with your neurologist and neurosurgeon about the variety of techniques possible and what is best for you.

DBS surgery is performed in two stages:

  • Stage I involves placing the electrode(s) into the intended deep brain target. This stage generally involves an overnight stay in the hospital, in a non-ICU setting.
  • Stage II involves placement of the extension wires and battery. This stage is an outpatient surgical procedure that requires one hour under general anesthesia.

Battery replacements are another surgical procedure that patients will require periodically (generally every three to five years, if a rechargeable device is not used), depending on the amount of stimulation required to treat their condition.

Here we will focus on Stage I.

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Preoperative Planning and Imaging

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Left: A preoperative brain MRI scan such as this helps the surgical team place the electrodes in the best location. Right: A preoperative brain MRI is used to help plan the surgical trajectory.
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In the month prior to surgery, we perform an MRI to get a highly detailed picture of brain anatomy and to plan surgical trajectory. We have typically requested an anesthesiologist to provide sedation for the MRI, as it is sometimes difficult for patients to remain still for the images. However, it is your choice whether we use sedation for the MRI.

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Day of Surgery

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Equipment for DBS Surgery
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On the morning of the stage I procedure, patients undergo placement of a headframe or halo. This frame helps us to ensure submillimetric accuracy when placing the deep brain leads. An anesthesiologist is also present for this portion of the procedure to ensure your comfort.

Once the headframe is in place, a CT scan is performed in the operating room. The CT scan and the MRI images are loaded into a sophisticated software system for the analysis in a process called "direct targeting" which is individualized for each patient.

During the surgery, several steps are taken to ensure precise placement of the DBS electrode(s).

Patients remain awake but are made comfortable with intravenous sedation provided by an anesthesiologist. This allows for recording of the brain activity in different brain regions (called "microelectrode recording") and for test stimulation (turning the DBS on to check for benefits and side effects). Both are described below.

Microelectrode recording (MER): Each part of the brain has a characteristic firing pattern that can be heard and analyzed as the electrode very slowly approaches and/or passes through that region. The electrode is advanced by fractions of a millimeter when the area of interest is reached. The neurosurgeon and neurologist use MER to identify when they have reached the proper brain structure and to determine how deep and how far to either side of the original target the electrode should be placed. Multiple recording tracts may be made to ensure the best location is found.

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The team can record intraoperative LFPs at the same time as traditional single unit recordings to optimize electrode placement and study brain function.
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The team can record intraoperative LFPs at the same time as traditional single unit recordings to optimize electrode placement and study brain function. Our team uses local field potential (LFP) analysis to complement MER. LFP recordings are obtained at the same time as MER. They represent a different type of electrical activity of the brain structures and can provide important information about disease features and electrode position. LFP analysis is a major part of our research program as well, as we seek to understand the basis of different movement disorders and the response of brain structures to stimulation.

Test stimulation: once the final electrode location is determined, the neurologist will turn on the stimulator at various settings to test for improvement in symptoms or for any side effects. This step is important in order to avoid complications in the post-operative programming stage that may limit the benefits of DBS therapy. If any side effects are noted during this step, the electrode position may be changed.

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About the DBS Device

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DBS Hardware
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The DBS electrode (also called a "lead") is surgically inserted into the desired target and fixed to the skull with a ring and cap, to keep it from moving around. A connector fastens the lead to an extension wire. The extension wire passes under the skin behind the ear, down the neck, and into the chest where it is connected to an implantable pulse generator (IPG). The IPG is a pacemaker-like device, which can deliver pulses with a variety of parameters, modes, and polarities to the target brain area. The IPG is surgically implanted under the skin in the upper chest area near the collar bone or under the skin in the lower abdomen. The IPG consists of a small battery that produces the electrical pulses needed for stimulation, and can be adjusted by a clinician according to the specific needs of the patient to optimize DBS therapy.

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A CT scan is merged back to the planning MRI to check the electrode position before the patient leaves the operating room.
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Post-operative CT:  While in the operating room, a CT scan is performed. The scan is then merged back to the planning MRI to make sure the DBS electrodes have been placed precisely where intended before the patient leaves the operating room.

In select situations, patients may benefit from different techniques for electrode placement. These may include:

• Frameless DBS – no halo is used
• Image (MRI or CT) – guided placement

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Patient Control Device

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Clinician adjusts a patient control device which allows the patient to monitor her therapy.
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A patient control device allows patients to monitor their therapy, or adjust it when appropriate. The clinician uses a separate programmer to adjust the parameters of stimulation.

The typical battery life is expected to be approximately three to five years, but this may vary depending on the individual settings and hours of use per day. Rechargeable IPGs are also available, with an expected battery life of 15+ years. The frequency of charging will depend on an individual patient’s settings.

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Common Questions About DBS Surgery

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See commonly asked questions and answers about DBS surgery.

Learn More
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More about DBS

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Click on the links below to find out more about DBS for Parkinson's Disease and Movement Disorders