How is deep brain stimulation (DBS) performed for the treatment of Parkinson disease (PD)?

Updated: Dec 09, 2020
  • Author: Konstantin V Slavin, MD; Chief Editor: Brian H Kopell, MD  more...
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Answer

The deep brain stimulation (DBS) system consists of a lead that is implanted into the targeted brain structure, such as STN, GPi, and VIM. The lead is connected to an implantable pulse generator (IPG), which is the power source of the system that is generally implanted in the subclavicular region of the upper chest. The lead and the IPG are connected by an extension wire that is tunneled down the neck under the skin (see the image below).

The Medtronics, Inc, Activa Tremor control system The Medtronics, Inc, Activa Tremor control system consists of 3 components: (1) the stimulating lead, which is implanted to the desired target; (2) the extension cable, which is tunneled under the scalp and soft tissues of the neck to the anterior chest wall; and (3) the pulse generator, which is the programmable source of the electrical impulses.

Implantation of the DBS system is performed in 2 stages as follows:

  • During the first stage, the DBS lead is implanted stereotactically into the target nucleus (see the image below)

  • During the second stage, the DBS lead is connected subcutaneously to an implantable pulse generator (IPG), which is inserted into a pocket beneath the skin of the chest wall, like a pacemaker

    Implantation of the deep brain stimulation (DBS) l Implantation of the deep brain stimulation (DBS) lead.

In DBS for Parkinson disease (PD), as in most stereotactic movement disorder procedures, the first stage is performed with the patient awake to allow monitoring of neurologic status. The stereotactic headframe (see the first image below) is applied to the patient's head on the morning of the procedure, and a targeting MRI is performed (see the second image below).

The stereotactic headframe is applied at the start The stereotactic headframe is applied at the start of surgery. The MRI-localizing box is attached to the frame only during the targeting MRI. The localizer defines the working volume of the frame and provides the reference coordinate system from which the target coordinates are derived.
Axial, fast spin-echo inversion recovery MRI at th Axial, fast spin-echo inversion recovery MRI at the level of the posterior commissure. The typical target for placing a thalamic stimulator is demonstrated (cross-hairs).

A combination of microelectrode recording (MER) and macroelectrode stimulation is used to refine the desired target physiologically (see the images below). Once the DBS lead has been implanted, it is anchored to the skull with a burr hole cap.

Intraoperative physiological monitoring equipment. Intraoperative physiological monitoring equipment. The surgical team, consisting of a neurosurgeon, a neurologist, and a highly trained neurophysiologist (pictured), employs single-cell microelectrode recording to define the surgical target physiologically.
Insertion of an electrode during deep brain stimul Insertion of an electrode during deep brain stimulation for Parkinson's disease.

After DBS electrode implantation, CT is performed to confirm no bleeding in the brain and MRI to confirm proper electrode placement. One or two weeks later, the patient will undergo the second stage of surgery – implantation of IPG under general anesthesia.

Postoperative coronal MRI demonstrating desired pl Postoperative coronal MRI demonstrating desired placement of bilateral subthalamic nuclei-deep brain stimulation (STN-DBS) leads.

The electrode is thin (approximately 1.3 mm in diameter) and flexible, so that it moves atraumatically with the brain. The device can be programmed to deliver stimulation in monopolar or bipolar fashion, employing any of the 4 electrode contacts, alone or in combination (see the image below).

The deep brain stimulating lead is equipped with 4 The deep brain stimulating lead is equipped with 4 electrode contacts, each of which may be used, alone or in combination, for therapeutic stimulation.

After proper patient selection and accurate lead location, competent programming of the implanted device is essential for optimizing DBS therapy. After approximately 2 weeks, therapeutic electrical parameters can be set by using a transcutaneous programmer (see the image below).

Deep brain stimulation parameters can be adjusted Deep brain stimulation parameters can be adjusted at any time using a transcutaneous programmer.

The primary goals of programming are to maximize symptom suppression and minimize adverse effects; minimizing battery drain is a secondary goal. These goals can be achieved by following a systematic, multistep approach. [19] The ability to deliver either monopolar or bipolar stimulation using any of the 4 electrode contacts (or combinations thereof) offers the treating physician a great deal of therapeutic flexibility, permitting customized stimulation for each patient. Moreover, stimulation parameters can be adjusted at any time if needed.

DBS provides monopolar or bipolar electrical stimulation to the targeted brain area. The amplitude, frequency, and pulse width of stimulation can be adjusted to control symptoms and minimize the adverse events. The patient can turn the stimulator on or off using an Access Review Therapy Controller or a handheld magnet. The usual stimulation parameters are an amplitude of 1–3 V, a frequency of 135–185 Hz, and a pulse width of 60–120 msec.

It has been suggested that DBS works by resetting abnormal firing patterns in the brain and thereby bringing about a reduction in parkinsonian symptoms. The response from DBS is only as good as the patient’s best “on” time, with the exception of tremor, which may show greater improvement than is seen with medication; however, after DBS, the amount of daily “on” time is significantly extended. DBS requires regular follow-up for adjustment of stimulation parameters to account for symptom changes due to disease progression and adverse effects.

Traditional DBS surgery is performed while patients stay awake. With improvement in high-resolution brain imaging, interventional MRI-guided DBS lead implantation (asleep DBS) has been developed, in which anatomic verification of target can be performed intraoperatively. [20] Moreover, study has shown that microelectrode recording (MER) and intraoperative MRI are both effective to ensure adequate electrode placement in DBS surgery. [21] Other advances include the mini-frame, robot (Rosa)-assisted stereotactic systems for DBS surgery, and rechargeable pulse generators. Currently, directional DBS with new electrode designs that have the capability to steer stimulation current for better and specific targeting, and closed loop DBS systems are under development.


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