In the more than 30 years that have passed since its introduction, deep brain stimulation (DBS) has been shown to be effective and safe for a growing number of diseases, such as depression and obsessive-compulsive disorder, as well as movement disorders such as Parkinson’s disease, dystonia, and essential tremor. As a result of population aging due to the increase in life expectancy, the number of patients requiring DBS implantation is increasing. These patients often require surgery or treatment for diseases other than the original disease that required DBS. Most diagnostic tests or procedures can damage the DBS system by various mechanisms, so clinicians unfamiliar with DBS have difficulty treating these patients. The purpose of this review is to summarize the knowledge necessary for patient management that will be useful for clinicians treating patients with DBS implantation.
Since the introduction of high-frequency unilateral thalamic stimulation by Benabid et al. [
Over the past 30 years since its introduction, more than 150,000 patients worldwide have been treated with DBS [
Patients with DBS implantation may require treatment for other diseases, but treatment may be limited because of the presence of the DBS system. DBS-related issues should be considered when considering treatment or surgery for other conditions. The purpose of this review is to summarize the knowledges necessary for patient management useful to clinicians treating patients with DBS implantation.
This article does not include any personal data. This article was exempt from IRB approval.
Current DBS systems consist of unilateral or bilateral intracranial electrodes, an implantable pulse generator (IPG) under the clavicle or axilla, and an extension wire connecting the electrodes to the IPG. The system delivers stimulation to the electrodes with an amplitude, pulse width, and frequency set by the clinician and the patient’s programming device.
Although DBS systems may look similar to the well-known implantable cardiac electronic devices (CIEDs) such as pacemakers and implanted defibrillators, they differ in mechanism of action, stimulation parameter, and method of operation. The CIEDs are usually more complex to neurostimulation system including DBS. Whereas program parameters are adjusted based on electrical feedback from the leads in CIEDs, neurostimulator provides continuous stimulation on the target region. As for stimulation parameter, neurostimulation uses higher frequency above 100 Hz and higher current, CIEDs uses lower frequency and lower current. DBS system can be turned off, but CIEDs cannot be turned off. In both systems, the function may be impaired by electromagnetic interference, which may lead to patient morbidity.
Previous DBS systems delivered current in a voltage controlled method by electrochemically induced changes in electrode impedance at the brain-electrode interface [
Patients who have DBS systems can safely undergo x-ray, diagnostic sonographic ultrasound, and computed tomography (CT) scans without additional management.
Magnetic resonance imaging (MRI) imaging of patients with DBS systems was previously absolutely contraindicated due to electromagnetic interactions. Problems caused by electromagnetic interactions include excessive heating of the DBS electrode tip due to the synthesis of the generated current, voltage induction proportional to the gradient pulse change over time, unintentional reprogramming of the IPG, image artifacts and distortion, and the functioning of the DBS system [
DBS manufacturers provide specific guidelines for the use of MRI in patients with DBS implantation. Boston Scientific has previously banned MRI scans after DBS, but states that the new system is only possible with a 1.5 T full body or head transmit/receive and RF quadrature only coil [
In situations where MRI cannot be replaced with CT or ultrasound, clinicians should always confirm with manufacture and check the following conditions prior to MRI scan (
Several medical devices used during surgery can interact with the DBS system, generating varying degrees of electromagnetic interference, potentially affecting the functioning of the neurostimulator. Even with the DBS system turned off, the conductivity of the metal case, leads and DBS device is maintained and current can pass through it.
Diathermy refers to the treatment via heat, with the generation of heat within body tissues from high-frequency electromagnetic currents to promote healing or aid in healing (
There have been case reports of serious brain damage due to heat generation at the tip of the DBS electrodes after using diathermy for dental treatment [
Electrocautery is a treatment in which heat is generated within a metal wire electrode by passing an electric current, typically used for tissue destruction to varying degrees, such as tissue hemostasis or removal of benign skin lesions (
The effect of electrocautery on cardiac pacemaker has been widely reported, and the effect on DBS can be estimated based on it. Cases of pacemaker failure due to electrocautery in an asynchronous mode resulting in hemodynamic instability have been reported [
Electrosurgery is generally used during surgery and includes various methods of cutting and coagulation as electrical energy flows from an active electrode to a distributed electrode (
In the unipolar mode, a current generated through an electrode enters the patient’s body and reaches a grounding pad. The presence of a conductive material between the monopolar device and the dispersive pad can redirect the path, which may inadvertently heat the tissue outside the surgical target due to the conversion of current to heat as energy passes through the tissue. Unipolar electrosurgery can induce thermal brain injury in patients with DBS system, so its use is not recommended by all DBS manufacturers. However, unlike diathermy, there are no experimental works or clinical trials for the use of electrosurgery.
Sometimes the surgeon may inevitably have to use monopole cauterization. In such a situation, the ground plane may be placed on the shoulder or occiput opposite the IPG [
In bipolar mode, the current only passes through the tissue between the two electrodes of the electrosurgical device, so the current spread is small. The bipolar mode of electrosurgery can be safely used in patients with implanted neurostimulators [
Electrical signals generated by the DBS system may affect the electrocardiogram (ECG) recording, so may need to be turned off to limit interference [
After the operation, the DBS system must be turned on again. In the case of general anesthesia, the recurrence of motor symptoms can be prevented by turning on the device before waking up from anesthesia [
The most frequent disease for which patients underwent DBS surgery is PD, and antidopaminergic drugs such as metoclopramide and dopamine depleting drugs should be avoided to avoid worsening symptoms [
Although diagnostic ultrasound can be safely performed in patients with an implanted nerve stimulator, the manufacturer recommends not placing the transducer directly over the implanted device. Therapeutic ultrasound depends on the output. There have been case reports that phacoemulsification for cataract removal was safely performed in patients with DBS [
The risk to the DBS system of radiation therapy can be assessed on the basis of reports of patients with CIED. In vivo and in vitro studies, ionizing radiation has been shown to affect voltage changes by causing permanent and/or potential damage due to ionization of semiconductors in circuits [
Because there are limited data on the safety of the laser use in patients with DBS, caution should be exercised prior to use and the risks should be fully discussed with the patient. When performing laser treatment, the DBS system should be turned off and the laser should be placed as far away from the system as possible [
Since external cardiac defibrillation and cardioversion are required for lifesaving purpose in emergent situations, its use should not be withheld in patients with DBS. There has been case report that 300 J of external cardioversion did not affect the DBS system [
When electroconvulsive therapy (ECT) is required in a patient implanted with DBS, safety concerns from heat generation at the DBS electrode due to induction of RF current by electric charge, functional disruption of the DBS system, and electrode displacement due to induced seizure activity should be considered. There have been case reports in which ECT was safely performed with the nerve stimulator turned off, the ECT electrode placed as far from the DBS electrode as possible, and using the lowest possible energy to induce seizures [
The implantation of pacemakers and/or implantable cardioverter defibrillators (ICDs) in patients using neurostimulators is not contraindicated. However, it requires the approach of a multidisciplinary team (e.g., cardiologist, DBS specialist, anesthesiologist) to optimize the patient’s clinical condition and adjust the settings of the underlying medical device as needed. Measures are needed to prevent potential interactions between devices. The pacemaker should be programmed for bipolar detection mode to avoid over-exaggeration and inappropriate response [
One of the things to be aware of when doing physical therapy in patients with DBS is Twiddler syndrome, which is a malfunction of the device due to damage to the IPG or lead [
Caution is required as overclocking may cause physical damage to the DBS device if the tissue is compressed too hard during mammography.
· X-rays, CT, and diagnostic ultrasound can be done relatively safely.
· If MRI cannot be substituted for other tests, it should be performed according to the recommendations by referring to the manufacturer’s guideline.
· The DBS system can interact with other medical device used during surgery by electromagnetic interference.
· If electrosurgery is required during surgery for hemostasis, use bipolar mode instead of unipolar mode.
· High-power ultrasound for therapeutic purpose should be avoided as much as possible. If absolutely necessary, make sure that the beam does not enter within 15 cm of the system.
· Radiation therapy using energy of 10 Gy or more can damage the DBS system.
Clinicians who manage patients with DBS should always pay attention to the device, and keep in mind that device can be damaged during procedure or surgery. A multidisciplinary approach involving DBS experts is often required. The DBS system should be reassessed to confirm if it works well.
No potential conflict of interest relevant to this article was reported.
Examples of medical devices that may affect the deep brain stimulation system. (A) Diathermy. (B) Electrocautery. (C) Electrosurgery.
Example of Twiddler syndrome, which is a malfunction of the device due to damage to the implantable pulse generator or lead.
Specific conditions to check prior to MRI scans in patients with a DBS system
Checklists prior to MRI scans in patients with a DBS system |
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• Only 1.5-T horizontal-bore MRI |
• Only a transmit/receive head coil |
• Calculation of the head SAR using correct patient weight |
• MRI parameters that allow an average head SAR≤0.1 W/kg |
• The gradient dB/dt≤20 T/s [ |
MRI: magnetic resonance imaging, DBS: deep brain stimulation, SAR: specific absorption rate.
Specific considerations before, during, and after MRI scans
Before MRI | Identify the implanted DBS system |
The model of the implanted DBS system | |
The presence of an implanted pocket adaptor | |
Implant status of the lead | |
Integrity of the system in terms of any suspicious wire breaks | |
Check for MRI contraindications | |
Receiver-only coil applied to the head or a transmission coil extending above the chest | |
Evidence of electrode or connecting wire breaks | |
Use of non-compliant parameters | |
Availability of safer diagnostic methods (e.g., computed tomography or sonography) | |
Other implants or limiting factors for which MRI is prohibited or contraindicated | |
Check the impedance of all electrodes and the battery voltage | |
Record the stimulation values | |
Turn off the neurostimulator | |
Set the stimulation amplitude to 0 V | |
Check the use of the appropriate MRI parameters | |
Limit the active scan time | |
Provide a sufficient explanation to the patient about possible complications and ask the patient to report any discomfort | |
Properly position the patient | |
During MRI | Avoid sedation for constant communication with the patient to identify early complications |
Warming sensation, pain, unpleasant stimulation, unusual sensations | |
Perform continuous patient monitoring | |
Check consciousness between MRI sequences | |
After MRI | Confirm the patient’s condition |
Have a DBS specialist check whether the stimulator is working | |
Turn on the device and reprogram the stimulator to its original settings |
MRI: magnetic resonance imaging, DBS: deep brain stimulation.
Risk classification of patients with CIEDs according to the cumulative dose and pacing dependence
<2 Gy | 2–10 Gy | >10 Gy | |
---|---|---|---|
Device-independent | Low risk | Intermediate risk | High risk |
Device-dependent | Intermediate risk | High risk | High risk |
CIED: implantable cardiac electronic device.