Robotic Deep Brain Stimulation (R-DBS)-“Awake” Deep Brain Stimulation Using the Neuromate Robot and O-Arm
Correspondence Address: Source of Support: None, Conflict of Interest: None DOI: 10.4103/0028-3886.302450
Source of Support: None, Conflict of Interest: None
Keywords: NeuroMate robot, Parkinson's disease, robotic deep brain stimulation
Deep Brain Stimulation (DBS) is an effective surgical technique used to improve the motor symptoms of Parkinson's disease. One of the key determinants of successful patient outcomes following DBS is the accurate placement of the DBS electrode within the sensorimotor region of the target nucleus.
Recently, several groups have reported on the use of surgical robots to perform DBS surgery.,, Robots in the operating room enhance surgeon capabilities by increasing the safety, accuracy, and precision of DBS surgery. According to the classification provided by Nathoo et al., here we describe the use of a supervisory-controlled robotic system, the Neuro|Mate™ (Renishaw plc, Wotton-under-Edge, United Kingdom) to accurately deliver a DBS electrode to target. The software associated with this robot, Neuro|Inspire (Renishaw plc, Wotton-under-Edge, United Kingdom) is used to plan entry, trajectory and target. We feel that the use of a surgical robot during DBS mitigates the potential errors that can be introduced during manual manipulation of the arc and ring associated with frame-based stereotactic techniques. In addition, the rigid positioning provided by the robot arm allows the creation of smaller (3.2 mm), yet highly accurate entry points. We use intraoperative imaging in the form of O-arm 3D CT (Medtronic Inc., Dublin, Ireland), in combination with the Neuro|Mate™ in order to confirm accurate electrode placement prior to skin closure.
Objective: To illustrate the surgical technique of deep brain stimulation using robotic assistance.
Several weeks prior to surgery, the patient undergoes Magnetic Resonance Imaging (MRI) of the brain under general anesthesia on a 3T Siemens Skyra (Erlangen, Germany). The dorsolateral, sensorimotor STN is targeted initially using standard anterior commissure-posterior commissure (AC-PC) coordinates. The targeting is further fine-tuned using T2 and Fast Gray Matter Acquisition T1 Inversion Recovery (F-GATIR) sequences following direct visualization of the nucleus.
On the day of surgery, the patient undergoes intravenous sedation. The patient's head is placed in a Cosman-Roberts-Wells (CRW) frame (Integra Radionics, Burlington, MA). The patient is then transferred supine onto the operating room table, and the CRW frame is attached to the Neuro|Mate™ robot base. The O-arm mobile x-ray system is positioned around the patient's head. A scalp staple is placed as a sample target to verify the robot's accuracy. The Luminant® reference is attached to the CRW frame and an O-arm spin is obtained. The images obtained are registered to stereotaxic space and merged to the preoperative planning MRI. The robot's accuracy is confirmed by driving the robot laser tool holder to the sample target.
The entry points are marked and the scalp is sterilely prepped and draped. The O-arm and the robot are sterilely draped as well. A curvilinear incision is made and a subgaleal pocket in the parieto-occipital region is created to house the booted distal portion of the DBS electrode. The robot is driven as close to the entry point as possible, and a 3.2 mm twist drill bur hole is made. The dura and initial 1-2 cm of cortex is pierced using a 1.6 mm Steinman pin.
The FHC (Bowdoin, Maine) Stardrive™ is secured to a custom bushing. The FHC microelectrode is placed 10 mm above target for electrophysiological recording and test stimulation to confirm accurate targeting. The macroelectrode is placed to target using the Stardrive™. Monopolar review of the four contacts of the macro-electrode is performed for therapy and side effects. The StarDrive™ and guide cannula are removed carefully around the macro-electrode while obtaining multiple spot x-rays to ensure there is no movement of the macro-electrode from the intended target. The macro-electrode is then secured to the skull using titanium plates armored with a silicone anchor. A final O-arm spin is obtained to confirm accurate targeting. The wounds are thoroughly irrigated and closed in standard fashion.
Video Link: https://youtu.be/uytnYw9Rurw
Video timeline with audio transcript:
Audio transcript for video
:02-:12: “This video illustrates the surgical technique used to place deep brain stimulation (DBS) electrodes using the Neuro|Mate™ Robot and the O-arm intraoperative mobile X-ray system”.
:14-:25: “The patient's consent has been taken and due precautions have been taken to anonymize the patient's identity. The following is purely a teaching video and is not meant to promote any doctor or hospital.”
:25-1:05: “Case—this is a 59 year old woman with tremor-predominant Parkinson's Disease (PD) of 5 years’ duration. The diagnosis of PD was confirmed with a DAT scan. Her preoperative MRI was normal. She had preoperative UPDRS testing with 39% change noted with on/off testing. Detailed preoperative physical therapy, occupational therapy, speech therapy, and neuro-psychometric assessments were also completed to assess candidacy for DBS surgery. Her case was presented at our multidisciplinary movement disorders surgery conference, and the patient was deemed to be a good candidate for bilateral subthalamic nucleus (STN) deep brain stimulation surgery.”
1:05-1:19: “DBS Planning MRI is performed several weeks prior to surgery under general anesthesia on a Siemens Skyra 3T system. Volumetric T1 with contrast, T2, and F-GATIR sequences are obtained.”
1:19-1:30: “Target Planning”
1:30-2:13: “The entries, trajectories, and targets are planned using Neuro|Inspire™, the software package associated with the Neuromate Robot. As can be seen here, the left subthalamic nucleus was targeted with AC-PC coordinates of 12 mm lateral, 4 mm posterior, and 4.9 mm inferior to the mid-commisural point. The objective here is to target the dorsolateral, sensorimotor portion of the STN. The cortical entry point is through the middle frontal gyrus at or just anterior to the level of the coronal suture. The right STN AC-PC coordinates as can be seen are 11.6 mm lateral, 4 mm posterior, and 4.9 mm inferior to the mid-commisural point.”
2:13-2:16: “Patient Positioning”
2:16-3:00: “The patient's hair is clipped and a scalp block using a 50/50 mix of bupivacaine and lidocaine is performed. Additional local anesthetic is used to infiltrate the pin sites. A CRW frame is then affixed to the patient's skull. The patient is then placed supine at zero degrees on the operating room table. The CRW frame is attached to the NeuroMate robot base via an adapter. The OR table is lowered to ensure the patient's airway is in optimal position. The luminant reference is affixed to the CRW frame after a single skin staple is placed on the scalp. This picture illustrates final positioning prior to registration.”
3:04-4:02: “The O-arm is brought onto the field and is positioned for intraoperative imaging. The Luminant reference must be adequately visualized on both AP and Lateral spot views. An O-arm spin is performed. The O-arm CT containing the Luminant fiducials is registered to the robot stereotaxic space and the CT itself is merged with the preoperative MRI. The previously placed skin staple is used as a sample target to verify the robot's accuracy. The Luminant fiducial can also be seen on this image. A laser tool holder, now attached to the robot arm, is driven to the target. As can be seen here, the laser is pointing to the medial edge of the staple, confirming excellent accuracy.”
4:02-4:24: “The robot is now driven with the laser to point to the entry points on the scalp. Entry points are then marked with a permanent marker.”
4:27-4:53: “The robot arm is draped with a custom drape that allows separation of the nonsterile portion from the sterile robot tool holder. The robot base is draped sterilely with a split sheet. One can see that curvilinear incisions are planned for the entry points. The O-arm and surgical field is covered with Ioban antimicrobial film drape.”
4:53-4:58: “Incision to setup of microelectrode recordings”
4:58-5:43: “Planned incision lines are infiltrated with a 50/50 mixture of lidocaine and bupivacaine. Incision is made through the pericranium and a periosteal elevator is used to create a subgaleal pocket in the region around the incision as well as in the parieto-occipital region for the DBS electrode wiring and connectors, respectively. Two titanium dog-bone plates are affixed in the vicinity of the planned skull entry point. Each of these titanium dog-bone plates is armored with a silicone anchor in order to pad the fixation of the DBS electrode. The blue dot marks the skull entry point.”
5:43-6:11: “A 3.3 mm bushing is inserted into the robot tool holder. This bushing will accommodate a 3.2 mm drill bit. The robot arm is brought as close to the entry point as possible to minimize drill distance, and skiving. The robot can usually be brought about 150-155 mm from target. Drilling is performed using an electric hand drill using an in and out technique, again in order to minimize skiving and entry point targeting error.”
6:11-6:34: “Next, a 1.8 mm bushing is inserted into the robot tool holder. This bushing accommodates a 1.6 mm Steinman pin, which is used to pierce the dura and make a path for the guide tube through the initial 1-2 cm of the trajectory through the cortex. Bovie cautery is used to coagulate the dura using the Steinman pin.”
6:34-7:44: “A custom bushing that can accommodate the FHC Stardrive™ is inserted into the robot tool holder. The Stardrive™ is inserted into the bushing and secured in place with a screw.
The Stardrive™ motor is then attached. The insertion guide tube is placed 20 mm above target and the inner portion of the guide tube is removed, and replaced with a cannulated inner portion that can accommodate the microelectrode. Fibrin glue is sprayed around the skull entry point to minimize CSF loss and brain shift. The microelectrode is inserted and recordings are undertaken beginning at 10 mm above target.”
7:44-8:13: “Microelectrode Recordings. The objective is to confirm accurate targeting of the dorsolateral, sensorimotor portion of the STN with good somatotopy. This part of the video shows portions of recording of both the right as well as the left STN. As can be seen here, the patient had improvement in preoperative symptoms, which was felt to be the result of a microlesion effect as well as test microstimulation.”
8:13-9:09: Satisfied with MER recordings along the initial track, a 3389 Medtronic DBS macroelectrode was placed at target using the Stardrive™ lead holder. Monopolar review of each of the 4 contacts was performed to ensure good therapy without side effects. A piece of tape is placed on the O-arm screen and the tip of the macro-electrode is marked on the tape prior to manipulation of the macroelectrode, and spot x-rays are obtained until after the macroelectrode is securely affixed to the skull via the previously placed armored titanium plates. The inner stylet of the macroelectrode is first removed, and the guide tube is carefully removed around the macroelectrode. Eventually, the stardrive is removed and the robot arm is moved to the “park position.” Most importantly, the assistant holds the macroelectrode with a bayoneted forceps at its exit site from the skull. Multiple spot x-rays are obtained using the O-arm to ensure the macro-electrode is not inadvertently dislodged.
9:09-9:39: Prior to incision closure, an O-arm spin is obtained to confirm accurate targeting. As can be seen here, the macro-electrode has been placed accurately, mirroring the intended trajectory and target. The distal ends of both the right and left-sided macro-electrodes are secured to a boot and passed into the parieto-occipital pocket created previously. Wounds are thoroughly irrigated with antibiotic impregnated sterile water. The scalp incisions are closed in standard fashion.
9:39-10:08: The patient underwent initial programming at her 4 week postoperative visit. At her 6 week postoperative visit, as can be seen here, the patient has a significant resting tremor with therapy turned off, and she enjoys substantial improvement in tremor with DBS therapy turned on.
Outcome: There were no immediate complications from placement of DBS electrodes. The patient had good intraoperative therapeutic response to test stimulation without limiting side effects. Postoperative CT scan did not show evidence of hemorrhagic complications. As can be seen in the video, the patient has had a good therapeutic response to DBS surgery at the 6 week postoperative visit.
Pearls and pitfalls
Preoperative MRIs done under general anesthesia provide high quality images for direct visualization of target nuclei. Performing these studies well in advance of the day of surgery allows careful target and trajectory planning.
On the day of surgery, in addition to anesthetizing the pin sites, a scalp field block helps to minimize incisional and pin site pain. After the patient's head is affixed to the robot via the CRW frame, and the robot is locked, the operating table is locked and unplugged to prevent inadvertent movement of the bed while the patient's head is immobilized.
Securing the armored titanium plates with only one end of the plate fixed to the skull soon after the scalp flap is created allows for easily securing the DBS macro-electrode at the final stages of the procedure.
Drilling the entry point with the robot arm as close to the skull as possible minimizes entry point targeting error. The use of a Steinman pin to create an initial path for the guide tube also helps to minimize targeting error.
The advantage of having the O-arm draped sterilely is that imaging can be performed easily at any stage of the procedure to verify targeting.
If MER recordings suggest altering the targeting in a particular direction (i.e. medially with a VIM target when capsular effects are noted), this can usually be performed by re-orienting the robot to the new target using the robot software, without modifying the entry point or having to convert the 3.2 mm twist drill to a larger, 14 mm bur hole.
One of the most critical steps in the procedure is to ensure the macro-electrode remains at the intended target as the StarDrive is removed. Following monopolar review, and impedance check, and with the guide tube still in place around the macro-electrode, removing the inner stylet of the macro-electrode minimizes any movement of the distal portion of the macro-electrode. As shown in the video, multiple spot x-rays should be taken to ensure there is no migration of the macro-electrode during disassembly of the Stardrive and fixation of the electrodes to the skull.
Final O-arm spin should be performed prior to skin closure in the event a significant error in targeting is identified that would require removal and revision of the electrodes.
Surgical technique and accuracy
To rationalize the adoption of any new surgical technology such as intraoperative robotics, one must be able to realize not only a significant enhancement in safety and efficiency, but ultimately also in patient outcomes. While a significant improvement in patient outcomes using R-DBS when compared with conventional DBS has not yet been reported in the literature, some groups have reported on the high degree of accuracy and safety afforded by these techniques.
Preliminary reports suggest that R-DBS may be more accurate than conventional DBS due to, among other factors, a decreased reliance on manual adjustments. Recently, the Bristol group published the largest series of Robotic DBS performed under “Asleep” technique with the Neuro|Mate™. They reported a mean radial displacement of 0.6 +/- 0.33 mm and a mean 3-dimensional vector error of 0.78 +/- 0.37 mm. They report a multi-step approach of serial dilation of the cortical entry point and trajectory with customized guide tubes to ensure a high degree of accuracy. Similarly, Von Langsdorff et al. reported an in vitro application accuracy of 0.44 +/- 0.23 mm and in vivo application accuracy of 0.86 +/- 0.32 mm using the Neuro|Mate™. Liu et al., using the ROSA® (Zimmer Biomet, Warsaw, Indiana) robot reported a mean radial error of 0.88 +/- 0.04 mm DBS lead placement error measured on postoperative CT scans.
The use of intraoperative O-arm CT is now an established method of verifying accuracy and is an extremely useful adjunct during R-DBS. Images can be obtained during any stage of the procedure without the need for patient or O-arm movement.
While every aspect of the DBS surgical workflow may potentially add error which is cumulative, with the end result being the degree of accuracy of the final DBS lead position, the surgeon must be meticulous in minimizing error at every stage. In this respect, the addition of robotics in DBS circumvents the need for manual adjustments associated with frame-based techniques. One additional source of error is with regard to image fusion. In a study comparing image fusion accuracy, Geevarghese et al. report that Neuro|Inspire software has the highest accuracy compared with other commonly available planning software. Performing the procedure with the patient supine at 0 degrees also helps to minimize brain shift and targeting error.
Awake vs. Asleep
The question of whether to place DBS electrodes with the patient “awake” with neurophysiological testing or under general anesthesia is currently a topic being intensely debated., While the case discussed in this work was performed with the patient awake, we have also used the Neuro|Mate™ with the patient under general anesthesia to accurately place DBS electrodes when we have felt that the patient would not tolerate an awake procedure, or when awake testing is not necessary. As imaging and DBS surgical techniques and technology improve, we believe that more centers will perform DBS under general anesthesia, and the use of robotics under these circumstances can be extremely useful in improving targeting accuracy, especially when no testing confirmation for efficacy or side effects is possible.
The use of a surgical robot is an extremely useful tool for the high accuracy required during the placement of DBS electrodes. The surgical workflow aims to minimize cumulative error. As more centers report on the safety, accuracy, precision, and efficiency associated with the use of R-DBS, we feel this technology will be more widely integrated into the DBS workflow.
The author would like to thank Dr. Chen Wu (Thomas Jefferson, University Hospital), Prof. Tipu Aziz (University of Oxford), Drs. Suneil Kalia and Mojgan, Hodaie (University of Toronto), Prof. Harith Akram (Queen Square, London), Prof. Steven Gill, (Bristol Southmead Hospital) Prof. Denys Fontaine (Centre Hospitalier Universitaire de Nice), Prof. Emmanuel Cuny (CHU Hopitaux de Bordeaux) and Dr. Phil Starr (University of California, San Francisco) for their teaching and support as we developed our surgical technique Lastly, this work would not have been possible without the immense support and encouragement of the entire neurosurgical team at Riverside Methodist Hospital.
A full and detailed consent from the patient has been taken. The patient's identity has been adequately anonymized. If anything related to the patient's identity is shown, adequate consent has been taken from the patient.
Financial support and sponsorship
The author hereby certifies that the work shown here is genuine, original and not submitted anywhere, either in part or full. I transfer the full rights of the video to Neurology India. All the necessary permissions from the patient, hospital and institution has been taken for submitting this video to Neurology India.
Conflicts of interest
The author has accepted travel funding from Renishaw and Medtronic to observe surgeries at outside institutions.