First US Stentrode implant heralds new field in neurointerventional surgery

first command implant
Shahram Majidi presenting at SNIS 2022

Following the first endovascular implantation of Synchron’s Stentrode brain-computer interface (BCI) device in the USA, physicians have highlighted the wider significance of this breakthrough case—not only in progressing a technology that stands to fulfil an unmet need for patients with severe paralysis, but also by illuminating new frontiers that may be on the horizon for neurointerventional surgery.

Synchron recently announced the successful completion of the first implant in its US COMMAND study, with lead clinical investigator Shahram Majidi (Mount Sinai Health System, New York, USA) delivering a detailed presentation of this case for the first time at the Society of NeuroInterventional Surgery’s (SNIS) 19th annual meeting (25–29 July, Toronto, Canada).

“This is an incredibly exciting milestone for the field, because of its implications and huge potential,” said Majidi, who performed this novel procedure at Mount Sinai. “The implantation procedure went extremely well, and the patient was able to go home 48 hours after the surgery.”

COMMAND, a prospective, open-label, single-arm, early feasibility study, is being conducted under what Synchron claims is the first investigational device exemption (IDE) awarded by the US Food and Drug Administration (FDA) to a company assessing a permanently implanted BCI. It is intended to assess the safety and efficacy of the company’s motor BCI technology platform, including the Stentrode device, in patients with severe paralysis—with the goal of utilising patient brain data to enable them to control digital devices hands-free and, ultimately, achieve improvements in functional independence.

“We are beyond excited to get to work with our patient, guiding them through the training process as they learn to use this device to live more independently and, most importantly, communicate with their family and friends,” said David Putrino (Mount Sinai Health System, New York, USA), principal investigator of the COMMAND study.

First COMMAND patient

Majidi began his presentation of this milestone procedure at SNIS 2022 by noting that more than five million people in the USA alone suffer from severe paralysis, with causes including stroke, trauma, neuromuscular disease and demyelination. The majority of these patients are completely dependent on caregivers to fulfil many of their basic daily needs, he added.

He also noted that the COMMAND study was set up to assess the Stentrode BCI device’s potential in improving functional independence for these patients by restoring neural signal transmission from the cerebral cortex and executing digital commands—with a planned enrolment of six consenting severe quadriparesis patients in total.

first command implant
Stentrode device

“Our first patient is a 67-year-old gentleman with severe quadriplegia from ALS [amyotrophic lateral sclerosis] on a ventilator,” Majidi reported, stating that pre-implant imaging included a magnetic resonance cerebral venogram and structural magnetic resonance imaging (MRI), which were used to ascertain patency of bilateral transverse sinuses and localisation of the premotor cortex on MRI. He further noted that the MRI markers were later co-registered into a live angiography and provided a “roadmap to ascertain accurate deployment of the device”.

Detailing the Stentrode implantation, Majidi said right internal jugular venous access was obtained to reach the ‘point of interest’ in the superior sagittal sinus. Once visual markers—corresponding to the location in which they intended to deploy the device—had been established on imaging, a 6Fr guide catheter and then a 4Fr preloaded delivery catheter carrying the Stentrode were advanced to the superior sagittal sinus next to the motor cortex.

“At this point, we pulled the guide catheter back to the proximal segment of the superior sagittal sinus, and carefully unsheathed the device while maintaining close visualisation of the target markers for precise deployment of the stent right next to the motor cortex,” Majidi told the SNIS audience. Postoperative three‑dimensional digital subtraction angiography (3D‑DSA) was then obtained to confirm patency of the superior sagittal sinus—and the position of the device in the intended location.

A subclavicular, subcutaneous pocket for implantation of an internal telemetry unit was created, and this unit was inserted and connected to an external device before intraoperative neuronal data were collected from the patient. Majidi reported that a postoperative X-ray confirmed the proper placement of the telemetry unit. “The patient was discharged within 48 hours and was placed on DAPT [dual antiplatelet therapy] for three months,” he added, also noting that the patient tolerated the procedure “extremely well”.

“The next step is to use AI [artificial intelligence] to obtain the electrocorticography signals from predefined attempted limb movements, and convert them to certain digital command outputs, so that the patient can have the freedom of controlling digital devices,” Majidi concluded.

Global physician reactions

William Mack

“The latest announcement from Synchron created significant excitement at the SNIS annual meeting and across the field of neurointerventional surgery,” SNIS past president William Mack (University of Southern California, Los Angeles, USA) told NeuroNews. “Enrolment of the first patient in the US COMMAND trial is an important step towards implementation of one of the most exciting advances our field has seen in decades. If this technology continues to progress, it could profoundly affect the lives of many of our patients and transform the field of neuroinerventional surgery.”

Mack—who disclosed that he is chair of COMMAND’s data safety monitoring board—also noted that the fact this BCI technology can be implanted via endovascular surgery is “very significant”, as minimally invasive access routes remove the need for direct implantation via craniotomy. “This is a breakthrough for the neurointerventional space; it indicates that we have only scratched the surface in terms of the types of procedures that can be performed through the cerebral vasculature,” he continued.

“Most of the procedures that we currently perform address pathologies directly related to blood vessels, such as aneurysms, arteriovenous malformations and stroke. However, application of this advanced technology demonstrates the ability to capture, process, and modulate neural signalling through minimally invasive techniques. Endovascular implantation of the Stentrode signifies an initial fusion of neurointerventional surgery and functional/restorative neuroscience—an important concept that could guide our field for years to come.”

Jens Fiehler

European Society for Minimally Invasive Neurological Therapy (ESMINT) president Jens Fiehler (University Medical Center Hamburg-Eppendorf, Hamburg, Germany) also spoke to NeuroNews to offer perspectives on this potentially “historic” study from the other side of the Atlantic. “The Stentrode technology represents a major hope for patients with severe paralysis and potentially a huge leap forward for treating this condition,” he said. “Unlike other options, the unique, minimally invasive approach for implanting this type of permanent BCI uses well-established vascular routes—which will make BCI technology accessible for more patients and allow a higher scale of usage, at an earlier time, to be achieved.

“The US COMMAND study will be a starting point for new treatment options the neurointerventional community can offer. We do not need to think very hard to come up with many more applications for a multitude of conditions and diseases. I am looking forward to getting this kind of technology in the hands of European neurointerventionists, making it available for European patients and—hopefully—starting an EU COMMAND study.”

Bruce Campbell (University of Melbourne, Melbourne, Australia), who earlier this year presented long-term safety data from four patients in the ongoing SWITCH trial at the American Academy of Neurology (AAN) annual meeting (2–7 April, Seattle, USA), echoed that this first US case is an “exciting step” towards restoring functionality for paralysed patients.

Bruce Campbell

“Synchron’s ongoing COMMAND trial, and subsequent first patient procedure at Mount Sinai Hospital, were made possible through the encouraging safety results from the SWITCH trial—which demonstrated that the Stentrode was safe in humans, stayed in place, and did not lead to blockage of the blood vessel in which the device was implanted,” he told NeuroNews. “These crucial early safety findings open the door to further trials and further enrolment.

“One of the key advantages of the Stentrode is its minimally invasive endovascular delivery into the superior sagittal sinus, compared to the craniotomy required for other BCI devices. This minimally invasive approach is unique in the BCI space and, with the rapidly growing community of experienced neurointerventionists who treat stroke, should enable faster application from clinic to real world—following approval from the FDA and other regulatory agencies.”

“The fusion of neuromodulation and neurointervention using Stentrode is an extremely exciting new field that is combining two of the most rapidly growing and successful minimally invasive techniques in the neurosciences,” Timo Krings (University of Toronto, Toronto, Canada) said, speaking to NeuroNews. “Not only does this technique—as Thomas Oxley [Synchron founder and CEO] so elegantly showed in his first publication—help us to record brain activity and thus act as a BCI, but it may also allow for less invasive neuromodulation in the future.

Timo Krings

“To this avail, our group recently investigated the relationship between targets of neuromodulation with both arterial and venous structures, enabling us to identify six potential DBS [deep brain stimulation] target sites in close proximity to either arteries or veins.” These findings were published in Brain Stimulation in 2020. “While there are still challenges to this approach,” Krings concluded, “the landmark work of Dr Majidi and the technology developed by Dr Oxley [make them] true trailblazers in the newly developed field of functional endovascular neurosurgery.”


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