Stentrode: revision 1 to 2 — Future Human Wiki

Revision 1

Revision 2

trl: 6

categories: ["cybernetics"]

tags: ["bci", "endovascular", "implants", "paralysis", "als", "neurotechnology"]

summary: "An endovascular brain–computer interface in which a stent carrying electrodes is delivered through the jugular vein into a vein overlying the motor cortex."

summary: "An endovascular brain-computer interface in which a stent carrying electrodes is delivered through the jugular vein into a vein overlying the motor cortex."

updated: "2026-07-27"

updated: "2026-10-29"

humanEvidence: "A small number of people with severe paralysis, mostly from ALS, have used the implant for discrete computer control over months to years; the published safety series covers four Australian participants."

humanEvidence: "A small number of people with severe paralysis, mostly from ALS, have used the implant for discrete computer control over months to years; the published safety series covers four Australian participants."

access: "Investigational only: implants have been placed solely within the SWITCH and COMMAND feasibility studies at a handful of centres, with no market authorisation anywhere and nothing on sale."

access: "Investigational only: implants have been placed solely within the SWITCH and COMMAND feasibility studies at a handful of centres, with no market authorisation anywhere and nothing on sale."

reversibility: "difficult"

}

```

**Stentrode** is a brain–computer interface built into a self-expanding stent. Rather than opening

**Stentrode** is a brain-computer interface built into a self-expanding stent. Instead of opening

the skull, a neurointerventional radiologist threads the device through the jugular vein and into

the skull, a neurointerventional radiologist threads the device through the jugular vein into the

the superior sagittal sinus, the large vein running along the midline of the brain, where it

superior sagittal sinus, the large vein running along the midline of the brain, where it expands

expands against the vessel wall directly above motor cortex. Electrodes on the stent record cortical

against the vessel wall directly above motor cortex. Electrodes on the stent record cortical

activity through the vein wall; a lead runs under the skin of the neck to a telemetry unit implanted

activity through the vein wall, and a lead runs under the skin of the neck to a telemetry unit

in the chest, which transmits wirelessly to an external computer.

implanted in the chest, which transmits wirelessly to an external computer.

The design trades signal quality for surgical accessibility. With sixteen electrodes

The design gives up signal quality in exchange for surgical accessibility. Its sixteen electrodes

recording population-level activity rather than individual neurons, the Stentrode captures far less

record population-level activity rather than individual neurons, so the Stentrode captures far less

information than a penetrating [[utah-array]]. It also requires no craniotomy, uses catheter

information than a penetrating [[utah-array]]. It also needs no craniotomy, relies on catheter

techniques that thousands of clinicians already practise, and does not place foreign material in

techniques that thousands of clinicians already practise, and places no foreign material in the

the brain parenchyma.

brain parenchyma.

## How it works

The stent is a nitinol mesh of the type used for treating venous stenosis, with electrode contacts

The stent is a nitinol mesh of the type used to treat venous stenosis, with electrode contacts

mounted on its struts. Delivered collapsed inside a catheter, it self-expands on release and

mounted on its struts. It is delivered collapsed inside a catheter, self-expands on release, and

presses the electrodes against the endothelium. Over the following weeks the vessel wall

incorporates the stent — the same endothelialization that makes vascular stents stable, and which

incorporates the stent. This is the same endothelialization that makes vascular stents stable, and

here fixes the electrodes in position without sutures or bone anchors.

here it fixes the electrodes in position without sutures or bone anchors.

Signals reach the electrodes through the vein wall, which acts as a spatial filter. The result

Signals reach the electrodes through the vein wall, which acts as a spatial filter. What the device

resembles what surface arrays record in [[ecog-interfaces]] but with fewer, larger, and more

records resembles the output of the surface arrays used in [[ecog-interfaces]], but with fewer,

distant contacts: local field potentials and band power, not action potentials. Participants

larger and more distant contacts: local field potentials and band power rather than action

generate control signals by attempting movements — typically of a foot or ankle, since the leg

potentials. Participants generate control signals by attempting movements, typically of a foot or

representation of motor cortex sits along the midline nearest the sagittal sinus — and a decoder

ankle, since the leg representation of motor cortex sits along the midline nearest the sagittal

maps the resulting change in band power to a discrete output the company calls a digital motor

sinus. A decoder maps the resulting change in band power to a discrete output that the company calls

output, essentially a click.

a digital motor output, which is essentially a click.

Because one reliable click is not enough to run a computer, the system is used with eye tracking or

One reliable click is not enough to run a computer, so the system is used with eye tracking or

switch-scanning software: gaze selects the target, the neural signal confirms it. This

switch-scanning software: gaze selects the target and the neural signal confirms it. The division of

division of labour is deliberate. The [[neural-decoding]] problem is much easier when the decoder

labour is deliberate. The [[neural-decoding]] problem is much easier when the decoder only has to

only has to distinguish attempted movement from rest.

distinguish attempted movement from rest.

```compare

{

"rows": [

{ "label": "Procedure", "values": ["Catheter via jugular vein", "Craniotomy and cortical insertion"] },

{ "label": "Signal type", "values": ["Local field potentials", "Single-unit spikes and LFP"] },

{ "label": "Electrodes", "values": ["16", "96–1,024"] },

{ "label": "Electrodes", "values": ["16", "96-1,024"] },

{ "label": "Accessible cortex", "values": ["Tissue adjacent to large veins", "Any surgically reachable area"] },

    { "label": "Demonstrated output", "values": ["Discrete selection", "Continuous multi-dimensional control, speech"] },

    { "label": "Demonstrated output", "values": ["Discrete selection", "Continuous multi-dimensional control, speech"] },

{ "label": "Removal", "values": ["Difficult once endothelialized", "Possible, at the cost of repeat surgery"] }

## Development history

The concept came from Thomas Oxley and Nicholas Opie's group at the University of Melbourne, who

The concept came from Thomas Oxley and Nicholas Opie's group at the University of Melbourne. They

reasoned that the cerebral venous system already reaches within millimetres of cortex and that

reasoned that the cerebral venous system already reaches within millimetres of cortex, and that

catheter delivery would avoid the complication profile of open neurosurgery. A 2016 report in sheep

showed that an endovascular array could record cortical activity chronically, with signal quality

that remained usable as the stent incorporated into the vessel wall.[^oxley2016] [[synchron]] was

that remained usable as the stent was incorporated into the vessel wall.[^oxley2016] [[synchron]]

founded to commercialize the device.

was founded to commercialize the device.

The first-in-human study, SWITCH, implanted the device in four participants with severe paralysis,

mostly from amyotrophic lateral sclerosis, at the Royal Melbourne Hospital beginning in

mostly from amyotrophic lateral sclerosis, at the Royal Melbourne Hospital beginning in 2019. The

2019. The published results reported no device-related serious adverse events, no vessel occlusion,

published results reported no device-related serious adverse events and no vessel occlusion, and

and participants able to use the system for texting, email, and online banking in combination with

participants were able to use the system with eye tracking for texting, email and online

eye tracking.[^oxley2021][^mitchell2023] A United States early feasibility study, COMMAND, began in

banking.[^oxley2021][^mitchell2023] A United States early feasibility study, COMMAND, began in 2022

2022 with the first implant at Mount Sinai in New York, and the company has reported that its

with the first implant at Mount Sinai in New York, and the company has reported that its primary

primary safety endpoint was met.

safety endpoint was met.

```timeline

[

  { "year": "2016", "title": "Chronic recording in sheep", "text": "An endovascular stent-electrode array records cortical activity for months, published in Nature Biotechnology." },

  { "year": "2016", "title": "Chronic recording in sheep", "text": "An endovascular stent-electrode array records cortical activity for months, published in Nature Biotechnology." },

  { "year": "2019–2021", "title": "SWITCH first-in-human study", "text": "Four participants with severe paralysis receive implants in Australia; the trial reports no device-related serious adverse events." },

  { "year": "2019-2021", "title": "SWITCH first-in-human study", "text": "Four participants with severe paralysis receive implants in Australia; the trial reports no device-related serious adverse events." },

  { "year": "2022", "title": "First US implant", "text": "The COMMAND early feasibility study begins at Mount Sinai under an FDA investigational device exemption." },

  { "year": "2022", "title": "First US implant", "text": "The COMMAND early feasibility study begins at Mount Sinai under an FDA investigational device exemption." },

  { "year": "2023–2025", "title": "Integration with consumer platforms", "text": "Synchron demonstrates control of commercial voice assistants and announces work with major computing platforms on native input support for neural devices." }

  { "year": "2023-2025", "title": "Integration with consumer platforms", "text": "Synchron demonstrates control of commercial voice assistants and announces work with major computing platforms on native input support for neural devices." }

]

```

## Clinical results and limits

What participants have demonstrated is real but narrow: reliable discrete selection sufficient for

Participants have demonstrated something real but narrow: reliable discrete selection sufficient for

communication and device control, sustained over months to years, in people who otherwise depend on

eye-gaze systems that fail when eye movement deteriorates. That is a meaningful clinical benefit

eye-gaze systems that fail when eye movement deteriorates. For a population with few options, that

for a population with few options.

is a meaningful clinical benefit.

What has not been demonstrated is continuous high-dimensional control. Nothing resembling the

Continuous high-dimensional control has not been demonstrated. No endovascular device has produced

robotic-arm work or the fluent [[speech-neuroprosthesis]] results obtained with penetrating

anything resembling the robotic-arm work or the fluent [[speech-neuroprosthesis]] results obtained

arrays[^willett2023] has come from an endovascular device, and there is a physical reason to expect

with penetrating arrays,[^willett2023] and there is a physical reason to expect the gap to persist.

that gap to persist. Speech motor cortex lies on the lateral surface of the brain, far from the sagittal

Speech motor cortex lies on the lateral surface of the brain, far from the sagittal sinus. The

sinus; the venous anatomy determines which cortex is reachable, and it does not reach everywhere.

venous anatomy determines which cortex is reachable, and it does not reach everywhere. Driving a

Driving a wheelchair or a powered [[exoskeleton]] would likewise require continuous multi-axis

wheelchair or a powered [[exoskeleton]] would likewise require continuous multi-axis control that a

control that a click cannot supply.

click cannot supply.

> [!debate] Bandwidth versus access

> Synchron's argument is that a device a vascular surgeon can implant in an ordinary catheter lab

> Synchron argues that a device a vascular surgeon can implant in an ordinary catheter lab scales to

> scales to a patient population that craniotomy never will, and that reliable simple control

> a patient population that craniotomy never will, and that reliable simple control covers most of

> covers most of the clinical need. Critics respond that sixteen field-potential channels cap the

> the clinical need. Critics respond that sixteen field-potential channels cap the device below the

> device below the applications that justify an implant at all, and that the comparison should be

> applications that justify an implant at all, and that the right comparison is with non-invasive

> against non-invasive eye trackers rather than against penetrating arrays.

> eye trackers rather than with penetrating arrays.

Other limitations follow from the vascular setting. The device is difficult to remove once the vein

wall has grown over it. Participants need antiplatelet therapy, at least initially, and venous

thrombosis or stenosis remains the principal safety concern even though the published studies did

not observe it. Long-term stability data extend to a few years across a small number of

not observe it. Long-term stability data extend to a few years in a small number of participants,

participants, which is not enough to characterize rare complications.

which is not enough to characterize rare complications.

## Strategy and context

Synchron has positioned the Stentrode against both invasive and non-invasive alternatives. Compared

with [[neuralink]] and other penetrating systems, it accepts a much lower ceiling in exchange for a

procedure that generalists can perform. Compared with [[non-invasive-neuromodulation]] and

scalp-electrode devices, it offers a stable, always-available signal that does not require setup or

scalp-electrode devices, it offers a stable signal that is always available, needs no setup, and is

tolerate hair and sweat artefacts.

not exposed to hair and sweat artefacts.

The company has also pursued integration with mainstream computing platforms, so that a neural

device appears to an operating system as an input source alongside touch and voice. If that

standardization takes hold, it would matter beyond any one device: the persistent complaint from

standardization takes hold, its effect would extend beyond any one device, because the persistent

users of assistive [[neuroprosthetics]] is that the hardware works and the software ecosystem does

complaint from users of assistive [[neuroprosthetics]] is that the hardware works and the software

not.

ecosystem does not.

## Outlook

The obvious next step is a pivotal trial in a defined indication — loss of communication in ALS

The obvious next step is a pivotal trial in a defined indication that could support market

being the clearest — that could support market authorization. No implanted BCI has cleared that

authorization, with loss of communication in ALS the clearest candidate. No implanted BCI has

bar anywhere, and the Stentrode's low channel count may actually help, because a simpler device

cleared that bar anywhere. The Stentrode's low channel count may help here, because a simpler device

with a simpler claim is easier to evaluate. The regulatory precedents that exist are for

with a simpler claim is easier to evaluate. The existing regulatory precedents are for stimulating

stimulating devices such as the [[cochlear-implant]] and [[deep-brain-stimulation]] systems, where

devices such as the [[cochlear-implant]] and [[deep-brain-stimulation]] systems, where the

the therapeutic claim is a change in symptoms rather than a measured rate of communication.

therapeutic claim is a change in symptoms rather than a measured rate of communication.

The unresolved technical question is whether channel count can grow. Multiple stents, longer arrays

extending further along the sinus, and improved electrode materials have all been proposed. Whether

extending further along the sinus, and improved electrode materials have all been proposed. It has

any of that lifts an endovascular interface out of the switch-like regime, or whether the vein wall

not been established whether any of these lifts an endovascular interface out of the switch-like

imposes a hard ceiling on what can be resolved, has not been established. As with every implanted

regime, or whether the vein wall imposes a hard ceiling on what can be resolved. As with every

neural device, the governance questions — data ownership, [[mental-privacy]], device support

implanted neural device, the governance questions arrive before the clinical ones are settled: data

obligations, the [[neurorights]] frameworks now emerging in several jurisdictions — arrive before

ownership, [[mental-privacy]], obligations to support the device, and the [[neurorights]] frameworks

the clinical ones are settled.

now emerging in several jurisdictions.

## See also