Stentrode · Grey Matter

The Stentrode is Synchron's brain-computer interface delivered through the blood vessels: a stent carrying electrodes is threaded up from the jugular vein into a large vein lying against the motor cortex, where it records the cortex's activity without any opening in the skull.

Stentrode. The Stentrode is Synchron's brain-computer interface delivered through the blood vessels: a stent carrying electrodes is threaded up from the jugular vein into a large vein lying against the motor cortex, where it records the cortex's activity without any opening in the skull.

The procedure borrows from interventional cardiology and neuroradiology. A catheter enters the internal jugular vein in the neck and is steered into the superior sagittal sinus, the vein that runs along the top of the brain between the hemispheres, right next to the motor cortex. There the stent expands against the vessel wall, carrying 16 platinum-iridium electrodes; a lead runs back down the vein to a receiver implanted in the chest, which sends the signals wirelessly out of the body. The first demonstration, in sheep, was published in 2016, and the stent became incorporated into the vessel wall over weeks.

It records through a vessel wall. The electrodes sit outside the brain, so they pick up field potentials of populations, as surface electrodes do, with no single-neuron spikes and fewer channels than penetrating arrays.

The procedure is the point. Placement needs a catheter lab and no craniotomy, which could make implantation accessible to far more hospitals.

It is in human trials. Four people were implanted in Australia first; in the US COMMAND study, six people with severe paralysis received it, with no serious device-related adverse events reported, and used it to text, email and browse by thinking of moving.

Its output is coarse and practical. Sixteen electrodes outside the brain support a few reliable commands (a click, a selection) rather than continuous fine control, and in the early studies these were combined with other inputs such as eye tracking to run ordinary devices.

Questions: What does a participant agree to when an implant is designed to stay in the body? A stent electrode is incorporated into the wall of the vein over the following weeks, as vascular stents are, so it is meant to remain for life even if the study ends or the device stops being used. Consent therefore covers more than the procedure: living with an inactive implant, the chest unit and its lead, and the question of who will support the hardware years later. Reviews of neural device trials ask for these post-trial plans to be agreed before implantation, because the participant bears the consequences long after the research is published. How does Synchron's Stentrode reach the motor cortex without opening the skull? It travels through the veins. A catheter enters the internal jugular vein in the neck and is steered up into the superior sagittal sinus, a large vein along the top of the brain that lies against the motor cortex, where a self-expanding stent carrying 16 electrodes is released against the vessel wall. A lead runs back down the vein to a unit in the chest that transmits the signals wirelessly, and the whole procedure resembles placing a stent in the heart more than brain surgery.