Sonorous Neurovascular has enrolled the first patient at St. Michael’s Hospital in Toronto into B-SILENT, an international clinical study testing whether an investigational cerebral venous stent can relieve severe pulse-synchronous tinnitus caused by venous sinus narrowing. BosSTENT is a braided, self-expanding stent designed specifically for the cerebral venous circulation rather than being repurposed from an arterial application. The Toronto procedure expands a trial already involving French and Canadian centers and moves Sonorous closer to generating the clinical evidence it says will support a future CE Mark submission.
The broader B-SILENT study is planned to enroll approximately 90 adults aged 18 to 80 with severe or catastrophic pulsatile tinnitus associated with greater than 50% transverse venous sinus stenosis. It is an open-label, single-arm trial without a placebo or sham procedure, and its primary performance endpoint asks whether tinnitus improves by at least two Tinnitus Handicap Inventory grades or 40 points within 30 days. Major device- or procedure-related complications are being assessed separately as a primary safety outcome.
What is pulsatile tinnitus and why is it different from ordinary tinnitus?
Most people who describe tinnitus hear ringing, buzzing or another sound without an external source. Pulsatile tinnitus is different because the sound often follows the heartbeat. Patients may describe a rhythmic whoosh, thump or pulsing sensation that becomes particularly noticeable in a quiet room or at night.
That rhythmic nature raises the possibility that blood flow itself is producing the sound. Several vascular abnormalities can cause pulsatile tinnitus, including arterial disease, abnormal connections between arteries and veins and abnormalities of the cerebral venous sinuses.
B-SILENT focuses only on a particular subset: patients whose pulse-synchronous tinnitus is associated with narrowing of the cerebral venous sinus.
When blood is forced through a narrowed venous segment, flow can become turbulent. Because these vessels lie close to structures involved in hearing, patients may perceive that turbulence as an internally generated sound synchronized with their heartbeat.
For some people the symptom is merely irritating. For others it can impair sleep, concentration, work and mental well-being to a severe or catastrophic degree.
Why would placing a stent in a brain vein reduce tinnitus?
A stent can expand a narrowed venous segment and help create a wider, more uniform pathway for blood flow. If venous stenosis is genuinely responsible for turbulent flow producing the sound, restoring the vessel lumen could reduce the haemodynamic disturbance and therefore reduce or eliminate the pulsatile tinnitus.
BosSTENT is described as a braided, self-expanding cerebral venous stent designed for this specific anatomy.
The biological logic is relatively intuitive, but patient selection is everything. Tinnitus can arise from many causes, and implanting a permanent intracranial stent in someone whose symptoms come from another mechanism would expose that person to risk without a clear reason to expect benefit.
B-SILENT therefore requires imaging-confirmed transverse cerebral venous sinus stenosis greater than 50% and severe symptom burden. The registry also requires tinnitus that responds to jugular-vein compression, a clinical clue suggesting a venous origin.
Who is eligible for the B-SILENT trial?
ClinicalTrials.gov lists adults between 18 and 80 years old with severe or catastrophic pulse-synchronous tinnitus, defined as a Tinnitus Handicap Inventory score of at least 58 and grade four or higher. Patients must have qualifying transverse venous sinus stenosis demonstrated using CT venography, MR venography or catheter cerebral angiography.
The trial excludes patients whose tinnitus is believed to arise from a non-venous cause. It also excludes several conditions that could increase procedural risk, including active systemic infection, venous sinus thrombosis, difficult venous anatomy, certain clotting disorders and recent stroke.
This restrictive design is appropriate for early device evaluation. Sonorous is not asking whether every patient with tinnitus should receive a stent. It is asking whether a carefully selected anatomical subtype can be treated safely and with sufficiently large symptom improvement to justify broader development.
That distinction is particularly important for patient-facing coverage because millions of people experience tinnitus, while only a minority are likely candidates for cerebral venous intervention.
How will investigators decide whether BosSTENT actually works?
The primary clinical-performance endpoint uses the Tinnitus Handicap Inventory, a validated questionnaire measuring the functional, emotional and catastrophic effects of tinnitus. Scores range from zero to 100, with higher scores representing greater burden.
B-SILENT defines a successful response as an improvement of at least two severity grades or a reduction of 40 THI points at 30 days.
That is a relatively large required change, which helps reduce the likelihood that a small fluctuation or expectation effect will be misclassified as success.
However, the study has no sham-control group. Everyone knows a stent has been implanted, and tinnitus severity is inherently patient reported. Expectation can therefore influence the outcome even when a large change threshold is used.
Longer-term follow-up becomes important because the device is permanent. A dramatic improvement after one month is encouraging only if symptoms remain controlled and the vein remains patent over time.
What safety events are especially important in a cerebral venous stent trial?
B-SILENT’s primary safety endpoint includes major stroke, neurological death, in-stent thrombosis, target-vessel restenosis, stenosis adjacent to the stent and stent migration during the first three months.
Those outcomes reflect the seriousness of placing a permanent implant within cerebral venous circulation. A device designed to eliminate an extremely disruptive symptom still needs an exceptionally convincing safety profile because many patients are otherwise neurologically intact.
Thrombosis is particularly important. A clot forming inside a cerebral venous stent could obstruct venous drainage and create consequences far more serious than the tinnitus being treated. Restenosis could cause symptoms to return, while migration or vessel injury could create acute neurological complications.
Patients undergoing venous stenting may also require antiplatelet or other medication strategies around the procedure. The precise regimen and longer-term risk profile will need to emerge from the completed clinical program rather than being assumed from arterial stenting experience.
Is BosSTENT FDA cleared or commercially approved?
No. BosSTENT is investigational in the B-SILENT study, and Sonorous’ announcement is explicit that the trial is generating safety and performance evidence for a future regulatory submission.
The September release concerns the first patient enrolled at the Toronto hospital, not the first patient ever treated in B-SILENT. This distinction matters because another Canadian site and French centers are participating in the international program.
ClinicalTrials.gov currently lists six study locations in Canada and France and estimated enrollment of 90 patients. Primary completion is expected in July 2027, with overall study completion projected for July 2028.
There is therefore a considerable distance between the current enrollment milestone and routine clinical availability.
Why has venous pulsatile tinnitus become a neurovascular rather than purely ear-related problem?
Historically, a patient hearing a sound in the ear might first be evaluated primarily within audiology or otolaryngology. Improved CT, MRI and angiographic imaging have made it easier to identify vascular causes that sit outside the ear itself.
That changes the specialist pathway. A patient with venous sinus stenosis may need evaluation by neuroradiology, neurointerventional surgery or neurosurgery in addition to traditional hearing specialists.
The symptom itself can become a clue to systemic intracranial haemodynamics. Venous sinus stenosis is also discussed in relation to conditions involving altered intracranial pressure, although B-SILENT has defined specific criteria rather than treating every form of venous narrowing the same way.
This multidisciplinary complexity is one reason a purpose-built clinical study matters. Procedures performed outside trials can generate anecdotes, but a prospective protocol can establish who was treated, how severe disease was and what complications occurred.
Why does jugular compression matter in patient selection?
B-SILENT requires severe tinnitus that responds to compression of the jugular vein.
The manoeuvre temporarily changes venous blood flow. If the rhythmic sound diminishes when venous flow is altered, that provides a functional clue that the patient’s symptom may originate from the venous circulation rather than an unrelated auditory or arterial mechanism.
It is not a definitive standalone diagnostic test. Imaging is still required to demonstrate significant venous sinus stenosis.
Combining anatomy with a physiological clue makes the selection strategy more convincing than implanting patients solely because an MRI happened to show narrowing.
If BosSTENT ultimately succeeds, this sort of diagnostic selection may become central to deciding who receives treatment.
Could the trial change how severe pulsatile tinnitus is treated?
Potentially, but B-SILENT first needs to establish that benefit is both substantial and durable.
A successful 90-patient study with very large THI reductions and low rates of major adverse events could support regulatory review and encourage more systematic screening for venous causes of pulsatile tinnitus.
The lack of a control group may still create evidentiary debate, particularly because symptom burden is subjective. Regulators and clinicians will need to examine the magnitude of improvement, objective imaging findings and consistency across sites.
Longer-term device performance will also matter. A stent that relieves tinnitus immediately but develops restenosis several years later has a very different benefit-risk profile from one that remains durable.
For patients with genuinely debilitating symptoms, however, the clinical problem is significant enough to justify investigation. A constant heartbeat-synchronized sound can severely impair sleep and quality of life, and some patients have few meaningful alternatives after a vascular cause is identified.
BosSTENT is testing an unusually direct idea: if turbulent venous blood flow is generating the noise, remodel the vessel responsible for the turbulence. B-SILENT will determine whether that attractive mechanical explanation survives the much harder tests of safety, patient selection and sustained symptom relief.
