Wearable Device Detects Stroke in Seconds

A medical device company has developed a portable visor system that uses volumetric impedance phase-shift spectroscopy (VIPS) technology to detect severe strokes within seconds.

by Mark Crawford
May 07, 2018

Stroke is one of the fastest and deadliest neurological events, making early and accurate detection critical for survival. Endovascular therapy within 24 hours of stroke onset is considered the window of opportunity for treating emergent large-vessel occlusion. The chances of a good outcome, however, decrease about 20 percent for every hour that passes before treatment starts.

This is why speed in responding to a stroke is so critical. Ambulance transportation to an ER or hospital, combined with the standard approach of physical examination and medical imaging, takes hours, increasing the risk of serious brain injury. Unfortunately, there is no accurate, early-stroke detection tool to help ambulance and emergency room first-responders quickly identify patients who need transport to need triage directly to specialty stroke hospitals for immediate surgical intervention.

To remedy this situation, Cerebrotech Medical Systems, a medical device company in Pleasanton, CA, has developed a portable device that can detect likely severe strokes within seconds. Called volumetric impedance phase-shift spectroscopy (VIPS), this technology can help detect large vessel occlusion strokes and large hemorrhagic strokes in patients, enabling earlier intervention to prevent further brain damage.

Not only is VIPS faster, it is also more accurate than the physical examination performed by emergency personnel in the field. In a recent clinical study, VIPS detected stroke with a 92 percent accuracy, compared to 40-89 percent using standard pre-hospital stroke assessments.

How It Works

Boris Rubinsky, a mechanical engineering professor at University of California, Berkeley, invented the core VIPS technology. Even though magnetic resonance imaging (MRI) and electrical impedance tomography (EIT) create excellent images for diagnosis, they are large, expensive, and generate large amounts of very complex data. Rubinsky realized that bioimpedance data, which reflect small changes in the brain's electrical properties over volume, could provide accurate, easy-to-use information about fluid changes in the brain.

When an individual is having a severe stroke, the fluids in the brain change. The VIPS device, known as the Cerebrotech VisorSystem, is placed on the head and sends low-energy radio waves through the brain, which are altered when passing through fluids. If the device detects a particular pattern of bioimpedance asymmetry, the patient is likely having a severe stroke.

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“The device measures the bioimpedance asymmetry, comparing the left and right hemispheres, looking for a problem on one side,” says Mitch Levinson, president and CEO of Cerebrotech Medical Systems. “This works especially well for detection of severe strokes, because strokes are usually unilateral, so tuning the algorithm to detect the bioimpedance asymmetry induced by a large stroke is both sensitive and specific.”

One of the challenges in developing the device was correct head placement. “We decided to reference the device on both ears and the nose—three points fully defining the registration—just like a pair of eyeglasses,” Levinson says. “Weight distribution, comfort, and stability were all important considerations when designing the headpiece.”

Noise factors, including movement artifact, had to be controlled to generate accurate readings. Also, because the human brain is so much larger and the shape is so much different from any other animal, “we developed the technology using mathematical and physical models first, and then jumped right to clinical trials instead of performing animal studies,” Levinson says.

A Better Standard of Care

Cerebrotech Medical Systems last December received clearance from the FDA for its visor. The clearance provides broad use as an aid in the assessment of fluid volume differences between the cerebral hemispheres in patients undergoing neurologic assessment. The Visor System will soon help emergency medical personnel to diagnose large-vessel occlusions quickly and transfer patients directly to a comprehensive stroke center, routing around less-equipped hospitals and saving valuable time in the process.  

"Transfer between hospitals takes a lot of time," says Dr. Raymond D. Turner, a professor of neurosurgery at the Medical University of South Carolina, who helped test the device. "If we can give the information to emergency personnel out in the field that this is a large-vessel occlusion, that should change their thought process in triage as to which hospital they utilize.”

The device is simple, easy to use, and requires minimal training. It generates a large amount of bioimpedance data across a range of frequencies and uses machine learning to identify specific brain pathologies, not just strokes.

“For example, we plan to use the technology for detecting progression of cerebral edema, traumatic brain injury, hydrocephalus, and a host of other applications,” Levinson says.

Mark Crawford is an independent technical writer based in Madison, WI.

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