Visor-like device can detect stroke in seconds

US researchers have evaluated a new device, worn like a visor, which can detect emergent large-vessel occlusion in patients with suspected stroke with 92% accuracy. Their results have been published in the Journal of Neurointerventional Surgery.

Endovascular therapy — a minimally invasive procedure that is conducted inside the blood vessels — is the standard of care for emergent large-vessel occlusion. Therapy is typically conducted within 24 hours — but the chance of achieving a good outcome decreases by approximately 20% for each hour that passes before treatment.

The volumetric impedance phase shift spectroscopy (VIPS) device, developed by Cerebrotech Medical Systems and dubbed the Cerebrotech Visor, works by sending low-energy radio waves through the brain that change frequency when passing through fluids. Such waves are reflected back through the brain and then detected by the device. When a patient is having a severe stroke, the brain’s fluids will change, producing an asymmetry in the radio waves detected by the VIPS device. The greater the asymmetry, the more severe the stroke.

The researchers believe the VIPS device will save valuable time when it is deployed with emergency medical personnel in the field. This is because the accuracy of the device simplifies the decision made by emergency personnel about where to take patients first, according to Professor Raymond D Turner from the Medical University of South Carolina (MUSC).

“Transfer between hospitals takes a lot of time,” said Professor Turner, who served as principal investigator for MUSC on the study. “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 go to.”

In the study, the device was deployed with emergency medical personnel in regions served by five Comprehensive Stroke Centers equipped with the endovascular capabilities to treat large-vessel occlusions that underlie severe stroke. Their goal was to use the device to accurately identify severe stroke and then compare the results to established physical examination methods practised by emergency personnel such as the Prehospital Acute Stroke Severity Scale.

Both healthy participants and patients with suspected stroke were evaluated by emergency personnel using the VIPS device. Three readings were taken and averaged — a process that takes about 30 seconds. Patients were also later evaluated by neurologists, who provided definitive diagnoses using neuroimaging.

Compared to the neurologists’ diagnoses, the device displayed 92% specificity — the ability to detect the difference between patients with severe stroke and those with other conditions such as mild stroke or healthy participants with no brain pathology. This places the VIPS device above standard physical examination tools used by emergency personnel that display specificity scores between 40 and 89%.

The researchers believe the device’s success may be found in its ability to give emergency personnel a clear answer as to whether a patient is experiencing a severe stroke. It requires very little training to operate compared to that required to learn standard emergency examination skills, thereby reducing the possibility of human error during emergency diagnosis. However, it is not clear how the device would work for patients with cranial implants, as metal interferes with the device’s operating radio frequencies.

In their next steps, the researchers are undertaking a study to determine if the VIPS device can use complex machine learning algorithms to teach itself how to discriminate between minor and severe stroke without the help of neurologists. If so, the device could have widespread clinical implications, helping emergency personnel decide whether to take a patient to a comprehensive stroke centre or a primary stroke centre for treatment.

Professor Turner likens the use of the VIPS device in detecting severe stroke to the use of electrocardiography (ECG) to definitively detect acute myocardial infarction. He predicts that the device has the potential to be used widely by emergency personnel but also to appear in other public spaces.

“This could potentially be something like a defibrillator,” he said. “You can find out if a patient is having a stroke, just like you can put a defibrillator on a patient to see if they’re having a heart attack.”

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