EMS World: Can a Simple Headset Detect LVO Strokes in the Field?

At the American Stroke Association’s 2015 International Stroke Conference, researchers declared that, based on overwhelming evidence, mechanical thrombectomy should be standard of care in the treatment of all large vessel occlusion (LVO) stroke patients. For the first time in history, patients experiencing one of the most debilitating types of strokes had a treatment option that could minimize or even eliminate the effects of the occlusion. Until the discovery of the thrombectomy, LVO patients’ treatment options were limited and had minimal impact on outcomes. Tissue plasminogen activator (tPA), while highly effective for small vessel occlusion (SVO) strokes, has minimal effects on LVO strokes. The thrombectomy—the ability to insert a stent retriever and remove a clot—changed the treatment pathway for LVO patients, creating hope for significant recovery.

Ensuring an LVO stroke patient arrives at an appropriate hospital in time to receive a thrombectomy is critical. Compared to the number of primary stroke centers (PSCs) that can treat SVOs, relatively few U.S. hospitals are designated as comprehensive stroke centers (CSCs), with the necessary equipment and expertise to treat LVOs. This has created a dilemma for prehospital caregivers—particularly EMS crews tasked with identifying a patient’s stroke type quickly and accurately. 

Identifying LVOs

With stroke EMS crews do not have objective measures such as an electrocardiogram (ECG) to identify the condition. Though subjective prehospital assessments such as the Cincinnati Prehospital Stroke Scale (CPSS) and Los Angeles Motor Scale (LAMS) are helpful, studies have shown these assessments are only about 60% accurate. Trained neurologists in emergency departments have been shown to be about 70% accurate, so it is not surprising that a dynamic prehospital environment presents challenges. 

Confounding this issue is that many conditions, such as seizure, overdose, hypoglycemia, and migraine, can all mimic strokes, leaving EMS professionals with difficult choices that could have significant consequences. Sending an SVO patient to a CSC potentially delays their time to tPA, and sending an LVO patient to a PSC will inevitably delay treatment. LVO patients at a PSC need to be transferred, a process that can be lengthy and have negative effects on outcomes. Given the binary nature of the decision-making process—PSC vs. CSC—a device that aids professionals in accurately identifying a patient’s stroke type could be incredibly beneficial to the prehospital armamentarium. It was with this goal in mind that MindRhythm was formed and its Harmony headset developed.

The Harmony Headset

MindRythm’s Harmony headset was invented by company cofounder Paul Lovoi, PhD, following his wife’s death from a stroke. Hoping to spare others this experience, Lovoi—a physicist, inventor, and entrepreneur—focused his efforts on stroke treatment. After consulting with Navy submarine tracking experts, he was convinced accelerometry technology could be adapted to stroke scenarios.

In simple terms, accelerometers measure motion, acceleration in particular, and are widely used across a broad range of technologies. When you pick up a smart phone and it lights up, this is an accelerometer at work. Lovoi’s theory was that a clot in the head would interrupt the motion of blood, and he could design a device to detect this. He approached Wade Smith, MD, PhD, a stroke specialist and neurologist at the University of California, San Francisco (UCSF), to perform research to develop the device. 

Two published papers followed that showed the technology was effective in detecting LVO stroke. The first confirmed the “headpulse” it measured correlated with cardiac contractions in normal patients but not those with LVO, meaning disruptions could be indicative of an occlusion;¹ the second found cranial accelerometry was 65% sensitive and 87% specific in identifying LVO strokes, and adding the symptom of asymmetric arm weakness increased its specificity to 91%.²  

These papers demonstrated, independently and in combination with subjective assessment, that the Harmony device could identify LVO strokes in an enriched population of suspected stroke patients in the ED. Their research also suggested the technology could detect other conditions, such as migraine, traumatic brain injury, and hemorrhagic stroke. However, LVO stroke is one of the most disabling conditions, and improving its triage could have a profound impact on patient outcomes. Lovoi and colleagues thus decided to form a company first focused solely on the critically important problem of stroke triage, with the possibility of expanding capabilities later. 

When MindRhythm was formed in 2019, the company had two primary objectives: 1) Develop a device optimized for EMS scenarios, and 2) validate that the technology could perform in the environment where it was intended to be used. Multiple meetings and surveys with EMS professionals created a clear design picture: The device needed to be small, lightweight, easy to read and interpret, and, most important, reliable. To this end, it developed a disposable, tiara-style headset with a go/no-go screen readout that provides an LVO diagnosis answer within 90 seconds. It also created an optional smart phone app with connectivity to standard technologies. With respect to validation, MindRhythm determined early that a multicenter prehospital trial demonstrating accuracy of detection would be the ideal pathway. 

Operationalizing Harmony for EMS

While there is no reason to believe Harmony will perform differently from a technological standpoint, the prehospital environment is very different from the ED, and human factors could have an impact. Additionally, nearly all EMS organizations have stroke triage protocols in place based on current practices. These are often determined by their state or county, and many of these practices mandate transport to a particular facility—typically the closest hospital or PSC. MindRhythm leaders hope a multicenter trial demonstrating the effectiveness of the device will give individual organizations the confidence to implement the technology within their programs. Certainly, changing stroke protocols will require objective, real-world data to support the decision-making process.

The clinical trial is being carried out through Wayne State University utilizing Detroit Receiving Hospital, Sinai-Grace Hospital, Henry Ford Health System, and Ascension St. John Hospital. The primary EMS crews involved are Detroit EMS, Superior Ambulance, and Rapid Response EMS, all in Michigan. The trial is designed to have two components: the first concerns primarily feasibility and usability, though data will be used to refine the algorithm. While going about their normal routines, paramedics will place the device on a patient’s head and gather a 90-second reading. This data will be gathered and analyzed by MindRhythm, along with device feedback and refinement. The second component will be performed following a presubmission with the FDA and with an expected design that will demonstrate enhancement to existing practices. Once the trial is complete, MindRhythm will submit to the FDA for a de novo approval and expects to have clearance within six months. From there it intends to make the Harmony device commercially available and work with individual and state organizations, as well as national associations, to gain widespread clinical adoption and improve stroke care in the U.S.

References

1. Smith WS, Keenan KJ, Lovoi PA. A unique signature of cardiac-induced cranial forces during acute large vessel stroke and development of a predictive model. Neurocrit Care, 2020 Aug; 33(1): 58–63.

2. Keenan KJ, Lovoi PA, Smith WS. The neurological examination improves cranial accelerometry large vessel occlusion prediction accuracy. Neurocrit Care, 2020 Nov 20; epub ahead of print.

John Keane is cofounder and CEO of MindRhythm. A medical device executive with three decades of experience developing and commercializing emerging medical technologies, Keane has been involved in more than 30 product launches with a focus on neurological disorders and brings a wealth of knowledge on product development, delivering clinical value, and gaining adoption in the marketplace.

See the original article on EMS World’s website