Investigators recently published evidence that appears to support the efficacy of mobile stroke units (MSU), specially equipped ambulances that essentially bring treatment to patients experiencing ischemic strokes. In a multicenter trial, researchers found patients treated on an MSU received clot-busting medication faster and demonstrated better health at 90 days than patients who were transferred to the hospital for treatment via traditional ambulance.1

While such results are exciting for MSU advocates, there remain financial and administrative obstacles that prevent many medical centers and EMS services from leveraging these units in their own communities, particularly at a time when the COVID-19 pandemic continues straining resources.

Meanwhile, there is growing interest in telestroke technology, capable of delivering expert care to ED patients and providers who do not otherwise have access to in-person neurologists. Although not necessarily a new innovation, the pandemic-era’s push to deliver more healthcare remotely has prompted some health systems to add telestroke programs to their arsenal of telemedicine options.

The study of MSUs began in 2014 in conjunction with the launch of The University of Texas (UT) Health’s mobile stroke unit. James Grotta, MD, one of the study authors, believed MSUs would speed care, but he knew evidence was needed. The UT Health arm of the trial was engaged in collecting data two years before other sites using MSUs joined the study. Eventually, Grotta and colleagues collected data from seven participating sites, all of whom agreed to a study design that involved alternating the use of their MSUs every other week so the care of stroke patients with MSUs could be compared with the care of stroke patients receiving care following transfer to the ED via traditional ambulance.

From 2014 to 2020, researchers enrolled more than 1,500 patients. Those treated on an MSU were more likely to receive the clot-busting medication tissue plasminogen activator (tPA) than the patients in the traditional ambulance group at a rate of 97% vs. 80%. Further, investigators reported MSU participants were more likely to receive tPA within the first hour of experiencing a stroke, faster than their traditional ambulance counterparts. Additionally, mortality at 90 days for the MSU patients was 9% vs. 12% for the traditional ambulance group.

“Even though most of the patients were in Houston, we had enough patients from the other [six] sites to say there really wasn’t a lot of heterogeneity in the results,” reports Grotta, director of the Houston Mobile Stroke Unit Consortium.

While there are some differences in how the various MSU programs operate, the basics are the same. Someone calls 911 about a suspected stroke, then an MSU responds to the scene at about the same time as a traditional ambulance. “We will evaluate the patient jointly. Then, if the patient is having a stroke and it looks like we can treat, we put [him or her] in the MSU. Otherwise, the patient gets transported [to the ED],” explains Grotta, director of stroke research at the Clinical Institute for Research and Innovation at Memorial Hermann-Texas Medical Center. “[Most] of the MSUs are similar in that they have a portable CT scanner on board. They have a [neurologist] available, either in person or via telemedicine.”

The MSU operating in Memphis is larger than other units that participated in the study, enabling it to carry a full-size CT scanner. “Their MSU was designed primarily to try to expedite endovascular therapy ... a second, complementary type of treatment for those strokes that are so large that they don’t respond to tPA,” Grotta says. “These cases require retrieval of the clot [causing the stroke] with a catheter. That procedure has to be done in the hospital.”

Patients who are candidates for endovascular therapy may not be recognized right away. They may end up at a hospital that does not perform the procedure, or they may have to wait longer for treatment once they reach the hospital. “Being able to do CT angiography ... in the MSU can speed that process along, enable the patient to [bypass the ED], and go directly up to an endovascular suite,” Grotta says. “It did appear that the Memphis team did achieve faster endovascular times, but they didn’t enroll enough patients to drive the trial results overall with regard to that therapy.”

Toward the end of the trial, some of the other participating MSUs, including the units at UTHealth and UCLA, began performing CT angiography, too. However, not all MSUs have added this evaluation as it requires added time and expense.

Going forward, there are several steps that can further improve stroke care and MSU performance. First, Grotta suggests people need to be willing to call 911 soon after symptoms appear. “So many people don’t call 911 in a timely fashion, and that is even worse with COVID-19,” he says.

Second, it is important to arm dispatchers with training so they know when a stroke has occurred and when to dispatch the MSU to the scene. “We get called about 10 times for every one patient we are able to treat,” Grotta notes. “Now that we know that stroke treatment is effective on the MSU, we should be able to develop ... a few simple [dispatcher] questions that can identify whether a patient is likely having a stroke.”

Every time the dispatchers in Houston undergo training sessions, the accuracy of the calls improves, but this is a constant challenge. “There are always new medics coming in. With COVID-19, there has been a lot of turnover in the prehospital arena,” Grotta says. “This requires a lot of continued in-servicing and education of EMS personnel, including the dispatchers.”

Grotta acknowledges that convincing hospitals and EMS services in a region to work together in support of an MSU can be challenging, particularly in areas where several EMS agencies operate according to strict boundaries and where hospitals are highly competitive. Further, funds usually must be raised to support the purchase and operation of an MSU. However, once those issues are solved, the trial data suggest such a program can deliver benefits.

At first glance, the idea of putting an MSU into operation may seem daunting, but Grotta says that ever since Houston put its MSU into operation, the program has been running smoothly and logically. “Whatever we do on the MSU is exactly the same thing we do in the ED,” Grotta says. “The system needs to be greased to make sure it works well, but from an emergency medicine perspective, it makes the workload easier.”

Many ambitious healthcare initiatives were curtailed or halted at the start of the pandemic, but the urgent demand for remote care options actually accelerated plans at the University of Chicago Medicine to implement its Telestroke Network. “There was a lot of movement toward telehealth, teleneurology, and services designed to allow access to patients or providers who were working remotely. While we knew this was always going to be a part of our overarching goals ... the pandemic kicked it into over-gear,” explains Scott Mendelson, MD, PhD, chief quality officer for the department of neurology at UChicago Medicine.

The program, which launched in April 2021, provides 24/7 access to a neurologist for patients who present with possible stroke symptoms at EDs of participating UChicago Medicine hospitals. “Not only are we able to see patients and coach ED staff in the exam ... to make treatment decisions very quickly, but now we can look at imaging as well,” Mendelson says. “[ED personnel] can do the diagnostic workup ... and then the teleneurologist remotely can review all of that information and help make decisions in the moment.”

In the past, ED physicians often made such decisions, either without consultation with a neurologist or perhaps with communication with a neurologist by phone. “What teleneurology does is really allows the neurologist to have a virtual presence in that room with the patient and to be able to make a diagnosis along with the ED physicians in a way that they just weren’t able to do before,” Mendelson notes.

Starting such a program required physical assets, including cameras that can be operated remotely and easily moved from room to room and screens that enable two-way visual communications. However, the biggest part of the implementation involved working with the participating ED providers to develop processes and protocols that fit with their normal workflows.

It is not unusual for a provider to suspect a patient may be experiencing a stroke, only to discover something else is going on. Still, emergency providers are encouraged to consult with the remote neurologist any time they are concerned about a potential stroke.

“Currently, we are working with two hospitals ... and it comes to about 30 or 40 [times] a month that we engage with them [remotely],” Mendelson says. “We have been able to facilitate administering acute stroke interventions about once per week.”

Typically, such interventions involve administering clot-busting medications to reverse the symptoms of stroke. Providers also might perform endovascular procedures. “That happens infrequently, but they happen more now that we have a teleneurologist available for these patients at these hospitals 24 hours a day, seven days a week,” Mendelson says.

Mendelson views the use of teleneurology networks and MSUs as complementary approaches in that both aim to shorten time to treatment for a time-sensitive condition. “We know that not all patients live nearby or have access to primary stroke centers or comprehensive stroke centers,” he says. “In areas where the density of these stroke centers is very low, there is a lot of advantage of doing telehealth in the field. If an [MSU] can get there and do the therapies more quickly than you could in transporting the patient to a stroke center, then it makes absolute sense to use an MSU as another model of neurology.”

However, Mendelson notes that in densely populated areas with many stroke centers, patients can go to the hospital and receive treatment almost as quickly as an MSU can provide similar treatment. “Both systems leverage the same technology,” he says. “Generally, there is no neurologist out in the MSUs ... it is just a matter of it is quicker to do this with a [specially equipped] ambulance or whether [the same care] is accessible to patients in the ED.”


  1. Grotta JC, Yamal JM, Parker SA, et al. Prospective, multicenter, controlled trial of mobile stroke units. N Engl J Med 2021;385:971-981.