Mobile Stroke Units: The Barriers to Timely tPA Administration in the US

Emergency mobile stroke unit. Ambulance van furnishes services to diagnose stroke patients.
Two neurologists discuss the barriers to timely tPA administration in acute stroke, including the implementation of mobile stroke units.

Stroke is one of the leading causes of death in the United States, with over 795,000 cases yearly. In particular, ischemic strokes have the highest prevalence, constituting 87% of all stroke cases.1

Early administration of tissue plasminogen activator (tPA) has proven to limit the risk for damage and functional impairment in patients with acute ischemic stroke.2-4 However, one of the most significant barriers to successful stroke management is administering tPA within the recommended window of 3 hours.5

The first mobile stroke unit (MSU) in the US was implemented in 2015 and allowed for earlier tPA administration, leading to significant improvements in functional outcomes for patients with stroke.

Recent pivotal studies, Berlin PRehospital Or Usual Delivery in Stroke Care (B_PROUD; Identifier: NCT02869386) and Benefits of Stroke Treatment Delivered by a Mobile Stroke Unit Compared with Standard Management by Emergency Medical Services (BEST-MSU; Identifier: NCT02190500), showed significant improvements in 90-day disability scores for patients with acute stroke treated on an MSU compared with emergency medical service (EMS) management in both Germany and the US. The B_PROUD study also showed that the median time from dispatch to initiation of thrombolysis for patients treated with an MSU was 20 minutes shorter than with conventional ambulances. 6,7

Essentially everything you need to do for a stroke is in the MSU.

While early studies show promising results for patients treated with MSUs, there are significant barriers to implementing and standardizing these services in the US. Many MSUs have not fully integrated into the existing EMS systems, making it difficult to streamline treatment processes. Additionally, most MSUs operate in densely populated cities. Research has suggested several methods for adapting these services to nonurban settings, such as air ambulances and various transport strategies, but further studies are necessary to prove these concepts.8,9

As a relatively new addition to EMS, MSUs do not have national clinical guidelines for standardized care. There is a call to action for guideline committees, medical societies, and stroke leadership to update the level of evidence of MSUs to reflect more recent efficacy trials. Another step for MSU expansion is for regulatory bodies to establish a process to accredit MSU programs using standardized quality measures.8

Additionally, MSUs face issues receiving reimbursements from insurance.8 The lack of reimbursements for MSUs in the US increased reliance on grants to support program costs and has limited the expansion of this service across the nation.10 The body of data supporting MSU cost-effectiveness is still in its early stages and additional data is necessary to support the need for reimbursement. Recent data shows that MSU cost-effectiveness is due to the reduction in long-term disability costs and that MSUs yield a gain of 0.591 quality-adjusted life years per dispatch.11

To discuss MSU implementation barriers, we spoke with James Grotta, MD, founder of the first MSU in the US and the director of stroke research at the Clinical Institute for Research and Innovation, Memorial Hermann-Texas Medical Center in Houston. We also spoke with Matthew T. Bender, MD, neurosurgeon and assistant professor in the division of stroke and cerebrovascular disease at the University of Rochester Medical Center in Rochester, New York, to gain insight on current barriers for treating acute ischemic strokes.

How similar is treating someone in an MSU compared with the emergency department? Is there something in the emergency department that’s not in an MSU?

Dr Grotta: For strokes, the answer is no. Everything that we need to treat a patient in the emergency room for a stroke, we can do in the MSU. In a hospital, there are other things we can do for patients with stroke — for example, a thrombectomy. Patients move from the emergency room into an endovascular suite. 

Essentially everything you need to do for a stroke is in the MSU. Now there are a host of other emergency procedures in the emergency room that could be done on an MSU.

Dr Bender: The MSU is essentially a stroke emergency department on wheels. Providers have all the tools needed to evaluate, stabilize, and treat a patient suffering a stroke. They have a narrower focus than emergency department providers and can defer non-neurologic diagnoses to the emergency room.

Could you elaborate on the gaps preventing timely administration and decision-making for tPA?

Dr Grotta: Most of the time, if the physician is on board the MSU, the CT scan comes up on the computer and you can see it right away. However, in some MSUs, often the physician is present through telemedicine. In some systems, the CT scan must be transmitted to a radiologist to be read. That might produce a few minutes of delay.

I think that’s an unnecessary step because you just have to read the CT to ensure there is no blood. That doesn’t usually require a neuroradiologist to read it. You get a more skilled reading from a neuroradiologist, but the neurologist can generally identify when treatment is appropriate.

The biggest thing we have shown is that treatment in the first hour after symptom onset is critically important. In that first hour, every little thing that takes up a few extra seconds makes a difference. 

Dr Bender: Stroke neurologists are making this decision via telemedicine. They need to formulate their own perspective based on the clinical scenario and imaging but then elicit preexisting goals of care and obtain consent from the patient or family.

It requires efficiency and parallel processing. As a result of our study findings, the MSU team has reviewed additional parallel procedures to facilitate faster treatment decision times.12

What is the most significant barrier to treatment for patients with stroke and what do you propose to help address these barriers?

Dr Grotta: The most significant barrier is that patients do not call 911. If everybody called 911 when they had a stroke, we would be treating many more patients right now. 

Only 12% of patients with stroke get treated with tPA. Admittedly, some cannot be treated with tPA because they have contraindications like bleeding problems, the stroke is not severe enough, or some other illness that precludes it.

If everybody called 911 when symptoms came on, we could quadruple the number of patients currently being treated. Our treatment, tPA, is pretty good, so treating more patients with the existing treatment would make the most significant difference. 

We need to figure out how to alert patients that they are experiencing a stroke and there is research on alerting devices that people might wear.

Dr Bender: Early recognition of stroke symptoms and alerting emergency services remains the most significant barrier. 

Through a partnership with the Cabrini Foundation, we are working to increase awareness and recognition of stroke symptoms in underserved communities within the Rochester metropolitan area.

There are currently no clinical guidelines on a national level for MSUs. Based on your experience and research, what massive overhauls and protocols are needed for MSUs? Who would be the decision-makers for these guidelines?

Dr Grotta: In our health care system, it is all about money. I do not mean to say that negatively, but things that are reimbursed get done, and things that are not reimbursed do not get done. In a sense, MSUs are an expensive operation for a hospital to implement, but they are worth it because we have shown that they are quite effective.

It requires an investment upfront, and right now, there is no adequate reimbursement for MSUs because they are a new thing. Insurers and Medicare do not recognize MSUs as a place of service.

The other impediment is that there are 20 or 30 MSUs right now, and you have to take a year between the time you order an MSU before one rolls out. There is no economy of scale because there is not a huge demand.

If and when MSUs get reimbursement with Medicare, then we will be able to scale up our production capability. 

Dr Bender: We are at a stage where the MSU concept is spreading. To foster that growth, MSU-based stroke treatment needs to be recognized by third-party payors and the Centers for Medicare & Medicaid Services, which is reasonable given that randomized prospective data shows MSU care expedites thrombolysis and leads to better clinical outcomes for patients with stroke. 

What additional data or research is needed to help inform future clinical guidelines?

Dr Grotta: One of the things we have yet to show about MSUs is how we can help patients with large vessel occlusion.

Right now, the main benefit of MSUs is to get tPA in faster. However, some patients do not qualify for tPA or need treatment beyond tPA. Those are the patients with large vessel strokes.

Thrombectomy is another treatment for patients who have the biggest strokes where tPA often does not work, and we pull the clot out with a catheter. However, there are only some hospitals that do that. 

What MSUs can do is triage patients more effectively to these thrombectomy centers and get thrombectomy done faster. Nevertheless, that remains to be proven. 

Most importantly, having an MSU be used for just one disease does not make logical sense. We must find other emergency conditions that MSUs can help with.

Editor’s Note: This interview was edited for clarity and length.


  1. Centers for Disease Control and Prevention. Updated October 14, 2022. Accessed February 25, 2023.
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