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NeuroVoices: Wayne Feng, MD, FAHA, on Changing the Approach to Poststroke Neuromuscular Symptoms

The division chief of stroke and vascular neurology at Duke Health discussed how clinicians have typically treated poststroke motor symptoms and how technology is expanding these capabilities.

Following stroke, an individual may be faced with several common physical conditions that include weakness, paralysis, or problems with balance, fatigue, difficulty swallowing, speech problems, and urinary or bowel incontinence, among others. If the stroke occurs on the right side of the brain, a patient might be more prone to developing left-side weakness, impulsive behavior, overconfidence in abilities, and vision problems, whereas if stroke impacts the left side of the brain, patients may experience more right-side weakness, speech and language problems, and slow behavior.

Not only have the acute treatments for stroke advanced over the years, but the overall outlook of recovery from stroke has changed, mainly because of advances in technology. Wayne Feng, MD, FAHA, a leading expert in the space, has been dedicated to improving the lives of stroke survivors through recovery methods that include brain modulation. He is currently a lead investigator for the ongoing TRANSPORT 2 study (NCT03826030), which is evaluating whether brain stimulation at different doses combined with an efficacy-proven rehabilitation therapy, can improve arm function.

To learn more about the neuromuscular symptoms patients typically experience, and how the community has approached treatment, NeurologyLive® sat down with Feng as part of a new NeuroVoices. The chief of the division of stroke and vascular neurology and director of the Neuromodulation and Stroke Recovery Lab at Duke University, discussed the ongoing efforts, and what clinicians should be aware of when treating these patients.

NeurologyLive®: How does stroke cause neuromuscular symptoms?

When stroke occurs, either the vessel is occluded or the pipe burst, and that's called a hemorrhagic stroke. When you have occlusion, we call it ischemic stroke. Essentially, the area was suppressed by the vessel, and it was basically dead in the brain. It depends on which area of the brain was affected, and you can have a variety of neurological and muscular symptoms. If you affected a cortical spinal tract, which is a connecting pathway between the brain and the legs, you're not going to be able to move your arm or leg, or you can’t move your face. You may not be able to swallow, and effectively, your language will not work, and you cannot talk. If you have had a sensory pathway, you're not going to be able to feel. It can also affect the vision and then you cannot see. It really depends on what part of the brain is affected, and thus, you’re going to have a variety of those symptoms. Some can recover, and some don’t recover. It depends on severity of stroke. It’s still the leading cause of disability in the US today.

How have clinicians typically approached caring for these neuromuscular defects?

Typically, if we we’re talking motor symptoms, a patient in the beginning will become completely flaccid, with no [muscle] tone and arms just loose like a noodle—they don’t move at all. As time goes on, the tone goes up, and then they have a kind of fractal synergy, where they want to move the arm, but instead it moves up and down, and the tone continues go up. You need tone, but if tone goes too high, then patient cannot move. But if the tone goes up and decreases, typically, the coordination and joints move on getting better. It depends on which stage this patient is in. When you have a complete fracture, you really have to support arm, and you cannot do much rehab. You do the passive movement, but at the same time, you have to protect your arm, otherwise you're going to take the shoulder and subluxate it because there's no tone, and the gravity can drag the shoulder out of the joint. Once the tone goes up, you can do more and customize the therapy. If it's too high, you may have to give medical medication to decrease the tone. But we find out, the first 3 months, particularly 1 to 3 months, is a critical repair window. If you can strategically provide more therapy during that period, the patient can have a little bit better outcome. After 3 to 6 months, you still have some noticeable recovery. But after 6 months, the growth becomes kind of flat. After 1 year, you can still see some small groups of patients—typically they are young—that can still recover. The most meaningful recovery is seen first the first 3 months or first 6 months.

Can you discuss your research using stimulating nerves to improve motor skills?

Our lab basically uses a variety of brain stimulation tools. They’re not necessarily nerve stimulation, but it's a neuromodulation of the brainstem region. One [tool] is called a magnetic stimulation, but it is electrostimulation using a magnetic field to generate electrical pause. It’s called transcranial magnetic stimulation, and we use other tools called transcranial direct current. It's a direct current, a very weak current. I’ve been studying these the last 10 years, and we moved it from a phase 1 to phase 2 study. I'm leading 12 centers in an NIH-funded study called TRANSPORT 2. Basically, it’s a dosing selection study to look at a high-dose, low-dose, and sham stimulation in a cohort of patients with ischemic stroke, but the windows are between 1-6 months. It's been going for 3-plus years. With COVID, we’ve had some challenges. We have 81 out of 129 patients, and it will probably still take one more year to complete. Hopefully, we select the right dose; we're not sure on high dose vs low dose, and then we can proceed to a phase 3 study. Other tools that we’re using in our lab that we’ve received grant funding from the American Stroke Association for is low intensity ultrasonic stimulation. We are in the initial baby steps, and this stimulation uses light. So, we have quite a few tools in the lab, but it all goes toward helping a patient recover better.

Transcript edited for clarity. Click here for more NeuroVoices.