Stroke survivors with physical deficits have to fight to get the muscles moving again. They also have to fight to stop some muscles from moving. Tone and spasticity are why our elbows curl, our fists squeeze tight, and our toes can curl under our feet so we crush our own toes as we walk. Dr. Wayne Feng is an expert in tone and spasticity after stroke and he joins us this week to explain how we can address these challenges If you don't see the audio player below, visit Strokecast.com/MSN/ToneBasics to listen to the conversation. Click here for a machine-generated transcript Who is Dr. Wayne Feng? From Dr. Feng's Duke Profile: I am the division chief for Stroke and Vascular Neurology in the Department of Neurology at Duke Health. I see stroke patient in the emergency department, inpatient service as well as in the outpatient clinic. I also treated post-stroke limb spasticity, a disabling complication after stroke. In addition to the patient care, I also run a brain modulation and stroke recovery lab at the Duke University campus to study stroke patients in my lab to develop new stroke recovery therapy. On my days off, my boys and I are big on fishing. I enjoy drinking and collecting tea. As a stroke doctor, I do not drink coffee at all (there is a reason for it). If you come to see, I will tell you. Current Appointments and Affiliations: Professor of Neurology, Neurology, Stroke and Vascular Neurology 2019 Chief of Stroke & Vascular Neurology in the Department of Neurology, Neurology, Stroke and Vascular Neurology 2019 Professor of Biomedical Engineering, Biomedical Engineering 2022 [youtube https://www.youtube.com/watch?v=SGeOGI2bry4&w=560&h=315] Tone and Spasticity Overview Mos of our limbs move because of the interaction between two types of muscles -- extensors and flexors. The flexors contract to bend a limb. The extensors contract to extend the limb. For example, the biceps are flexors. They pull our forearm up or into an angle. When people want to show off their arm muscle, the flex their arm -- they activate their flexors. The triceps on the back of the upper arm are extensors. When they activate, they extend the arm -- they pull the arm straight.  When flexors contract extensors relax. When extensors contract, flexors relax. That's how we control our limbs. After stroke, the flexors can activate on their own. And they can be, well, overenthusiastic, in those actions. That happens because the default behavior of the flexors is to be active and curl up. When we talk about curling up into the fetal position, that's most of our flexors activating. The reason we can go through life upright and with our limbs straight is that the cortex of the waking brain is constantly suppressing the normal contracting of the flexors. After stroke impacting the motor cortex of the brain, the corticospinal tract is disconnected. With that disconnect, the brain can no longer suppress the flexors so they do what they do -- they contract and curl and cause all sorts of problems. Peripheral vs Cortical Problems Categorizing issues as cortical or peripheral is a fancy way of saying brain or limb. A stroke is a cortical issue. The problem exists in the brain. That's where the disconnect happens. A peripheral issue is when something goes wrong in the limb. Shoulder subluxation, for example, is peripheral issue. Most PT and OT works with the limbs to treat the cortical issues. Tone and spasticity are caused by cortical issues. The long-term problems caused by tone and spasticity are peripheral issues. One of those peripheral issues is contracture. When tone and spasticity is severe and long term, the muscles, tendons, ligaments, and other soft tissue can actually shrink in the contracted position. When that happens, getting the extensors back online and suppressing the flex