A new test for people who have difficulty moving their arms and hands after a stroke can help identify those likely to recover well and those who probably will not. This information helps doctors, nurses and therapists tailor recovery care to achieve the best possible outcome for patients.

TRANSCRANIAL MAGNETIC STIMULATION DELIVERS A BRIEF MAGNETIC PULSE AT THE SCALP THAT CREATES A SMALL CURRENT IN THE BRAIN.
Photo by Jay Fram

“The test helps therapists decide how much effort should be spent trying to recover as much function as possible, and how much should be devoted to teaching compensatory strategies,” says Alexandre Carter, MD, PhD, Washington University neurologist at Barnes-Jewish Hospital, who has begun performing the test on his patients. In the first days after a stroke, patients undergo a series of tests to measure how much function was lost. Patients whose stroke affected their arms, for example, are asked to lift their arms and extend their fingers. Those who perform well on these initial evaluations are likely to recover arm function. And those who perform very poorly are unlikely to recover much arm function at all.

It is tricky, however, to predict recovery for those whose responses fall somewhere in the middle. Some of these people may regain use of their arms and hands with time and therapy, but until recently, there was no reliable way to predict who they would be.

A new approach that uses transcranial magnetic stimulation, or TMS, is now making such predictions easier. TMS involves delivering a brief magnetic pulse at the scalp that creates a small current in the brain, just enough to get nerve cells to fire as they would normally. If the pulse is applied to the part of the brain that controls the hand, for example, the hand should twitch in response. Lack of movement reveals that the neurological link between the brain and the hand has been severed and that recovering function in the hand is unlikely.

TMS IS THE FIRST OBJECTIVE TOOL THAT WE HAVE HAD IN NEUROLOGY TO MEASURE BRAIN MOTOR FUNCTION AFTER A STROKE.

The TMS test forms the basis of an algorithm known as Predicting Recovery Potential that predicts whether a patient will experience complete, notable, limited or no recovery of hand and arm function. The algorithm, developed by Cathy Stinear and Winston Byblow of the University of Auckland in New Zealand, helps therapists provide individually tailored care. In the first three months after a stroke, therapists and their patients are working against the clock to recover as much function as possible; after that point, recovery stalls. TMS gives them an objective basis to decide whether their time is best spent trying to restore function or teaching compensatory strategies.

“Even a negative result is information we can use to individualize and improve a patient’s care,” Carter says. “TMS is the first objective tool that we have had in neurology to measure brain motor function after a stroke. If you break a bone, you take an X-ray. You would never evaluate the severity of a fracture by asking the patient how much it hurts when they try to walk on it. But that’s where we’ve been with stroke patients.”

Not all people with stroke benefit from a TMS test. For those with the mildest or the most severe strokes, the test is unnecessary. And the algorithm was designed to predict recovery of motor skills in the arms and hands; it has not been shown to predict recovery of other abilities, such as walking. Still, Carter estimates that a third of stroke patients with difficulty moving their arms could benefit from the test every year.

“If we continue doing the same things that we have been doing, we’re going to continue getting the same results,” Carter says. “I don’t think anybody who works in stroke rehabilitation can say that they’re really satisfied with the results that we’re providing to patients. This is a step towards individualized — and better — care.”