Deep brain stimulation, or neurostimulation with electrical current signals, is a proven form of therapy for Parkinson's patients, among others. A similar technology, transcranial direct current stimulation, has been used for many years in the treatment of mental disorders or neurological conditions. New research has shown that the latter form of electrical stimulation of the brain also has a positive effect on the recovery ability of athletes with a cruciate ligament (ACL) injury.
A torn or damaged anterior cruciate ligament is an injury common in athletes such as (professional) skiers and soccer players. Surgery is often required to repair the initial damage. The subsequent rehabilitation process can take several months to over a year. Muscle weakness plays an important role in this process.
“The brain makes a huge effort to stop the contraction of these muscles. We know that in people with ACL, over time the brain starts recruiting unrelated parts of the brain, such as the visual centers, to help activate the leg muscles,” said Dr. Myles Murphy, postdoctoral researcher at Edith Cowan University.
Brain stimulation for muscle recovery
The recovery of leg muscles (quadriceps) is delayed from the patient's brain because it blocks their use. Using transcranial direct current stimulation, according to research by Dr. Murphy, in collaboration with sports doctor Casey Whife, can speed up that recovery process.
The researchers showed that by sending a small electric current (transcranial direct current stimulation) through the part of the brain responsible for leg muscles, at times when patients are doing standard rehabilitation exercises, muscle strength can be maintained and the brain does not have to work as hard.
“The technique of electrical brain stimulation has been around for decades and has been widely used in other fields, such as to treat mental disorders or neurological conditions. Because the current is so small and administered externally, patients only report feeling 'tingling or itching' at the point where the sponges are connected to the head,” said dr. Murphy. The study's findings were recently published in BMJ Open Sport & Exercise Medicine.
“This research highlights an important step forward in addressing the neural barriers to recovery after ACL reconstruction. By focusing on cortical inhibition, we pave the way for more effective and efficient rehabilitation strategies that could help patients regain strength and function faster,” Dr. Whife added.
Further research and proper screening
So while the initial results of the study show that this form of electrical stimulation of the brain during the recovery process after cruciate ligament surgery is effective, the long-term effects of this type of intervention on injury recovery and outcomes still need further study. So does the possible application of these interventions in other patients undergoing rehabilitation to rebuild muscle strength. And although the equipment for transcranial direct current stimulation is already available in many hospitals and other medical rehabilitation settings, the researchers stress the importance of proper screening. For patients with cochlear implants, pacemakers or other implanted devices, this therapy may not be appropriate.
“Electrical brain stimulation during rehabilitation could be a low-cost, easy-to-apply intervention that could be performed as an adjunct to current exercise rehabilitation and address unadapted changes in the primary motor cortex postoperatively,” says Dr. Murphy.
