Can Your Brain Heal After Injury?
With strokes affecting COVID-19 patients, what are the chances of complete recovery?
There has never been a better time to study the brain’s ability to recover than now, particularly when COVID-19 has been shown to incur damage to the brain and the central nervous system. Melinda Wenner Moyer of the New York Times writes, “The virus may, in effect, injure and thereby age the brain through a number of mechanisms that aren’t yet fully understood.” Research suggests that the virus can enter neurons and replicate inside the cells, affecting how they function.
Sustaining a brain injury is never a good sign. The brain is a soft organ composed of non-regenerating cells that communicate through long tails called axons. When an injury occurs, whether through a stroke, trauma, tumor, infection, or surgery, people often struggle to return to their baseline functionality. However, that’s not to say complete recovery is impossible. Doctors have been describing miraculous re-establishment of functionality for years. So how does the brain fix itself?
The Brain’s Ability to Build New Connections
When a person experiences brain damage, neuronal cell death occurs. Permanently injured brain matter does not easily recover, which leads to people having changes in sensation, muscular weakness, an inability to speak, or cognitive abnormalities.
While neurons typically provide excitatory stimulation, they also serve a role to inhibit nearby processes. A study published in Neuroscience explains that damage to a region of neurons leads to decreased inhibition of cortical pathways, providing a mechanism for the “unmasking phenomenon.”
The unmasking phenomenon is where existing brain structures find alternative pathways to help recover lost function. For example, damaged sensory areas in the left side of the brain that allow for sensation of the face may recruit neuronal involvement from the corresponding sensory area on the right side of the brain. The brain’s ability to create new connections is termed “neuroplasticity.”
The brain’s supporting cells — termed glial cells — are vital in the plasticity mechanism. Dr. Mark Ashley from the Dana Foundation explains, “Mechanisms of plasticity include the creation of new neurons, synapses, glial cells, and blood vessels, along with genetic changes.” Once the plasticity mechanisms have begun, the brain’s metabolism resets, allowing for the normalization of function.
Alex Teghipco from the University of Rochester wrote a study about a patient who lost their ability to speak after a brain tumor surgery. However, the patient fully recovered. The researchers found that the patient’s left hemisphere — containing neurons responsible for our speaking abilities — recruited new connections to the patient’s right hemisphere.
So if the brain is capable of rewiring itself in new configurations to restore function, why doesn’t every patient fully recover?
Why Doesn’t Every Patient Fully Recover
Recovering from a brain injury is a slow and arduous process. Still, it is vital that patients with brain injuries begin the rehabilitation process as soon as possible.
A research group from The Zuckerman Institute at Columbia University demonstrated using lab mice that the time to neural recovery plays an essential role in the re-establishment of pre-injury function. Their experiment consisted of impairing a group of mice’s sensory cortex followed by allowing half of the mice to begin sensory training after 24 hours while the other half after 72 hours. The 24-hour group regained full use of sensation compared to the 72-hour group, which experienced only partial recovery.
“Our study in mice demonstrates that re-engaging the brain immediately after injury can actually be more helpful than resting it,” says Dr. Randy Bruno, the principal investigator of the study.
Hypothetically, if every person with a brain injury were allowed the resources and support to retrain their lost skills in the quickest time possible, the prognosis for injured patients would be remarkable. But, our healthcare system is not easily navigatable.
Deb Brandon required three surgeries to remove a tangle of blood vessels — called cavernous angiomas — from her brain. Her recovery was not as smooth and coherent as she’d hoped.
“My physical therapist told me to continue working on my gait when I went home. My occupational therapist reminded me to contact a neurophysiologist and a neuro-opthalmologist. My hospital discharge instructions included a note to arrange a follow-up appointment with my neurologist.”
During the process, Ms. Brandon’s journey to recovery displayed the frustrations of hopping amongst multiple specialists, yet attending the plethora of rehabilitation appointments is pivotal. “Many rehabilitation approaches don’t include psychological treatment that can help people develop appropriate coping strategies,” explains Dr. Mark Ashley. Without coping strategies, it may become overwhelmingly tricky for patients to remain motivated in what can turn into a multi-year period. Recovery after a brain injury takes a concerted effort between the patients and multiple health care providers.
Janet Cahill, a patient who underwent surgery for a brain aneurysm, described her rehabilitation process after suffering a stroke during the procedure. It took Ms. Cahill 18 months to return her reading ability to baseline.
“I had to complete the same process for relearning pretty much everything. When I say that I could not read, write, walk or talk, people do not believe me.”
How To Maximize Recovery Potential
Why is the repetitive practice of the lost functional skill so important in neural recovery?
It has a lot to do with the molecules that cells release when stimulated by the performance of a particular activity. “Physical exercise can result in an increase in the expression of trophic (growth) factors, while stress and poor diet can result in a decrease in trophic factor production,” says Dr. Ashley.
“The brain appears to respond preferentially to combination approaches that include pharmacological, neuroendocrine, dietary factors, and other adjuvant treatments in addition to traditional therapies as compared to any one type of therapy alone.”
It is crucial to engage in the exercise of the affected areas to enhance the brain’s rehabilitation process. Physical therapists often encourage patients to move the impaired limbs allowing for increased recruitment of neurons to the damaged portion of the brain.
Furthermore, a study from the Frontiers of Neuroscience suggests that adult neural stem cells (NSCs) allow for an increased release of trophic factors and chemokines, which enable existing neurons to localize to new areas. NSCs can become neurons, but also can contribute to the population of the brain’s supporting cells, including astrocytes, oligodendrocytes, and glial cells.
In the future, NSCs may prove to be a valuable treatment option for brain injuries. Although the prevalence of brain injuries are on the rise, with emerging evidence for neuroplasticity, rehabilitation methods, and NSCs, the prospects for complete recovery are no longer so grim.
