Penn Medicine Declares “Mild Traumatic Brain Injury an Oxymoron”
The University of Pennsylvania Perelman School of Medicine issued a press release on November 23, 2015 declaring “mild brain injury an oxymoron” based on newly released research. The research, performed in collaboration with the University of Glasgow, demonstrates how brain wiring can be damaged after a concussion–damage that in some cases never repairs.
The research, published online in November in Acta Neuropathologica, builds on prior studies showing that nerve fiber damage in the brain can be demonstrated by the presence of a brain protein called SNTF. As reported by the authors of the Penn study, the prior research indicates that:
While affected axons rarely rupture completely at the moment of impact, their sudden deformation causes abnormal inflows of sodium and calcium ions that help regulate a neuron’s function. Investigators surmise that that most affected axons manage to pump the sodium and calcium levels back to normal, regain their function, and slowly repair whatever structural damage they have sustained. In other axons, however, levels of calcium become high enough to trigger a self-destructive process, in which protein-breaking enzymes are unleashed, begin to degrade the axonal structure, and ultimately sever the nerve fiber completely.
“Once an axon disconnects and degenerates,” the Penn researchers state in their press release, “ it’s never going to regrow to restore that communication pathway across the brain.” The protein SNTF is a tell-tale byproduct of this destructive enzyme activity and therefore a biomarker of permanent axonal injury. As the researchers point out in their press release, this research help explain why approximately one in five concussion patients suffer from long term cognitive impairment.
Since concussed brains rarely show signs of bleeding, bruising or other obvious abnormalities on standard CT or MRI scans, the reasons for this continued disability in some patients has in the past been somewhat speculative. This research helps to solve this mystery. Sadly, as the researchers point out, “for these individuals, there are no evidence-based rehabilitation strategies or therapies currently available.”
“We’re starting to believe that the term ‘mild traumatic brain injury’ is an oxymoron,” concludes Douglas Smith, director of the Penn Center for Brain Injury and senior author on the study. “For some people there’s nothing mild about it.”