WIRED

A blood test of “NfL” proteins answers questions about damage severity that doctors—and families—desperately need.

NEIL GRAHAM SEES a lot of head injuries: “Car accidents, violence, assault, gunshots, stabbing—the works, really,” says Graham, a neurologist from Imperial College London who practices at St. Mary’s Hospital nearby.

Doctors stop the bleeding, they relieve any pressure building inside the skull, maybe they’ll put the patient into a coma to keep the brain from overworking when it needs to relax and heal. Imaging can also help—to an extent. CT scans or MRIs pinpoint bruising or specks of hemorrhage in gray matter, the brain’s outer layer where neurons do most of their processing. But a clean scan isn’t a clean bill of health. Trauma to axons—a neuron’s root-like fibers that extend toward other neurons—often appears only in the deeper white matter, sometimes eluding simple scans.

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