TBI severity classification
/ TBI, say tee-bee-eye /
Two people both hit their heads in a car crash. One is dazed for a moment, never loses consciousness, and is back at work in a week. The other is in a coma for ten days and will need a year of rehabilitation. Calling both of them brain injured is true but almost useless, the word covers a vast range. To plan care, predict recovery, and compare patients, clinicians need a way to say how severe a given traumatic brain injury is. That is what TBI severity classification provides.
Traumatic brain injury, TBI, is graded into mild, moderate, and severe using three early measures that each capture a different angle on how hard the brain was hit. The first is the Glasgow Coma Scale (GCS) at presentation: roughly 13 to 15 is mild, 9 to 12 moderate, 8 or below severe. The second is the duration of loss of consciousness: from none or seconds (mild), to minutes to hours (moderate), to longer than a day (severe). The third is the duration of post-traumatic amnesia (PTA), the time before continuous memory returns: under a day is mild, one to seven days moderate, more than a week severe. When the three disagree, the most severe indicator usually wins. Of these, PTA duration is often the single best early predictor of long-term outcome, more so than the GCS snapshot.
This grading drives almost everything that follows: the urgency of neurosurgery, whether someone is admitted or sent home with concussion advice, the intensity and setting of rehabilitation, and the conversation with families about likely recovery. Two honest cautions: first, mild does not mean trivial, a mild TBI (the medical term for most concussions) can still cause weeks or months of real symptoms; second, the categories describe the initial injury, not the destiny, plenty of people classed severe go on to good recoveries, and the labels are a starting point for planning, never a verdict.
A cyclist had a GCS of 14 in the ambulance, lost consciousness for under a minute, and was confused for about three hours before his memory came back. All three measures point the same way, this is a mild TBI. A separate patient with GCS 6, two weeks unconscious, and a month of PTA is plainly severe; the three indicators agree, and where they ever disagreed, the team would classify by the worst.
Severity blends GCS, loss-of-consciousness time, and PTA duration; the worst of the three usually decides.
Mild TBI is not the same as no injury, and the severity label is the initial injury, not the outcome. Many severe TBIs recover well; the classes guide planning, they do not predict any one person's future.