The emergency room said the CT was clean, so the adjuster says nothing happened. Six weeks later you cannot hold a conversation in a noisy room, you have lost words mid-sentence in a meeting, and the headaches have not stopped. A Daly City Personal Injury Attorney sees this pattern constantly, and the medicine is on the injured person’s side even though the paperwork is not. A normal head CT rules out bleeding. It does not rule out a brain injury, and confusing the two is the most common error in how these claims get valued.
Why does a CT scan come back normal when the brain is injured?
Because CT is designed to find blood and broken bone, not damaged cells. A head CT in the emergency department exists to answer one urgent question: is there a hemorrhage, hematoma, skull fracture, or swelling that requires surgery in the next few hours? It answers that question well and is normal in most concussion patients.
What CT cannot show is diffuse axonal injury, which is stretching and shearing damage to the microscopic nerve fibers connecting regions of the brain. That damage happens at a scale far below CT resolution. When imaging does show a visible abnormality alongside mild symptoms, clinicians call it a complicated mild TBI, and the label itself tells you the uncomplicated version is the one where scans look fine.
What actually qualifies as a mild traumatic brain injury?
Less than most people assume, and losing consciousness is not required. The diagnostic criteria long used by the American Congress of Rehabilitation Medicine, updated in a 2023 revision published in the Archives of Physical Medicine and Rehabilitation, require a plausible mechanism of injury plus clinical signs such as any period of lost consciousness, any gap in memory for events around the incident, or any alteration of mental state at the time, including feeling dazed or disoriented.
The severity thresholds are specific. Loss of consciousness, if it occurred at all, lasting no more than 30 minutes. A Glasgow Coma Scale score of 13 to 15, that scale being the standard 3 to 15 measure of eye, verbal, and motor responsiveness. Post-traumatic amnesia under 24 hours. The CDC reports that the large majority of traumatic brain injuries fall in this mild category, which means the typical brain injury is precisely the kind that imaging misses.
What evidence proves an injury the scans cannot see?
Objective testing of function rather than structure, gathered from several directions so no single source carries the case.
Neuropsychological testing
A full battery run by a clinical neuropsychologist typically takes several hours across one or two sessions and measures processing speed, working memory, attention, executive function, and verbal fluency against normative data adjusted for age and education. It is the closest thing to an objective measurement of cognitive deficit that exists.
The critical component is validity testing. Performance validity tests, including instruments like the Test of Memory Malingering, are built into the battery specifically to detect exaggerated or feigned deficits. Passing them is what makes the rest of the results credible, and defense neuropsychologists will look there first.
Advanced imaging and whether it gets admitted
Diffusion tensor imaging measures the movement of water along white matter tracts and can reveal disruption invisible on CT. Susceptibility weighted imaging detects microhemorrhages. Both come with an admissibility fight in California.
California does not follow the federal Daubert standard. New scientific techniques must satisfy People v. Kelly (1976), requiring general acceptance in the relevant scientific community, and expert opinion is separately screened under Sargon Enterprises v. USC (2012) along with Evidence Code sections 801 and 802. Individual-patient DTI findings have drawn serious challenges in California courtrooms. Treat advanced imaging as supporting evidence rather than the foundation of the case.
How do insurers attack these claims, and what defeats it?
Through three predictable arguments, each of which is answered with documentation created early rather than later.
Adjusters point to the normal CT, to gaps in treatment, and to any pre-existing condition in the records. Delayed care is the easiest to fix and the most damaging when ignored, because a person who first reports cognitive symptoms four months after a crash hands the defense its causation argument. Pre-existing conditions are less dangerous than clients fear. California instructs juries under CACI 3928 that a defendant takes the plaintiff as found, so an unusually susceptible person still recovers fully, and CACI 3927 allows recovery for aggravation of a prior condition.
Lay testimony carries unusual weight here. A supervisor who can describe specific work product before and after, a spouse who kept a symptom log, or a coach who noticed changed behavior often persuades a jury more than a chart of test scores.
How does a Daly City Personal Injury Attorney build a mild TBI case?
By getting the right specialists involved in the first weeks and closing the documentation gaps before the defense finds them. That means referral to a neurologist or concussion clinic rather than relying on a primary care visit, formal vestibular and oculomotor assessment where dizziness or visual symptoms exist, and neuropsychological testing timed so that persistence of deficits can be shown rather than just their presence.
Local logistics matter. Serious head trauma in the Daly City area is frequently routed to Zuckerberg San Francisco General, the region’s Level I trauma center, while less severe presentations are seen closer to home and discharged with a concussion handout and no follow-up scheduled. That discharge instruction sheet is often the only mention of head injury in the entire record, and it needs to be located immediately.
The two year deadline under Code of Civil Procedure section 335.1 applies to most of these claims, dropping to a six month written claim requirement if a public entity was involved. If your symptoms have outlasted a clean scan, speak with a Daly City Personal Injury Attorney before an adjuster convinces you the absence of a finding on CT is the same as the absence of an injury. It is not, and the medical literature says so plainly.