The concern that there is “no objective evidence of injury” is predictable but flawed.
MRI or CT scans are not the only “objective” findings in medicine. Our approach to looking for “footprints of pathology” also a search for objective findings. When an individual cannot see, even if the cause of the blindness cannot be determined, this “footprint of pathology” is sufficient for a diagnosis. This is objective evidence. When a person cannot hear, there is “footprint of pathology”. When a neurologists exam shows focal neurological deficits, that is another “footprint of pathology”.
Neuropsychological testing is a search for “footprints of pathology” As such the assessment provides objective evidence of injury. Neuropsychological testing is designed to determine the brains current capacities.
I believe that these various pieces of objective evidence can provide a triangulation of pathology that cancel out the skepticism that interferes with proper diagnosis.
It is a change in how the brain functions, that is key to the diagnosis of brain injury. An injury to the brain, if it does not involve a change in function, may not be signiticant. But when the way the brain functions is changed, there may be a changed person. Even if the change is subtle, when it results in disability, the breakdown of relationships, the loss of enjoyment of life, that is dianostically significant. Further, depression, anger and sorrow, are footprints of pathology that more clearly triangulate brain injury, than the most modern MRI or even the neurosurgeon’s view of an intracranial hemorrhage.