They are sometimes referred to as “thingomometer central,” the alphabet soup of shiny metal tubes which are supposed to be our guides out of the dark ages of medical diagnosis. Too often we turn to the lords of the thingomometer central, the radiologist, to give the answer to the question of whether there is brain damage. We want the certainty of the objective scan and believe these computerized machines will show us the truth.
But normal brain imaging does not rule out brain injury. The only one way to conclusively rule out brain pathology, to “see” brain pathology is autopsy.
Brain cells are microscopic and can’t be seen on any scan. Only through use of a microscope, as is done in autopsy studies can actual cellular brain damage be seen. Imaging studies would have to improve a thousand fold, to see dead brain cells.
What MRI and CT are getting better at doing is seeing intracranial conditions which will cause cell damage: hemorrhage and hematoma, or the macroscopic phenomenon of large clusters of dead cells. But when the primary cause of brain damage is diffuse damage to brain cells, there continues to be a likelihood of normal imaging studies. MRI and CT can even be normal for pathology that can result in prolonged coma and death.
It is also to see scanning within the context of the entire approach to diagnosis of brain injury, that imaging may show us a it is possible to see the footprint of pathology. Even if an eye doctor cannot see the damage to the optic nerve, he can emphatically diagnose blindness. Likewise, with the ENT, if you can no longer hear, can diagnose deafness. Would one question the objectivity of either a diagnosis? Of course not.
Yet, in either case, the physician is not seeing the pathology, but basing the diagnosis upon the footprint of abnormal function – blindness/deafness. The footprint approach to the diagnosis of brain injury is the premise behind the field of neuropsychology.
So what is important to understand about imaging studies? In the treatment of acute injuries, the CT scan has saved lives because of its ability to identify life threatening pathology and guide the neurosurgeon’s decision making. But after the acute stage, the value of MRI and CT studies is the subject of fair debate.
We believe that there are cases where brain injury might have been identified by MRI and CT, if the scans had been ordered at the appropriate time. Each thingomometercentral has its relative merit, each thingomometer central has its temporal niche when it is the better tool. Each thingomometer central has specific conditions for which it is most sensitive. The goal of this section of our information is to help understanding what these modern tools can show, and what they cannot.