How is Abusive Head Trauma Diagnosed?
Courtesy of Godoy Medical Forensics
The purpose of these newsletters is to aid criminal defense attorneys in early recognition of cases that should be investigated further by medical experts. Regardless, no case should simply be written off as child abuse until every alternative explanation can be ruled out.
Child abuse comes in many forms: sexual, physical, emotional. It also has many associated phrases: abusive head trauma, shaken baby syndrome, neglect, failure to thrive, molestation, Munchausen’s Syndrome by proxy, and several others. It is the responsibility of the persons involved in the child’s care and the referring agencies, such as Child Protective Services in California, to fully investigate the injuries before charges are filed. It is unfortunate that many times charges are brought before a full medical evaluation has been done to rule out other causes of the injuries or the condition of the child. There are many “mimics” or other contributing factors that could explain why the child was flagged as a possible abuse victim, such as bruising and bone fractures.
Shaken Baby Syndrome
Also known as Abusive Head Trauma (AHT) and Non-Accidental Trauma (NAT), Shaken Baby Syndrome (SBS) is a widely controversial topic in the medical and legal fields. For the purposes of this newsletter, I will refer to it by the more politically correct name of AHT. The task set forth to the medical and legal systems is to determine if there was a pathological process and, thus, the injury was unpredictable and unpreventable, or if there was a traumatic process. If it was a traumatic process, the key for the defense is to determine if it is accidental or not. In order to make this determination, it is critical that the attorneys understand the cascade that occurs and the potential triggers. In this newsletter, I will attempt to simplify the sequence of events from trigger to cardiopulmonary arrest; however, the pathology is yet to be understood fully and there are many different theories as to what occurs and how.
Generally, AHT is accepted as a triad of symptoms consisting of retinal hemorrhage, subdural hematomas, and brain swelling. There is also the possibility of other types of intracranial bleeds to be a part of the diagnosis with or without a subdural hematoma.
- Retinal hemorrhages (RH) are very small capillary level blood vessel bursts (similar to petechiae) in the back of the eye. They are not visible to the naked eye, and even the exam performed in the emergency department is limited because it is not a dilated exam. A full (dilated) ophthalmological exam is needed to fully evaluate the presence of RH.
- Subdural hematoma (SDH) is a collection of blood in the brain that exists outside the vascular space. Think goose-egg inside the head.
- Brain swelling is a result of the brain is reacting to the trauma and an increase in blood and cells in the brain, causing swelling and increased pressure.
First, there is some kind of insult to the brain. It could be a lack of oxygen, infection, a clot, an aneurysm, trauma, or a number of other things. The insult itself can result in a SDH or some other kind of brain bleed, or the SDH itself can be the insult. This insult sends a message to the body to repair the injury, and the “first responders” (blood and cells) flood into the area. The brain swells up due to the influx of fluids and starts pushing back on the skull. The skull is still not fully formed and, therefore, can expand to some degree, but eventually the swelling overfills the cavity within the skull and the intracranial pressure (ICP) goes up. This increase in pressure causes an increase in the retinal (eye) pressure and the blood vessels in the back of the eye burst from this pressure. The increase in the ICP also puts pressure on the brain stem, which controls all of our vital functions, such as breathing and pulse. The absence of those vital signs leads tocardiopulmonary arrest and a call to 911.
The prosecution will argue that the shaking that occurs in abusive situations actually tears the vessels in the brain and in the back of the eye. The torn vessels cause excessive bleeding into the brain and the pressure increases, leading to the absence of vital signs from lack of perfusion to the brain stem as described above.
Defending the AHT Case
The single most difficult component in building a defense case is explaining what else it could be other than trauma, and then explaining how it happened. If the pathology behind these injuries is not even fully understood by the medical community, how can we expect the jury to understand it? The case is even harder to defend when the parents or guardians can’t provide a good explanation for the injuries; then, we are forced to rely solely on the medical findings to explain the diagnosis.
When I am asked to consult on these cases, I look deep into the history of both the child and the mother. Infection, seizures (which are often missed), and birth trauma are key points to start with. Recent ground-level falls should be considered, but are usually dismissed early in the defense team’s investigation. Diving deeper, I look at chronic subdural hematomas, blood disorders, hypoxia, and many others.
There are so many possible causes for these injuries that it is difficult to rule them all out; the investigative team often defaults to abuse. It is widely accepted in medicine that if the caregiver cannot explain it, then it must be considered for abuse. This is a safety net that ensures that no abused child slips through the cracks, but the end result is that there are many cases that are criminalized that should not be. These cases have the potential to ruin the lives of everyone in that child’s life and, therefore, the stakes are very high to get it right and it’s not just about winning the case.
Barnes, P. (2009). Child Abuse – Issues and controversies for neuroradiology in the era of evidence-based medicine. Stanford University Medical Center, Palo Alto.
Lantz, P. E., & Stanton, C. A. (2006). Postmortem Detection and Evaluation of Retinal Hemorrhages Abstract G104. American Academy of Forensic Sciences.
Luthert, P. (2003). Why do histology on retinal haemorrhages in suspected non-accidental injury? Histopathology, 43, 592-602.