Acute subdural hematoma (ASDH) is a serious complication following traumatic brain injury. Large volume hematomas or those with underlying brain injury can cause mass effect, midline shift, and eventually herniation of the brain. Most acute subdural hematomas (ASDHs) develop after rupture of a bridging vein or veins. The anatomy of the bridging vein predisposes to its tearing within the border cell layer of the dura mater. Thus, the subdural hematoma actually forms within the dura. The hematoma grows by continued bleeding into the border cell layer. However, the venous pressure would not be expected to cause a large hematoma.
A 56 year old gentleman with no known medical comorbidities presented with sudden onset of severe headaches with repeated vomiting. No loss of consciousness or focal deficits. A noncontrast CT scan Head was requested which revealed a right Frontoparietal acute subdural hematoma.
As there was no history of trauma an MR Imaging was requested to ascertain the cause.
No definite cause could be found!
ASDHs in the young are associated with high-energy trauma and often have underlying contusions, while ASDHs in the elderly are associated with minor trauma and an absence of underlying contusions, even though the elderly are more likely to be on anticoagulants or anti-platelet therapy.
In the young patients with high impact injuries the hematomas tend to be small and the underlying brain injury and swelling is responsible for the increased intracranial pressure and midline shift. A common complication of traumatic brain injury (TBI) is subdural hematoma. One in four of Traumatic Brain Injury (TBI) patients can present to the Emergency Department with subdural hematoma, which contributes to the extensive morbidity and mortality associated with TBI.
In the elderly, the injuries are low impact (e.g fall from standing), the underlying brain is intact, and the volume of the hematoma itself produces symptoms. In addition the use of anticoagulants and antiplatelet agents in the elderly population has been thought to be a poor prognostic indicator and is considered to be responsible for larger hematomas and poor outcome.
When managed conservatively, ASDHs can sometimes progress to chronic subdural hematoma formation, further enlargement, seizures, and progressive midline shift. Another potential difference in the young and the elderly is brain atrophy, which increases the potential space to accommodate a larger hematoma. It is not known if these two groups differ in other ways that might have implications for treatment or prognosis.
The progression to chronic subdural hematoma is not uncommon, 20%, but must be considered, diagnosed and managed appropriately in order to reduce overall morbidity and mortality.