Review Question - QID 106155

This patient with a high velocity mechanism of injury and loss of consciousness has a non-contrast CT scan of the head demonstrating a lens-shaped hyperdensity. This patient has most likely developed an epidural hematoma.

Epidural hematoma most often develops in patients that have sustained high velocity head trauma, such as this one. Classically, patients will have an initial loss of consciousness at the time of injury, followed by a lucid interval lasting minutes to hours, and then rapid deterioration in mental status and loss of consciousness. In the majority of cases, bleeding occurs due to rupture of the middle meningeal artery which runs along the inside of the skull. High pressure arterial bleeding leads to a rapid accumulation of blood and increase in intracranial pressure. Non-contrast CT scan of the head is the imaging study of choice to diagnose this condition. CT will demonstrate a lens shaped hyperdenisty with or without overlying skull fracture or scalp hematoma. Management is typically centered on operative intervention to evacuate the hematoma and prevent herniation. Osmotic agents such as mannitol or hypertonic saline may be used as a temporizing measure to lower intracranial pressure until the patient can be taken to the operating room.

Chmielewski discuss the clinical importance of the middle meningeal artery. They state that its laceration is responsible for up to 85% of all cases of epidural hematomas, with higher rates attributed to those patients who have underlying skull fractures. They also state that for most cases, surgical evacuation via burr holes is most important as the bleed can cause transtentorial, or worse, tonsillar herniation leading to coma and brainstem damage.

Zhao et al. discuss a novel treatment of using needle puncture and drainage of epidural hematomas without the need for burr holes using CT imaging for guidance. They state that the improvement rate and the cure rate among their patients was 100%. They also note that the re-bleeding rate was 0% and the local infection rate was 0%, making this a safe and effective procedure under CT guidance.

Figure A demonstrates a non-contrast CT scan of the head with features characteristic of an epidural hematoma. Note the lens shaped hyperdensity.

Incorrect Answers:
Answer 1: Caput succedaneum is a collection of fluid that forms between the periosteum of the skull and the scalp, most commonly in newborn infants following prolonged or instrument-assisted delivery. It would not be expected in this adult following high velocity trauma.

Answer 3: Subarachnoid hemorrhage may occur spontaneously or due to trauma. CT imaging typically reveals collections of blood in the subarachnoid space, often visualized in the basal cisterns. This patient's imaging findings point toward epidural hematoma as the diagnosis.

Answer 4: Subdural hematoma often occurs due to trauma. However, CT imaging typically reveals a crescent shaped hyperdense collection between the brain and skull due to the lower pressure accumulation of blood from the venous system.

Answer 5: Skull fracture often occurs with epidural hematoma. However, this patient's CT imaging suggest epidrual hematoma as the more obviously apparent injury.

Bullet Summary:
Epidural hematoma occurs following high velocity head trauma and presents on CT imaging with a lens-shaped hyperdensity.