Acute Epidural Hematoma

Computed tomography scan shows a variably sized oval or “lens-shaped” hyperdensity between the bone and the dura.

The most common clinical location for an EDH is the temporal fossa, typically associated with a temporal bone fracture that lacerates the middle meningeal artery and leads to arterial bleeding. This can result in the well-known transtentorial herniation syndrome. As the ipsilateral temporal lobe is forced medially, the third nerve is trapped against the brainstem, resulting in ipsilateral pupillary dilation. As more pressure develops, the ipsilateral posterior cerebral artery may be so severely compressed as to result in an occipital lobe stroke that is typically seen on CT scan a day or two after the event. With increasing shift of the brain to the opposite side, the brainstem is compressed, and the cerebral peduncle is forced into the edge of the tentorium, creating a so-called Kernohan notch and resulting in hemiparesis ipsilateral to the dilated pupil. If the compression remains severe for too long, Duret hemorrhages occur in the brainstem from compression or tearing of the small perforating arteries coming off the basilar artery. Such hemorrhages can be seen on magnetic resonance imaging (MRI) and portend a poor prognosis.

Venous epidural hematomas may also occur and are most common in the posterior fossa in children.

The following are recently published guidelines by the Brain Trauma Foundation (New York) for the treatment of EDH:

• An EDH greater than 30 cm³ should be surgically evacuated regardless of the patient’s score on the Glasgow Coma Scale (GCS).

• An EDH less than 30 cm³ and with less than 15-mm thickness and with less than a 5-mm midline shift in patients with a GCS greater than 8 without focal neurologic deficit can be managed conservatively with serial CT scanning and close neurologic observation in a neurosurgical center.

• It is strongly recommended that patients with an acute EDH in coma (GCS < 9) with anisocoria undergo surgical evacuation as soon as possible.

In a truly urgent situation when, for example, weather or distance precludes getting the patient to a center with neurosurgical capabilities, a burr hole may release sufficient blood to be lifesaving. Definitive treatment is evacuation through a large “trauma” bone flap. An active bleeding point is virtually always found on the dura. Occasionally, bleeding may be seen to be coming from underneath the temporal lobe, and the middle meningeal artery will be found lacerated at or within the foramen spinosus. With rapid, aggressive treatment, mortality across all age groups and all GCS scores is less than 10%.

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