Laboratory Studies
Hematocrit level, chemistries, and coagulation profile (including platelet count) are essential in assessment of patients with EDH, whether spontaneous or traumatic.
Laboratory studies such as international normalized ratio (INR), partial thromboplastin time (PTT), thromboplastin time (PT), and liver function test (LFT) may be obtained to assess for increased bleeding risk or underlying coagulopathies. [1]
Severe head injury can cause release of tissue thromboplastins, which can result in disseminated intravascular coagulation. Prior knowledge of coagulopathy is required if surgery is to be undertaken. If surgery is required, appropriate factors are administered preoperatively and intraoperatively. The presence of coagulopathy may be associated with worse outcomes. [16]
In adults, EDH rarely causes a significant drop in hematocrit level within the rigid skull cavity. In infants, whose blood volume is already limited, epidural bleeding within an expansile cranium with open sutures can result in significant blood loss. Such bleeding may lead to hemodynamic instability; therefore, careful and frequent monitoring of the hematocrit level is required.
Imaging Studies
Advances in contemporary computed tomography (CT) imaging have made confirmation of an EDH diagnosis rapid and accurate. Although EDH is relatively uncommon (approximately 2% of all patients with head injuries and < 10% of those who are comatose), it should always be considered in evaluation of a serious head injury.
Radiography
Skull radiographs often reveal a fracture crossing the vascular shadow of the middle meningeal artery branches. An occipital, frontal, or vertex fracture also might be observed.
The presence of a fracture does not necessarily guarantee the existence of EDH. However, more than 90% of EDH cases are associated with skull fracture. In children, this rate is less because of greater skull deformability.
CT scanning
Computed tomography scanning is the most accurate and sensitive method of diagnosing acute EDH. Findings are characteristic. The space occupied by EDH is limited by adherence of the dura to the inner table of the skull, especially at the suture lines, contributing to a lenticular or biconvex appearance. Hydrocephalus may be present in patients with a large posterior fossa EDH exerting a mass effect and obstructing the fourth ventricle.
(See the image below.)
CT scan of an acute left-sided epidural hematoma. Note the typical convex or lens-shaped appearance. The hematoma takes this shape as the dura strips from the undersurface of the cranium, limited by the suture lines. A midline shift of the ventricular system is present. This hemorrhage requires immediate surgical evacuation.
Cerebrospinal fluid is not commonly mixed with EDH; therefore, the hematoma is denser and is homogeneous. The quantity of hemoglobin in the hematoma determines the amount of radiation absorbed.
Signal density of the hematoma compared with the brain parenchyma changes over time after injury. The acute phase is hyperdense (ie, bright signal on CT scan). The hematoma becomes isodense at 2-4 weeks; it becomes hypodense (ie, dark signal) thereafter. Hyperacute blood may be observed as isodense or low-density areas, possibly indicating ongoing hemorrhage or a low serum hemoglobin level. [9, 17, 18]
Another less frequently involved area is the vertex; confirming the diagnosis on CT scans may be difficult. Vertex epidural hematoma can be mistaken for artifact in traditional axial CT scan sections. Even when correctly detected, volume and mass effect may be underestimated. In some cases, coronal and sagittal reconstructions can be used to evaluate the hematoma in coronal planes.
(See the images below.)
Axial CT scan that demonstrates a large vertex, bifrontoparietal epidural hemorrhage (EDH). Air bubbles are within the hematoma.
CT bone window image of same patient in Media file 2 that demonstrates a large midline fracture.
Coronal CT scan reconstruction that further clarifies the thickness and mass effect associated with this vertex epidural hemorrhage (EDH).
Sagittal CT scan reconstruction that further defines the anterior-posterior extent of the vertex epidural hemorrhage (EDH).
Approximately 10-50% of EDH cases are associated with other intracranial lesions. These lesions include subdural hematomas, cerebral contusions, and intracerebral hematomas.
A case report of a rare case of spontaneous resolution of EDH describes a 20-year-old male with a history of a fall from height for whom initial scan showed a large EDH requiring surgical evacuation. Subsequent scans showed near-complete resolution, changing the management approach from surgical to conservative. Study authors state that rare cases like this should always be kept in mind, and the importance of a repeat scan should never be disregarded. [19]
Gean et al reported a series of 21 patients with anterior temporal tip epidural hematoma. [8] These lesions usually were limited by the orbital fissure medially and by the sphenotemporal suture laterally and were confined to the anterior temporal fossa without expansion on subsequent imaging.
MRI
Brain magnetic resonance imaging (MRI) is more sensitive than CT scanning, particularly when one is assessing for EDH in the vertex. Magnetic resonance imaging should be conducted when high clinical suspicion for EDH accompanies a negative initial head CT scan. [1]
For suspected spinal EDH, spinal MRI is the preferred imaging modality, as it affords higher resolution than spinal CT. [1]
Diagnosis of symptomatic postoperative EDH requires correlation of clinical signs and symptoms with a compressive hematoma on MRI. Patient reports of a marked increase in axial pain, followed by radicular symptoms in the extremities and then motor weakness and sphincter dysfunction, should be investigated by an MRI obtained emergently; if a compressive hematoma is confirmed, surgical evacuation should be carried out as quickly as possible. [14]
Acute blood on MRI is isointense, making this modality not well suited to detection of hemorrhage in acute trauma. However, mass effect may be observed. [9]
Angiography
When EDH located in the vertex is evaluated, the healthcare professional should look for the presence of a dural arteriovenous fistula that may have arisen from the middle meningeal artery. Angiography may be required to fully evaluate the presence of such a lesion. [1]
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CT scan of an acute left-sided epidural hematoma. Note the typical convex or lens-shaped appearance. The hematoma takes this shape as the dura strips from the undersurface of the cranium, limited by the suture lines. A midline shift of the ventricular system is present. This hemorrhage requires immediate surgical evacuation.
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Axial CT scan that demonstrates a large vertex, bifrontoparietal epidural hemorrhage (EDH). Air bubbles are within the hematoma.
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CT bone window image of same patient in Media file 2 that demonstrates a large midline fracture.
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Coronal CT scan reconstruction that further clarifies the thickness and mass effect associated with this vertex epidural hemorrhage (EDH).
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Sagittal CT scan reconstruction that further defines the anterior-posterior extent of the vertex epidural hemorrhage (EDH).
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CT image of a pre-adolescent male with a left posterior fossa epidural hemorrhage (EDH). Such hemorrhages need to be watched carefully, and the surgical team should have a low threshold for surgical intervention because this region has less room to accommodate mass lesions.
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Bone window of the same patient as Media file 6 that reveals a diastasis (separation) of the left mastoid suture.
