Epidural Hematoma, Variant

KEY FACTS

TERMINOLOGY

• "Typical" epidural hematoma (EDH)

○ Arterial laceration

○ 90-95% supratentorial (temporoparietal most common)

○ Biconvex, unilateral

• Atypical EDH

○ Unusual etiology

○ Unusual location

○ Unusual shape or density

IMAGING

• Venous EDH (10% of EDHs)

○ Fracture (linear, diastatic) crosses dural venous sinus

○ Skull base, vertex

○ Easily overlooked

○ Coronal, sagittal reformats key to diagnosis

• Anterior temporal EDH (10% of EDHs)

○ Middle cranial fossa

– In front of, not lateral to, temporal lobe

○ Fracture crosses sphenoparietal sinus

○ Generally asymptomatic (1-2 cm, stable size)

○ No reported cases requiring surgery

• Vertex EDH (1-2% of EDHs)

○ Fracture crosses, lacerates superior sagittal sinus

○ Accumulates slowly

○ Symptoms often delayed

○ Easily overlooked, size underestimated on axial CT

○ Coronal, sagittal reformatted images key

• Clival EDH (< 1% of EDHs)

○ Lacerates clival venous plexus

○ Self-limited; dura tightly attached, so rarely large

○ Asymptomatic unless associated vascular, cranial nerve

injury

○ Biconvex hyperdensity immediately posterior to clivus

○ Sagittal reformatted images key to diagnosis

(Left) Axial graphic depicts

different basilar skull

fractures that cross, and may

injure, important vascular

structures. Linear skull

fracture crosses the right

transverse sinus ﬈. The

lacerated sinus causes a

venous epidermal hematoma

(EDH) ﬊ to accumulate. The

injured sinus often thromboses

﬉. (Right) Axial NECT scan in

a 26-year-old man who fell 10

meters onto his head shows a

large left temporal lobe

contusion ﬇. A small

biconvex hyperdense fluid

collection ſt is seen adjacent

to the right transverse sinus.

(Left) Bone CT in the same

patient shows a diastatic

fracture through the right

lambdoid suture ſt. (Right)

Sagittal CT venogram shows

that the transverse sinus ſt is

elevated and displaced

anteriorly by a hyperdense

venous EDH. Note that the

venous EDH ﬊ lies both

above and below the site of

dural attachment. Venous

EDHs commonly cross dural

attachments, whereas classic

arterial EDHs rarely do.

Brain: Pathology-Based Diagnoses: Malformations,

Trauma, and Stroke

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