Brain - Trauma

Question 1

Scalp and Skull Injuries

Answer 1

• Cephalohematoma = subperiosteal, does not cross sutures, resolves spontaneously
• Subgaleal Hematoma = Forms under aponeurosis (galea) of occipitofrontalis muscle, not limited by sutures, can be large and extend around entire circumference
• Fractures (differentiate from sutures in peds)

Question 2

Missile and Penetrating Injuries

Answer 2

When looking for bullet entrance verus exit site, the entrance site has a small defect on the outer table and large defect on inner table.

Question 3

Epidural Hematoma, Classic

Answer 3

Arterial (90-95%)
–Arterial epidural hematoma (EDH) is most often near middle meningeal artery (MMA) groove fracture

Venous EDH (5-10%)

• -Fracture is adjacent to dural sinus
• -Common sites: Vertex, anterior middle cranial fossa

Air in EDH (20%) suggests sinus or mastoid fracture

Mixed Density internal contents may be due to active bleeding with swirl sign OR subacute blood that is dissolving (can differentiate clinically or if acute fx etc.)

May peripherally enhance if subacute/chronic due to granulation, can be confused with collection/epidural empyema

Question 4

Epidural Hematoma, Variant

Answer 4

Venous EDH (10% of EDHs)
o Fracture (linear, diastatic) crosses the outside of a dural venous sinus
o Easily overlooked!!!
o Coronal, sagittal reformats key to diagnosis
o Very rarely can occur without a fx

Anterior temporal EDH (5-10% of EDHs)
o Middle cranial fossa, in front of, NOT lateral to, temporal lobe (look if fracture close to MMA course)
o Fracture crosses sphenoparietal sinus (not MMA!)
o Generally asymptomatic (1-2 cm, stable size)
o No reported cases requiring surgery

Clival EDH (< 1% of EDHs)
o Lacerates clival venous plexus
o Self-limited; dura tightly attached, so rarely large
o Asymptomatic unless associated vascular, cranial nerve injury
o Biconvex hyperdensity immediately posterior to clivus
o Sagittal reformatted images key to diagnosis

If fracture crosses sinus, get CTV!

DDx: (if no hx of trauma…)Hyperdense neoplasm (meningioma, lymphoma, mets) or Dural Pseudotumors (IgG4, Histiocytosis)

Question 5

Acute Subdural Hematoma

Answer 5

• B/w dura and arachnoid, so can track all over inside the dura.
• Don’t call isoattenuating subdural subacute unless you confirm they are not anemic.
• Mixed attenuation can be seen with active bleeding. Notify clinician.

DDx:
Mixed SDH (acute on chronic/subacute SDH)
o Hyperdense foci in pockets of iso-, hypodense fluid

Subdural hygroma
o Torn arachnoid; common with surgery, trauma
o Clear CSF, no encapsulating membranes

Subdural effusion
o Near CSF density

Subdural empyema
o Peripheral enhancement, hyperintensity on FLAIR; restricted diffusion on DWI

Pachymeningeal thickening (intracranial hypotension, chronic meningitis, neurosarcoid; these should enhance?)

Question 6

Subacute Subdural Hematoma

Answer 6

• Subacute = ~ 3 days to 3 weeks
• Partially liquified clot, resorbing blood products
• Surrounded by granulation tissue (“membrane”)
• Consider contrast enhanced MR with DWI (or just CECT) if suspected isodense SDH to look for membrane formation/loculations
• Remember: MR signal of SDH is quite variable. Generally (but not always) evolves in pattern similar to intracerebral hemorrhage. For T1 and T2 generally follow memorized rules for blood
• **FLAIR – variable signal depending on T1 and T2. In early sSDHs, you may miss it if small on FLAIR because it is usually hypointense due to T2 dark signal, but it also may be bright from T1
• **T2* GRE - Susceptibility artifact (blooming) common
• **DWI - Signal intensity varies with hematoma age; Crescentic high intensity with low-intensity rim next to brain
• **T1WI C+ - Enhancing and thickened dura is common. Enhancing membranes may be seen and suggest unstable SDH prone to rehemorrhage.
• **Delayed scans may show contrast diffusion into SDH (and it will look like whole thing is enhancing! Confused with pachymeningitides??)
• Enhancement pattern is helpful to differentiate sSDH and chronic SDH from pachymeningopathies
• **If sSDHs present without trauma history, evaluate coagulation status
• **Look for signs of intracranial hypotension!!! (Brain sagging, Dura-arachnoid thickening, Engorged dural venous sinuses, “Fat” pituitary gland)