PNR Head 25
History
6 yo M, concern for NAT (non-accidental trauma), distal humeral fracture
Major Findings
Teaching Points
Terminology:
Subdural collection = nonspecific umbrella term which encompasses the following
- Subdural hematoma (SDH) = unilateral or bilateral, along cerebral convexities and does not cross midline, may have varying densities depending on age of blood products
- Subdural hygroma (SDHy) = CSF-density fluid which does not contain blood or neomembranes
- Subdural hematohygroma (SDHHy) = combination of blood + CSF-like fluid, can be homogeneous or heterogeneous (see below)
- Chronic subdural hematoma (cSDH) = serosanguinous collection, can be loculated, may contain neomembranes; rare in children
- Subdural effusion = sequela of bacterial meningitis or sinusitis
- Subdural empyema = an infected subdural effusion
Differential Diagnoses:
Heterogeneous, mixed density (hypo- + hyperdense) subdural collections are tricky, especially in the setting of suspected NAT. Though they are often seen in NAT, they do not definitively indicate repeated trauma. Here are some differential considerations to think through:
- Hyperacute + acute SDH (unclotted + clotted blood) = 1 event
- Acute SDH (compacted clot + serum separation) = 1 event
- SDHHy (acute bleed + CSF from arachnoid tear) = 1 event
- Acute + chronic SDH (acute hemorrhage in a pre-existing cSDH/SDHy) = 2+ events
Likewise, a homogeneous (iso- to hypodense) subdural collection does not always indicate a chronic process. Other differential considerations include:
- Hyperacute SDH (unclotted blood) = 0-24 hours
- Acute SDH + anemia (clotted blood but decreased RBCs) = 1-3 days
- SDHy or SDHHy (CSF or CSF + trace acute blood) = 1 day-1 week
- Late subacute SDH (lysis of RBCs) = 1-3 weeks
- Chronic SDH (serosanguinous) = 2+ weeks - look for neomembranes, higher density than CSF (> 5-10 HU), lack of associated cerebral edema
Since it is difficult to tell the difference between many of these entities on CT, when you see a subdural collection in the setting of suspected NAT, an MRI should be recommended to look for more definitive evidence of chronic subdural hematomas.
More details in this helpful article on subdural collections in pediatric head trauma: 
Accession: CL1068
Study description: Head^DE_PEDS_HEAD_TRAUMA_0_6YO (Child)
