Benign anterior temporal epidural hematoma: indolent lesion with a characteristic CT imaging appearance after blunt head trauma.

PURPOSE: To study the incidence, pathogenesis, imaging characteristics, and clinical importance of a unique subtype of epidural hematoma (EDH) associated with blunt head trauma.

MATERIALS AND

METHODS

This study was reviewed and approved by the hospital's Institutional Review Board and was compliant with HIPAA. Informed consent was waived. The investigation was a retrospective study of 200 patients with acute supratentorial EDH, defined as a biconvex, high-attenuating, extraaxial hematoma. A subgroup of 21 patients in whom the EDH was located at the anterior aspect of the middle cranial fossa was defined. Computed tomographic images and inpatient medical records of these 21 patients were evaluated for imaging characteristics of the EDH, presence or absence of associated fracture, presence or absence of midline shift and/or mass effect, additional intracranial injury, and hospital clinical course.

RESULTS

Twenty-one (10.5%) of 200 traumatic EDHs localized to the anterior middle cranial fossa. All of these 21 anterior temporal EDHs were juxtaposed to the sphenoparietal sinus, and all but one were limited laterally by the sphenotemporal suture and medially by the orbital fissure; none extended above the lesser sphenoid wing. Maximum thickness was less than 1 cm in 13 (62%) of 21 and less than 2 cm in 20 (95%) of 21 patients. Isolated fractures of the greater sphenoid wing and ipsilateral zygomaticomaxillary fractures were present in 12 (57%) of 21 and nine (43%) of 21 patients, respectively. Concomitant intracranial injury was identified in 15 (71%) of 21 patients. Twenty (95%) of 21 lesions were present at the admission study, and all 21 were stable or smaller at follow-up imaging. No patient required neurosurgical intervention of their anterior temporal EDH.

CONCLUSION

Acute EDHs isolated to the anterior aspect of the middle cranial fossa constitute a subgroup of traumatic EDHs with a benign natural history. It is postulated that they arise from venous bleeding due to disruption of the sphenoparietal sinus.