Neuroradiology Case of the Week

Case 17

Ramon de Guzman, MD, and P-L Westesson, MD, PhD, DDS

Clinical Presentation: The patient is a 20-year-old man with history of motor vehicle collision that involved a rollover of a truck which turned upside-down. Patient crawled out and phoned his family but later became confused. At the emergency room, the patient was intubated and had a Glasgow coma score of 15. He sustained lacerations on the left eyelid and left side of his nose.

Radiographic Findings: The nonenhanced CT scan of the head showed left frontal bone fracture involving the left frontal sinus (Fig. 1), left fronto-temporal bone fracture and zygomatic fracture with a left epidural hematoma (Figs. 2 & 3) and pneumocephalus (Fig. 3).

Figure 1: Fracture at the left frontal sinus (arrow) with possible hemoantrum.
Figure 2: Epidural hematoma along the left frontal convexity (arrow).	Figure 3: Epidural hematoma (arrow) with small pneumocephalus (arrowhead).

Diagnosis: Epidural Hematoma

Discussion:
Clinical Discussion
   Traumatic epidural hematoma (EDH) is relatively uncommon, occurring in approximately 2% of head injuries, and is associated with an 18% to 30% mortality in adults and a 2% to 10% mortality in children [1, 2, 3].
   It results from laceration of a meningeal vessel or dural sinus, often associated with fracture. Air is often intermixed with blood. The most common site is the posterior branch of the middle meningeal artery that crosses the thin portion of the temporal bone as it begins to arch over the hemisphere [4]. Less frequently, the posterior meningeal branch to the occipital dura or the lateral sinus may be torn resulting in a posterior fossa EDH [4]. Meningeal arterial bleeding can be rapid, and a potentially fatal hematoma can accumulate in a few hours [4].

Neuro Imaging Discussion
   Blood accumulates in the epidural space, stripping the dura from the inner table of the skull. EDH is the only form of ICH that can cross the midline. The resulting hematoma usually has an almost circular margin and forms a convex collection that compresses the underlying brain [4].
   An initially normal imaging examination does not exclude a subsequent growth of a fatal EDH. As an EDH expands it will first force cerebrospinal fluid (CSF) out from the cisterns and ventricles, and blood from the compressible veins. The volume of these components is about 150 ml. If the EDH expands beyond this brain volume, herniation will occur with potentially catastrophic results. In rare cases, a slowly expanding chronic EDH will form, probably by a process similar to that seen in chronic SDH [5].

References:

1. Mohanty A, Kolluri VRS, Subbakrishna DK, et al. Prognosis of extradural hematomas in children. Pediatr Neurosurg 1995; 23:57-63.
2. Lindenberg R. Pathology of craniocerebral injuries. In Newton TH, Potts DG (eds). Radiology of the Skull and Brain: Anatomy and Pathology, pp.3049-3087. St. Louis, C V Mosby, 1977.
3. Jamjoom A, Cummins B, Jamjoom ZA. Clinical characteristics of traumatic extradural hematoma: A comparison between children and adults. Neurosurg Rev 1994; 17:277-281
4. Kirkpatrick JB, Hayman LA. Pathophysiology of intracranial hemorrhage. In Hayman LA, Taber KH (eds). Nontraumatic Intracranial Hemorrhage. Neuroimaging Clin N Am 1992; 2:11-23.
5. Watanabe T, Nakahara K, Miki Y, et al. Chronic expanding epidural haematoma. Case report. Acta Neurochir (Wien) 1995; 132:150-153.