Rapid Spontaneous Redistribution of Acute Epidural Hematoma : Case Report and Literature Review

Abstract

Acute epidural hematoma (AEDH) occurring as a result of traumatic head injury constitutes one of the most critical emergencies in neurosurgery. However, there are only several reports that show the rapid disappearance of AEDH without surgical intervention. We suggest redistribution of hematoma through the overlying skull fractures as the mechanism of rapid disappearance of AEDH. A 13-year-old female fell from a height of about 2 m and presented with mild headache. A computed tomography (CT) scan performed 4 hours after the injury revealed an AEDH with an overlying fracture in the right temporal region and acute small hemorrhagic contusion in the left frontal region. A repeat CT scan 16 hours after injury revealed that the AEDH had almost completely disappeared and showed an increase in the epicranial hematoma. The patient was discharged 10 days after injury with no neurological deficits. This case is characterized by the rapid disappearance of an AEDH associated with an overlying skull fracture. We believe that the rapid disappearance of the AEDH is due to the redistribution of the hematoma, rather than its resolution or absorption, and fracture plays a key role in this process.

INTRODUCTION

A rational therapeutic approach for treating an acute epidural hematoma (AEDH) is based on clinical and radiological parameters. Although there have been several reports of asymptomatic AEDH cured through non-operative treatment in a period of weeks⁸⁾, early spontaneous disappearance of an AEDH within 24 hours is very rare and, to the best of our knowledge, has been reported only for eight cases^1-6,9,11). Here, we describe a case of AEDH that disappeared rapidly without surgical intervention and review the literature about this rare phenomenon.

CASE REPORT

A 13-year-old female fell from a height of about 2 m and hit her right temporal region against the floor. She reportedly lost consciousness for a few minutes. On admission, she complained only of a mild headache. Physical examination revealed swelling in the right temporal area. However, the results of neurological examination were unremarkable. A computed tomography (CT) scan performed 4 hours after the injury revealed an AEDH (about 1.8 cm in maximum thickness) of heterogeneous density with an overlying fracture in the right temporal region and acute small hemorrhagic contusion in the left frontal region. Air bubbles in the AEDH were noted (Fig. 1). Although she remained alert after admission, a repeat CT scan was obtained 16 hours after injury in an effort to rule out delayed occurrence of intracranial hematoma. At this time, the AEDH had almost completely disappeared, and there was an increase in the size of the epicranial hematoma (Fig. 2). The patient was discharged after 10 days with no neurological deficits.

Fig. 1.

Computed tomography scans without contrast medium (A) and with bone setting (B) obtained 4 hours after injury reveals an acute epidural hematoma of heterogeneous density with an overlying fracture in the right temporal region and acute small hemorrhagic contusion in the left frontal region. Air bubbles in the acute epidural hematoma are noted.

Fig. 2.

Computed tomography scan obtained 16 hours after injury reveals a marked decrease in the acute epidural hematoma and increase in the epicranial hematoma.

DISCUSSION

The spontaneous resolution process during the natural course of AEDH starts in the second week⁷⁾. Therefore, disappearance of an AEDH within 24 hours after trauma is extremely rare and only nine cases have been reported in the English literature, in addition to our present case^1-6,9,11) (Table 1). Although various mechanisms of disappearance of hematoma have been suggested, the underlying mechanism is still unclear. Aoki²⁾ emphasized the potential for communication between intracranial and epicranial hematomas through a fracture; this communication provides useful information for predicting a favorable prognosis. Kuroiwa et al.⁴⁾ hypothesized that the hematoma may be forced out of the intracranial region through the fracture line due to the pressure gradient between the venous EDH in the transverse sinus and the intradural space. Malek et al.⁵⁾ proposed that the hematoma may be caused by an increase in epicranial/subcutaneous pressure after focal head trauma, which causes serosanginous fluid to leak into the epidural space through an underlying skull fracture. When the epicranial tissue pressure subsides, the fluid would leak back out through the fracture into the epicranial space. Ugarriza et al.¹¹⁾ hypothesized that the AEDH communicated with the fractured external auditory canal, making possible its ultraearly drainage without any need to postulate intracranial hypertension. Kang et al.³⁾ emphasized that the pressure gradient between the subgaleal and epidural space may be important in the rapid disappearance of AEDH. Neely et al.⁶⁾ postulate that bleeding from the diploic space of the calvarium initially extends into both the subgaleal and epidural compartments in these patients, with the blood preferentially decompressing into the subgaleal space as it increases in volume in the immediate posttraumatic period, aided by CSF pulsation. In our case, a follow-up CT 16 hours after injury revealed that the hematoma had almost completely disappeared, while the size of the epicranial hematoma had increased. Therefore, we speculate that the mechanism underlying the rapid disappearance of the AEDH in our case is the redistribution of the hematoma through overlying skull fractures that commonly accompany AEDH. Consistent with this hypothesis, other studies have reported a higher rate of spontaneous resorption in patients with additional skull fracture compared to patients with isolated EDH¹⁰⁾.

Table 1.

Literature review of cases of spontaneous disappearance of an acute epidural hematoma within 24 hours

BA : bicycle accident, MVA : motor vehicle accident, LOC : loss of consciousness, DAI : diffuse axonal injury, PTA : posttraumatic amnesia, NA : non available, HD : hospital day

CONCLUSION

This report describes the mechanism underlying the rapid disappearance of an AEDH associated with an overlying skull fracture. We believe that the rapid disappearance of the AEDH is due to redistribution of a hematoma, rather than its resolution or absorption, and there is no doubt that the fracture plays a key role in this process.