acute subdural hemorrhage requires emergent neurosurgery or close observation because of its high mortality rate .
a number of cases who showed rapid resolution of acute subdural hemorrhage with neurological improvements have been reported2,6,7 ) .
herein , we present a case who showed rapid resolution of acute subdural hemorrhage spontaneously within 2 days after severe head injury .
initially , she was stuporous and measured as glasgow coma scale ( gcs ) score of 6 .
brain computed tomography ( ct ) revealed an acute subdural hematoma with a thickness of 10 mm in the right frontotemporoparietal region .
however , an unexpected neurological improvement was noted within 1 hour following the accident . the patient was obeyed and gcs score was 10 even though intubated .
a follow - up brain ct showed a decrease in the thickness of hematoma and improvement of the midline shift ( fig .
following the accident , brain ct showed a remarkable reduction of acute subdural hematoma and mass effect .
the hemorrhages of subdural space around falx , tentorium , posterior fossa , and upper cervical spinal canal were not found ( fig .
usually , it requires emergent neurosurgery for decompression or close observation because of the possibility of irreversible brain damages or abrupt neurological deteriorations .
rapid resolution of acute subdural hemorrhage resulting in neurological improvement is uncommon and several reports about that have been documented2,6,7 ) .
wen et al.7 ) summarized some characteristics in most patients who showed rapid resolution of acute subdural hemorrhages as followings : transitory coma which last no longer than 12 hours , exclusion of cerebral contusion , widely distributed hematoma with thin width , a band of low density between the hematoma and inner table of the skull on images , a minor or moderate head trauma sustained on insults . in our present case , similar clinical findings were found except for minimal contusion of left temporal lobe .
flow of cerebrospinal fluid ( csf ) through the arachnoid membrane tear site and retrograde flow into the subarachnoid space may result in dilution of the hematoma5 ) .
a low density band in the subdural hematoma which is seen on the images seems to mean csf that comes from the subarachnoid space through arachnoid membrane tear .
redistribution of the hematoma towards another subdural space or extracranial spaces through the skull fracture site can be another acceptable explanation1,4 ) .
our present case did not show definite skull fractures or hemorrhages in another subdural space except for minimal cerebral contusion was found .
so , it is thought that the dilution of acute subdural hematoma caused by csf flow is more consistent with our case rather than redistribution of hematoma .
brain swelling caused by cerebral contusion may contribute the redistribution of hematomas resulting in rapid resolution of subdural hematomas3 ) .
however , it is more likely to obstruct csf circulation and would mitigate the dilution and redistribution1 ) . as seen in our case , minimal cerebral contusion dose not seem to influence the obstruction of csf circulation .
it is very difficult to predict the rapid resolution of acute subdural hematoma which may undergo prompt neurosurgical treatment .
therefore , meticulous observation and concomitant imaging should be required even though some characteristics which may develop rapid resolution of acute subdural hematoma were seen .
 acute subdural hematoma is usually a neurological emergency that requires hematoma evacuation or close observation . 
 however , spontaneous resolutions of an acute subdural hematoma without surgical interventions have been reported rarely . 
 we report on a case who showed rapid resolution of an acute subdural hematoma with neurological improvement and review the relevant literatures . 
INTRODUCTION
CASE REPORT
DISCUSSION
CONCLUSION