You will be presented with the full text of a biomedical research paper. Please write an abstract for this paper. Your response should include the abstract and no additional text.

Paper text:
in contrast with severe head traumas that might cause irreversible neuronal injuries , repeated mild head injuries rarely induce destructive brain injuries .
the effect of this trauma is usually transient ; however , it has been reported that prolonged and repeated concussions cause permanent cognitive impairment.8)10)13 ) we treated a young football player who presented with acute subdural hematoma , cerebral edema , and seizure due to a ruptured pseudoaneurysm of middle cerebral artery ( mca ) . through surgical findings and literature review
, we were convinced that the pseudoaneurysm with dural calcification and adhesion on underlying brain may have been formed by repeated concussions .
an 18-year - old american college football player presented with a vague headache since he was tackled during exercise several weeks ago .
brain computed tomography ( ct ) was performed at a local hospital a few days before visiting our hospital because the headache worsened and was not relieved through medication .
initial brain ct revealed a small amount of subdural hematoma on the left cerebral convexity ( fig .
however , it was initially considered a simple traumatic hemorrhage and was managed by conservative means .
several days later , the headache aggravated and the patient experienced an episode of generalized partial seizure . on the magnetic resonance imaging ( mri ) performed immediately after the seizure , the size of acute hematoma and cerebral edema was markedly increased , and a small enhancing mass was observed at the left cerebral convexity ( fig .
2 ) . magnetic resonance angiography ( mra ) revealed a 4 mm sized aneurysmal dilatation of the cortical branch of the mca , which supplies the superior temporal region ( fig .
emergency craniotomy was performed to eliminate the aneurysm and lower the elevated intracranial pressure by removing the hematoma .
a large craniotomy was done , and the subdural hematoma was removed by repeated gentle irrigation and suction after small dural incision . while further opening of the dura , we were encountered by several irregularly shaped , hard subdural nodules which were tightly adhered to the dura and the underlying brain ( fig .
, these nodules were noted to be buried in the sulcus while being severely adhered to the brain cortex and the cortical arteries . between the nodules was an organizing hematoma and upon careful removal , a pseudoaneurysm of the cortical mca branch was exposed .
the involved mca branch was carefully dissected and was trapped by clips at the proximal and distal portion of the severely injured and adherent segment , along with the pseudoaneurysm .
the ischemic injury was minimized because the collateral flow retrogradely supplied the distal part of the occluded artery .
approximately 300,000 sport - related concussions occur annually in the united states , and the likelihood of serious sequelae might increase with repeated head injury.7)19 ) many studies about repeated head injuries have been published , and subdural hematoma is known as the most common cause of brain injury - related fatality in sport - related injuries.5)6)17 ) subdural hematoma occurs due to severe head trauma such as skull fracture , but not by minor head trauma .
brain injury - related fatalities are dramatically reduced by wearing protective helmets that prevent severe head trauma.6 ) most of the reports about repeated mild brain trauma focus on neurodegeneration.2)3)4 ) our case differed from the reported cases in the context that repeated brain injury may have formed calcification of the dura over a long period of time , which in turn may have caused mechanical irritation and injury of the mca branch , resulting in pseudoaneurysm formation and rupture .
pseudoaneurysm formed at the cortical mca in minor blunt head trauma was very unusual because the location of pseudoaneurysms reflects the mechanism of injury .
for example , basal skull fracture might cause pseudoaneurysm at the vertebrobasilar system.11)14)15)21 ) arterial contusion by the anterior clinoid process causes supraclinoid internal cerebral artery pseudoaneurysms.14)15 ) distal anterior cerebral arteries might be injured by the proximal falcine edge.16 ) cortical artery aneurysms commonly form because of an overlying skull fracture.21 ) however , these general injury mechanisms could not explain our case .
calcification of the intracranial dural meninges is rare ; however , it may occur due to degeneration , irritation , inflammation , hemorrhage , or trauma.1)12)20)22 ) for example , calcifications might develop in chronic subdural hematomas due to trauma and inflammation and the degree of calcification extends from thin calcified inner membranes to dense calcification , including ossification of the hematoma.1)12 ) the physiology of dural calcification has not been fully understood ; however , it might be due to calcium and , sometimes , iron deposition in the blood vessels of different structures of the brain.1)9 ) applying this hypothesis to our case , we conjectured that the repetitive concussion and inflammation might be the cause of dural calcification and its adherence to the brain .
the cortical mca pseudoaneurysm may have arisen from mechanical irritation of the arterial wall by the adherent dural calcification , resulting in subsequent arterial wall shear and tear .
the adhesion of calcified dura mater on the injured brain was confirmed in the operation field .
the most common clinical presentation of traumatic pseudoaneurysm is delayed intracranial hemorrhage with subsequent neurological deterioration ; however , it can be prevented by early diagnosis.15)18 ) hence , traumatic pseudoaneurysm must be taken into consideration even in mild traumatic brain injury , along with all other entities . among patients with repeated mild head trauma ,
if acute subdural hematoma is seen in the brain ct , traumatic pseudoaneurysm must be suspected and angiographic evaluation , either direct or indirect , should be attempted immediately .
traumatic pseudoaneurysms rarely regress spontaneously and have a high incidence of rupture and mortality.14)21 ) hence , treatment should be performed immediately if traumatic pseudoaneurysm is diagnosed . surgical treatment including clipping , excision of the aneurysm , coiling or wrapping , should be considered . in our case ,
prompt mra was performed under the suspicion of pseudoaneurysm due to this calcific nodule and the patient 's history of repeated head injury .
after prompt work - up and successful surgical management , the patient was treated before fatal rebleeding and discharged home without any sequelae .
we report an unusual case where a traumatic pseudoaneurysm was the cause of an acute sdh after repeated mild head injury .
we speculate the repeated injury to the head may have resulted in chronic formation of dural calcification , which in turn may have resulted in mechanical injury of the cortical mca branch .
when calcified nodules are seen in the initial ct scan of such patients , pseudoaneurysms must be taken into consideration as the underlying cause .
repeated concussion is common among football players ; however , these minor blunt head trauma rarely result in serious complications . 
 we report a case of a young college football player who presented acute subdural hematoma , cerebral edema , and seizure due to pseudoaneurysm rupture . 
 the pseudoaneurysm , located at the cortical branch of the middle cerebral artery , was speculated to be formed by dural calcification and adhesion with the underlying brain , possibly due to repeated concussions . following successful excision of the pseudoaneurysm and control of brain swelling , the patient recovered without sequelae and was discharged after a short while .