The Second Impact Syndrome occurs when an athlete who has received an initial head injury suffers a second head injury before the symptoms of the first have fully cleared. The second injury is followed by the rapid onset of diffuse cerebral swelling which, if untreated, can progress to brainstem herniation and death.



(1) medical review after a witnessed first head impact

(2) documentation of ongoing symptoms following the first impact up to the time of the second impact

(3) a witnessed second head impact with a subsequent rapid cerebral deterioration

(4) neuropathologic or neuroimaging evidence of cerebral swelling without (a) significant intracranial hemorrhage or (b) other cause for cerebral edema such as encephalitis

Criteria Present

Diagnosis of Second Impact Syndrome

1 AND 2 AND 3 AND 4


(1 OR 2) AND 3 AND 4


3 AND 4 only


3 OR 4 absent



To read more or access our algorithms and calculators, please log in or register.