====== Late-onset posttraumatic seizures ======

Estimated [[incidence]] of Late-onset [[posttraumatic seizures]] 10–13% within 2 yrs after “significant” [[head trauma]] (includes LOC > 2mins, GCS < 8 on [[admission]], [[epidural hematoma]]...) for all age groups
((McQueen JK, Blackwood DHR, Harris P, et al. Low Risk of Late Posttraumatic Seizures Following Severe Head Injury. J Neurol Neurosurg Psychiatry. 1983; 46:899–904))
((Young B, Rapp RP, Norton JA, et al. Failure of Prophylactically Administered Phenytoin to Prevent Early Posttraumatic Seizures. J Neurosurg. 1983; 58:231–235))
Relative risk: 3.6 times control population. The incidence of [[severe head injury]] > moderate > mild
((Annegers JF, Grabow JD, Groover RV, et al. Seizures After Head Trauma: A Population Study. Neurology. 1980; 30:683–689)).

The incidence of early PTS is higher in children than adults, but late seizures are much less frequent in children (in children who have PTS, 94.5% develop them within 24 hrs of the injury
((Hahn YS, Fuchs S, Flannery AM, et al. Factors Influencing Posttraumatic Seizures in Children. Neurosurgery. 1988; 22:864–867))).
Most patients who have not had a seizure within 3 yrs of [[penetrating head injury]] will not develop 
seizures
((Weiss GH, Salazar AM, Vance SC, et al. Predicting Posttraumatic Epilepsy in Penetrating Head Injury. Arch Neurol. 1986; 43:771–773)).
The risk of late PTS in children does not appear related to the occurrence of early PTS (in adults: only true for mild injuries). Risk of developing late PTS may be higher after repeated head injuries.