The grades of evidence (I-III) and levels of recommendations (I-III) are defined at the end of the "Major Recommendations" field.
Level I
There are insufficient data to support a Level I recommendation for this topic.
Level II
Prophylactic use of phenytoin or valproate is not recommended for preventing late posttraumatic seizures (PTS).
Anticonvulsants are indicated to decrease the incidence of early PTS (within 7 days of injury). However, early PTS is not associated with worse outcomes.
Summary
The majority of studies do not support the use of the prophylactic anticonvulsants evaluated thus far for the prevention of late PTS. Routine seizure prophylaxis later than 1 week following traumatic brain injury (TBI) is, therefore, not recommended. If late PTS occurs, patients should be managed in accordance with standard approaches to patients with new onset seizures. Phenytoin has been shown to reduce the incidence of early PTS. Valproate may also have a comparable effect to phenytoin on reducing early PTS but may also be associated with a higher mortality.
Definitions:
Grades of Evidence
Class I - Good quality randomized controlled trial (RCT)
Class II - Moderate quality RCT, good quality cohort, or good quality case-control
Class III - Poor quality RCT; moderate or poor quality cohort; moderate or poor case-control; or case series, databases, or registries
Levels of Recommendation
Levels of recommendation are Level I, II, and III, derived from Class I, II, and III evidence, respectively.
Level I - Recommendations are based on the strongest evidence for effectiveness, and represent principles of patient management that reflect a high degree of clinical certainty.
Level II - Recommendations reflect a moderate degree of clinical certainty.
Level III - Recommendations for which the degree of clinical certainty is not established.