Preventing Epilepsy After Traumatic Brain Injury With Topiramate

Inclusion Criteria: 1. Moderate to severe traumatic brain injury, defined as one or more of the following: penetrating head wound seizure within the first hour after injury intracerebral hematoma or cortical contusion subdural or epidural hematoma Glasgow Coma Score \<= 12 or motor score 1-5 (if intubated). Patients who have been pharmacologically paralyzed will be evaluated after the paralytic has worn off or been pharmacologically reversed depressed skull fracture requirement for emergent neurosurgical procedure 2. Time since TBI less than 24 hours 3. Age greater than or equal to 18 years 4. Subject capable of giving informed consent or have an acceptable surrogate capable of giving consent on the subject's behalf. - Exclusion Criteria: 1. Known prior history of epilepsy or unprovoked seizures. Patients with a history of acute symptomatic seizures (e.g. febrile seizure, alcohol withdrawal seizure) will not be excluded 2. Administration of an antiepileptic drug before enrollment 3. History of allergy to topiramate or phenytoin 4. Pregnancy or breast-feeding. Women of childbearing potential must have a negative pregnancy test (urine pregnancy test or serum beta-HCG) before randomization 5. Compromised renal function with serum creatinine \> 2 6. Severe concurrent illness with life expectancy \<6 months 7. Treatment with another investigational agent for TBI 8. Unable to take medications orally and contraindication to placement of nasogastric tube. 9. Irreversibly fatal TBI 1. All four findings: Glasgow Coma Score = 3, no pupillary reaction, age \> 45 years, and severe coagulopathy OR 2. Severe brainstem lesion on neuroimaging studies 10. Patients with a history of kidney stones or glaucoma. 11. Inability to maintain adequate fluid intake while taking topiramate. 12. Patients whose TBI is a result of self inflicted injury 13. Patient's who are currently using illicit drugs -