Post-traumatic seizures are well-known sequelae of brain injury. Posttraumatic seizures may be classified into three groups: Immediate (within 24 hours after injury); Delayed Early (within the first week after injury); and Late (greater than one week after injury). The first two groups are considered to result from direct reactions to brain damage, and may be termed early posttraumatic seizures (EPTSs). Factors involved in the origin of late posttraumatic seizures (LPTSs) however, are multifactorial: depressed skull fractures, intracranial hematoma, EPTSs, prolonged unconsciousness prolonged posttraumatic amnesia, and low Glasgow Coma Scale scores are all postulated to increase the risk for LPTSs.

The influence of LPTSs on outcome in TBI patients, however, is not well-known. In 1998, a group from the Department of Neurology at the University of Helsinki followed 490 patients with problems in education and employment who were followed at the outpatient neurological clinic between 1978 and 1993. An analysis of LPTSs, including the influence of LPTSs on outcome, was made in follow-ups ranging from 5-10 years (48%), 11-15 years (26%), 16-20 years (17%) and over 20 years (9%). A CT scan to detect posttraumatic brain lesions, EEG, and neuropsychological tests were performed. Possible risk factors for LPTSs such as type and severity of brain injury, length of coma, duration of PTA, and early seizure activity was noted. Occurrences of EPTSs and LPTSs were then analyzed separately in relation to age at injury.

Children age 7 years or younger at the time of injury were most prone to early seizures (30.8%), followed by children 8-16 (20%) and then patients older than 16 years (8.4%). Occurrence of LPTSs in children 7 years or younger were similar the EPTSs (32.7%); however, patients in the older groups had a higher occurrence of late seizures (31.4% in patients 8-16, and 18.9% in patients older than 16). Late seizures also occurred earlier in younger patients: within 6 months post injury in patients 7 years or younger, versus after five years in patients 8-16 (47.5%) and those older than 16 (26. 1 %).

In this population, early seizures and depressed skull fractures were statistically significant risk factors. Permanent posttraumatic focal neurologic deficit, linear skull fracture, permanent post-traumatic local brain lesion documented on CT scan, severity of brain injury (GCS score) were not found to be statistically significant. Local abnormality on acute stage EEG reflecting a local brain lesion was a risk factor for LPTSs in univariate analysis. Patients with late seizures more often had worse functional outcomes with Glasgow outcome Scores of 2 or 3. There was no relation between LPTS and employment in this population, however.

There may be a stigma against patients with epilepsy, as this study shows. Even though employment status was equivalent to those without LPTSs, patients with epilepsy had slightly worse functional and social outcomes. The importance of proper antiepileptic medical treatment may help improve chances of employment, as well as increased awareness against discrimination of affected patients in their social and professional lives.

For more information:

Asikainen, I., Kaste, M., and Sarna, S. Early and Late Posttraumatic Seizures in Traumatic Brain Injury Rehabilitation Patients: Brain Injury Factors Causing Late Seizures and Influence of Seizures on LongTerm Outcome. Epilepsia: 40(5): 584-589, 1999.

Lisa Palen Hu, M.D.