PTA for over 24 hours. On followup after 4 years, late epilepsy was present in 28 (10%) of 275 patients. The latter population included all who experienced early epilepsy and 100 randomly selected patients with uncomplicated injures and PTA of less than 24 hours. Of those with early epilepsy, 29% experienced late epilepsy—an incidence 4 times higher compared to those without (Jennett and Lewin, 1960).
Jennett (1969) expanded the Oxford series to include a total of 189 patients with epilepsy (within 8 weeks of injury); 150 cases of epilepsy within the same period were also added and known as the Glasgow series. Results were consistent with previous studies: an increased risk of late epilepsy was found in people with nonmissile injuries who had early epilepsy. Early epilepsy (within 1 week of injury) occurred 30 times more often than in the following 7 weeks (Jennett, 1969, 1973). A group of 73 patients with missile injuries was included for comparison; results indicated that early epilepsy is not necessarily predictive of late epilepsy in such patients, inasmuch as the baseline risk of late epilepsy is already high; 45% of those with missile injuries develop late epilepsy (Jennett, 1969, 1973).
Jennett (1962) examined early and late epilepsy by studying 381 patients who sustained blunt head injuries: 139 had early epilepsy, 282 late epilepsy, and 40 both early and late epilepsy. The population was drawn from the 46 patients with early epilepsy in the Oxford series, 93 patients with early epilepsy in Manchester and Cardiff, England, and patients at the Oxford Infirmary outside the study dates. The late-epilepsy series consisted of 58 followup patients with late epilepsy (drawn from 75 patients with early epilepsy and 240 without early epilepsy in the 1,000-patient Oxford series) and 224 patients who presented with a history of head injury and epilepsy. Results were consistent with previous and later studies of this cohort in that a relationship was found between more severe injury (longer PTA, depressed fracture, and early epilepsy) and development of late epilepsy.
The effect of depressed fractures on the incidence of epilepsy was studied in over 600 patients from both the Oxford and Glasgow series—333 patients were followed for over 1 year after injury, and 219 were followed for more than 4 years. Early epilepsy was seen in 10% of those with depressed fractures and 4% of those without; late epilepsy was seen in 21% of those with depressed fractures and 8% of those without (Jennett, 1969).
Jennett (1973) studied patients from the original Oxford series, patients from the Glasgow series, and 250 patients with depressed fractures from Rotterdam to investigate known risk factors for late epilepsy: early epilepsy, intracranial hematoma (evacuation within 14 days of injury), and depressed fracture. The results supported those of previous studies. In addition, 75% of patients who had one late epileptic episode experienced seizures over the following 2 years, and over 33% experienced at least one seizure per month.
Jennett (1975) summarized previous findings on nonmissile injuries from the combined Oxford, Glasgow, and Rotterdam series.
Roberts (1979) examined the relationship between a single nonmissile head injury and characteristics of mental and physical disability 3–25 years after injury in two groups of patients. The study population consisted of 548 patients (11 eventually lost to followup) from a total population of 7,000 patients admitted after accidental head injury to the Accident and Neurosurgical Services of the Radcliffe Infirmary, Oxford, England, in 1948–1961. The study