This retrospective study conducted in a referral hospital in Cameroon, aimed to describe different features of post-traumatic epilepsy (PTE) for the first time.
In about 6% of patients with epilepsy, traumatic brain injury (TBI) is thought to be the cause . In this study, patients with PTE represented 8.1% of the patients followed up for epilepsy in our institution. The male predominance found in this study is consistent with the findings of Ogunrin et al. in Nigeria and Zhao et al. in China [13, 14]. This concordance of results could be explained by the fact that men are more active and carry out more risky activities exposing them to TBI. Two patients out of five were within the 18 to 28 age group. These results are similar to those found in China by Zhao et al. with a mean age of 40.07 years and the most represented age group varying between 20 and 29 years . Similar findings were reported by Ogunrin et al. found also a mean age of 38.6 years this agreement of the results is explained by the fact that the young population is more active and consequently more at risk of undergoing TBI . In Cameroon, young people are mainly involved in motorcycle taxi with very few regulations. This contributes to the burden of trauma in general, and TBI in particular.
In this study, road traffic accidents (RTA) were the TBI mechanism in more than three-quarters of cases. This is consistent with other studies which reported RTA as the main mechanism of TBI in different countries [15,16,17]. TBI was classified as severe in close to two-thirds of cases. Severe TBI has been found to be associated with PTE . Similar findings were also reported by other studies [15, 19]. The time to the first seizure, which corresponds to the duration of epileptogenesis, varies depending on the individual. In this study, more than two patients out of five underwent their first seizures within one year following the TBI, and close to three-quarters of cases within the first 2 years. These results are similar to other studies who reported 80% of patients with first seizure during the first 2 years following the TBI [13, 15, 20, 21].
In this study, close to half of cases presented a generalized tonic–clonic seizures (GTCS). Other seizures types included focal seizures, and focal seizures with secondary generalization. Similar results were reported by Haltiner et al. with 51% of GCTS, 33% of focal seizures, and 17% focal seizures with secondary generalization . Englander et al. found a higher frequency of GTCS . However, our findings were different from the results of da Silva et al. who described 54.6% of focal seizure, and 37.6% of GTCS in a military population . The focal of seizure could be overshadowed by the spectacular presentation of GTCS. Families of patients tend to report secondary generalization more frequently. In addition, the mechanisms of TBI in the military population are different from RTA.
Neuroimaging (brain CT scan or MRI) allows after a TBI to visualize the type and extent of brain damage. After epileptogenesis, neuroimaging contributes to rule out other causes, and to demonstrate TBI sequelae. In this study, the commonest traumatic lesions were brain contusions, diffuse axonal injuries (DAI), and epidural haematoma (EDH). Studies conducted in Africa reported mainly depressed skull fracture, and EDH [13, 15]. In these latest studies depressed skull fracture were associated with contusions. In any type of epilepsy, EEG is very useful not only for diagnosis, but also the monitoring of patients. This was demonstrated in this study where we found abnormal EEG findings in more than four patients out of five (81.5% of cases). These EEG abnormalities were: generalized spikes-and-waves discharges (41.6%), frontal spikes-and-waves discharges (30.8%), temporal spikes-and-waves discharges (6.2%), and focal slow wave activity (3%).
The choice of ASMs in PTE depends on the availability, seizure type, and tolerance and drugs interactions [25, 26]. In a resource limited setting like Cameroon, the panel of ASMs available is narrow. Based on their availability, commonest ASMs are sodium valproate, carbamazepine, phenobarbital, and diazepam. More than half of patients were on monotherapy with either sodium valproate, carbamazepine, or phenobarbital. For Ogunrin et al. patients received mainly phenytoin, carbamazepine, and sodium valproate as molecules . Right after a moderate to severe TBI, patients can be placed on ASMs in order to prevent the progression of epileptogenesis to late seizures and epilepsy . Phenytoin is the ASMs with most evidence in seizure prevention . In this study, two patients received seizure prevention medication with phenobarbital. phenytoin is almost not available in our setting. The use of ASMs in prophylaxis is still controversial. According to Pingue et al., the use of ASMs was associated with a poor rehabilitation outcome, independently of the onset of epilepsy during treatment .
The use of ASMs in this study showed some benefits with more than two-thirds of cases with seizures freedom after a mean treatment duration of 2.5 years. For other patients, there was a reduction in seizure frequency. In Nigeria, Ogunrin et al. found 87% of patient’s seizures free after 3 months of ASMs and 100% after 6 months . In this latest study, phenytoin was frequently prescribed. This demonstrates the effectiveness of phenytoin in seizure control in patients with PTE. When ASMs do not significantly reduce seizures, epilepsy surgery and vagus nerve stimulation may improve seizures control [16, 30]. In this study, no patients underwent surgery, which is not available in Cameroon.