Wiedemayer et al. (2002) retrospectively analyzed a consecutive series of 1868 adult patients with head injury and found that the first epileptic seizure was generalized in 69 patients (63.3%) and partial in 40 patients (36.7%). Fifty-eight patients (53.2%) experienced a second early seizure during the follow-up period. Based on multiple studies, the incidence by seizure type is as follows: complex or simple partial seizures with secondary generalization, 16%-77% (Di Luca & de Lacerda 2013; Kazemi et al. 2012; Sapina et al. 2014; Zhao et al. 2012); generalized tonic-clonic seizures, 30%-53.6% (Di Luca & de Lacerda 2013; Zhao et al. 2012; Zheng et al. 2013); simple partial seizures, 14%-42.3% (Zhao et al. 2012; Zheng et al. 2013); complex partial seizures, 4.1%-16% (Sapina et al. 2014; Zhao et al. 2012; Zheng et al. 2013); and generalized atonic seizures, 2% (Di Luca & de Lacerda 2013).
There has also been a correlation found between the type and frequency of seizures; those with simple or complex partial seizures experience a higher frequency of seizures (Kazemi et al. 2012). In a study examining 66 individuals who developed LPTS, it was determined that 79% had generalized seizures and 21% had focal seizures (Englander et al. 2003). Another study found focal epilepsy was the most common subtype of PTE, diagnosed in 93% of patients and arising most commonly from the temporal lobes and frontal lobes (Gupta et al. 2014). More specifically, 57% had temporal lobe epilepsy, 35% had frontal lobe epilepsy, 3% had parietal lobe epilepsy, and another 3% had occipital lobe epilepsy (Gupta et al. 2014).
Seizures following TBI may themselves be a source of significant morbidity and it has been noted that the recurrence of seizures is an important cause of non-elective hospitalization in patients with severe TBI (Cifu et al. 1999). Potential complications include deterioration in cognitive and behavioural functioning and overall functional status, impaired neurological recovery, status epilepticus and death.
Cognitive and Behavioral Function
Post-traumatic seizure disorders may lead to cognitive and behavioural disorders (Yablon & Dostrow 2001). Cognitive problems may arise during the interictal state in the absence of active seizures (Aarts et al. 1984; Binnie & Marston 1992). Patients with PTS can experience persistent behavioural abnormalities and a higher incidence of psychiatric-related hospitalizations even compared to patients with penetrating TBI who do not experience PTS (Swanson et al. 1995).
Influence on Neurologic Recovery
Neurological recovery can be influenced by PTS (Hernandez & Naritoku 1997; Yablon & Dostrow 2001). Yablon and Dostrow (2001) have noted that, in rodent models, brief and infrequent PTS occurring early after brain damage do not appear to impact functional recovery; however, more severe and widespread seizures occurring within the first 6 days post brain injury result in permanent impairments of functional recovery. Seizures occurring after the sixth day result in no change in somatosensory recovery (Hernandez & Naritoku 1997).
Recurrent PTS may exert a negative impact on functional status following TBI, an adverse effect independent of the severity of the injury (Barlow et al. 2000; Schwab et al. 1993). In the case of penetrating TBI, PTS have been reported to be an important and independent factor which affects both employment status and cognitive performance (Schwab et al. 1993). However, in the case of non-penetrating TBI, the impact of PTS on functional prognosis and cognition is less clear (Armstrong et al. 1990; Asikainen et al. 1999). Within a population of individuals with LPTS, Kolakowsky-Hayner and colleagues (2013) discovered that occupational and social integration were the most difficult areas for recovery post-injury. However, Haltiner et al. (1997) found no significant differences at 1 year as a consequence of LPTS in terms of neuropsychological performance and psychosocial functioning when adjusted for injury severity. Asikainen et al. (1999) found that patients with PTS did have poorer outcomes on the Glasgow Outcome Scale. A more recent study found that of individuals with LPTS, 20% were severly disabled, 52% moderately disabled and 28% had a good recovery, as measured by the Extended Glasgow Outcome Scale. No significant differences in employment outcome associated with the presence of PTS have been found (Asikainen et al. 1999). Further Kolakowsky-Hayner et al. (2013) found that among a group on individuals with TBI-LPTS, 40% (7 of 20) of individuals who were driving pre-injury had their license suspended due to their first seizure; 3 were able to re-obtain their license.
Status epilepticus can be defined as either more than 5 minutes of continuous seizure activity or two or more sequential seizures without full recovery of consciousness between seizures. Status epilepticus is regarded as the most serious of the complications of PTS and may actually lead to additional neurological damage. Simple partial status epilepticus is a subset of status epilepticus characterized as a partial focal seizure that does not cause loss of consciousness or secondary generalization (Hadjigeorgiou et al. 2013). Fortunately, clinically apparent status epilepticus and simple partial status epilepticus are infrequent complications of PTS (Kollevold 1979), with only 0.16% of individuals hospitalized with TBI with status epilepticus (Dhakar et al. 2015).
In earlier studies mortality was reported to be high among those who sustain a TBI and develop PTS (Corkin et al. 1984; Walker & Blumer 1989; Walker & Erculei 1970). More recently, Englander et al. (2009) found mortality rates to be higher for patients with TBI who had been diagnosed with LPTS when compared with those who had no recorded history of LPTS. Those in the LPTS group who died tended to be younger than individuals who did not have LPTS. Earlier studies found that patients with penetrating TBIs had a higher risk of dying; however, this is more likely due to the initial trauma rather than PTS (Rish & Caveness 1973; Rish et al. 1983). Yablon and Dostrow (2001) have noted that the complications of a single LPTS are no different than those seen after any seizure, and are generally minimal. However, increased seizure frequency and severity are associated with an increased risk of mortality and morbidity in the form of worsened cognition and overall function.
The risk associated with a single late post-traumatic seizure is minimal and no different than that seen after any seizure.
Following TBI, seizure recurrence can be a significant source of morbidity. Severe and widespread seizure recurrence during the first six days post TBI can be associated with permanent impairments in functional recovery. Those patients with a higher seizure frequency and severity are at increased risk of complications.
Status epilepticus is a rare complication of post-traumatic seizure.
Mortality rates are higher in those patients with TBI diagnosed with post-traumatic seizures, compared to those without seizures.