Long-term outcome of patients with disorders of consciousness with and without epileptiform activity and seizures: a prospective single centre cohort study

Brain-injured patients can experience epileptic seizures beyond 1 week from injury (unprovoked remote symptomatic epileptic seizures). In our longitudinal observational study, we analysed occurrence of unprovoked remote epileptic seizures and interictal epileptiform activity in 130 traumatic, vascular or anoxic inpatients with disorders of consciousness (DOC), with a clinical diagnosis of vegetative state (n = 97) or minimally conscious state (n = 33). We also investigated impact of epileptic seizures and epileptiform activity on clinical outcome (30 months post-onset). Epileptic seizures occurred in 35/130 patients (26.9 %), epileptiform activity in 61/130 (46.9 %) patients, without significant differences related to clinical diagnosis or aetiology. Among patients with epileptiform activity, only 26/61 (42.6 %) developed clinically evident seizures. Mortality at 30 months was not significantly influenced by the presence of seizures or epileptiform activity. The proportion of patients who recovered at long-term follow-up was higher in patients without than in patients with epileptic seizures, but was similar in patients with or without epileptiform activity. The presence of epileptic seizures but not of epileptiform activity, significantly affected the level of responsiveness at final outcome. In conclusion, seizures were detected in about one third of the whole sample, and in about a half of patients with epileptiform activity, regardless of clinical diagnosis or aetiology. Although epileptic seizures or epileptiform activity did not significantly affect mortality rate, we demonstrated that epileptic seizures could hamper recovery of consciousness. Epileptic seizures thus qualify as one of the factors largely undetermined at the moment which can influence prognosis in DOC patients.