To better describe seizure type, frequency, and electroencephalographic (EEG) findings in posterior reversible encephalopathy syndrome (PRES) and correlate these data with clinical and magnetic resonance imaging (MRI) data, we retrospectively assessed medical charts and EEG studies of patients with PRES treated between 2004 and 2011. Data collected included patients' underlying pathology, lesion distribution by MRI, seizure type and frequency, EEG pathologic background activity, focal pathology, and epileptogenic activity. Thirty-eight of 49 adults with PRES suffered from seizures; 17 underwent EEG and were included in the analysis. Perpetuating factors were similar to those reported in the literature. In 15 of 17 patients, MRI showed widespread involvement rather than purely occipital lesions. Nine patients had subcortical and cortical involvement. Seizures were single short grand mal (GM) in 11, serial GM in 2, recurrent GM in 2, and additional focal seizures in 2. No seizures were noted beyond the first day. After discontinuation of antiepileptic medication, no patients experienced seizure recurrence during 6-month follow-up. EEG showed diffuse theta/delta slowing in 13 patients and epileptogenic activity with focal sharp-wave and periodic lateralizing epileptiform discharges in 2 patients. Seizures in PRES are most commonly single GM and are usually of limited duration. EEG shows variable theta/delta slowing. Focal EEG pathology is seen in patients with focal seizures. Seizures occur early after disease onset and terminate spontaneously or under therapy during the first 24 h. Seizure recurrence beyond 24 h and chronic epilepsy were not seen. Seizures in PRES are frequent but appear to be uncomplicated and do not herald worse prognosis. EEG is helpful in evaluating the degree of encephalopathy and monitoring epileptic activity. Long-term antiepileptic medication does not appear to be warranted.

We report on two young patients with an encephalitic syndrome and bilateral thalamic lesions following a presumably viral or mycoplasma respiratory tract infection with the main clinical symptoms of organic psychosis in the first and a prolonged amnestic syndrome and ataxia in the second case. Four months later the patients had recovered clinically and the thalamic lesions had resolved on magnetic resonance imaging in one case and almost completely in the other. We interpret the patients' illness as rare cases of a post-infectious acute thalamic encephalitis in adults. The cases and their relationship to possible post-infectious autoimmune inflammatory or toxic pathophysiological mechanisms are discussed and a review of the literature is provided.

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