Ambulatory non-convulsive status epilepticus evolving into a malignant form

We retrospectively analysed the clinical characteristics, electroencephalogram (EEG) records, brain magnetic resonance imaging (MRI) scans, antiepileptic therapy and prognosis of a case series with ambulatory non-convulsive status epilepticus (NCSE) which evolved into a malignant form (mNCSE). mNCSE was defined as NCSE that continues or recurs five days or more after the onset of general anaesthesia, including those cases where NCSE recurs upon reduction or withdrawal of anaesthetic therapy. Four women and two men were studied. The mean age was 42.8 years (range: 19-63 years). Two of six patients had a previous diagnosis of epilepsy. Four patients died. Two patients had a good outcome with return to consciousness and activities of daily life, and one of these subjects developed temporal lobe epilepsy. In four patients, the cause of mNCSE was encephalitis. Clinical presentation was complex partial status epilepticus (CPSE) in three patients and generalised NCSE (GNCSE) in the other three. Two of the latter had encephalitis and one was diagnosed with progressive myoclonus epilepsy (PME) of Lafora type. The mean duration of the NCSE episode was 47.5 days (range: 9-139 days; SD: 53.1). In three patients, continuous or rhythmic focal epileptiform discharges were the EEG pattern at onset. In the other three, continuous rhythmic generalised spike-wave, polyspike-wave or sharp slow-wave complexes were observed. Antiepileptic treatment was heterogeneous and patients were treated with an average of 6.0 AEDs (range: 3-10; SD: 3.0). In summary, mNCSE is a severe epileptic condition that occurs often in the context of encephalitis or pre-existing epilepsy. Both CPSE and GNCSE may occur. Although high mortality is associated with mNCSE, some patients may survive with normal or good recovery.