Periodic EEG patterns in cerebral fat embolism.

A 24-year-old male developed fat embolism syndrome (FES) 18 hours after accidental tibial and metatarsal fractures. The onset was characterized by coma, generalized seizures, respiratory distress and hypoxemia. Multiple prolonged portable electroencephalographic (EEG) recordings showed a variety of progressively changing patterns including continuous high amplitude EEG rhythmical synchronous slowing (CHERSS), triphasic waves, bilateral independent periodic lateralized epileptiform discharges (BIPLEDs), frontal intermittent delta activity (FIRDA), and low amplitude irregular generalized theta. Three months after the accident, the patient was neurologically normal and his EEG exhibited only rare brief bursts of anterior theta in the waking recording. I conclude that EEG periodic activity such as CHERSS, triphasic waves, BIPLEDs, and FIRDA can occur in patients suffering from cerebral fat embolism. It reflects a non-specific diffuse encephalopathy not necessarily associated with a poor prognosis. Prolonged and frequent bedside EEG recordings will demonstrate better these fluctuating abnormalities in cerebral fat embolism (and probably in coma of other origin) than standard less frequent recordings. Very likely, these periodic EEG patterns have not been previously identified in cerebral fat embolism because they were not in vogue among electroencephalographers nor widely accepted at the time studies dealing with this syndrome were written.