PURPOSE: to investigate the semiology of subtle motor phenomena in critically 
ill patients, with- versus without nonconvulsive status epilepticus (NCSE).
METHODS: 60 consecutive comatose patients, in whom subtle motor phenomena were 
observed in the intensive care unit (ICU), were analysed prospectively. The 
semiology of the subtle phenomena was described from video-recordings, blinded 
to all other data. For each patient, the type, location and 
occurrence-pattern/duration were described. EEGs recorded in the ICU were 
classified using the Salzburg criteria for NCSE.
RESULTS: only 23% (14/60) of the patients had NCSE confirmed by EEG. None of the 
semiological features could distinguish between patients with NCSE and those 
without. In both groups, the following phenomena were most common: discrete 
myoclonic muscle twitching and discrete tonic muscle activation. Besides these, 
automatisms and eye deviation were observed in both groups.
CONCLUSION: subtle motor phenomena in critically ill patients can raise the 
suspicion of NCSE. Nevertheless, EEG is needed to confirm the diagnosis, since 
none of the semiological features are specific.