Triphasic waves.

Triphasic waves (TWs) are a distinctive, although non-specific EEG pattern, which are quite frequently encountered and sometimes difficult to interpret. Although initially considered pathognomonic of hepatic encephalopathy, TWs have been described in association with a large number of conditions. TWs may occur in encephalopathies (metabolic or structural) or as an ictal pattern. Nonepileptic TWs with sharply contoured morphology may resemble epileptic patterns encountered in nonconvulsive status epilepticus (NCSE), thus leading to misinterpretation and overinterpretation of this pattern as ictal, if only the EEG is considered. An electroclinical response to benzodiazepines and the evaluation of consciousness impairment should be considered when interpreting TWs. Evaluating only the EEG without considering also clinical and laboratory findings is not only useless and meaningless, but may even lead to serious consequences.