Significance of atypical triphasic waves for diagnosing nonconvulsive status epilepticus

Nonconvulsive Status Epilepticus During Perioperative Period of Cerebrovascular Surgery

“…The triphasic waves show asymmetry and predominantly focal location in NCSE, whereas the triphasic waves tend to be symmetric, anterior, and bilateral in encephalopathy. 4,21) In the present cases, although triphasic waves were located in the bilateral frontal regions, triphasic waves on the right exhibited larger amplitude and were extended more posteriorly. In addition, laboratory data found neither liver nor renal dysfunction.…”

“…However, many of these are controversial, particularly as to any ictal character. 4,20) Patterns include PLEDs, bilateral independent PLEDs, periodic epileptiform discharges which can be either focal or generalized, and triphasic waves, 4,20,21,25) which have been standardized by a subcommittee of the American Clinical Neurophysiology Society. 15) Functional stratification of NCSE can be based on focal or generalized features of EEG, and clinical criteria have been proposed as follows: localizationrelated NCSE, generalized NCSE, and undetermined or intermediate NCSE.…”

“…The word``triphasic'' has been used to describe a waveform characterized by an initial small amplitude sharp negative component, followed by a large amplitude sharp positive wave, and ending with a slow negative wave. 1,3,10,20,21) These findings were originally limited to patients with hepatic failure, so triphasic wave encephalopathy became synonymous with hepatic encephalopathy. Subsequently, triphasic wave encephalopathy has become associated with a wide range of toxic, metabolic, and structural abnormalities.…”

“…1) However, triphasic waves are now generally accepted as one of the EEG features in patients with NCSE, although the triphasic waves of NCSE are often difficult to distinguish from those of encephalopathy. 4,21) The distribution of triphasic waves is one of the differential points between NCSE and encephalopathy. The triphasic waves show asymmetry and predominantly focal location in NCSE, whereas the triphasic waves tend to be symmetric, anterior, and bilateral in encephalopathy.…”

A Case of Nonconvulsive Status Epilepticus Presenting with Triphasic Waves

“…Yapılan çalışmalara göre; metabolik ensefalopatiye özgü trifazik dalgalar bilateral simetrik ve anterior bölgelerde ağırlıklı olarak gözlenmekte, fokal ya da bilateral asimetrik yerleşimli atipik trifazik dalgaların varlığı NKSE'yi akla getirmektedir. [9] Antiepileptik ilaç uygulamasıyla EEG'de trifazik dalgaların silinmesi, NKSE ve ensefalopati ayırıcı tanısında yardımcı olabilmektedir. Ancak ensefalopatiye bağlı trifazik dalgalar da benzodiazepine yanıtlı olabildiğinden tanıda kesin bir kriter olarak görülmemektedir.…”