Comparison of Triphasic Waves and Epileptic Discharges in One Patient With Genetic Epilepsy

Abstract

Genetic epilepsies with generalized spike-wave complexes (GSWCs) and encephalopathy triphasic waves (TWs) may resemble each other and have three phases per complex. Electroencephalographic (EEG) interpretation is subjective, and EEGers have noted "TWs" in cases labeled nonconvulsive status epilepticus (NCSE). Direct comparison of both wave forms under the same conditions is rarely possible. In a single patient with generalized spike waves who developed hepatic TWs, morphologic characteristics of both were compared, and it was found that GSWCs have higher frequency first, second, and third phases; steeper phase 2 slope; and briefer after-going slow waves maximal at F3 to F4. Total complex duration was approximately 0.12 seconds. The TWs had dominant high-voltage phases 2 and 3 located more posteriorly, in the frontocentral region, lasting an average of approximately 0.32 seconds. These morphologic distinctions may help differentiate TWs from GSWCs.

Clinical and Electroencephalographic Correlates of Acute Encephalopathy

“…They are usually bilateral, often diffuse, and synchronous but with a frontocentral predominance, an anterior-posterior, or posterior-anterior time lag, and a frequency of 1.5 to 2.5 Hz (Brigo and Storti, 2011). TWs can usually be distinguished from epileptiform patterns by their longer complex duration (.80 ms), the low amplitude of the initial negative (up-going) phase, and the long duration between the beginning of the second (down-going) phase and the end of the vertical portion of the ascending part of the third phase (before the aftergoing slow wave) (Brigo and Storti, 2011;Kaplan and Schlattman, 2012;Kwon et al, 2007). TWs may be misinterpreted as ictal patterns, especially when they appear asymmetrically or are unilateral.…”

“…The most frequent background activity seen in patients with TWs is in the theta/delta range (Sutter et al, 2013). The usual maximal amplitude and representation in the central frontal, rather than the anterior frontal EEG derivations, may also help to differentiate them from ictal patterns (Brigo and Storti, 2011;Kaplan and Schlattman, 2012;Kwon et al, 2007). TWs can usually be distinguished from epileptiform patterns by their longer complex duration (.80 ms), the low amplitude of the initial negative (up-going) phase, and the long duration between the beginning of the second (down-going) phase and the end of the vertical portion of the ascending part of the third phase (before the aftergoing slow wave) (Brigo and Storti, 2011;Kaplan and Schlattman, 2012;Kwon et al, 2007).…”

Typical Versus Atypical Triphasic Morphology Waveforms

“…I read with interest the article by Kaplan and Schlattman (2012). Historically, the presence of triphasic morphology waveforms on the EEG has been considered to indicate a metabolic or a toxic cause of cerebral dysfunction compatible with a diffuse encephalopathy such as hepatic encephalopathy.…”

Significance of Triphasic Waves in Metabolic Encephalopathy

“…The risk of having GCS ≤ 10 was at least 6 times higher in the patients with triphasic waves than those without triphasic waves, and also the risk of having acute symptomatic seizures was at wider angle between the second and third phases of triphasic waves. [12][13][14] In addition, GPEDs can have phase reversals and polyspikes, whereas triphasic waves have fewer phase reversals and polyspikes. 12 Response of waveforms to stimulation is another useful way to discriminate triphsic waves and GPEDs.…”

“…[12][13][14] In addition, GPEDs can have phase reversals and polyspikes, whereas triphasic waves have fewer phase reversals and polyspikes. 12 Response of waveforms to stimulation is another useful way to discriminate triphsic waves and GPEDs. Triphasic waves increase with stimulation such as auditory, visual, and noxious method, whereas GPEDs are not influenced by external stimuli.…”