Source Localization of Triphasic Waves: Implications for the Pathophysiological Mechanism

Abstract

To investigate the current source location from the electroencephalograms (EEGs) of 12 patients who showed typical triphasic waves attributable to various causes, using the combination of a dipole source model and a distributed source model. The triphasic waves were explained by a single main dipole in 10 of the 12 patients, and 2 patients had two dipoles responsible for the triphasic waves. All the main dipoles had a radial orientation with respect to the frontal pole. The current density of the triphasic waves was distributed mainly in the bilateral medial frontal regions along the cingulate cortices. These findings suggest that current sources located in the medial frontal area are crucial for generating triphasic waves. The source localization may be useful for elucidating the pathophysiologic mechanism of generalized non-epileptic EEG activities, such as triphasic waves.

Creutzfeldt–Jakob Disease–Like Periodic Sharp Wave Complexes in Voltage-Gated Potassium Channel–Complex Antibodies Encephalitis

“…The clinical association of toxic, metabolic or anoxic factors as an etiologic explanation for the encephalopathy, none being present in our case, is also important to consider in the presence of triphasic waves (Wieser et al, 2006). Interestingly, it has been suggested in the past that triphasic waves may have a source located in the medial frontal area, which was one of the main region involved in our patient according to the MRI (Kwon et al, 2007). In a study of 214 definite sCJD cases and 77 definite non-CJD cases in which EEG, cerebrospinal fluid 14-3-3 protein and MRI were compared, PSWCs were found to have the lowest sensitivity (44%) but the highest specificity (92%) to diagnose sCJD (Zerr et al, 2009).…”

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

“…In 10/12 patients, TWs had a single dipole with radial orientation to the frontal pole. Current density projected to medial frontal regions (Kwon et al, 2007). In contrast, source analysis of GSWCs in IGE showed dipoles localized to bilateral frontal, parietal, and temporal lobes, maximal in frontomedial and frontoorbital regions with current source in the midsagittal region (Santiago-Rodriguez et al, 2002).…”

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).…”