# Approaching Electroencephalographic Pathological Spikes in Terms of Solitons
## 4 The Remarkable Physical Features of Solitons
### Solitons in Pathological EEG Traces  
Reviewing the neuroscientific literature, it is easy to notice that quite a few EEG electric spikes detectable in disease states look like solitons [51]. Emerging from the noisy background of normal electric activity, high-amplitude, low-frequency EEG solitary waves of different shapes can be observed in various human diseases. A few EEG snapshots are illustrated in Figure 2.  
1. Figure 2A illustrates a case of Herpesvirus-6 limbic encephalitis with lateralized periodic discharges over the left temporal region, with no apparent inter-discharge interval between the spike-and-wave complexes (modified from [52] [PERSON] et al. (2023). 2. Figure 2B illustrates a bilateral synchronous symmetrical delta burst pattern with almost flat amplitude during burst intervals, recorded during wakefulness in the advanced stages of subacute sclerosing pancencephalitis in an adult patient; modified from [53]. 3. Figure 2C illustrates an example of a 3 to 4 Hz generalized spike-wave in a child affected by juvenile absence epilepsy; modified from [[https://www.epilepsy.com/what-is-epilepsy/syndromes/juvenile-absence-epilepsy](https://www.epilepsy.com/what-is-epilepsy/syndromes/juvenile-absence-epilepsy)]([https://www.epilepsy.com/what-is-epilepsy/syndromes/juvenile-absence-epilepsy](https://www.epilepsy.com/what-is-epilepsy/syndromes/juvenile-absence-epilepsy)) (accessed on 23 March 2024). 4. Figure 2D illustrates a typical EEF in a case of sporadic Creutzfeldt-Jacob disease. Note the disease-typical periodic sharp wave complexes that occur in the middle and late stages; modified from [[https://www.euroyd.ed.ac.uk/images/typical-eeg-sporadic-cjd](https://www.euroyd.ed.ac.uk/images/typical-eeg-sporadic-cjd)]([https://www.euroyd.ed.ac.uk/images/typical-eeg-sporadic-cjd](https://www.euroyd.ed.ac.uk/images/typical-eeg-sporadic-cjd)) (accessed on 23 March 2024). 5. Figure 2E illustrates an EEG snapshot showing a right temporal focal seizure in an adult. A focal slowing occurs in the temporal region; modified from [54]. 6. Figure 2F illustrates the coexistence of focal and generalized epileptiform discharges in a 7-year-old boy with benign childhood epilepsy with occipital paroxysms [55]. Figure 2: Pathological EEG patterns resembling trains of solitons. (**A**) Herpesvirus-6 limbic encephalitis; modified from [52]. (**B**) Typical “metronomic” delta burst pattern with almost flat amplitude during burst intervals, recorded during advanced stages of subacute sclerosing pancencephalitis; modified from [53]. (**C**) Juvenile absence epilepsy; modified from [[https://www.epilepsy.com/what-is-epilepsy/syndromes/juvenile-absence-epilepsy](https://www.epilepsy.com/what-is-epilepsy/syndromes/juvenile-absence-epilepsy)]([https://www.epilepsy.com/what-is-epilepsy/syndromes/juvenile-absence-epilepsy](https://www.epilepsy.com/what-is-epilepsy/syndromes/juvenile-absence-epilepsy)) (accessed on 23 March 2024) (**D**) Creutzfeldt-Jacob disease; modified from [[https://www.eurocjd.ed.ac.uk/images/typical-eeg-sporadic-cjd](https://www.eurocjd.ed.ac.uk/images/typical-eeg-sporadic-cjd)]([https://www.eurocjd.ed.ac.uk/images/typical-eeg-sporadic-cjd](https://www.eurocjd.ed.ac.uk/images/typical-eeg-sporadic-cjd)) (accessed on 23 March 2024) (**E**) EEG snapshot showing a right temporal focal seizure; modified from [54]. (**F**) Coexistence of focal and generalized epileptiform discharges in a 7-year-old boy with benign childhood epilepsy with occipital paroxysms [55]. Similarities between solitons and pathological EEG patterns can be identified by comparing the waves illustrated in Figures 1 and 2. Distinct medical conditions, including critically ill patients, encephalitis and epilepsy, are characterized by EEG traces with features that remind solitons trains, i.e., repeated patterns or stereotyped activity with or without interchange intervals, at an approximately regular rate or intervals [55]. Just as solitons, pathological EEG waveforms may display relatively uniform morphology and duration.