Table 3.
HFO investigation in epilepsy using scalp EEG.
| References | Patient population | Age range | N | Measurement | Detection method | Application/finding |
|---|---|---|---|---|---|---|
| Kobayashi et al. (132) | West syndrome | 3m-4y | 11 | Ictal HFA | Time-frequency plot | HFA during epileptic spasms and hypsarrhythmia |
| Kobayashi et al. (133) | Lennox-Gastaut syndrome | 3y-29y | 20 | ictal HFA | Time-frequency plot | HFA during tonic seizure onset |
| Kobayashi et al. (135) | children with epilepsy and continuous spike-waves | 6y-9y | 10 | Interictal ripples | Time-frequency plot and visual | Co-occurrence with spikes |
| Andrade-Valenca et al. (38) | Focal epilepsy | 19y-63y | 15 | Interictal ripples | visual | Co-occurrence with spikes; SOZ localization accuracy for ripples 81%; lower sensitivity but higher specificity than spikes |
| Kobayashi et al. (136) | Childhood epilepsy with centrotemporal spikes and Panayiotopoulos syndrome | 2y-9y | 45 | Interictal ripples | Time-frequency plot and visual | Co-occurrence with spikes; Negative correlation of HFO rates with time since last seizure |
| Iwatani et al. (134) | West syndrome | 9m-14m | 4 | Ictal ripples | Time-frequency analysis and visual | HFO sources during epileptic spasms localized to lesion |
| Melani et al. (88) | Focal epilepsy | 22y-68y | 32 | Interictal ripples | Visual | Ripple rates depend on spike rates; Localization of SOZ: lower sensitivity but higher specificity than spikes |
| Fahoum et al. (137) | Focal epilepsy | 18y-43y | 22 | Interictal ripples | Visual | Greater thalamic BOLD changes during IEDs with high HFO rates |
| Lu et al. (138) | Focal epilepsy | 25y-53y | 5 | Interictal HFA events | Visual and ICA | Association with SOZ and resection area |
| Zelmann et al. (139) | Epilepsy with FCD | 17y-52y | 11 | Interictal ripples | Automated detection and visual confirmation | Proof-of-principle; SOZ identification |
| Chaitanya et al. (140) | Childhood/juvenile absence epilepsy | 6y-10y | 9 | Interictal and ictal ripples | ICA, time-frequency analysis | Co-occurrence with spike-waves |
| Kobayashi et al. (141) | West-Syndrome | 3m-9m | 17 | Interictal ripples | Time-frequency plot and visual | Pharmaco-response monitoring of adrenocorticotropic hormones |
| Toda et al. (142) | Early epileptic encephalopathy | 0-17w | 6 | Interictal ripples | Time-frequency analysis | Co-occurrence with epileptic bursts during suppression-burst patterns |
| Papadelis et al. (143) | Epilepsy with encephalomalacia | 11y-15y | 2 | Interictal ripples | Automated detection and visual confirmation | SOZ identification |
| Pizzo et al. (144) | Genetic generalized and focal epilepsy | 21y-60y | 17 | Interictal ripples | Visual | Concordance between ripple-dominant hemisphere with clinical lateralization; differential diagnosis |
| Pizzo et al. (145) | Focal epilepsy | 21y-59y | 10 | Interictal fast ripples | Visual | Proof-of-principle; concordance with SOZ |
| Qian et al. (146) | Childhood epilepsy with centrotemporal spikes | 4y-11y | 14 | Interictal ripples | Visual | Ripple rates identified atypical forms; pharmaco-response monitoring of methylprednisolone |
| van Klink et al. (147) | Focal and multifocal epilepsy | 18y-76y | 31 | Interictal ripples | Visual | Ripples preceded epileptic spikes |
| van Klink et al. (148) | Childhood epilepsy with centrotemporal spikes | 3y-15y | 22 | Interictal ripples | Visual | Differentiation of atypical and self-limited forms; seizure prediction |
| von Ellenrieder et al. (87) | Focal epilepsy | 19y-68y | 17 | Interictal ripples | Automated detection and visual confirmation | Localization concordance with clinical data or resected area (65% sensitivity) |
| Cuello-Oderiz et al. (149) | Lesional epilepsy | 18y-71y | 58 | Interictal ripples | Visual | HFO rates higher with superficial lesions compared to deep seated focus |
| Mooij et al. (150) | Different types of epilepsy | 11m-14y | 23 | Interictal ripples | Visual | Proof-of-principle; comparison with controls |
| Gong et al. (151) | Epileptic encephalopathy with continuous spike-and-wave during sleep | 4y-13y | 21 | Interictal ripples | Visual | Concordance with MRI abnormalities in patients with structural etiologies; pharmaco-response monitoring under methylprednisolone |
| van Klink et al. (152) | Focal epilepsy | 3y-42y | 9 | Interictal ripples | Visual | Localization concordance with clinical data or resected area (sensitivity: 55.4%, specificity: 72.2%) |
| van Klink (153) | Focal epilepsy | 8y-54y | 30 | Interictal ripples | Automated detection and visual confirmation | 50% localization concordance with clinical data or resected area |
| Bernardo et al. (154) | Children with tuberous sclerosis simplex and healthy controls | 2m-5y | 11 | Interictal fast ripples | visual and automated detection | proof-of-principle; occurrence comparison between pediatric patients and controls |
| Ikemoto et al. (155) | Childhood epilepsy with centrotemporal spikes | 2y-9y | 25 | Interictal ripples and HFA | Time-frequency analysis and Visual | Ripple rates identified atypical forms |
| Kobayashi et al. (156) | Myoclonic epilepsy | 5m-17y | 21 | Ictal HFA events | Time-frequency analysis and visual confirmation | Involvement of HFA in generation of myoclonic seizures |
| Kuhnke et al. (157) | Epilepsies of different etiologies | 8y-52y | 13 | Interictal ripples | Visual | Comparison of high-density and conventional EEG; higher ripple rates and better concordance with SOZ for high-density EEG |
| Mooij et al. (158) | Different types of epilepsy | 11m-8y | 23 | Interictal ripples | Visual | Co-occurrence with sleep specific transients; occurrence rate during sleep stages |
m, month(s); y, year(s); w, week(s); HFA, high frequency activity; SOZ, seizure-onset zone; HFO, high frequency oscillations; BOLD, blood oxygen level-dependent; IEDs, interictal epileptiform discharges; ICA, independent component analysis; FCD, focal cortical dysplasia.