Table 1.
Summary of prior studies of midline or parasagittal seizures and spikes in adult or pediatric populations
| Population of interest | Abnormality of interest | Number of EEGs | All SZ/ES, N (% of EEGs) | Parasagittal SZ/ES, N (% of EEGs) | Associated generalized SZ*, N (% of parasagittal SZ/ES) | |
|---|---|---|---|---|---|---|
| Pedley et al. [8] | A + P | ES | 8708 | 272 (3.1%) | 14 (0.2%) | 5 (35.7%) |
| Ehle et al. [12] | P | ES | 11,000 | NR | 37 (0.3%) | 16 (43.2%) |
| Nelson et al. [13] | A + P | ES | 8055 | NR | 44 (0.5%) | 24 (54.5%)† |
| Pourmand et al. [14] | A + P | ES | 7125 | 1166 (16.3%) | 34 (0.5%) | 21 (61.8%) |
| Molaie [15] | A | ES | 1000 | NR | 9 (0.9%) | 3 (33.3%) |
| Fischer and Clancy [16] | P | ES | 7051 | NR | 21 (0.3%) | 3 (14.3%) |
| Marshall [17] | A + P | ES | 10,173 | NR | 43 (0.4%) | 23 (53.5%) |
| Scher [18] | P | ES + SZ | 1008 | ES: NR; SZ: 92 (9.1%) | ES: 154 (15.3%); SZ: 22 (2.2%) | NR |
| Scher and Beggarly [19] | P | ES | 1114 | 57 (5.1%) | 21 (1.9%) | 4 (19.0%) |
| de Paola et al. [20] | A + P | ES | 14,463 | 1957 (13.5%) | 57 (0.4%) | 9 (15.8%) |
| Bagdorf and Lee [21] | A + P | ES | 28,500 | 211 (0.7%) | 57 (0.2%) | 23 (40.4%) |
| Kutluay et al. [22] | A + P | ES | 20,000‡ | NR | 35 (0.2%) | 16 (45.7%) |
| Sanders et al. [23] | P | ES | 424 | 228 (53.8%) | 21 (5.0%) | NR |
| Yong et al. [24] | A + P | ES | 7929 | NR | 17 (0.2%) | 12 (70.6%) |
| Vendrame et al. [25] | P | ES | 12,000 | NR | 69 (0.6%) | 15 (21.7%) |
| Datta et al. [26] | P | ES | 30,760 | NR | 576 (1.9%) | 49 (39.8%)§ |
| This study [7] | A | SZ | 300 | 17 (5.7%) | 2 (0.66%) | 0 (0%) |
| Summary | 169,510 | 1211 (0.71%) | 223 (21.5%) |
A adult, EEG electroencephalogram, ES epileptiform spikes, NR not reported, P pediatric, SZ seizures
*Includes both clinical generalized seizures (i.e., generalized motor [tonic and/or clonic, myoclonic, atonic] and non-motor [absence] and focal to bilateral tonic–clonic per ILAE 2017 classification [27]) and electrographic generalized seizures
†Of 34 patients were noted to have seizures, 11 had multiple seizure types, and the precise number of purely focal seizures was not reported; therefore, we used only the reported number of tonic–clonic seizures
‡Kutluay and colleagues reported “~ 20,000 EEGs,” so that estimate was used for calculations
§The authors used 123 patients out of 576 patients with midline spikes as the study group in their case–control study, and since the prevalence of generalized seizures was not reported among the excluded patients, the percentage was calculated with the study group sample size as the denominator