Table 1.
Characteristics of studies with qualitative, clinical description of EEG abnormalities.
| Study | Sample (n: Age) | EEG Settings | EEG Characteristics |
|---|---|---|---|
| [59] | RTT: 1, 4 y o | Video EEG | Needle-like central spikes evoked by contralateral passive finger-tapping drug-resistant |
| [60] | RTT: 1, 5 y o | Video EEG (24 h) | Multifocal bilateral discharges precipitated by right-hand tapping lips (but not cheek or abdomen, or the left-hand tapping lips, or observer’s hand tapping the lips) and immediately disappearing when the movement stopped. |
| [61] | RTT: 1, 12 y o | EEG | Paroxysmal runs of fluctuating 4- to 5-Hz rhythmic frontocentral theta activity at rest that abated with movement or tactile stimulation |
| [62] | RTT: 1, 4 y o | A 32-channel scalp EEG (24 h) | Centrotemporal spikes (CTS) disappeared after hand clapping |
| [63] | 6 RTT among 74 genetic-dysmorphic syndromes |
EEG video monitoring with at least one EEG including awake and spontaneous afternoon nap recording | Abnormal EEG in 3 RTT |
| [64] | RTT: 1, 7 y o Lhermitte-Duclos syndrome//Neurofibromatosis: 1, 8 y o |
Multiple daytime and sleep EEGs | Continuous spike and wave in slow-wave sleep Focal epileptiform discharges while awake |
| [65] | RTT: 64: 3–9 | Awake and sleep video EEG (24 h) | Unilateral, highly rhythmic hand tapping accompanied by contralateral synchronous centrotemporal spikes and not responsive to drugs (n = 5) |
| [56] | RTT: 8: 7–20 y o | Video-polygraphic, EEG + EMG + EKG recording | – Slowing of the background activity – Epileptiform abnormalities (spike and sharp wave discharges) – Abnormal sleep patterns – Epilepsy: drug-resistant in half//misdiagnosed (n = 6) – Multifocal and asynchronous cortical myoclonus (n = 5), myoclonic seizures (n = 4), myoclonic status (n = 2) |
| [66] | RTT: 3: 14, 18, 22 y o | Video-EEG and polygraphy (with confirmed reflex seizures in n = 1). | Reflex seizures, triggered by food intake (n = 1) or self-provoked by rhythmic pressure on hands (n = 2) or by taking someone’s hand or holding on to a table (n = 1) |
| [50] | Zappella RTT MECP2 high-intermediate performance (HIP): 11: 11–38 y o low-performance (LP): 5: 8–19 y o |
8-channel EEG referenced to linked mastoids continuous awake and sleep (at least 30 min) | Centro-temporal spikes: HIP > LP Multifocal EEG activity: HIP < LP EEG encephalopathy: HIP < LP Spindles and K-complex: HIP > LP Epilepsy (recurrent unproved seizures): HIP < LP (ns) |
| [49] | RTT: 18: 7–21 y o All with seizures |
20–30 min video EEG awake | Correlation between epilepsy and behavior: EEG stage III (moderate to marked slowing of background activity with dominant theta and delta activity) EEG stage IV (no occipital dominant rhythm and marked slowing of background activity). (1) theta slow activity over the frontal and central regions (eight cases) (2) frontocentroparietal spikes (eight cases) (3) generalized spike and waves (one case) (4) diffuse subcontinuous spike and waves suggestive of epileptic encephalopathy (one case) |
| [44] | RTT (165 including Classic (140) Preserved speech variant (PSV) (15) Hanefeld (6) 130 (78%) with epilepsy |
Video EEG (not reported) Italian multicenter retrospective study |
Epilepsy and RTT variants//mutation type no epilepsy (n = 35), drug-responsive (n = 81) and drug-resistant (n = 49) |
| [67] | RTT: 2: 7, 12 y o | EEG and lower limb EMG during gait | EMG burst were not associated with clinical jerking but EMG burst-locked averaging of the EEG showed contralateral centroparietal spiking preceding the burst by about 35 ms, indicating a cortical reflex myoclonus. |
| [45] | RTT (154 including 65% with seizures) | 8-channel EEG referenced to linked mastoids continuous awake and sleep (at least 30 min) | Epilepsy and RTT variants//mutation type Drug-resistant epilepsy, DRE (n = 16) No relationship between EEG characteristics and DRE |
| [68] | RTT: 11: 1–33 y o | Seizures (n = 8) Epileptiform activity (n = 7) |
|
| [69] | RTT: 3: 9.5, 7.4, and 9.4 y o, each with a mutation of the CDKL5 gene. | Video EEGs | Seizure onset 1.5 months |
| [70] | Girl with mutation of MECP2 but no clear RTT phenotype: 8 y o | EEG | 5 and 7 y o EEG: presence of high-amplitude delta waves with a notched appearance and a persistent theta activity over posterior regions (EEG of Angelman Syndrome) |
| [71] | RTT: 50: 1–14 y o | 16-channel EEG |
Descriptive EEG, epilepsy presence is not reported Changes with RTT progression |
| [72] | RTT: 1: MECP2 mutation At age 2 and 6 |
EEG | Age 6: rhythmic triphasic 2- to 3-Hz, high voltage (200–500 mkV) activity, mixed with spikes or sharp waves, with a maximum over the frontal regions (EEG of Angelman Syndrome) |
| [73] | RTT: 10: < 5 y o Angelman Syndrome (AS):10 Mental retardation:10 |
Central and/or centro-temporal spike-wave complexes as specific to RTT | |
| [74] | RTT: 191 (detailed survey) 78–EEG |
Awake and sleep EEG | 76% clinical seizures 78% epileptiform activity that preceded seizure onset |
| [75] | RTT: 13: 2–17 y o | Awake and sleep EEG, SPECT | Epileptiform activity (n = 10) Frontal hypoperfusion that is not correlated with EEG abnormalities |
| [76] | RTT: 10: 2–16 y o The reported 10 cases were selected because of their peculiar slow EEG rhythms |
The EEG studies were performed in wakefulness (whenever possible) and sleep, mostly induced with moderate dosages of chloral hydrate. Passive movement carried out whenever spikes or central theta activity occurred. |
CTS/abnormal theta reduced after hand movement (n = 4) |
| [77] | RTT: 16: 8 months-20 y o 44 EEG |
EEG, respiration | Pseudoperiodic pattern, the short bursts of high-amplitude slow waves tending to be associated with apnea and the lower-amplitude faster rhythms with normal breathing or with hyperventilation (n = 8) |
| [78] | RTT: 14: 6–17, mean 7 y o TD: 12: 6–18, mean 14 y o |
Day time video records, respiration | General EEG abnormality with excess of polymorphic slowing and poorly developed (daytime) sleep change (all n = 14) Unreactive Theta (n = 10) Absence of normal slow-wave response to hyperventilation (all n = 14) Attacks of vacancy and staring not associated with significant EEG changes (n = 6) No-epileptic slow-waves mostly during normal breathing (n = 11) |
| [79] | RTT: 4: 4–11 y o | All-night electroencephalograms (EEGs)/polysomnograms on 2 consecutive nights | Epileptiform activity maximum over 1–2 SWS sleep stage and in the morning hours |
| [80] | RTT: 4: 3.5, 6, 11 and 12 y o | Light no-REM sleep or the state lethargy (wake without slight index of awareness) | Epileptiform activity, in particular, CTS, blocked or attenuated by passive finger movements |
| [81] | RTT: 30: 2–22 y o 127 EEG-recordings |
Awake and sleep EEG, EMG | Epileptiform activity (n = 26) CTS (n = 10) Pseudoperiodic delta bursts (n = 13) Flat record (n = 2) Developmental changes |
| [82] | RTT: 13: 2–17 y o | Awake and sleep EEG, EMG | Seizures (n = 5) Epileptiform activity (n = 10) Pseudorhythmic flattering (n = 4) |
| [83] | RTT: 8: 2–16 y o | Awake and sleep EEG | Background EEG slowing Epileptiform activity A monotonous theta rhythm (MTR), which was not influenced by either opening or closing of the eyes but attenuated only by a big noise or strong pain stimuli, characteristically dominated the waking tracing EEG through disease progression |
| [84] | RTT: 52: 1–13 y o 83 EEG recordings |
Awake and sleep 8-channels EEG, EMG |
Seizures (n = 26 + 3) Epileptiform activity, enhanced during sleep (n = 43) CTS often coincided with stereotyped hand wringing or tapping and facilitated over the contralateral central regions by passive tactile stimulation (9 of 26 girls tested) Excesses of theta and delta activity (n = 12, n = 7) |
| [39] | RTT: 9: 1–6 y o 22 EEG recordings |
EEG, video EEG in two patients |
Seizures (n = 7) Epileptiform activity (n = 9, in 3 epileptiform activity preceded development of seizures) Abnormalities increases with age |
| [85] | RTT: 7: 1–7 y o | Awake and sleep EEG | Reactive Theta, Excessed Delta, Flattering EEG, epileptiform activity, atypical sleep EEG CTS (n = 4) including those evoked by tactile stimulation (n = 2) Changes with RTT progression |
| [86] | RTT: 18: 1–17 y o | Awake and sleep EEG, respiration biogenic amine metabolites |
Reduced % stage REM (n = 15) EEG slowing Epileptiform activity Absent vertex transients and spindles during NREM |
| [87] | RTT: 11: 4–14 y o | Awake and sleep EEG |
Slowing of background EEG (n = 11) activity while awake Multifocal spike-waves (centrotemporal regions) (n = 9) Intermittent, high-amplitude discharges followed by relative attenuation of background activity during sleep (n = 6) |
| [88] | RTT: 9: 2–15 y o 35 EEG recordings |
EEG |
Seizures (n = 7) Epileptiform activity (n = 7) Slowing of background EEG Progression through disease |
| [89] | RTT: 8: 4–13 y o | Awake and sleep EEG, EMG |
Myoclonic jerks (n = 8) EEG is poorly organized with high amplitude slow waves short, non-periodic bursts; focal or diffuse spike and wave complexes increased in sleep |
| [90] | RTT: 1, 2 y o | EEG | Unspecific modification on EEG, no seizures |