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Clapping-surpressed focal spikes in EEG may be unique for the patients with rett syndrome : a case report
© The Author(s). 2016
Received: 25 November 2015
Accepted: 27 May 2016
Published: 13 June 2016
Rett syndrome is a severe neurodevelopmental disorder that primarily affects females. Typical features include a loss of purposeful hand skills, development of hand stereotypies, loss of spoken language, gait abnormalities, and acquired microcephaly. However, Rett syndrome hasn’t been recognized by clinical doctors at the early stage. So we need to find some special characters.
We reported a Chinese case of Rett syndrome, exhibiting continuous centrotemporal spikes in EEG with paroxysmal suppression by hand stereotypies (hand clapping). The child, female, 4 years old, presented with a significant regression in her spoken language skills, hand stereotypies (hand clapping and hand wringing), a wider based gait with difficulties in balance, repeated abnormal behaviors (bruxism and head banging). With her clinical-history, Rett syndrome was suspected and genetic testing with mutation in MECP2 confirmed the diagnosis. Her EEG showed slow acticity in background and revealed a specific feature that continuous centrotemporal spikes can be suppressed by the repeated hand clapping. And when the hand stopped, the spikes reoccured again.
This unique EEG signature has rarely been reported, which will expand the spectrum of EEG abnormalities in Rett syndrome.
Rett syndrome is classically characterized by early normal development for at least the first 6 months of life, followed by a period of regression and later recovery or Stagnation . The main features of typical Rett syndrome include a partial or complete loss of purposeful hand skills, development of hand stereotypies, partial or complete loss of spoken language and gait abnormalities .
We reported one Chinese child diagnosed of Rett syndrome, with a specific electroencephalogram (EEG) feature that continuous centrotemporal spikes can be suppressed by the repeated hand clapping. The purpose of this report is to present a novel, rarely reported EEG characteristic, which may also aid diagnosis.
We described a girl with Rett syndrome and unique EEG findings consisting of continuous centrotemporal spikes, which can be suppressed by the repeated hand clapping. Such an unusual EEG pattern has been rarely reported in individuals with Rett syndrome in recent years. However, early in 1990, Niedermeyer and Naida reported four cases of the Rett syndrome, where paroxysmal activity and especially spike discharges over the central region, could be blocked or attenuated by passive finger movements. Such blocking response are similar to our case and are also in the support of our findings. Besides this, Niedermeyer and Naida also presumed that the phenomenon found in RS is based on dysfunction rather than on structural impairment .
Rett syndrome often follow such four stages proposed: Normal development (0–6 months); Stage 1 (6–12 months), decreased head growth, delays in gross motor skills, loss of hand skills, less eye contact, social interaction and interest in toys; Stage2 (18 months–3 years), autistic features, intellectual disability, decreased head growth, respiratory abnormalities, hand stereotypies, motor dysfunction; Stage 3 (2–10 years), seizures are usually prominent, autonomic dysfunction; Stage 4 (≥10 years), loss of mobility, dystonia, scoliosis [2, 4].
The emphasis on the correlation of clinical and EEG findings should be clarified. The EEG findings often assume stereotypical patterns that similarly progress through the four clinical stages of the disease [5–7]. The most common EEG findings are summarized as follows: Stage1, normal, or slowing posterior background rhythm; Stage2, focal spikes in the centrotemporal regions, absent sleep spindles; Stage3, bilaterally synchronous delta activity and generalized spike discharges; Stage 4, slowing background activity, multifocal spikes in the waking, generalized spike activity during sleep, monorhythmic generalized or frontal-central slow theta (3–6 Hz) activity. Although an attempt to associate clinical staging with EEG abnormalities, the EEG changes are not specific to make a diagnosis of Rett syndrome. However, in our report, we found an special, or unique EEG signature that continuous centrotemporal spikes can be suppressed by the repeated hand clapping, once the hand stereotypies stopped, the spikes reoccured. This EEG feature has rarely been reported, which will expand the spectrum of electroencephalography abnormalities in Rett syndrome.
Additionally, Mu rhythm in EEG falls between 8 and 13 Hz, and is recorded from electrodes over the central area such as sensorimotor cortex, which suggests desynchronization of the underlying cell . Both execution of actions, and passive or active movements have been found to block the activity of Mu rhythm . Such blocking-response seems much more similar to RS. Furthermore, Jaime A Pineda [10, 11] argued that mirror neuron in Sensorimotor cortex played a critical role in the generation of Mu rhythm. Whether the underlying cells of mirror neurons involved in the blocking-response in RS, should be discussed in future research.
The clapping-surpressed EEG pattern has rarely been described in Rett syndrome, which may provide clues for clinicians to the ultimate diagnosis. It remains to be determined whether this EEG pattern can also be encountered in other individuals with Rett syndrome. So we reported this pattern firstly, then hope our colleagues can pay attention to it.
EEG, electroencephalogram; MRI, magnetic resonance image.
We thank Dr. Jiang Wu who was involved in the conceiving manuscript or revising it critically for important intellectual content.
We receive no funding support.
Availability of data and materials
YL participated in the drafting the manuscript. CL collected the clinical data. MS participated in the design of the case report. LC conceived of the case and be accountable for the integrity of any part of the work All authors read and approved the final manuscript.
The author (s) declared no conflicts of interest with respect to the research, authorship, funding, and/or publication of this article.
Consent for publication
Written informed consents were obtained from the patients’ mother for publication of this case report and any accompanying images. A copy of the written consent is available for review by the Editor of this journal.
Ethics approval and consent to participate
This case report has been approved by the First hospital of Jilin university’s Research Ethics Board.
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