Praxis‐induced reflex seizures in two Japanese cases with ring chromosome 20 syndrome

Abstract

Ring chromosome 20 syndrome is an epileptic and neurodevelopmental encephalopathy that occurs in children, characterised by a triad of refractory frontal lobe seizures, recurrent non‐convulsive status epilepticus and frontal lobe‐dominant paroxysmal discharges. However, details of other clinical features associated with ring chromosome 20 syndrome remain unknown. Here, we report two patients with ring chromosome 20 syndrome who had praxis‐induced reflex seizures. Case 1 was an 11‐year‐old girl who presented with seizures triggered by specific activities such as mental and written calculations, writing, decision‐making, recall, sudden changes in routine or ambient temperature and bathing. During calculations, left frontal lobe‐dominant, 3‐Hz slow‐wave bursts were observed on EEG. Lacosamide effectively suppressed her tonic seizures. Case 2 was a six‐year‐old boy who presented with seizures triggered by specific activities such as calculations, recall and bathing. During calculations, frontal lobe‐dominant, 3‐Hz spike and slow‐wave bursts were observed on EEG. Although his epilepsy was refractory, gabapentin reduced the frequency of focal seizures. In both cases, the hyperexcitability in the frontal lobe may have spread to the motor cortex and precipitated praxis‐induced seizures. Therefore, in addition to the known characteristic triad, praxis‐induced reflex seizures may also be a feature of ring chromosome 20 syndrome.

Status Epilepticus in Chromosomal Disorders Associated with Epilepsy: A Systematic Review

“…Sodium thiopental, after administration of MDZ, phenytoin (PHT), and high-dose PB resolved one tonic CSE [49]. In two cases, lacosamide (LCS) led to clinical and EEG improvement [47,51]. LTG alone and as add-on therapy with VPA led to a slight improvement, according to Vignoli et al [48].…”

“…In particular, mutism, aphasia, dulling of consciousness, loss of facial emotional expression and behavioral arrest with possible subtle motor features were reported as suggestive features of NCSE in these patients (Table 5); a peculiar sign pointing to NCSE may be the occurrence of spontaneous speech (one or two words) immediately after the resolution of ictal aphasia [78]. NCSE episodes recur over time in patients with R20; psychogenic stressors, such as concentration, fatigue, and emotional stress, turned out to be common triggers, while no fever-induced NCSE was reported [34,48,51]. Inoue et al describe video games as NCSE facilitators in one patient in their sample; however, it is not clear whether this effect would be mediated through the same mechanism of other psychogenic stressors or by photic stimulation.…”

“…Further details about CSE semiology were not provided. Potential triggers leading to NCSE were reported: (1) hyperventilation [32]; (2) CBZ [44]; (3) verbal stimuli-such as trying to respond to commands and questions [38]; (4) psychological fatigue [48], concentration [51] or emotional stress [34]; (5) hot bath [48]; (6) playing video games [32].…”

“…Information about EEG recording during NCSE was available for 55 patients with R20; the ictal records highlighted (1) slow waves and spikes or SW complexes predominantly over the frontal regions (n = 45) [30,32,34,36,45,46,48,51]; (2) generalized rhythmic slow waves or SW (n = 10) [36][37][38]40,42,45,49]. The overall duration of SE episodes spanned from 20 min to several days; Wechapinan reported one episode of NCSE lasting one month [46].…”

Ring Chromosome 20 Syndrome: Genetics, Clinical Characteristics, and Overlapping Phenotypes

“…This depends on the challenge inherent to the mosaic state of r(20) syndrome, which may vary in degree in different tissues, thus limiting the explorative approaches to the most accessible tissues. The survey of genomic results indicates as unlikely the loss of genetic material, as about 50 of the tested affected individuals did not harbor chromosomal deletions (or duplications) detectable by CMA (10,12,24,28,30,38,90,91).…”