A locus for autosomal dominant reflex epilepsy precipitated by hot water maps at chromosome 10q21.3-q22.3

Hot water epilepsy with alone and spontaneous seizures in childhood

OBJECTIVES

Hot water epilepsy (HWE) is a type of epilepsy that primarily affects children. This study was aimed to evaluate the clinical, electroencephalogram (EEG), neuroimaging findings, and treatment options in children with HWE.

METHODS

The medical records of 24 patients who had HWE were evaluated retrospectively.

RESULTS

There were 2767 patients diagnosed with epilepsy during the seven-year period, and 0.86 % of the patients had HWE. The median age of the patients was three (range 1.2-7 years), with a male predominance (male/female ratio: 7.1). Six patients (25 %) had HWE with spontaneous seizures (HWESS) and 18 patients (75 %) had HWE alone (HWEA). 11 patients had focal onset seizures, 13 patients had generalized onset seizures. EEG abnormalities were found in 7 patients (29.2 %). Three patients (12.5 %) had nonspecific MRI findings. Developmental abnormalities (autism spectrum disorder, learning disability and speech disturbance.) were detected in 8 patients (33.3 %). Only one patient's (4.2 %) seizure could be controlled by changing bathroom habits. Twenty-three patients (95.8 %) were given antiepileptic drugs. 18 of 24 patients had come for follow-up visits for two years, nine of them used monotherapy and seizures did not recur. The treatment response was 55.5 %. Oxcarbazepine (8 patients, 33.3 %) and valproic acid (7 patients, 29.2 %) were the most chosen two drugs for HWE. The genetic tests performed were not accepted relevant to the patients' clinical conditions and epilepsy.

CONCLUSION

The frequency of the HWE was not as high in the literature. Male predominance, EEG abnormalities may be seen. Changing bath room habits did not improve the treatment as a first line management, all the patients except one used antiepileptic drug treatment. Until now, there has been no study in Turkey showing the frequency of HWE exclusively in children.

Long-term clinical course and prognosis of hot water epilepsy: 15-Year follow-up

OBJECTIVE

Hot water epilepsy (HWE) is a type of reflex epilepsy triggered by bathing with hot water. Hot water epilepsy is generally considered as a self-limiting benign disease although its long-term course and prognosis remains unknown. In this study, we aimed to determine the long-term clinical course and prognosis of hot water epilepsy and possible factors affecting them.

METHODS

The diagnosis of HWE was made based on the clinical history obtained from patients and their first degree relatives witnessing to the seizures and video recordings of seizures if available; then, the type of seizure was identified. Good prognosis was defined as patients whose seizures were controlled with or without preventive measures and who did not require antiepileptic treatment. The poor prognosis was defined as patients whose seizures continued despite preventive measures and required antiepileptic treatment.

RESULTS

The study included 50 (31 male and 19 female) patients with a mean follow-up of 17.63 ± 10.46 (median, 15.0) years. The age at onset of seizure was 14.52 ± 12.71 (median: 10.0) years. There were 38 (76%) patients in the good prognosis group. 18 (36%) of them achieved complete remission, who did not require preventive measures. In the remaining 20 (40%) patients, seizures could be controlled with only preventive measures. Seizures could be controlled with antiepileptic treatment in only 1 (2%) of 12 (24%) patients in the poor prognosis group. A significant relationship was found between the frequency of hot water seizures (HWSs) and poor prognosis (p = 0.019), as well as the presence of spontaneous seizures outside of bathing and poor prognosis (p = 0.000).

SIGNIFICANCE

Hot water epilepsy, as previously known, is not a self-limiting benign disease. Approximately ¾ of the cases have a good prognosis, but the rest are in the case of chronic epilepsy. The low response rate to antiepileptics' treatment suggests that the pathogenesis of the HWE may differ from other epilepsies.

Clinical and Genetic Features in Patients With Reflex Bathing Epilepsy

Objective

To describe the clinical and genetic findings in a cohort of individuals with bathing epilepsy, a rare form of reflex epilepsy.

Methods

We investigated by Sanger and targeted resequencing the SYN1 gene in 12 individuals from 10 different families presenting with seizures triggered primarily by bathing or showering. An additional 12 individuals with hot-water epilepsy were also screened.

Results

In all families with bathing epilepsy, we identified 8 distinct pathogenic or likely pathogenic variants and 2 variants of unknown significance in SYN1, 9 of which are novel. Conversely, none of the individuals with hot-water epilepsy displayed SYN1 variants. In mutated individuals, seizures were typically triggered by showering or bathing regardless of the water temperature. Additional triggers included fingernail clipping, haircutting, or watching someone take a shower. Unprovoked seizures and a variable degree of developmental delay were also common.

Conclusion

Bathing epilepsy is genetically distinct reflex epilepsy caused mainly by SYN1 mutations.

White-Sutton syndrome with hot water epilepsy and coexistence of SHOX gene variations

The purpose of this study is to reveal the effect on the clinical phenotype of variants detected at family examination of a case of combined pogo transposable element derived with zinc finger domain (POGZ) gene, tubulin folding cofactor E (TBCE) gene, and short stature homeobox (SHOX) gene variation. A Turkish non-consanguineous family consisting of five members was investigated. Whole exome sequence analysis and chromosomal microarray analysis (CMA) were performed for a 2-year-old male patient (the proband) with global developmental delay, hypotonia, dysmorphia, and hot water epilepsy. Targeted sequence and chromosomal microarray analyses were performed for each family member. A heterozygous c.3908_3911delTCTG/p.V1303fs*6 variant was detected in the POGZ gene and a heterozygous c.626 T > G(p.L209X) variant in the TBCE gene in the proband. In addition, a gain of 0.1 MB was detected in the Xp22.33(602488-733497) × 3/Yp11.32(552488-683497) × 3 region at CMA. The SHOX (312865) gene defined in Online Mendelian Inheritance in Man is located in this region. While the proband's father and brother had heterozygous variations only in the TBCE gene, neither TBCE nor POGZ mutations were detected in the mother or sister. A gain in Xp22.33(419224-883640) × 3 was detected in the mother at CMA. Except for short stature and Madelung deformity, no phenotypical findings were detected in the mother. Other family members were also phenotypically normal. The family screening confirmed that dysmorphic findings and global developmental delay in the proband resulted from the variation in the POGZ gene, while short stature was caused by the gain in the Xp22.33(602488-733497) × 3/Yp11.32(552488-683497) × 3 region. In addition, the pathogenic POGZ gene variation in our patient may be a possible cause of hot water epilepsy. Heterozygous variation in the TBCE gene was clinically insignificant. Hot water epilepsy has not previously been reported in the rare patients with POGZ gene mutation. Additionally, in contrast to the previous literature, the proband exhibited no features of autism. It should also be remembered that posterior fossa abnormalities are frequently seen in these patients. We think that this case and family review involving POGZ and SHOX gene mutations will make a useful contribution to the existing literature.

Conserved Role of the Large Conductance Calcium-Activated Potassium Channel, KCa1.1, in Sinus Node Function and Arrhythmia Risk

BACKGROUND

KCNMA1 encodes the α-subunit of the large-conductance Ca²⁺-activated K⁺ channel, K_Ca1.1, and lies within a linkage interval for atrial fibrillation (AF). Insights into the cardiac functions of K_Ca1.1 are limited, and KCNMA1 has not been investigated as an AF candidate gene.

METHODS

The KCNMA1 gene was sequenced in 118 patients with familial AF. The role of K_Ca1.1 in normal cardiac structure and function was evaluated in humans, mice, zebrafish, and fly. A novel KCNMA1 variant was functionally characterized.

RESULTS

A complex KCNMA1 variant was identified in 1 kindred with AF. To evaluate potential disease mechanisms, we first evaluated the distribution of K_Ca1.1 in normal hearts using immunostaining and immunogold electron microscopy. K_Ca1.1 was seen throughout the atria and ventricles in humans and mice, with strong expression in the sinus node. In an ex vivo murine sinoatrial node preparation, addition of the K_Ca1.1 antagonist, paxilline, blunted the increase in beating rate induced by adrenergic receptor stimulation. Knockdown of the K_Ca1.1 ortholog, kcnma1b, in zebrafish embryos resulted in sinus bradycardia with dilatation and reduced contraction of the atrium and ventricle. Genetic inactivation of the Drosophila K_Ca1.1 ortholog, slo, systemically or in adult stages, also slowed the heartbeat and produced fibrillatory cardiac contractions. Electrophysiological characterization of slo-deficient flies revealed bursts of action potentials, reflecting increased events of fibrillatory arrhythmias. Flies with cardiac-specific overexpression of the human KCNMA1 mutant also showed increased heart period and bursts of action potentials, similar to the K_Ca1.1 loss-of-function models.

CONCLUSIONS

Our data point to a highly conserved role of K_Ca1.1 in sinus node function in humans, mice, zebrafish, and fly and suggest that K_Ca1.1 loss of function may predispose to AF.

Reflex Epilepsy with Hot Water: Clinical and EEG Findings, Treatment, and Prognosis in Childhood

Hot water epilepsy (HWE) is a subtype of reflex epilepsy in which seizures are triggered by the head being immersed in hot water. Hot water or bathing epilepsy is the type of reflex epilepsy most frequently encountered in our clinic. We describe our patients with HWE and also discuss the clinical features, therapeutic approaches, and prognosis. Eleven patients (10 boys, 1 girl), aged 12 months to 13 years, admitted to the pediatric neurology clinic between January 2018 and August 2019, and diagnosed with HWE or bathing epilepsy based on International League Against Epilepsy (ILAE)-2017, were followed up prospectively for ∼18 months. Patients' clinical and electroencephalography (EEG) findings and treatment details were noted. All 11 patients' seizures were triggered by hot water. Age at first seizure was between 2 months and 12 years. Seizure types were generalized motor seizures, absence, and atonic. EEG was normal in two patients, but nine patients had epileptiform discharges. Magnetic resonance imaging of the brain was performed and reported as normal (except in one case). Histories of prematurity were present in two patients, unprovoked seizures in one, and low birth weight and depressed birth in the other. Patients with HWE have normal neuromuscular development and neurological examination results, together with prophylaxis or seizure control with a single antiepileptic drug, suggesting that it is a self-limited reflex epilepsy.

Reflex epileptic mechanisms in ictogenesis and therapeutic consequences

Recent studies of reflex epileptic mechanisms in human epilepsy using advanced methods of neurophysiology and functional neuroimaging have contributed much to elucidate pathophysiological processes of seizure generation. Whereas in lesional focal epilepsies reflex mechanisms usually relate directly to the anatomical focus, in system epilepsies they have helped to define which functional anatomical systems serving physiological function are recruited by the ictogenic mechanisms. Reflex epileptic seizures can often be prevented by avoidance or modification of triggers or by prophylactic benzodiazepine administration. Surgical options apply to focal cases. According to restricted experiences with pharmacotherapy, without controlled studies and little information on new AEDs, reflex seizures in system epilepsies appear to respond best to valproic acid and in focal epilepsies, to carbamazepine.

Genetics of reflex seizures and epilepsies in humans and animals

INTRODUCTION

Reflex seizures are epileptic events triggered by specific motor, sensory or cognitive stimulation. This comprehensive narrative review focuses on the role of genetic determinants in humans and animal models of reflex seizures and epilepsies.

METHODS

References were mainly identified through MEDLINE searches until August 2015 and backtracking of references in pertinent studies.

RESULTS

Autosomal dominant inheritance with reduced penetrance was proven in several families with photosensitivity. Molecular genetic studies on EEG photoparoxysmal response identified putative loci on chromosomes 6, 7, 13 and 16 that seem to correlate with peculiar seizure phenotype. No specific mutation has been found in Papio papio baboon, although a genetic etiology is likely. Mutation in synaptic vesicle glycoprotein 2A was found in another animal model of photosensitivity (Fayoumi chickens). Autosomal dominant inheritance with incomplete penetrance overlapping with a genetic background for IGE was proposed for some families with primary reading epilepsy. Musicogenic seizures usually occur in patients with focal symptomatic or cryptogenic epilepsies, but they have been reported in rare genetic epilepsies such as Dravet syndrome. A single LGI1 mutation has been described in a girl with seizures evoked by auditory stimuli. Interestingly, heterozygous knockout (Lgi1(+/-)) mice show susceptibility to sound-triggered seizures. Moreover, in Frings and Black Swiss mice, the spontaneous mutations of MASS1 and JAMS1 genes, respectively, have been linked to audiogenic seizures. Eating seizures usually occur in symptomatic epilepsies but evidences for a genetic susceptibility were mainly provided by family report from Sri Lanka. Eating seizures were also reported in rare patients with MECP2 duplication or mutation. Hot water seizures are genetically heterogeneous but two loci at chromosomes 4 and 10 were identified in families with likely autosomal dominant inheritance. Startle-induced seizures usually occur in patients with symptomatic epilepsies but have also been reported in the setting chromosomal disorders or genetically inherited lysosomal storage diseases.

DISCUSSION

The genetic background of reflex seizures and epilepsies is heterogeneous and mostly unknown with no major gene identified in humans. The benefits offered by next-generation sequencing technologies should be merged with increasing information on animal models that represent an useful tool to study the mechanism underlying epileptogenesis. Finally, we expect that genetic studies will lead to a better understanding of the multiple factors involved in the pathophysiology of reflex seizures, and eventually to develop preventive strategies focused on seizure control and therapy optimization.

Hot water epilepsy: A form of reflex epilepsy - from infancy to adolescence

Hot water epilepsy (HWE) is a type of reflex epilepsy which occurs when hot water is poured over the head. Most cases have been reported from Southern India. Genetic, cultural, and geographical factors can be responsible for HWE. HWE can be treated by clobazam 1-2 h prior to take a bath rather than continuous anti-epileptic therapy. Medication prior to bathing may be useful in treating older children, eliminating the need to be accompanied by an adult during bathing. It can also be treated by reducing the temperature of the water used for bathing. Here, we report three cases of HWE in varying age groups.

Epilepsy: Indian perspective

There are 50 million people living with epilepsy worldwide, and most of them reside in developing countries. About 10 million persons with epilepsy are there in India. Many people with active epilepsy do not receive appropriate treatment for their condition, leading to large treatment gap. The lack of knowledge of antiepileptic drugs, poverty, cultural beliefs, stigma, poor health infrastructure, and shortage of trained professionals contribute for the treatment gap. Infectious diseases play an important role in seizures and long-term burden causing both new-onset epilepsy and status epilepticus. Proper education and appropriate health care services can make tremendous change in a country like India. There have been many original researches in various aspects of epilepsy across India. Some of the geographically specific epilepsies occur only in certain regions of our country which have been highlighted by authors. Even the pre-surgical evaluation and epilepsy surgery in patients with drug-resistant epilepsy is available in many centers in our country. This article attempts to provide a complete preview of epilepsy in India.

Generalized versus partial reflex seizures: a review

In this review we assess our currently available knowledge about reflex seizures with special emphasis on the difference between "generalized" reflex seizures induced by visual stimuli, thinking, praxis and language tasks, and "focal" seizures induced by startle, eating, music, hot water, somatosensory stimuli and orgasm. We discuss in particular evidence from animal, clinical, neurophysiological and neuroimaging studies supporting the concept that "generalized" reflex seizures, usually occurring in the setting of IGE, should be considered as focal seizures with quick secondary generalization. We also review recent advances in genetic and therapeutic approach of reflex seizures.

Eating Epilepsy in Oman: A case series and report on the efficacy of temporal lobectomy

Eating epilepsy (EE), where seizures are triggered by eating, is rare and has not been reported in the Gulf region. In EE, the ictal semiology includes partial or generalised seizures. Focal brain changes on imaging, if present, are often confined to the temporal lobe or perisylvian region. Therapeutic options, especially in those patients who are refractory to pharmacotherapy, have not been well-established. We report a series of five patients with EE from Oman, a country located in the eastern part of the Arabian Gulf region, and highlight the usefulness of temporal lobectomy in one patient who had medically-intractable EE. Surgical intervention could be considered as a potential therapeutic option in carefully selected patients with medically-intractable seizures.

Hot water epilepsy with pachygyria

Hot water epilepsy (HWE) refers to a specific type of reflex epilepsy precipitated by the stimulus of bathing in hot water. Pathogenesis is still unknown and temporal lobe has been thought to take part in the epileptogenesis. HWE can be symptomatic of focal cortical malformation, and few cases were reported. This is the third report of HEW in which a parietal malformation has been observed. Our hypothesis that sensory cortex might be implicated in the epileptogenic process is corroborated by two previous reports on patients with HWE and malformation of the parietal cortical development.

Hot water epilepsy: A rare form of reflex epilepsy

Hot water epilepsy is a form of reflex epilepsy in childhood. We report two children from Saudi Arabia, who presented with seizures following pouring hot water on their head, while bathing. They were not treated by anti-epileptic medication. By decreasing the temperature of the water used for bathing, the seizures were avoided to a large extent in them. This form of epilepsy is reported to be seldom present in various countries but there are no records of its presence in Saudi Arabia.