Intermittent clobazam prophylaxis in hot water epilepsy is safe and effective: a prospective study

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.

Seizures Induced by Exiting Water: A Unique Form of Reflex Epilepsy

INTRODUCTION

Reflex epilepsies represent a form of epilepsy in which unique modes of seizure precipitation are characterized by endogenous or exogenous stimuli. Hot water epilepsy represents a subtype of reflex epilepsy in which seizure precipitation arises from the act of immersing the head with hot water. Bathing epilepsy represents another subtype of reflex epilepsy in which seizure precipitation arises from the immersion with water at lukewarm temperatures.

CASE SERIES

We report on 2 boys with a unique form of bathing epilepsy characterized by the act of exiting out of water. The first patient had a family history significant for a brother with frontal lobe epilepsy. He underwent an evaluation in the epilepsy monitoring unit in which a reflex seizure was recorded while exiting the shower. This seizure was characterized by an ictal onset in the left frontal lobe and subsequent secondary generalization. The second patient initially had nonreflex seizures arising from the left temporal lobe and went on to develop reflex seizures upon exiting water. For both patients, the precipitation of seizures was independent of water or environmental temperature, exposure of specific body parts, or duration of water immersion. Both children experienced a sensation of coldness, followed by convulsive or atonic activity.

CONCLUSIONS

Our cases represent a unique form of bathing epilepsy in which seizure precipitation is dependent upon exiting water.

Reflex epilepsy: triggers and management strategies

Reflex epilepsies (REs) are identified as epileptic seizures that are consistently induced by identifiable and objective-specific triggers, which may be an afferent stimulus or by the patient's own activity. RE may have different subtypes depending on the stimulus characteristic. There are significant clinical and electrophysiologic differences between different RE types. Visual stimuli-sensitive or photosensitive epilepsies constitute a large proportion of the RE and are mainly related to genetic causes. Reflex epilepsies may present with focal or generalized seizures due to specific triggers, and sometimes seizures may occur spontaneously. The stimuli can be external (light flashes, hot water), internal (emotion, thinking), or both and should be distinguished from triggering precipitants, which most epileptic patients could report such as emotional stress, sleep deprivation, alcohol, and menstrual cycle. Different genetic and acquired factors may play a role in etiology of RE. This review will provide a current overview of the triggering factors and management of reflex seizures.

Hot Water Epilepsy Successfully Treated With Daily Clobazam

Hot water epilepsy (HWE) is a rare form of reflex epilepsy precipitated by a bath or shower in hot water. Although the condition is benign and a decreased bath temperature will help, antiepileptic drugs may be needed in some cases. Prophylactic clobazam is currently the first choice treatment option. Here we report the case of a 10-year-old boy with HWE successfully treated with daily doses of clobazam. Daily clobazam was preferred over prophylactic clobazam because of the patient's frequent bathing and parental concern. Daily clobazam is a novel treatment option for HWE and seems to be a good choice where antiepileptic drugs are necessary.

Reduced small world brain connectivity in probands with a family history of epilepsy

BACKGROUND AND PURPOSE

The role of inheritance in ascertaining susceptibility to epilepsy is well established, although the pathogenetic mechanisms are still not very clear. Interviewing for a positive family history is a popular epidemiological tool in the understanding of this susceptibility. Our aim was to visualize and localize network abnormalities that could be associated with a positive family history in a group of patients with hot water epilepsy (HWE) using resting-state functional magnetic resonance imaging (rsfMRI).

METHODS

Graph theory analysis of rsfMRI (clustering coefficient γ; path length λ; small worldness σ) in probands with a positive family history of epilepsy (FHE+, 25) were compared with probands without FHE (FHE-, 33). Whether a closer biological relationship was associated with a higher likelihood of network abnormalities was also ascertained.

RESULTS

A positive family history of epilepsy had decreased γ, increased λ and decreased σ in bilateral temporofrontal regions compared to FHE- (false discovery rate corrected P ≤ 0.0062). These changes were more pronounced in probands having first degree relatives and siblings with epilepsy. Probands with multiple types of epilepsy in the family showed decreased σ in comparison to only HWE in the family.

CONCLUSION

Graph theory analysis of the rsfMRI can be used to understand the neurobiology of diseases like genetic susceptibility in HWE. Reduced small worldness, proportional to the degree of relationship, is consistent with the current understanding that disease severity is higher in closer biological relations.

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.