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

Introduction

Epilepsy precipitated by the stimulus of bathing with hot water poured over the head is known as hot water epilepsy (HWE).[1234567] These were also known as water-immersion epilepsy[8] or bathing epilepsy.[91011] HWE is a term used to encompass a reflex epileptic condition, characterized by pouring hot water (40–50°C) on the head.[3] although it has been reported from all parts of the world, it is more prevalent in the Southern Indian population as most of the reported cases have been from there.[4] It has been rarely reported in other European countries, and isolated case reports have been published from Japan and Turkey.[5]

Geographically, specific epilepsy syndromes are of epidemiologic interest and may assist in understanding the pathogenic mechanism of epilepsy in general. It may have a genetic basis with added environmental influence.

Here, we report three cases of HWE from India.

Case Reports

Discussion

Reflex epilepsy is a condition in which the seizures are provoked exclusively by an external stimulus and account for 6% of all epilepsies.[6] HWE is a form of reflex epilepsy, precipitated always, by bathing in hot water. Thus, this mode of reflex epilepsy requires a specific thermal cutaneous stimulus. Both partial and generalized tonic seizures have been described secondary to hot water bathing, however, one third of all reported cases have primary generalized tonic-clonic seizures.[6910] The highest incidence of HWE is in Yelandur, a rural area near Mysore in Karnataka-India and quoted a prevalence rate of 255/100,000 for HWE. Interictal scalp EEG is usually normal, but 15–20% might show diffuse abnormalities.[467] The exact mechanism of HWE remains uncertain, but altered thermoregulation is a cause. Familial HWE cases with more than one affected member have been noted in 7–15% of Indian patients.[34567] A genetic locus in the 10^th chromosome had been identified (10q21, 3-q22,3).[111213]

Interictal scalp EEG is technically difficult, but when performed it is usually normal. However 15–20% might show diffuse abnormalities. Lateralized or localized spike discharges in the anterior temporal regions have been reported in a few cases.

HWE in humans was managed in two ways previously: (a) Using lukewarm water for a head bath or sponging with hot towels,[34] and (b) use of conventional AEDs such as PHT or carbamazepine (CBZ). The use of PHT or CBZ is generally indicated in children who have spontaneous seizures in addition to seizures triggered by hot water. Satishchandra et al.[4] evolved a newer method of intermittent oral prophylaxis with benzodiazepines. They advocated the use of 5–10 mg of oral CLB 1.5–2 h before a head bath and not every day. This approach was used by us in the first case and was found to have satisfactory results. This approach minimizes the cost and side effects of these AEDs. Treatment with CLB can be considered in older children and in those with children with prolonged seizures following head bath with hot water, and in those who continue to have seizures even during regular baths with normal water temperature or nonreflex seizures It may be useful when the temperature of water cannot be reduced due to cultural and religious reasons.

Children with HWE generally have an excellent prognosis. HWE tend to subside with advancing age. There is no increased chance of developmental delay.

The above case descriptions were made to highlight the rarity of its occurrence and to emphasize that HWE could be controlled with CLB prior to bath and/or lifestyle modifications.