Hot water epilepsy: Clinical and electrophysiologic findings based on 21 cases

Purpose: Our aim is to outline the clinical and electroencephalograph ic (E EG) features of patients with hot water epilepsy (HWE), a rare and unique f orm of reflex epilepsy. Methods: Twenty-one patients with HWE, seen in our clinic until 1999, were studied. Mate outnumbered female subjects in a ratio of 3:1. The age at the onset of seizures ranged from 19 months to 27 years (mean age at onset, 12 years). Results: The main factors precipitating seizures were bathing with hot wate r and/or pouring water over the head. Six patients reported self-induction, either by increasing the heat or the amount of water and/or recalling earl ier bathing experiences. Nine patients expressed feeling pleasure during th e seizures. Twenty patients had partial seizures, eight of whom also had se condarily generalized seizures. One patient had apparent generalized seizur es only. Spontaneous seizures were present in 62% of the cases. Interictal epileptogenic abnormalities were documented in the EEGs of eight patients; the other eight had normal EEGs. The major sites of epileptogenic activity were over the unilateral temporal regions (in 40% of patients). Neuroimagin g studies available for 12 patients (four cranial computed tomography and e ight cranial magnetic resonance imaging scans) revealed normal findings. Se izure control in patients who were followed up was achieved by reducing the temperature or the duration of the bath or shower; several of the patients required medication. Conclusions: The major findings of this study are that HWE has a male prepo nderance, can be self-induced, is often done for pleasure, has complex trig gering factors, and shows temporally located abnormalities in the EEGs. Alt hough HWE is generally known to be self-limited, antiepileptic drug treatme nt may sometimes be necessary to control seizures. Hot water epilepsy shoul d be classified separately among the epileptic syndromes.