INTRODUCTION It has been observed that if topiramate (TPM) is given together with other antiepileptic drugs when the temperature of the environment is high, a disorder involving sweating and thermo­regulation may be seen as a side­effect.

PATIENTS AND METHODS We describe ten patients, of an average age of 7 years and 8 months, with refractory epileptic seizures. All were treated with topiramate, associated with the antiepileptic drugs they had been taking previously. During the summer months, when the environmental temperature was over 37 ºC, they had slight hyperthermia, hypohydrosis or more usually anhydrosis, red faces and tiredness which was markedly worse on effort. In one case there was also retention of urine and four others had known side­effects. In seven patients the symptoms disappeared when the dose of TPM was reduced or the environment became cooler. In the other three cases TPM was withdrawn, due to the severe adverse effects seen in two cases and for being ineffective as treatment in the other cases.

CONCLUSIONS It is considered that in predisposed children, TPM causes autonomic dysfunction, probably of central origin, which is seen as a disorder of sweating and thermoregulation. Although the mechanism of this disorder is not known, since it occurs when the temperature is over 37 ºC, it would seem that it is due to a reduction in carbonic anhydrase isoenzymes II and IV. We suggest that it would be useful to establish a method to predict the patients at risk in summer, in hot regions, at the first sign of fatigability.

Introducción Se ha observado que el tratamiento con topiramato (TPM) añadido a otros fármacos antiepilépticos, cuando la temperatura ambiental es alta, produce un trastorno de la sudación y termorregulación como efecto adverso.

Pacientes y métodos En 10 pacientes, con edad media de 7 años y 8 meses, afectos de crisis epilépticas refractarias y en tratamiento con TPM combinado con los fármacos que tomaba con anterioridad, durante los meses de verano, cuando la temperatura ambiental sobrepasa los 37 ºC, se ha presentado leve hipertermia, hipo o habitualmente anhidrosis, enrojecimiento facial y cansancio que se acentúa sensiblemente con el esfuerzo. En un caso se ha asociado a retención de orina y en otros cuatro a efectos adversos ya conocidos. En siete pacientes, los síntomas desaparecieron al disminuir la dosis de TPM o al bajar la temperatura ambiental. En otros tres casos se suspendió TPM, por la gravedad de los efectos adversos en dos, y en otro, por ineficacia terapéutica.

Conclusiones Se estima que el TPM produce en niños predispuestos una disfunción autonómica, de probable origen central, que se expresa por un trastorno de la sudación y termorregulación. Aunque el mecanismo de producción de este trastorno se desconoce, el hecho de que aparezca a partir de los 37 ºC sugiere que se deba a la disminución de las isoenzimas II y IV de la anhidrasa carbónica. Se sugiere la conveniencia de establecer un método para predecir los pacientes de riesgo en verano, en regiones calurosas, al menor signo de fatiga.