1. Otorhinolaryngology and Neurotology Department, Instituto Nacional de Neurología y Neurocirugía Dr. Manuel Velasco Suárez, México, DF, Mexico
2. Neurology Center, Centro Médico American British Cowdray, México, DF, Mexico
3. Otorhinolaryngology and Neurotology Depaertment, Instituto Nacional de Rehabilitación, México, DF, Mexico