Impairment of Habituation of the Auditory Brain Stem Response in Migrainous Vertigo

Objectives: We evaluated the auditory brain stem response (ABR) in migrainous vertigo (MV). Methods: Four subjects who met clinical criteria for definite MV and 4 subjects with non-vertiginous migraine (NVM) underwent ABR testing while asymptomatic and within 16 hours of a symptomatic episode. Four control subjects were also tested. A set of 4 consecutive 750-click series was administered at 50-, 60-, and 70-dB intensities. We compared the groups in terms of habituation of the amplitude of wave IV-V (habituation of IV-V) from the first through fourth series for each set. Results: The habituation of IV-V amplitude to 50-dB stimuli was significantly less (p = 0.047) in the symptomatic MV group (5.08% +/- 22.32%) than in the symptomatic NVM group (-21.44% +/- 13.50%) or the control group (-26.06% +/- 9.76%). The habituation of IV-V amplitude to 70-dB stimuli in the MV group was significantly less (p = 0.031) during symptomatic testing (-3.43% +/- 8.89%) than during asymptomatic testing (-21.23% +/- 6.41%). Conclusions: The habituation of IV-V amplitude is reduced during MV attacks. This finding suggests impaired brain stem inhibition at the level of the inferior colliculus, which shares serotonergic connections with the dorsal raphe nucleus, an area hyperactive in migraine.