AUDITORY BRAINSTEM FUNCTION IN WOMEN WITH VESTIBULAR MIGRAINE: A CONTROLLED STUDY
Introduction The link between vestibular symptoms and migraine led to the publication of diagnostic criteria of a new disorder named vestibular migraine (1,2,3). Even though there is a high frequency of auditory symptoms associated with migraine, there is not enough information on how it occurs. The psychoacoustic evaluation is normal in most cases, although hearing loss is reported in acute migraine and vestibular migraine situations, probably as results of cochlear vasospasms (3-8). Specific auditory symptoms such as phonophobia, hearing loss and tinnitus suggest impairment of auditory pathways in migraine cases (2). Auditory brainstem responses can be assessed by electrophysiological exams. Furthermore, brainstem electric disorders could also affect the stapedius muscle reflex or the acoustic reflex due to dysfunctions in higher auditory centers areas or supratentorial structures (9,10). Objective The aim of this study is to assess auditory brainstem auditory function in women with vestibular migraine by means of electrophysiological testing and acoustic reflex threshold and to verify the presence of hyperacusis in vestibular migraine population, according to loudness discomfort level as defined by to Nields et al. (11). Materials and Methods This case-control study enrolled 29 women with vestibular migraine according to the criteria of Neuhauser et al. modified by the Bárány Society and International Headache Society (2) in the study group, during their interictal period. The control group was comprised by 25 healthy women matched to the study group according to their age. The subjects in the study group were recruited from the vestibular migraine outpatient clinic at the Neurotology service. The control group subjects were volunteers. The following tests were performed in both groups Auditory brainstem response Auditory brainstem response suppression Frequency following response Loudness discomfort level assessment Contralateral acoustic reflex assessment Binaural interaction component A descriptive analysis of the data taking into consideration absolute and relative frequencies, central tendency measures and dispersion measures was performed. For quantitative variables, the standard distribution was verified, and the t-Student test used to compare both groups. The equality of variance was not assumed when homogeneity could not be confirmed within a certain variable. In the association analyses between independent qualitative variables and the outcome measures, the Qui-square test was used. For statistical significance, a descriptive level of 5% (p<0.05) was considered. Results In this study, 54 women were analyzed. Their ages ranged from 23 to 74 years old, with average age of 49.7 years old. There was no statistically significant difference in age between the groups. There was no statistically significant difference between the average of latency and amplitude binaural interaction component values when comparing the study group and the control group. The same was observed when analyzing the average absolute and interpeak latencies obtained on auditory brainstem response and auditory brainstem response suppression (p>0.05). The frequency following response latency of the study group showed average values significantly higher to those for the control group in both ears (p<0.05), except for the latency of wave I in the left ear (p=0.102). The frequency following response interpeak I-III variable in the left ear resulted in significant difference between groups (p=0.003). The average in study group was 2.00 msec (SD=4.1) while in control group was 1.6 msec (SD=0.52). There was statistically significant difference when comparing the average of loudness discomfort level threshold for the right ear between groups, 250 Hz (p=0.006), 500 Hz (p=0.013) and 3000 Hz (p=0.023). When analyzing the left ear, significant differences between groups were noted for the frequencies of 500 Hz (p=0.02), 1000 Hz (p=0.014), 2000 Hz (p=0.01) and 3000 Hz (p=0.02) with higher levels being obtained for the control group. When analyzing the loudness discomfort level classification, statistically significant differences were observed for both right and left ears. For the right ear, women with mild hyperacusis showed higher tendency to be in study group when compared to women in control group (52% versus 18%; p=0.019). Similarly, this tendency was verified in the left ear (p=0.039). For the acoustic reflex threshold, there was no statistical difference between study group and control group (p>0.05). Conclusion The current study suggested that the temporal auditory processing as well as the loudness discomfort level are altered in VM patients during the interictal period and may be used as diagnostic criteria
16 Migranas incluyendo migrana vestibular
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