Función vestibular en la mutación A1555G del ADN mitocondrial

Abstract

Objectives/Hypothesis: To evaluate vestibular function in patients with 1555 A to G mutation in the 12S ribosomal RNA gene_x000D_ Study design: It’s an observational cross-sectional study._x000D_ Material and Method: Thirty-four patients carrying the mitochondrial A1555G DNA mutation from thirteen unrelated families were enrolled. Clinical histories especially aminoglycosides exposure and the audiological and vestibular symptoms were recorded. Audiological evaluation with pure tone audiograms was performed. Vestibular examinations including caloric testing and cervical vestibular evoked myogenic potentials (VEMPc) in response to air-conducted sound were used as measures of canalicular and saccular function, respectively. _x000D_ Results: Ten patients had vestibular symptoms. Twenty-two patients presented hearing loss and thirteen subjects had received aminoglycosides. The auditory defect was a bilateral symmetrical sensorineural hearing loss affecting mainly the high tones. The presence of deafness and its severity was significantly correlated with the aminoglycoside exposure. Aminoglycosides increase 5 times the risk of developing profound hearing loss or cofosis. Therefore, twenty-two of the 34 patients showed abnormal caloric responses. The caloric deficiency was bilateral canal paresis in 20 cases and unilateral hipofunction in two cases. Aminoglycoside treatment history, hearing impairment and its severity are not significantly correlated with the abnormal canal response. On the other hand, eleven patients had abnormal VEMPc: nine showed low amplitude (6 cases bilaterally and 3 unilaterally) and six patients had an asymmetric amplitude. None had absence of the VEMPs response or abnormal latencies. Aminoglycoside administration and the degree of hearing loss are not correlated with the pathologic VEMPc, but an abnormal VEMPc response is significantly associated with hearing loss. Global dysfunction, saccular and canalicular, increase 4 times the risk of developing deafness not related to hearing loss degree._x000D_ Conclusions: The findings suggest that the A1555G mutation can cause vestibular dysfunction involving both the superior and inferior vestibular nerve systems, especially canalicular dysfunction. It looks like aminoglycoside might not be a causal factor for vestibular impairment in patients carrying this mutation. Furthermore, our overall results of pathological vestibular tests suggest that there is a relationship between hearing loss and vestibular dysfunction.

Date of Award	10 Dec 2015
Original language	Undefined/Unknown
Awarding Institution	Vall d'Hebron University Hospital (HUVH)
Supervisor	Pedro Quesada Marín (Director) & Ana María García Arumí (Director)