Do Changes in Transtympanic Electrocochleography (TT-ECochG) Reflect the Dynamics of Endolymphatic Hydrops on MRI? Audiological and Radiological Longitudinal Analysis in Patients with Severe Ménière's Disease After Vestibular Neurectomy-A Pilot Study.

Objectives: The aim of this study was to evaluate long-term changes in transtympanic electrocochleography (TT-ECochG) following vestibular neurectomy in patients with Ménière's disease (MD) and to investigate their relationship with endolymphatic hydrops (EH) degree and hearing outcomes. Methods: This pilot study included five patients with unilateral MD eligible from a cohort of twenty patients who underwent middle fossa vestibular neurectomy. All participants completed preoperative and 2-year postoperative clinical and audiological tests, including TT-ECochG; EH degree was analyzed in delayed gadolinium-enhanced magnetic resonance images (MRI). Changes in TT-ECochG parameters were analyzed in relation to MRI findings. Results: All patients achieved complete control of vertigo and improvement in the AAO-HNS functional level. Hearing deterioration of ≥10 dB was observed in two patients (40%). Cochlear EH remained unchanged in all patients, whereas vestibular EH reduction was visualized in two patients (40%) after surgery. Decreased SP/AP amplitude and/or area ratios were observed in two patients (40%), whereas increased values were found in two others (40%). No postoperative TT-ECochG response was obtained in one patient because of profound postoperative hearing loss. Overall, changes in TT-ECochG parameters did not parallel MRI findings. Conclusions: This pilot study demonstrates that postoperative TT-ECochG changes after vestibular neurectomy are heterogeneous and do not consistently parallel MRI changes in endolymphatic hydrops.