{'fraction_non_alphanumeric': 0.02583423035522067, 'fraction_numerical': 0.02906350914962325, 'mean_word_length': 5.432525951557094, 'pattern_counts': {'":': 0, '<': 2, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Stability of hearing preservation and regeneration capacity of the cochlear nerve following vestibular schwannoma surgery via a retrosigmoid approach.

OBJECTIVE The purpose of this research was to examine the stability of long-term hearing preservation and the regeneration capacity of the cochlear nerve following vestibular schwannoma (VS) surgery in a prospective study. METHODS A total of 112 patients were recruited for a randomized multicenter trial between January 2010 and April 2012 to investigate the efficacy of prophylactic nimodipine treatment versus no prophylactic nimodipine treatment in VS surgery. For the present investigation, both groups were pooled to compare hearing abilities in the early postoperative course and 1 year after the surgery. Hearing was examined using pure-tone audiometry with speech discrimination, which was performed preoperatively, in the early postoperative course, and 12 months after surgery and was subsequently classified by an independent otorhinolaryngologist using the Gardner-Robertson classification system. RESULTS Hearing abilities at 2 time points were compared by evaluation in the early postoperative course and 1 year after surgery in 102 patients. The chi-square test showed a very strong association between the 2 measurements in all 102 patients (p < 0.001) and in the subgroup of 66 patients with a preserved cochlear nerve (p < 0.001). CONCLUSIONS There is no significant change in cochlear nerve function between the early postoperative course and 1 year after VS surgery. The result of hearing performance, as evaluated by early postoperative audiometry after VS surgery, seems to be a reliable prognosticator for future hearing ability. Clinical trial registration nos.: 2009-012088-32 ( clinicaltrialsregister.eu ) and DRKS 00000328 ("AkNiPro," drks-neu.uniklinik-freiburg.de/drks_web/ ).