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Abstract This study is a prospective hospital based case series conducted on 356 patients during the period from May 2018 to December 2019, at Tokyo Medical University Hospital to address the safety and the efficacy of surgical management of Vestibular Schwannoma and importance of intraoperative neurophysiological monitoring. Patients included with unilateral vestibular schwannoma, with or without hydrocephalus and received preoperative radiotherapy or not. Clinical assessment was done through medical history, general examination and neurological examination Investigations were done as lab, MRI and audiological assessment. Surgical excision of vestibular schwannoma through retro-sigmoid approach to the posterior fossa is the main surgical technique as it gives a wide view of the posterior fossa. Intraoperative facial nerve monitoring and auditory brain stem monitoring seem to decrease morbidity of surgical intervention. All patients will be followed up postoperatively, during hospital stay. Regarding Pre-operative data: We found that the results was follow: Age of all patients was (42.57 ± 12.3) years. Regarding gender of the patients, the majority (54.8%) of patients were females; while (45.2%) were males. The average size of tumour was (28.75 ± 9.7) mm; with (50.8%) of patients had Lt-sided tumours, (47.8%) had Rt-sided tumours, and (1.4%) had bilateral tumours. KOOS classification; the average size of tumour was (28.75 ± 9.7) mm; with (20.2%) of patients had grade 2 tumour, (34.6%) had grade 3 tumour, and (45.2%) had grade 4 tumour. Hannover classification; (69.6%) of patients had large tumours, and (3.4%) had small and medium tumours. Regarding presenting (initial) symptoms; (64.6%) of patients presented with Hearing loss, (73.3%) presented with Tinnitus, (53.7%) presented with Face numbness, (2.2%) presented with Imbalance, (57.6%) presented with Dizziness or vertigo, (6.7%) presented Incidentally, (1.4%) presented with Facial paralysis, and (1.1%) presented with Trigeminal neuralgia. The average PTA “degree of hearing loss” was (39.72 ± 24.66) dB; with (29.9%) of patients had A “≤ 30 dB” degree, (56%) had B “> 30 ≤ 50 dB” degree, (2%) had C “> 50 dB” degree, and (52.4%) had D degree Hearing loss type; (10.1%) of patients were normal, while (7%) had Cochlear hearing loss, (25%) had retro-cochlear hearing loss, (52.2%) had mixed hearing loss, while (5.6%) had unknown type of hearing loss. Origin prediction on MRI; (38.8%) of patients had inferior origin, (40.7%) had superior origin, and (20.5%) had unknown origin. Facial nerve preservation; (98.6%) of patients had preserved function, (0.3%) had lost function, and (1.1%) were morphological. Cochlear nerve preservation; (14.4%) of patients had preserved function, (66.7%) had lost function, (18.6%) were morphological, while (0.3%) had originally absent nerve. Pre-operative facial nerve function; (93.8%) of patients had none (0-HB) grade, (3.1%) had (2-HB) grade, (1.7%) had (3-HB) grade, (0.3%) had (4-HB) grade, (0.8%) had (5-HB) grade, and (0.3%) had (6- HB) grade. Regarding Intra-operative data: We found that; the average Resection ratio was (96 ± 4.5) %; with (16.7%) of patients had total resection, (69.2%) had near total resection, and (14.1%) had subtotal resection. Comparative study between pre and post-operative facial nerve function revealed; highly significant increase in HB-1 grade, in postoperative assessment; compared to pre-operative assessment of facial nerve functions; with highly significant statistical difference (p < 0.0001). Pearson’s correlation analysis shows that; Age, size of tumour and degree of hearing loss, had a highly significant positive correlation with post-operative HB grade; with highly significant statistical difference (p < 0.01 respectively). Resection ratio had a highly significant negative correlation with post-operative HB grade; with highly significant statistical difference (p < 0.01). Multiple regression analysis shows that; after applying (Forward method) and entering some predictor variables; the increase in age, and the decrease in resection ratio; had an independent effect on increasing post-operative HB grade; with significant statistical difference (p < 0.05 respectively). RECOMMENDATIONS Complete microsurgical tumour removal is the optimal management for patients with growing VS. The procedure is safe, associated with favourable facial nerve outcome, and may also improve existing neurological symptoms. The retro-sigmoid suboccipital approach to the skull base can be safely and successfully achieved using a microsurgical technique, with minimal or no damage to neurovascular structures, even for large tumours. The management goals of vestibular schwannomas have shifted from total resection to functional preservation. As shown in our work regarding the special importance of intraoperative neurophysiological monitoring to improve the outcome of CPA lesions, we would emphasise the great need to get hands on such equipment in our institutions. Special attention should be given regarding training of junior neuro-surgeons on surgical approaches and new microsurgical techniques considering the long steep learning curve for skull base surgeries specially CPA. CONCLUSION Surgical management of Vs using retrosigmoid approach is safe and effective but after advancement of microsurgical techniques like drilling and neurophysiological monitoring specially for seventh and eighth cranial nerves, the possibility of preserving the fascial and cochlear functions became more feasible with excellent results. We found also, that the age of the patient, size and consistency of the tumour, degree of intra-meatal extension, duration of symptoms, and resection ratio have a highly significant correlation with patients` outcome specially facial nerve function. |