Abstract
It has been established that selective retrosigmoidal neurectomy of the vestibular nerve can be performed to cure severe vertigo in patients with Meniere's disease, to avoid postoperative hearing loss and to shorten operation time. It has been considered that the vestibular and cochlear subdivisions of the eighth nerve can be clearly separated in the posterior cranial fossa in most cases, while the vestibulocochlear cleavage plane is hardly visible to the naked eye.This study was conducted to clarify this discrepancy. We found no macroscopically visible vestibulocochlear cleavage plane in the eighth cranial nerve in the posterior cranial fossa in 18 specimens taken from cadavers for anatomic dissection. We examined histologically cross sections of the nerves about 5 mm distal to the surface of the brain stem using a new staining method (luxol fast blue-PAS-hematoxylin stain : discriminative staining method) that permits simultaneous observation of the axon, surrounding myelin sheath, connective tissue and glia. After confirming the lack of a cleavage plane between the vestibular and cochlear nerves, we were able to differentiate vestibular and cochlear nerve fibers by the transverse area of their axons, the former appearing larger than the latter. The difference was not statistically singificant between the total cross-sectional area of vestibular nerve and that of cochlear nerve. The cross-sectional area of the cochlear nerve decreased slightly with age, but the vestibular nerve did not change with age.
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call