Middle Turn Of Cochlea Research Articles

The endoscopic transcanal approach to the internal auditory canal: an anatomic study.

The internal auditory canal (IAC) plays a key role in lateral skull base surgery. Although several approaches to the IAC have been proposed, endoscope-assisted transcanal corridors to the IAC have rarely been studied. We sought to provide a step-by-step description of the transcanal transpromontorial approach to the IAC and analyze anatomic relationships that might enhance predictability and safety of this approach. Ten cadaveric specimens were dissected and the extended transcanal transpromontorial approach to the IAC was established. Various morphometric measurements and anatomic landmarks were reviewed and analyzed. The proposed technique proved feasible and safe in all specimens. There was no inadvertent injury to the jugular bulb or internal carotid artery. The chorda tympani, a key landmark for the mastoid segment of the facial nerve, was identified in all dissections. The spherical recess of the vestibule and middle turn of cochlea are important landmarks for identification of the labyrinthine segment of the facial nerve. Identification of all boundaries of the working area is also essential for safe access. Among various morphometric measurements, the modiolus-IAC angle (≈150°) proved particularly consistent; given its ease of use and low variability, we believe it could serve as a landmark for identification and subsequent dissection of the IAC. The extended transcanal transpromontorial approach to the IAC is feasible and safe. Relying on anatomic landmarks to ensure preservation of the involved neurovascular structures is essential for a successful approach. The modiolus-IAC angle is a consistent, reproducible landmark for IAC identification and dissection.

Distance between the middle turn of cochlea and labyrinthine portion of the facial nerve: A surgical-radiologic comparison and clinical importance.

AbstractObjectiveTo highlight the close anatomical relationship between the middle turn of the cochlea and the labyrinthine segment of the facial nerve, which will be helpful to predict the probability of occurrence of facial nerve stimulation following cochlear implant surgery.MethodsHigh-resolution computed tomography of 40 cadaveric temporal bones was performed, followed by microscopic dissection. Cochleo-facial distance was measured with the help of a Digital Imaging and Communications in Medicine (‘DICOM’) viewer on high-resolution computed tomography and by a millimetre scale in the dissected specimen.ResultsThe cochleo-facial distance on high-resolution computed tomography was 0.62 ± 0.09 mm, ranging from 0.41 to 0.81 mm, and on dissection it was 0.57 ± 0.10 mm, ranging from 0.35 to 0.74 mm.ConclusionThe labyrinthine segment is the most likely area of stimulation in patients suffering from facial nerve stimulation following cochlear implantation. Pre-operative high-resolution computed tomography of the temporal bone can be used to examine the bone separating the labyrinthine segment of the facial nerve from the middle turn of the cochlea. This has clinical significance regarding implant side selection and pre-operative patient counselling.

Hericium erinaceus enhances neurotrophic factors and prevents cochlear cell apoptosis in senescence accelerated mice

• Hericium erinaceus prevents hearing degeneration in SAMP8 mice. • Hericium erinaceus increases nerve growth factor expression. • Hericium erinaceus prevents outer hair cell loss in the cochlea. • Hericium erinaceus reduces caspase-independent apoptosis. This study aimed to investigate the effects of Hericium erinaceus (HE) on auditory function. Twenty-four 9-month-old male senescence-accelerated prone 8 (SAMP8) mice were randomly and equally assigned to the control group (group A) and two groups supplemented with 215.25 (group B) or 430.5 mg/kg BW of HE (group C) for 12 weeks. Compared with group A, group C had significantly smaller threshold shifts by auditory brainstem responses at the end of study. HE increased nerve growth factor (NGF) expressions in the spiral ganglion neurons (SGNs) and the temporal lobes, and also prevented outer hair cells (OHCs) loss in the middle turn of cochlea. In addition, group C had significantly lower apoptosis-inducing factor and poly (ADP-ribose) polymerase-1 expressions in the middle turn of cochlea, brainstem and temporal lobes. In conclusions, HE could prevent hearing degeneration possibly by increasing neurotrophic expression, preventing OHCs loss, and reducing the caspase-independent apoptosis signalings.

高脂食投与Ｒａｔの内耳所見

We studied the morphology of the inner ear of Wistar Kyoto rat with hyperlypidemia, induced by hyperlipid food, using transmission electron microscopy.No changes were seen in the Preyer's reflex of the alimentary hyperlipidemic rats. In the organ of corti (middle turn of cochlea), the outer hair cell of 1st row showed marked degenerative changes such as extensive clear vacuolization, not limited by a membrane. In the ampulla of lateral semicircular canal, banded structures were observed in the supporting cell and Type I sensory hair cells. Lysosomal granules were diffusely scattered throughout the membranous cochlea and labyrinth, such as outer and inner hair cells of the organ of corti, vascular stria, and sensory hair cells of the ampulla of semicircular canal.