Neurilemmoma is a benign neoplasm arising from the Schwann cell of the nerve sheath. Acoustic nerve is the most common site of neurilemmoma and mandible is the most frequently involved in intraosseous neurilemmoma. Extradurally located dumbbell type neurilemmoma was rarely reported. The histology of neurilemmoma was first described by Verocay in 1908 and elaborated upon by Stout in 1935. Characteristic histologic patterns of neurilemmoma were encapsulation and Verocay bodies, Antoni type A and B areas, palisading nuclei, and lack of malignant characteristics. We experienced such a rare case of neurilemmoma which probably arised from the left first lumbar spinal nerve root, and located extradurally and paravertebrally, and confirmed by radiologic and pathologic findings.
Cochlear Nerve ; Mandible ; Neurilemmoma ; Spinal Nerve Roots

Although cochlear implantation using posterior tympanotomy has been performed worldwide, other alternative approaches might be more beneficial and convenient in some selected cases. Of these, suprameatal approach was reported to be one of useful options in cases with narrow facial recess, anteriorly located facial nerve and an ossified cochlea. We describe a case of cochlear implantation using the modified suprameatal approach in a severely contracted mastoid cavity and suggest another indication of this approach.
Cochlea ; Cochlear Implantation* ; Cochlear Implants* ; Facial Nerve ; Mastoid*

Cochlear Implantation ; Cochlear Implants ; Humans ; Vestibulocochlear Nerve Diseases

Refinement of surgical techniques has allowed hearing preservation after tumor resection to be prioritized. Moreover, restoration of hearing after tumor removal can be attempted in patients with bilateral vestibular schwannomas or those with a schwannoma in the only-hearing ear. Cochlear implantation (CI) has emerged as a proper method of acoustic rehabilitation, provided that the cochlear nerve remains intact. Studies of electrical promontory stimulation in patients after vestibular schwannoma resection have demonstrated favorable results. We describe herein two cases of hearing rehabilitation via CI implemented at the time of vestibular schwannoma resection. Tumors were totally removed, and cochlear implant electrodes were successfully inserted in both cases. Also, post operative CI-aided hearing showed improved results.
Acoustics ; Cochlear Implantation* ; Cochlear Implants* ; Cochlear Nerve ; Ear ; Electrodes ; Hearing ; Humans ; Methods ; Neurilemmoma ; Neuroma, Acoustic* ; Rehabilitation

OBJECTIVE: By watching the effects of cochlear implants in the children with cochlear nerve defects, to evaluate the relationship and efficiency of HRCT AND MRI in diagnostic for cochlear nerve defects. METHOD: The imaging dates and the post-operative effects of the 10 cochlear nerve defect patients were retrospectively analyzed. RESULT: Three patients with bilateral IAC stenosis by HRCT and cochlear nerve defects by MRI but no other abnormal. Seven other patients showed normal IAC by HRCT including 1 showed type IP- I plus vestibular semi circular canal dysplasia. These 7 patients MRI showed 3 bilateral cochlear nerve absent and 4 bilateral cochlear nerve dysplasia. Ten cases of children after 12-32 month follow-up, 3 patients began speaking simple language, whose MAIS scale, CAP and SIR scores improved. One case just began speaking but pronunciation vague. Four cases had reactions to sounds, and can say monosyllabic words. Two cases without effects (1 CI abolished). Compared with other patients with normal cochlear nerve, the effects of the 10 cases were disappointed. CONCLUSION The effects of cochlear implant for the patients with cochlear nerve defects were poor. The preoperative MRI as sessment including oblique sagittal view for cochlear nerve is necessary. The preoperative communication with the parents telling ineffective result possibility is important.
Child, Preschool ; Cochlear Implantation ; Cochlear Implants ; Cochlear Nerve ; abnormalities ; Female ; Humans ; Infant ; Male ; Retrospective Studies

BACKGROUND AND OBJECTIVES: An essential part of the successful application of a cochlear implant is to adjust the stimulation levels to the patient's dynamic range. To test the subjective behavioral threshold (T-level) and the most comfortable loudness level (C-level), however, it may be troublesome or even impossible in very young children who are not able to perform such tasks appropriately. Therefore, utilization of objective measurements is important in children to estimate T- and C-levels. One of the objective measurements is the electrically evoked stapedial reflex (ESR) test. It has also been suggested that ESR may have applicability in confirming and quantifying electrical stimulation through a cochlear implant. The purpose of this study is to examine the feasibility of utilizing ESR to test device function during cochlear implant surgery and to predict ultimate behavioral T- & C-levels. MATERIALS AND METHODS: The ESR measurements were performed in 18 subjects during a cochlear implant surgery. Eight subjects received the Nucleus 22 multichannel cochlear implant (CI 22M) and 10 subjects received Nucleus 24 multichannel cochlear implant system (CI 24M). To test the ESRs, three electrodes, namely, apical electrode (E20), medial electrode (E12) and basal electrode (E5), were stimulated in each case. ESR thresholds were measured by visual observation of the stapedius muscle contraction in response to electrical stimulation delivered to the auditory nerve via a cochlear implant system. And the ESR thresholds were compared with the behavioral T- and C-levels in each electrode. RESULTS: ESRs were presented in 19/23 electrodes (82.6%) in subjects who received the CI 22M and 26/30 electrodes (86.7%) in subjects with CI 24M. The mean ESR threshold was the lowest in apical electrodes (E20) in both groups. In subjects with CI 22M, ESR thresholds were significantly correlated with behavioral T- and C-levels in apical electrodes (E20). In subjects with CI 24M, ESR thresholds were highly correlated with the C-levels in E5, E12, and E20. CONCLUSION: ESR provides an objective, accurate and rapid method to evaluate the device function during cochlear implant surgeries and in estimating T-/C- levels, which may be useful in the initial programming of younger children and the difficult-to-tests.
Child ; Cochlear Implantation* ; Cochlear Implants* ; Cochlear Nerve ; Electric Stimulation ; Electrodes ; Humans ; Muscle Contraction ; Reflex* ; Stapedius

Less traumatic electrode insertion along the basal turn of cochlea is essential to cochlear implantation. However, immoderate attempts to insert the electrode beyond the point of resistance can result in electrode kinking within the basal turn of cochlea. Electrode kinking tends to occur 1) in the use of contour or hugging type of electrode, 2) in the cochlear ossification or fibrosis, and 3) in wrong angle insertion in the approach of round window membrane or cochleostomy near the round window. Intra-operative radiologic evaluation and intra-operative measurement of the neural response telemetry or auditory nerve response telemetry during cochlear implantation is essential to check the status and proper insertion of electrode. Recently, we experienced two cases of electrode kinking in cochlear implantation and discovered that both patients showed abnormal impedances and crumpled electrode in X-ray. Based on these cases, we suggest routine impedance and radiologic measurement during the cochlear implantation.
Cochlea ; Cochlear Implantation* ; Cochlear Implants* ; Cochlear Nerve ; Electric Impedance ; Electrodes* ; Fibrosis ; Humans ; Membranes ; Telemetry

Schwannomas usually arise from sensory nerves, and most often from the vestibular component of the acoustic nerve. Intrasellar and parasellar schwannomas are exceedingly rare. It is difficult to distinguish them from typical pituitary macroadenomas because of their clinical and radiological resemblance. In this report, we present an unusual case of an intrasellar schwannoma with a suprasellar extension that radiographically simulated a pituitary macroadenoma.
Cochlear Nerve ; Neurilemmoma* ; Neuroma ; Sella Turcica

The central projections of the peripheral cochlear nerve fiber from each turn to the cochlear nuclei (CN) in the mongolian gerbil were investigated using retrograde transportation of horseradish peroxidase (HRP). The organ of Corti and the osseous spiral lamina were scratched with an electrolytically-sharpened fine needle via a small hole at each turn of the cochlea. The cochlea was filled with a 30% horseradish peroxidase (HRP) solution. After 48 hours, 50 microns transverse serial sections of the brainstem were made with a vibratome. The tissue was processed with the diaminobenzidine procedure of the cobalt-glucose method. Our experiment revealed that the fibers from the basal turn terminated at the dorsomedial portion of anteroventral cochlear nuclei (AVCN), but those from the apical turn were distributed among the ventrolateral portion of the AVCN. In the posteroventral cochlear nuclei (PVCN) and dorsal cochlear nuclei (DCN), the fibers from basal to apical turns extend from the dorsal to the ventral portion of each nuclei. A distinct tonotopic arrangement could be found between the origin of cochlear fibers of each turn and their termination in the regions of the cochlear nuclei (CN). Also, the results suggested that the scratch method combined with retrograde transportation of horseradish peroxidase was useful in investigating the tonotopic arrangement of the peripheral auditory nerve in the CN.
Animal ; Cochlear Nerve/*anatomy & histology ; Cochlear Nucleus/*anatomy & histology ; Gerbillinae ; Horseradish Peroxidase ; Nerve Fibers

The classic surgical technique for cochlear implantation was first introduced by House in 1961. This technique includes a mastoidectomy and a posterior tympanotomy, which has been most widely used for cochlear implantation. However, this approach may result in the injury of the chorda tympani nerve or the facial nerve. To avoid the risk of the neural injury, several alternative surgical methods have been developed. The endomeatal approach is one of the several alternative techniques. We present, along with a review of literatures, a case of cochlear implantation using the endomeatal approach performed in a child with an extremely hypoplastic mastoid.
Child* ; Chorda Tympani Nerve ; Cochlear Implantation* ; Cochlear Implants* ; Facial Nerve ; Humans ; Mastoid*