Intralabyrinthine schwannoma: Surgical management and cochlear lumen preservation

The present video reports the surgical removal of an intralabyrinthine schwannoma. The video contains patient's medical history, preoperative radiological evaluations and detailed description of surgical steps of the procedure, consisting in labyrinthectomy, cochleostomy and insertion of a dummy electrode in the preserved cochlear lumen within the context of a subtotal petrosectomy.

Does labyrinthectomy have an impact on hearing in the contralateral ear during long-term follow-up?

OBJECTIVE

To quantify contralateral hearing outcomes after labyrinthectomy for unilateral Ménière's disease (MD).

STUDY DESIGN

Retrospective case series.

SETTING

Tertiary neurotology referral center.

PATIENTS

Labyrinth removal for the management of MD or translabyrinthine (TLAB) acoustic neuroma resection between 2008 and 2012.

MAIN OUTCOME MEASURE

Long-term hearing changes via pure tone averages (PTA).

RESULTS

Upon comparison of low-frequency PTA (250, 500, 1000 Hz), MD patients experienced a greater degree of hearing loss during the follow-up period when compared to the TLAB lab group (7.54 ± 2.11 dB vs 2.39 ± 1.10 dB, p = 0.035). This difference as attributable to 12 (28.6 %) MD patients experiencing a ≥30 dB increase in low-frequency PTA, whereas none (0.0 %) of the TLAB surpassed this threshold.

CONCLUSIONS

At 10 years post-labyrinthectomy there is a heightened risk for MD patients to develop low-frequency sensorineural hearing loss. Clinicians should monitor for audiometric changes through regular testing in the decade following labyrinth removal.

The effects of vibration on the neuronal activity of lateral vestibular nuclei in unilaterally labyrinthectomized rats

Unilateral labyrinthectomy causes distinct oculomotor and postural disorder syndromes that gradually deteriorate. Simultaneously, compensatory mechanisms for the suppression of pathological disorders were activated. The current study aimed to investigate the characteristics of impulse activity in the ipsilateral and contralateral neurons of the lateral vestibular nucleus of unilaterally labyrinthectomized rats during various periods of vibration exposure. A program analysis of the background impulse activity of the neurons in the right- and left-lateral vestibular nuclei of rats under normal condition and after right-sided labyrinthectomy was performed. The animals were subjected to different periods of vibration exposure 2 days after surgery (5-, 10-, and 15-day periods). A comparison of the characteristics of the background impulse activity of neurons in both nuclei of intact rats revealed an initial asymmetry in the values of the mean impulse frequency and coefficient of variation of interimpulse intervals. After 5 days of vibration exposure, the values of the mean impulse frequency of neurons in both Deiters' nuclei were almost equal in labyrinthectomized rats. The mean impulse frequency of neurons on the uninjured side was higher than that on the injured side on the days following vibration exposure. The characteristics and functional significance of the findings are discussed.

Labyrinthectomy: Our Experience in a Tertiary Care Centre

Labyrinthectomy is an effective surgical procedure for the management of poorly compensated unilateral peripheral vestibular dysfunction in the presence of a nonserviceable hearing. It involves removal of labyrinthine portion of the inner ear and exenteration of the neuroepithelium. In our institution, 8 cases underwent surgical labyrinthectomy from a period of 2013-2018 for various extensive disease manifestations, age ranges from 2 to 48 years. Includes, a child of 2 years age presented with bilateral foul smelling otorrhoea with external auditory canal cartilaginous stenosis, 5 cases of extensive cholesteatoma with labrynthitis and 2 cases of purulent labrynthitis among them 1 were suffering from Tuberculosis and was on Category 1 ATT and other one suffering from extensive granulation at the tympanomastoid area which was inconclusive of the diagnosis even after histopathological examination, so treated as tuberculosis and started on prophylactic antitubercular treatment in addition to surgery. All patients except the child gave past history of giddiness, but at the time of presentation they were not having giddiness or noticeable nystagmus and all had profound unilateral sensorineural hearing loss. Thus all the patients underwent a radical mastoidectomy with total labyrinthectomy and blind sac closure in 2 patients.

Congenital Cholesteatoma in Adults-Interesting Presentations and Management

To report a series of adult patients diagnosed with congenital cholesteatoma (CC) with respect to symptoms, different varieties of presentation, surgical findings and approach used, complications and the postoperative results. A retrospective chart review of adult cases of CC who were treated in the period from January 2014-2017 was carried out in a tertiary care center. Levenson's criteria were used for diagnosis. Diagnosis was confirmed by imaging and intraoperatively. Postoperative results and complications were also analyzed. Six adult cases of CC were studied with a mean follow up of 10 months. Interesting presentations included otitis media with effusion, non-resolving facial nerve palsy, post aural discharge and meningitis. It included 3 cases of petrous apex cholesteatoma, 2 patients with cholesteatoma involving both the middle ear and mastoid and 1 patient with mastoid cholesteatoma. The operative procedures included canal wall up mastoidectomy (1 patient), atticotomy (1 patient), canal wall down mastoidectomy (1 patient), translabyrinthine and transotic excision of mass with blind sac closure (2 patients) and partial labyrinthectomy (1 patient). Complications encountered during surgery were cerebrospinal fluid leak and worsening of hearing in 2 patients and 1 patient respectively. CC can have variety of interesting presentations in adult population and they may or may not have the classical white mass behind the tympanic membrane. Appropriate individualized surgical planning and intervention gives good results.

Comparison among ultrasonic, electrical apparatus, and toxic chemicals for vestibular lesion in mice

BACKGROUND

The vestibular lesion (VL) is required to examine the physiological function of the vestibular system in animals. Toxic chemicals or electrical apparatus have been used for the VL, however, they are not ideal as they have low specificity, and can result in unintended damage, and systemic toxic effect.

NEW METHOD

Localized vibration-induced VL, using an ultrasonicator, is expected to overcome the problems associated with chemical and electrical lesions. Thus, we examined the effect of the ultrasonication on the VL from the aspects of both the physiological function and histology in the present study.

RESULTS

and Comparison with Existing Method(s) Complete VL, which was evaluated by deterioration of swimming skills, righting reflex, and body stability, was induced using an ultrasonicator or electrical apparatus. Histological evaluation shows that hair cell layers in the saccule and utricle were completely destroyed in both methods Furthermore, significant drop in body mass was observed in VL. However, abscess at the cranial base was observed in VL induced by the electrical apparatus in ICR mice. Complete chemically-induced VL was observed in C57BL/6J but not ICR mice, and systemic leakage of the toxic chemicals (arsenic) was not detectable even 1day after surgery.

CONCLUSIONS

Compared to the electrical apparatus, the ultrasonicator is useful for inducing VL in ICR and C57BL/6J mice, as it results in less non-specific damage. Toxic chemicals can be used for inducing VL in C57BL/6J mice; however, this method does not ensure complete disruption of the hair cells in the saccule and utricle.

Short-term galvanic vestibular stimulation promotes functional recovery and neurogenesis in unilaterally labyrinthectomized rats

Current experimental research on the therapeutic effects of galvanic vestibular stimulation (GVS) has mainly focused on neurodegenerative disorders. However, it primarily stimulates the vestibular nuclei and could be potentially effective in modulating imbalance between them in the case of unilateral labyrinthectomy (UL). Fifty male Wistar rats (180-220g) were used in 5 groups of 10: intact, sham, right-UL (RUL; without intervention), and two other right-UL groups with GVS intervention [one group treated with low rate GVS (GVS.LF; 6-7Hz), and the other treated with high rate GVS (GVS.HF; 17-18Hz)]. The UL models were prepared by intratympanic injection of sodium arsanilate. GVS protocols were implemented 30min/day and continued for 14 days via ring-shaped copper electrodes inserted subcutaneously over each mastoid. Functional recovery was assessed by several postural tests including support surface area, landing and air-righting reflexes, and rotarod procedure. Immunohistochemical investigations were performed on ipsi- and contra-lesional medial vestibular nuclei (MVN) using bromodeoxyuridine (BrdU) and Ki67, as markers of cell proliferation. Behavioral evaluations showed significant functional recovery of GVS-treated groups compared to RUL group. The percent of marked cells with BrdU and Ki67 were significantly higher in the ipsilesional MVN of both GVS-treated groups compared with other groups. Our findings confirmed the effectiveness of GVS-intervention in accelerating static and dynamic vestibular compensation. This could be explained by the cell proliferation in ipsilesional MVN cells and rapid rebalancing of the VNs and the modulation of their motor outputs. Therefore, GVS could be promising for rehabilitating patients with unilateral vestibular weakness.

Sensitivity of the cochlear nerve to acoustic and electrical stimulation months after a vestibular labyrinthectomy in guinea pigs

Single-sided deafness patients are now being considered candidates to receive a cochlear implant. With this, many people who have undergone a unilateral vestibular labyrinthectomy for the treatment of chronic vertigo are now being considered for cochlear implantation. There is still some concern regarding the potential efficacy of cochlear implants in these patients, where factors such as cochlear fibrosis or nerve degeneration following unilateral vestibular labyrinthectomy may preclude their use. Here, we have performed a unilateral vestibular labyrinthectomy in normally hearing guinea pigs, and allowed them to recover for either 6 weeks, or 10 months, before assessing morphological and functional changes related to cochlear implantation. Light sheet fluorescence microscopy was used to assess gross morphology throughout the entire ear. Whole nerve responses to acoustic, vibrational, or electrical stimuli were used as functional measures. Mild cellular infiltration was observed at 6 weeks, and to a lesser extent at 10 months after labyrinthectomy. Following labyrinthectomy, cochlear sensitivity to high-frequency acoustic tone-bursts was reduced by 16 ± 4 dB, vestibular sensitivity was almost entirely abolished, and electrical sensitivity was only mildly reduced. These results support recent clinical findings that patients who have received a vestibular labyrinthectomy may still benefit from a cochlear implant.