Vestibular function disorders and potential mechanisms in irradiation nasopharyngeal carcinoma patients

The advantages of vestibular-evoked myogenic potentials induced by bone-conducted vibration in patients with otitis media

BACKGROUND

At present, there is no consensus on the optimal methods for the diagnosis of vestibular dysfunction.

OBJECTIVE

To explore the advantages of bone-conducted vibration (BCV) related vestibular-evoked myogenic potentials (VEMPs).

MATERIAL AND METHODS

Fifty patients with otitis media volunteered for VEMP examination. They were randomly selected with air-conducted sound and BCV stimulation VEMPs assessed in both ears.

RESULTS

The provocation rate of BCV-VEMPs was significantly higher than that of air-conducted sound VEMPs. Among 50 affected ears, there was no significant difference in the provocation rate of BCV-VEMPs between patients with air-bone conduction gaps lower or higher than 20 dB. There was no significant difference in the provocation rate of BCV-VEMPs between both ears in 30 patients with unilateral otitis media and the comparison of BCV-oVEMP parameters made no significant difference in amplitude, N1 latency, P1 latency, or N1-P1 duration, except for the threshold. A comparison of BCV-cVEMP parameters between affected and healthy ears revealed no significant difference between groups in terms of threshold, amplitude, N1 latency, P1 latency, or n1-p1 duration.

CONCLUSIONS AND SIGNIFICANCE

BCV-VEMPs may be stably induced in patients with conductive hearing loss.

A unique radioprotective effect of resolvin E1 reduces irradiation-induced damage to the inner ear by inhibiting the inflammatory response

Background

In addition to the direct effects of irradiation, the induced inflammatory response may play an important role in the damage to the inner ear caused by radiotherapy for the treatment of head and neck cancers. Resolvin E1 (RvE1) has anti-inflammatory activity, acting by reducing neutrophil infiltration and proinflammatory cytokine expression. Therefore, in this study we sought to confirm whether the inflammation induced by irradiation was involved in damage to the inner ear after radiotherapy and to investigate the protective effect and underlying mechanism of RvE1 using mouse models.

Methods

A dose of RvE1 was delivered by intraperitoneal injection to mice before irradiation. Changes in the auditory brainstem response (ABR), relative balance ability, inner ear morphology and the expression levels of inflammatory factors in the inner ear were analyzed on days 7 and 14 after irradiation and compared among different experimental groups.

Results

Changes of ABR and relative balance ability showed the inner functions of experimental mice presented severe damage after irradiation, but the damage was significantly alleviated after RvE1 pretreatment compared to irradiation alone. Morphological analysis of the inner ear showed severe damage to the cochlea and vestibule after irradiation. In contrast, damage to the cochlea and vestibule was significantly reduced in the RvE1-pretreated group compared to that in the irradiation alone group. Along with these functional and morphological changes, the mRNA expression level of anti-inflammatory factors interleukin-2 was significantly increased, while those of proinflammatory factors interleukin-6 and tumor necrosis factor-α were significantly decreased in the inner ear of mice after RvE1 pretreatment compared to irradiation alone.

Conclusions

We believe that inflammation induced by irradiation is involved in the damage to the inner ear caused by radiotherapy, and that RvE1 reduces the damage caused by irradiation to the inner ear by regulating the induced inflammatory response.

Dosimetric parameters associated with conductive or sensorineural hearing loss 5 years after intensity-modulated radiation therapy in nasopharyngeal carcinoma

BACKGROUND

Most previous studies are separate dosimetric analyses of conductive or sensorineural hearing loss, and they are not conducive to a comprehensive assessment of auditory radiation damage.

AIMS/OBJECTIVES

Our study aimed to evaluate the long-term incidence of sensorineural hearing loss (SNHL) or conductive hearing loss (CHL) in patients with nasopharyngeal carcinoma (NPC) after intensity-modulated radiation therapy (IMRT), and to investigate the relationship between SNHL or CHL and patient factors, treatment-related factors, and radiation dose parameters.

MATERIAL AND METHODS

Seventy patients (117 ears) with NPC, who were also treated with IMRT in our hospital from 2006 to 2014, were retrospectively analyzed. Radiation doses to the Eustachian tube (ET), middle ear (ME), cochlear (Co), and internal auditory canal (IAC) were assessed. Pure tone audiometry and impedance audiometry were performed before and during the follow-up period. The relationships between low-frequencies (0.5-2 kHz) or high-frequency (4 kHz) SNHL/CHL and radiotherapy dose parameters were analyzed.

RESULTS

Of the 117 ears studied, 7.69% had low-frequency SNHL, 35.9% had high-frequency SNHL, 23.93% had low-frequency CHL, and 18.80% had high-frequency CHL. The incidence of high-frequency CHL was higher in the T4 group than in the T (1-3) group (p < .05). When IAC D_max > 42.13 Gy or IAC D_mean > 32.71 Gy, the risk of high-frequency SNHL increased in NPC patients. When ME D_max > 44.27 Gy, ME D_mean > 29.28 Gy, or ET D_max > 57.23 Gy, the risk of high-frequency CHL in NPC patients increased.

CONCLUSIONS AND SIGNIFICANCE

SNHL and CHL remain common ear complications after IMRT for NPC. IAC D_max, IAC D_mean, ME D_max, ME D_mean, and ET D_max all need to be carefully considered during the IMRT treatment protocol.