[The causes and coping strategies for refractory vertigo].

Refractory vertigo is a disease entity characterized by uncontrollable recurrent vertigo and/or persistent dizziness instability, which can be caused by various diseases. The main pathogenesis may be related to recurrent episodes of the primary disease and compensatory dysfunction of the vestibular system. Understanding the common causes and pathological mechanisms of refractory vertigo, and comprehensively analyzing the relevant factors that cause symptoms, can facilitate accurate diagnosis and effective differentiation, and then provide comprehensive treatment targeting various factors such as etiology, symptoms, functional status, and psychological problems, ultimately achieving the goal of controlling the occurrence and development of refractory vertigo. Based on the characteristics of symptoms, this article focuses on analyzing possible mechanisms, relative factors, diagnosis and differential diagnosis of common diseases that lead to refractory vertigo, effective coping strategies, key issues that need attention, and future prospects, in order to improve clinical diagnostic accuracy and treatment effectiveness.

[Standardized vestibular rehabilitation should be emphasized after surgical treatment involving vestibular system].

Surgical treatment involving vestibular system includes intractable vertigo surgery, inner ear surgery and vestibular tumor surgery. These operations often lead to the weakening or even loss of vestibular function, or further aggravation of the original dysfunction. If there is no standardized treatment after operation, patients are prone to recurrent vertigo, or long-term blurred vision and/or imbalance, as well as other symptoms. Through the use of medicines to promote vestibular compensation and standardized non-invasive vestibular rehabilitation training, symptoms can be eliminated as soon as possible, the duration of vestibular compensation can be shortened, stable vestibular compensation could be rapidly established, and thus the postoperative quality of life for those patients could be improved. Therefore, we should pay attention to standardize the vestibular rehabilitation after surgical treatment involving vestibular system.

[Direct projection pathway between medial vestibular nucleus and vestibular efferent neurons in rats and its electrophysiological characteristics].

Objective: To confirm the direct projection pathway between the medial vestibular nucleus (MVN) and vestibular efferent (VE) neurons and explore its electrophysiological characteristics. Methods: Newborn [(9±1) day-old] male and female Wistar rats were used in the study. The postsynaptic currents of VE were recorded after stimulating neurons in MVN by the whole-cell patch clamp recording technique. The action potentials (APs) of the afferent neurons in MVN were recorded retrogradely after stimulating the area of VE neurons distribution medial to genu of facial nerve (g7), and the position and shape of the recorded neurons were determined by biocytin staining. Results: The resting membrane potentials of VE neurons located medial to g7 ranged between -70 mV and -55 mV in current clamp recordings. Excitatory postsynaptic currents (EPSCs) were recorded in the VE neurons medial to the g7 evoked by single-pulse (0.08 mA, 0.1 Hz, 100 µs) electrical stimulation of MVN. The mean values of amplitude and duration were (195.6±23.7) pA and (23.9±5.9) ms, respectively. APs were recorded in MVN after stimulating the distribution area of VE neurons. The mean amplitude of the action potentials was (62.0±4.3) mV, and the mean duration was (94.9±4.7) ms. Biocytin staining indicated that the recorded neurons located in MVN and the axons' terminals went into the area medial to g7 in which VE neurons located. Conclusions: There is a direct excitatory pathway projecting from MVN to VE neurons medial to g7. Its physiological function may be related to the feedback regulation of vestibular center to peripheral vestibular afferent signals.

SGN nerve filaments develop synapses with IHCs earlier than with OHCs in C57BL/6 mouse inner ear.

OBJECTIVE: To explore the connections between hair cells and spiral ganglion neurons (SGNs) during the development of the C57BL/6 mouse inner ear. MATERIALS AND METHODS: The specimens of C57BL/6 mouse inner ear, from E15 (embryo day 15) to adult mouse, were collected; immunohistochemistry was employed to explore the frozen sections of specimens. RESULTS: The development of cochlea starts sequentially from the basal turn to the apex turn. Morphological development of SGNs occurs mainly from E16 to P12 (postnatal day 12). Hair cells appear from E18 to P12, and inner hair cells (IHCs) develop earlier than outer hair cells (OHCs). The connections between hair cells and SGNs begin to develop during E18-P1, morphologically resemble mature synapses during P8-P12, and completely mature in adult mice. CONCLUSIONS: The genesis of auditory ribbon synapse occurs from E18 to P1. Synchronized with the development of SGNs and hair cells, the functional filaments remain connected to hair cells, while the spare ones get disconnected from the surface of hair cells. Connections between SGN nerve filaments and IHCs occur earlier than those between SGN nerve filaments and OHCs.

[A review about the research progress of the acoustical-electrical transducer for totally implantable cochlear implant].

Cochlear implantation has become a crucial approach for the treatment for patients with severe and profound sensorineural hearing loss. However, some patients would be embarrassed by the exterior components, which limited the patient's social activities. The idea of totally implantable cochlear implant (TICI) was put forward to alleviate these inconveniences. The implantable acoustical-electrical transducer would be a breakthrough in the study of TICI. In this paper, a summary of all kinds of designs ideas was made.

Detection of common deafness mutation by maternal plasma cell-free DNA.

OBJECTIVES: The aim is to investigate the use of the ligase detection reaction (LDR) microarray to examine the difference of the single nucleotide between the pregnant woman and the fetus by cell-free DNA in the maternal plasma in congenital deafness. MATERIALS AND METHODS: The proband and the couples' venous blood samples and the amniotic fluid/ chorionic villi collected from seven deafness families for prenatal diagnosis were analyzed. The cell-free DNA from maternal plasma was examined to determine if they carried the mutations of GJB2 235delC. RESULTS: Three samples were found to carry the mutation of GJB2 235delC. It is in agreement with the sequencing results. The affected fetuses were suggested to take invasive procedure for confirmation. CONCLUSIONS: The chip may be a potential method to screen for congenital deafness based on maternal plasma DNA.

Therapeutic efficacy of topical application of dexamethasone to the round window niche after acoustic trauma caused by intensive impulse noise in guinea pigs.

OBJECTIVE: To assess the therapeutic efficacy of dexamethasone administered topically to the round window niche, following acoustic trauma induced by intensive impulse noise, in guinea pigs. METHODS: Adult, male, albino guinea pigs with a normal Preyer's reflex were exposed to 80 impulse noises (peak value 167 dB, duration 0.5 ms, interval 2 s). Dexamethasone (40 mg/ml) or saline was then topically applied to the round window niche. Each animal's auditory brainstem response was measured before and one day after exposure, and three weeks after topical treatment. Cochlear morphology was examined to assess hair cell loss and spiral ganglion cell damage. To assess oxidative activity, cochlear malondialdehyde and superoxide dismutase concentrations were determined three weeks post-treatment. Following topical application, the pharmacokinetic characteristics of dexamethasone in cochlear perilymph were analysed using high-performance liquid chromatography. RESULTS: Animals receiving dexamethasone showed reduced noise-induced outer hair cell loss (three weeks post-treatment), and significant attenuation of noise-induced auditory brainstem response threshold shifts (one day post-exposure and three weeks post-treatment), compared with controls. There was no difference in spiral ganglion morphology. Animals receiving dexamethasone also showed a significantly lower malondialdehyde concentration and a higher superoxide dismutase concentration, post-exposure. Following topical application, the perilymph dexamethasone level peaked at 5330.522 µg/ml (15 minutes post-treatment), and was 299.797 µg/ml 360 minutes later. CONCLUSION: Topical application of dexamethasone to the round window niche has protective effects against intensive impulse noise induced trauma in the guinea pig cochlea. This drug can diffuse into the inner ear through the round window membrane and persist in the perilymph for a relatively long period. The mechanism of protection may involve an anti-oxidant effect.

[The development of body posturography device using inclinometer technique].

A kind of body posturography device using inclinometer technique is described in this paper. Comparing with a device using gravimeter technique it shows following advantages: 1) As the signal of body sway angle is obtained by the incline-sensor, it is easy to test subject's balance function on the multifarious body supporters; 2) When the platform of the global bottom is used, the subject may come into contact with ground at one point, so as to weaken significantly subject's somatosensory of moving center of gravity.

[Distribution of cholinergic efferent vestibular neurons].

OBJECTIVE: To investigate the effect and distribution of cholinergic efferent vestibular neurons in normal wistar rat. METHOD: HPR retrograde tracer and Immunocytochemical techniques were used. RESULT: Results show that AchT immunoreactive neurons locate in dorsolateral and dorsomedial to genu of the facial. Few neurons scatter in the parvocellular nucleus. CONCLUSION: As a neural transmitter, acetylcholine distribute in efferent vestibular neurons and play an important role.

The reinnervation of regenerated hair cells in the basilar papilla of chicks after kanamycin ototoxicity.

When newly hatched chicks were injected with kanamycin on 8 successive days, the hair cells were destroyed completely in the area 0.4 to 0.8 mm from the proximal end of the basilar papilla. At this time, and 1 and 7 days following the completion of 10 days of injections, the nerve fibres in the basilar papilla of chicks show no sign of injury. On the first day following 10 days kanamycin administration the regenerated hair cells obtained not only afferent innervation, but also efferent innervation. At 15 days following drug cessation, afferent innervation of the regenerated hair cells was already similar to the controls, and the thresholds measured at this time were significantly better than those at 1 and 7 days. The chalice efferent terminals did not appear until the 60th day of drug cessation. Efferent innervation of the regenerated hair cells also approached maturity at this time. Compared with the half month after the completion of drug injection, the hearing of birds had no evident increase. It was obvious that afferent innervation of the regenerated hair cells was related more to the recovery of hearing than efferent innervation. The regenerated hair cells beginning reinnervation early and maturing were important factors influencing the recovery of the birds' hearing function after kanamycin ototoxicity.