In order to know the effects of caloric stimulation on neuronal firing in medial vestibular nuclei (MVN) by middle ear irrigation, the middle ear was irrigated with ice (4 degrees C), hot (44 degrees C), and warm (37 degrees C) water, and the firing rate of MVN neuron was extracellularly recorded. The results showed that the firing rate of MVN neuron was changed by caloric stimulation, and the majority of MVN neurons showed excitation by irrigation with hot water and inhibition by ice water (type A). The neuronal firing was recovered immediately after the cessation of the stimulation. I It was concluded that the neuronal firing rate in MVN was changed by caloric stimulation in middle ear cavity. The response was different in various neurons.
Cold ; Ear, Middle ; Electrophysiology ; Endolymph/physiology ; Heat ; Irrigation ; Neurons/classification ; Neurons/physiology ; Rats, Wistar ; Vestibular Nerve/*physiology ; Vestibular Nuclei/*physiology

Objective:This study aims to compare the examination results of the vestibular evoked myogenic potential（VEMP） and video head impulse testing（vHIT） in patients with vestibular neuritis（VN）, thus exploring the methods to distinguish superior and inferior vestibular nerve damages in VN patients, and their feasibility. Methods:A total of 25 patients with unilateral VN treated in the Otology Department of the First Hospital of Qinhuangdao from May 2018 to July 2021 were recruited. They were respectively tested for ocular VEMP（oVEMP）, cervical VEMP（cVEMP） and vHIT, and the examination results were analyzed. Results:Examination results of oVEMP showed that 96%（24/25） patients had one-ear abnormalities with the amplitude decline or no waveform introduced, and 4%（1/25） patient had no waveform introduced of both ears. The overall abnormal rate examined by oVEMP was 100%（26/26）. Examination results of cVEMP showed that 36%（9/25） patients had one-ear abnormalities with the amplitude decline or no waveform introduced, and 4%（1/25） patients had no waveform introduced of both ears. The overall abnormal rate examined by cVEMP was 40%（10/25）, and 60%（15/25） patients had normal waveforms of both ears. Examination results of vHIT showed that 100%（25/25） patients had semicircular canal gain decline of one side, 92%（23/25） had anterior Semicircular canal decline of one side, and 36%（9/25） had posterior semicircular canal decline of one side. VEMP and vHIT results were compared. Examination results of VEMP showed that 60%（15/25） VN patients had superior vestibular nerve damage, and 40%（10/25） had both superior and inferior vestibular nerve damages. Examination results of vHIT showed that 64%（16/25） VN patients had superior vestibular nerve damage, and 36%（9/25） had both superior and inferior vestibular nerve damages. There was no significant difference in the ratio of VN patients with superior and inferior vestibular nerve damages examined by VEMP or vHIT（χ²=0.085, P>0.05）. The matching ratio of VEMP and vHIT results was 80%（20/25）, and the non-matching ratio was 20%（5/25）. Conclusion:Consistent results obtained from both VEMP and vHIT can preliminarily identify the type of vestibular nerve damage. If their results are not consistent, it is recommended not to identify the scope of the vestibular nerve damage.
Humans ; Vestibular Neuronitis/diagnosis* ; Vestibular Nerve ; Head Impulse Test/methods* ; Semicircular Canals ; Vestibular Evoked Myogenic Potentials/physiology*

In order to know the effects of caloric stimulation on neuronal firing in medial vestibular nuclei (MVN) by middle ear irrigation, the middle ear was irrigated with ice (4 degrees C), hot (44 degrees C), and warm (37 degrees C) water, and the firing rate of MVN neuron was extracellularly recorded. The results showed that the firing rate of MVN neuron was changed by caloric stimulation, and the majority of MVN neurons showed excitation by irrigation with hot water and inhibition by ice water (type A). The neuronal firing was recovered immediately after the cessation of the stimulation. I It was concluded that the neuronal firing rate in MVN was changed by caloric stimulation in middle ear cavity. The response was different in various neurons.
Animals ; Cold Temperature ; Ear, Middle ; Electrophysiology ; Endolymph ; physiology ; Female ; Hot Temperature ; Male ; Neurons ; classification ; physiology ; Rats ; Rats, Wistar ; Therapeutic Irrigation ; Vestibular Nerve ; physiology ; Vestibular Nuclei ; physiology

BACKGROUNDDetermining the nerve of origin for vestibular schwannoma (VS), as a method for predicting hearing prognosis, has not been systematically considered. The vestibular test can be used to investigate the function of the superior vestibular nerve (SVN) and the inferior vestibular nerve (IVN). This study aimed to preoperatively distinguish the nerve of origin for VS patients using the vestibular test, and determine if this correlated with hearing preservation.

METHODSA total of 106 patients with unilateral VS were enrolled in this study prospectively. Each patient received a caloric test, vestibular-evoked myogenic potential (VEMP) test, and cochlear nerve function test (hearing) before the operation and 1 week, 3, and 6 months, postoperatively. All patients underwent surgical removal of the VS using the suboccipital approach. During the operation, the nerve of tumor origin (SVN or IVN) was identified by the surgeon. Tumor size was measured by preoperative magnetic resonance imaging.

RESULTSThe nerve of tumor origin could not be unequivocally identified in 38 patients (38/106, 35.80%). These patients were not subsequently evaluated. In 26 patients (nine females, seventeen males), tumors arose from the SVN and in 42 patients (18 females, 24 males), tumors arose from the IVN. Comparing with the nerve of origins (SVN and IVN) of tumors, the results of the caloric tests and VEMP tests were significantly different in tumors originating from the SVN and the IVN in our study. Hearing was preserved in 16 of 26 patients (61.54%) with SVN-originating tumors, whereas hearing was preserved in only seven of 42 patients (16.67%) with IVN-originating tumors.

CONCLUSIONSOur data suggest that caloric and VEMP tests might help to identify whether VS tumors originate from the SVN or IVN. These tests could also be used to evaluate the residual function of the nerves after surgery. Using this information, we might better predict the preservation of hearing for patients.

Adult ; Female ; Hearing ; Humans ; Male ; Neuroma, Acoustic ; pathology ; physiopathology ; Vestibular Nerve ; physiology

OBJECTIVE: To evaluate the influence of inferior vestibular and part of mandibular branch of trigeminal neurotomy on sound-induced masseter reflex potentials. METHOD: Twenty guinea pigs were randomly divided into four groups, including 5 normal control guinea pigs, 5 received unilateral inferior vestibular neurotomy, 5 received unilateral inferior alveolar nerve neurotomy, and 5 received auriculotemporal nerve neurotomy. Click sound-induced masseter reflex potentials were recorded in four groups, respectively. RESULT: The thresholds of negative peak (NP) of click sound-induced masseter reflex potentials in normal control group were (90.00 +/- 8.16) dBnHL. The response rates of the NP of the masseter reflex potentials using 100, 90, 80 and 70 dBnHL monaural acoustic stimulation with unilateral recording were 100%, 70%, 40% and 0, respectively. The mean latencies of the NP were (6.55 +/- 0.25) ms, (6.61 +/- 0.16) ms and (6.70 +/- 0.13) ms, when elicited by 100,90 and 80 dBnHL acoustic stimulation respectively. There was no significant difference between the stimulus intensity and the mean latency of the NP (P > 0.05). Negative peak of click sound-induced masseter reflex potentials was not observed in the inferior vestibular neurotomy group. The NP was preserved in the inferior alveolar nerve and auriculotemporal nerve neurotomy groups. There were no significant difference of the mean thresholds and latencies of NP between normal control group and inferior alveolar nerve and auriculotemporal nerve neurotomy group (P > 0.05). CONCLUSION Click sound-induced masseter reflex potentials originates from vestibular afferents. Afferent of inferior alveolar nerve and auriculotemporal nerve can not influence the vestibular evoked masseter reflex potentials.
Afferent Pathways ; surgery ; Animals ; Guinea Pigs ; Masseter Muscle ; physiology ; Reflex, Acoustic ; Trigeminal Nerve ; surgery ; Vestibular Nerve ; surgery

To assess the clinical application of video head impulse test (vHIT) for vestibular function in vestibular neuritis (VN) and benign paroxysmal positional vertigo (BPPV) patients.Thirty-three patients with VN and 43 patients with BPPV were enrolled from Sir Run Run Shaw Hospital and Ningbo Second Hospital from March 15 to September 10, 2015; and 50 healthy controls were also enrolled in the study. vHIT was used to quantitatively test the vestibulo-ocular reflex (VOR) gains of a pair of horizontal semicircular canals. VOR gains two pairs of vertical semicircular canals, and the corresponding asymmetrical value of three VOR gains. The saccades information was also recorded.Compared with the healthy control group and BPPV patients, the affected horizontal and vertical VOR gains were declined and the corresponding asymmetries were increased in VN patients (all<0.01). BPPV group also showed higher vertical VOR gain asymmetries compared with the healthy control group (all<0.01), but no significant difference was observed in VOR gains and horizontal VOR gain asymmetry (all>0.05). The sensibility of vHIT in diagnosis of VN was 87.9%. Among 33 VN patients, 22 were diagnosed with superior vestibular nerve dysfunction, 7 were found with inferior vestibular nerve dysfunction and 3 were with both dysfunction; and 1 case was not distinguished.Video head impulse test can quantitatively evaluate the vestibular dysfunction of VN and can help early diagnosis of VN, which may be widely used in clinic.
Benign Paroxysmal Positional Vertigo ; diagnosis ; Head Impulse Test ; Humans ; Reflex, Vestibulo-Ocular ; physiology ; Saccades ; physiology ; Semicircular Canals ; innervation ; physiopathology ; Sensitivity and Specificity ; Vestibular Diseases ; classification ; diagnosis ; Vestibular Nerve ; pathology ; Vestibular Neuronitis ; classification ; diagnosis

AIMTo investigate membrane electro-physiological features in vestibular ganglion neuronal population using a voltage-sensitive dye and optical recording technique.

METHODSDissociated and cultured mouse vestibular ganglion neurons were stained with an absorption voltage-sensitive dye, RH 155, and were imaged in 16 x 16 elements Photodiode arrays (PDA) optical recording system.

RESULTSWhen the cells were depolarized during perfusion with 150 mmol/L potassium solution, optical absorption of the dye that bound to the external surface of neuron membranes increased. The relative ratio (delta I/I) of optical absorption change was 0.23% +/- 0.08% (x +/- s, n = 28). These optical responses were wavelength dependent. Under our experimental conditions, photo toxicity and pharmacological effects of the dye were either absent or insignificant.

CONCLUSIONOur results suggest that optical recording provides a new, practical and less toxic method to simultaneously monitor changes in membrane potential from several cultured vestibular ganglion cells.

Action Potentials ; physiology ; Animals ; Cells, Cultured ; Female ; Fluorescent Dyes ; Male ; Membrane Potentials ; physiology ; Mice ; Mice, Inbred ICR ; Neurons ; physiology ; Patch-Clamp Techniques ; methods ; Vestibular Nerve ; physiology