Reproducibility (test–retest) of vestibular evoked myogenic potential

IntroductionThere is still no consensus in the literature as to the best acoustic stimulus for capturing vestibular evoked myogenic potential (VEMP). Low-frequency tone bursts are generally more effective than high-frequency, but recent studies still use clicks. Reproducibility is an important analytical parameter to observe the reliability of responses.ObjectiveTo determine the reproducibility of p13 and n23 latency and amplitude of the VEMP for stimuli with different tone-burst frequencies, and to define the best test frequency.MethodsCross-sectional cohort study. VEMP was captured in 156 ears, on the sternocleidomastoid muscle, using 100 tone-burst stimuli at frequencies of 250, 500, 1000, and 2000 Hz, and sound intensity of 95 dB nHL. Responses were replicated, that is, recorded three times on each side.ResultsNo significant difference was observed for p13 and n23 latencies of the VEMP, captured at three moments with tone-burst stimuli at 250, 500, and 1000 Hz. Only the frequency of 2000 Hz showed a difference between captures of this potential (p < 0.001). p13 and n23 amplitude analysis was also similar in the test–retest for all frequencies analyzed.Conclusionp13 and n23 latencies and amplitudes of VEMP for tone-burst stimuli at frequencies of 250, 500, and 1000 Hz are reproducible.     

恒河猴坐姿着陆冲击内耳损伤的观察

为研究机体及各组织器官对冲击力的耐受限值，探讨致伤原因及提出防护措施，利用着陆冲击塔，使实验动物恒河猴的坐姿状态下，进行冲击试验，试验后１ｈ左右处死，作大体解剖观察并取心，肝，脾，肺，颞骨等组织，固定，切片，镜检。同时重点观察了内耳的损伤。结果表明，冲击载荷不大（平台过载值为≤２５Ｇ）时内脏虽然有轻度损伤，但内耳可避免受员，当冲击力加大到一定程度（平台过载值为３０～３５Ｇ）导致内脏中等损伤时，内耳     

Fenestration and occlusion of the posterior semicircular canal for benign positional vertigo

Benign positional vertigo is a potentially disabling condition characterized by episodic vertigo following certain provocative head movements. In most patients it is self limiting; however, in a few it may prove intractable, causing considerable social morbidity. In these patients surgery may be considered. Surgery previously involved section of the vestibular or singular nerves, involving a significant risk to hearing and to the facial nerve. Ablation of the labyrinth may even be considered. The new surgical technique of occlusion of the posterior semicircular canal has proved to be curative in most patients with benign positional vertigo with little risk to hearing. This paper describes our experience of fenestration and occlusion of the posterior semicircular canal in four patients.     

Anatomic variations of surgical importance in ethmoid labyrinth and sphenoid sinus. A study of radiological anatomy

Summary The present study was performed on axial and coronal CT scans of 100 patients, most of whom were affected by nasal polyposis. Five observers had to analyse the radiograms and answer a questionnaire including the following items: presence of a supraorbital recess; identification of anterior and posterior ethmoidal canals; dehiscences in the lamina papyracea; pneumatized middle turbinate; presence of a spheno-maxillary plate; presence of Haller's cells; presence of Onodi's cells; relationships of the optic canal; relationships of the internal carotid artery; relationships of the maxillary nerve; relationships of the vidian nerve; level difference between the ethmoid roof and nasal vault; depth of the sphenoethmoidal recess. The data obtained were compared with those drawn from anatomical studies. The fair agreement between them proves the value of CT as an alternative method for studying paranasal sinuses anatomy.

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Anatomie radiologique des variations du labyrinthe ethmoïdal et du sinus sphénoïdal et leurs conséquences chirurgicales

Résumé Cette étude a été réalisée sur 100 patients dont la plupart présentait une polypose nasale étudiée en coupes T D M axiale et coronale. Cinq lecteurs ont revu les clichés et répondu au questionnaire suivant: présence d'un récessus supra orbitaire; identification des canaux ethmoïdaux antérieur et postérieur; déhiscence de la lame papyracée; pneumatisation du cornet moyen; présence d'un plateau sphéno maxillaire; présence de cellules de Haller; présence de cellules d'Onodi; rapports du canal optique; rapports de l'artère carotide interne; rapports du nerf maxillaire; rapports du nerf vidien; dénivelé entre le toit ethmoïdal et le toit nasal; profondeur du récessus sphéno-ethmoïdal. Les données obtenues ont été comparées avec celles provenant de travaux anatomiques. La concordance acceptable entre les deux démontre la valeur du scanner comme méthode d'étude alternative de l'anatomie des sinus para nasaux.

     

大鼠肠系膜淋巴结高内皮微静脉与淋巴迷路之间的网状纤维支架的研究

目的 研究大鼠肠系膜淋巴结内高内皮微静脉与淋巴迷路之间淋巴细胞归巢的通路.方法 用镀银染色光镜观察法和冻裂割断扫描电镜观察法观察健康、成熟Wistar大鼠肠系膜淋巴结的基质网状结构.结果 位于高内皮微静脉和淋巴迷路周围有网状纤维支架,在二者相临近部位有密集交织的网状纤维网.结论 淋巴结内高内皮微静脉和淋巴迷路之间密集交织的网状纤维网,为细胞的居留和迁移提供结构支持和适宜的微环境,可能是淋巴细胞归巢的重要通路.     

Vestibular and audiological findings in the Alport syndrome

Alport syndrome (AS) is caused by mutations in collagen IV, which is widespread in the basement membranes of many organs, including the kidneys, eyes, and ears. Whereas the effects of collagen IV changes in the cochlea are well known, no changes have been described in the posterior labyrinth. The aim of this study was to investigate both the auditory and the vestibular function of a group of individuals with AS. Seventeen patients, aged 9–52, underwent audiological tests including pure‐tone and speech audiometry, immittance test and otoacoustic emissions and vestibular tests including video head impulse test, rotatory test, and vestibular evoked myogenic potentials. Hearing loss affected 25% of the males and 27.3% of the females with X‐linked AS. It was sensorineural with a cochlear localization and a variable severity. 50% of the males and 45.4% of the females had a hearing impairment in the high‐frequency range. Otoacoustic emissions were absent in about one‐third of the individuals. A peripheral vestibular dysfunction was present in 75% of the males and 45.4% of the females, with no complaints of vertigo or dizziness. The vestibular impairment was compensated and the vestibulo‐ocular reflex asymmetry was more evident in rotatory tests carried out at lower than higher speeds; a vestibular hypofunction was present in all hearing impaired ears although it was also found in subjects with normal hearing. A posterior labyrinth injury should be hypothesized in AS even when the patient does not manifest hearing disorders or evident signs of renal failure.     

Pressure Transfer Between Intracranial and Cochlear Fluids in Patients With Meniere's Disease

Objectives: To elucidate the pressure transfer between intracranial and labyrinthine fluids in patients with well‐defined unilateral Meniere's disease. Study Design: Eleven patients previously exposed to hypobaric pressure agreed to be investigated further with the tympanic membrane displacement (TMD) technique. TMD was used to indirectly analyze perilymph pressure changes as the result of changes in body position. Methods: Repeated measurements for both the diseased and the healthy ears were made with the patients supine and then in a sitting position. The TMD parameters for the maximum inward displacement, the Vi, and the mean volume displacement, the Vm, were calculated and compared. Results: The paired comparison showed statistically significant larger Vi values for both ears in the supine position. A similar tendency was observed for the Vm value. This difference of the Vi was significantly larger for the diseased ear compared with the currently healthy ear. The results were compared to the audiometric and electrocochleographic results previously obtained on the same patients when they were subjected to hypobaric pressure. Patients who experienced the largest differences in hearing level thresholds in the lower frequencies also showed the greatest differences in TMD values as the result of postural changes. Conclusions: Despite the limited number, the statistically supported results suggest a relation between the efficiency of the routes of pressure transfer and the observed effect of hypobaric exposure. The results also indicate that for the patients tested, the routes of communication are more effective in the diseased ear than in the healthy ear—a condition that may relate to the pathogeneses of Meniere's disease.