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Purpose: To investigate the prevalence of reversal nystagmus in individuals with benign paroxysmal positional vertigo (BPPV)., Study Design: Prevalence of reversal nystagmus was assessed in 28 subjects with unilateral posterior canal BPPV, canalithiasis type. Six trials of Dix-Hallpike testing were completed for each subject., Results: Reversal nystagmus was present in 129 out of 167 Dix-Hallpike maneuvers that were performed (77.2%). In 19 trials where nystagmus was absent with the dependent position of Dix-Hallpike testing, reversal nystagmus was nonetheless demonstrated in 11 trials (57.9%)., Conclusion: Reversal nystagmus is commonly demonstrated in individuals with posterior canal BPPV, canalithiasis type. It is frequently evoked even when there is no nystagmus with the dependent position of Dix-Hallpike testing. Observation of reversal nystagmus may enhance the identification of BPPV during Dix-Hallpike testing., Competing Interests: None declared., (American Academy of Audiology. This article is published by Thieme.)

Objectives: Although the Dix-Hallpike testing is generally considered as the gold standard for the identification of the posterior canal benign paroxysmal positional vertigo (BPPV), we investigated a modification of the maneuver termed the "loaded Dix-Hallpike.", Study Design: Prospective randomized controlled trial., Materials and Methods: Twenty-eight patients participated in this prospective study comparing the standard Dix-Hallpike (S-DH) to the loaded Dix-Hallpike (L-DH) test. Each patient underwent repeated testing with the S-DH and the L-DH. The patients were placed into two groups. Fourteen patients underwent 3 rounds of S-DH testing followed by 3 rounds of L-DH testing. The other fourteen patients underwent 3 rounds of L-DH testing followed by 3 rounds of S-DH testing. The duration of nystagmus and the latency prior to the onset of nystagmus were measured for each test. Additionally, the patients were asked to rate the severity of their symptoms following each test., Results: The duration of nystagmus of the L-DH was significantly longer than that of the S-DH (p<0.0001). The patients reported a higher severity score with L-DH as compared to with S-DH (p<0.001). The L-DH was found to be more sensitive than the S-DH (p=0.0131)., Conclusion: The L-DH produces significantly longer duration of nystagmus, stronger symptoms, and improved sensitivity when compared to the S-DH.

Objectives/hypothesis: Objectives were to describe the use of round window plugging for superior semicircular canal dehiscence syndrome and review further recommendations regarding the procedure based on our experience and to compare results with recent literature on round window plugging., Study Design: Retrospective case series., Methods: Fourteen patients underwent round window plugging for superior semicircular canal dehiscence at our institution from 2012 to 2015. All patients underwent the same surgical procedure. Available pre- and postoperative data were reviewed., Results: Fourteen patient charts were reviewed. Symptoms of autophony improved in nine of 14 (64%) patients. Symptoms of pressure-induced vertigo improved in seven of 12 (58%) patients. Hennebert's sign that was positive preoperatively only improved in one of six (17%) patients. A positive preoperative vestibular evoked myogenic potential improved in only one of six (17%) patients. Six of 13 (46%) patients had increased air conduction thresholds postoperatively., Conclusions: Round window plugging has been described as a less-invasive treatment for patients with superior semicircular canal dehiscence. Although the procedure did benefit some of our patients, successful outcomes were not predictable. Improvement in at least one objective finding was seen in only 21% of the patients studied. Hennebert's sign and vestibular evoked myogenic potentials that were positive preoperatively only improved in 17% of patients. At our institution, round window plugging is no longer considered a reasonable treatment option for most patients with superior semicircular canal dehiscence. We recommend that further study on this topic follow a standardized pre- and postoperative assessment., Level of Evidence: 4. Laryngoscope, 128:1445-1452, 2018., (© 2017 The American Laryngological, Rhinological and Otological Society, Inc.)

Although the chinchilla is widely used as a model for auditory research, little is known about the distribution and morphology of its olivocochlear neurons. Here, we report on the olivocochlear neurons projecting to one cochlea, as determined by single and double retrograde fluorescent tracer techniques. 10 adult chinchillas were anesthetized and given either unilateral or bilateral injections of a fluorescent tracer (either Fluoro-Gold or Fast Blue) into scala tympani or as a control, a unilateral injection into the middle ear cavity. The results indicate that there are similarities as well as significant differences between the chinchilla and other species of rodents in the distributions of their olivocochlear neurons. Based on three well-labelled cases, there was a mean total of 1168 olivocochlear neurons in the chinchilla. Of these, the majority (mean 787) were small, lateral olivocochlear neurons found almost exclusively within the ipsilateral lateral superior olivary nucleus. The next largest group consisted of a mean of 280 medial olivocochlear neurons virtually all of which were located in the dorsomedial peri-olivary nucleus. Chinchilla medial olivocochlear neurons were more predominantly crossed in their projections (4:1) than in any known species. The smallest group of olivocochlear neurons (mean 101) consisted of larger lateral olivocochlear neurons (shell neurons) which were located on the margins of the superior olivary nucleus and which projected mainly (2.2:1) ipsilaterally. Double retrograde labelling was observed only in medial olivocochlear neurons and occurred in only 1-2% of these cells. The results confirm previous findings which indicated a relative paucity of fibers belonging to the uncrossed as compared to the crossed olivocochlear bundle. This, together with the strong apical bias of the uncrossed projection reported previously, offers possible explanations for the apparent absence of efferent-mediated suppressive effects of contralateral acoustic stimulation in this species. Regarding the lateral olivocochlear system, the chinchilla is shown to possess both intrinsic and shell neurons, as in the rat.

The distribution and density of noradrenergic (NA) and serotonergic (5-HT) varicosities in the superior olive (SO) and periolivary region (PO) and their relationship to olivocochlear neurons was studied. Antibodies against 5-HT and the NA precursor enzyme dopamine beta-hydroxylase were utilized to examine the density of innervation of SO and PO. To determine the relationship of these varicosities to efferent neurons projecting to the cochlea, olivocochlear neurons were retrogradely labeled with biotinylated dextranamine (BDA). NA and 5-HT varicosities were found adjacent to labeled olivocochlear neuron cell bodies and dendrites. More than 50% of labeled medial olivocochlear (MOC) neurons showed likely contact with NA varicosities and more than 90% of labeled MOC neurons with 5-HT varicosities. There was no apparent difference in the number of lateral olivocochlear (LOC) neurons in close proximity to NA and 5-HT varicosities versus MOCs in close proximity to NA and 5-HT varicosities. Our results suggest that the NA and 5-HT systems are in a position to modulate auditory brainstem processing. The specific relationship of NA and 5-HT varicosities to olivocochlear neurons suggests that one possible level of modulation is prior to signal transduction., (Copyright 1999 Elsevier Science B.V.)

The external, central and dorsal subnuclei of the inferior colliculus (ICX, ICC, ICD respectively) have different patterns of descending projections to the periolivary region. We found that electrical stimulation of these subnuclei in anesthetized rats causes suppression of 2f1-f2 distortion product otoacoustic emissions (DPOAE). The responses in DPOAEs to stimulation of ICX and ICC are characterized by a large (7-25 dB), initial suppression which lasted 25-30 s (early phase) followed by a sustained smaller (3-15 dB) suppression (late phase). ICX stimulation produces the largest suppressions of DPOAEs in both contralateral and ipsilateral ears equally. Stimulation of the ICC causes large suppressions in the contralateral ear DPOAEs but much smaller than the suppressions of DPOAEs caused by ICX stimulation. Stimulation of the ICC causes a much smaller suppression in the ipsilateral ear DPOAEs than in the contralateral ear DPOAEs. ICD stimulation, however, produces little or no suppression of DPOAEs in either ear when compared to other subnuclei. No frequency-specific changes in DPOAEs were seen with stimulation of any of the subnuclei of the inferior colliculus (IC). Sectioning of middle ear muscles did not negate the suppressive effects of IC stimulation on DPOAEs. These findings verify that the IC has a subnucleus-specific influence over cochlear micromechanics.