“…The peculiar connections of CAEM to the tensor tympani fossa, on the other hand, are a very interesting separate issue, because they would provide the route that was hypothesized for inflammatory signals from the cochlea to the tensor tympani in the acoustic shock model linked to tinnitus, hyperacusis, and ear fullness ( 82 ). The tensor tympani muscle, connecting the malleus to the Eustachian tube ( 83 ), can be activated by both auditory and non-auditory stimuli, such as tactile stimulation of the external canal, movements of the jaw, and even acute or chronic stress ( 84 ). In the acoustic shock model, noise trauma to the cochlea occurring together with additional factors activating the tensor tympani could induce inflammation in the muscle, triggering a positive feedback cycle that would induce muscle damage similarly to what has been found in myofascial trigger point, involving the release of inflammatory molecules, mast cell degranulation, and pain ( 79 ).…”
Calvarial bone marrow has been found to be central in the brain immune response, being connected to the dura through channels which allow leukocyte trafficking. Temporal bone marrow is thought to play important roles in relation to the inner ear, but is still largely uncharacterized, given this bone complex anatomy. We characterized the geometry and connectivity of rat temporal bone marrow using lightsheet imaging of cleared samples and microCT. Bone marrow was identified in cleared tissue by cellular content (and in particular by the presence of megakaryocytes); since air-filled cavities are absent in rodents, marrow clusters could be recognized in microCT scans by their geometry. In cleared petrosal bone, autofluorescence allowed delineation of the otic capsule layers. Within the endochondral layer, bone marrow was observed in association to the cochlear base and vestibule, and to the cochlear apex. Cochlear apex endochondral marrow (CAEM) was a separated cluster from the remaining endochondral marrow, which was therefore defined as “vestibular endochondral marrow” (VEM). A much larger marrow island (petrosal non-endochondral marrow, PNEM) extended outside the otic capsule surrounding semicircular canal arms. PNEM was mainly connected to the dura, through bone channels similar to those of calvarial bone, and only a few channels were directed toward the canal periosteum. On the contrary, endochondral bone marrow was well connected to the labyrinth through vascular loops (directed to the spiral ligament for CAEM and to the bony labyrinth periosteum for VEM), and to dural sinuses. In addition, CAEM was also connected to the tensor tympani fossa of the middle ear and VEM to the endolymphatic sac. Endochondral marrow was made up of small lobules connected to each other and to other structures by channels lined by elongated macrophages, whereas PNEM displayed larger lobules connected by channels with a sparse macrophage population. Our data suggest that the rat inner ear is surrounded by bone marrow at the junctions with middle ear and brain, most likely with “customs” role, restricting pathogen spread; a second marrow network with different structural features is found within the endochondral bone layer of the otic capsule and may play different functional roles.
“…The peculiar connections of CAEM to the tensor tympani fossa, on the other hand, are a very interesting separate issue, because they would provide the route that was hypothesized for inflammatory signals from the cochlea to the tensor tympani in the acoustic shock model linked to tinnitus, hyperacusis, and ear fullness ( 82 ). The tensor tympani muscle, connecting the malleus to the Eustachian tube ( 83 ), can be activated by both auditory and non-auditory stimuli, such as tactile stimulation of the external canal, movements of the jaw, and even acute or chronic stress ( 84 ). In the acoustic shock model, noise trauma to the cochlea occurring together with additional factors activating the tensor tympani could induce inflammation in the muscle, triggering a positive feedback cycle that would induce muscle damage similarly to what has been found in myofascial trigger point, involving the release of inflammatory molecules, mast cell degranulation, and pain ( 79 ).…”
Calvarial bone marrow has been found to be central in the brain immune response, being connected to the dura through channels which allow leukocyte trafficking. Temporal bone marrow is thought to play important roles in relation to the inner ear, but is still largely uncharacterized, given this bone complex anatomy. We characterized the geometry and connectivity of rat temporal bone marrow using lightsheet imaging of cleared samples and microCT. Bone marrow was identified in cleared tissue by cellular content (and in particular by the presence of megakaryocytes); since air-filled cavities are absent in rodents, marrow clusters could be recognized in microCT scans by their geometry. In cleared petrosal bone, autofluorescence allowed delineation of the otic capsule layers. Within the endochondral layer, bone marrow was observed in association to the cochlear base and vestibule, and to the cochlear apex. Cochlear apex endochondral marrow (CAEM) was a separated cluster from the remaining endochondral marrow, which was therefore defined as “vestibular endochondral marrow” (VEM). A much larger marrow island (petrosal non-endochondral marrow, PNEM) extended outside the otic capsule surrounding semicircular canal arms. PNEM was mainly connected to the dura, through bone channels similar to those of calvarial bone, and only a few channels were directed toward the canal periosteum. On the contrary, endochondral bone marrow was well connected to the labyrinth through vascular loops (directed to the spiral ligament for CAEM and to the bony labyrinth periosteum for VEM), and to dural sinuses. In addition, CAEM was also connected to the tensor tympani fossa of the middle ear and VEM to the endolymphatic sac. Endochondral marrow was made up of small lobules connected to each other and to other structures by channels lined by elongated macrophages, whereas PNEM displayed larger lobules connected by channels with a sparse macrophage population. Our data suggest that the rat inner ear is surrounded by bone marrow at the junctions with middle ear and brain, most likely with “customs” role, restricting pathogen spread; a second marrow network with different structural features is found within the endochondral bone layer of the otic capsule and may play different functional roles.
“…An animal model investigating middle-ear and intracranial pressure and its effect on electrocochleographic response has shown that static middle-ear pressure and an unimpaired eustachian tube are vital in maintaining normal cochlear function [ 33 ]. A recent study demonstrated that pressure changes in the external auditory canal can result in middle ear muscle contractions and eustachian tube dysfunction, which, in turn, can lead to tinnitus [ 34 ]. With regards to direct cochlear effects, atmospheric pressure changes have been shown to cause alterations in the cochlea of rats including partial loss of stereocilia [ 35 ].…”
Purpose
Extreme weather events are rising due to the accelerating pace of climate change. These events impact human health and increase emergency room visits (EV) for many morbidities. Tinnitus is a common cause of EVs within otolaryngology in Germany and Austria. The effect of extreme weather conditions on tinnitus-related EVs is unknown.
Methods
A total of 526 tinnitus-related EVs at a tertiary care hospital in Vienna were identified. A distributed lag non-linear model with a maximum lag period of 14 days was fitted to investigate the immediate and delayed effect of single-day and prolonged (three-day) extreme atmospheric pressure, relative humidity, mean temperature, precipitation and mean wind speed on EV rates. Extreme conditions were defined as the 1st, 5th, 95th, and 99th percentile of the meteorological variables. Relative risk (RR) is defined as risk for tinnitus-related EVs at an extreme condition compared to the risk at the median weather condition. Cumulative RR (cRR) is the total cumulated EV risk for a given time period.
Results
High relative humidity increased same-day RR for tinnitus-related EVs to 1.75. Both low and high atmospheric pressure raised cRR as early as three days after an event to a maximum of 3.24. Low temperatures mitigated cRR within 4 days, while high temperatures tended to increase risk. Prolonged precipitation reduced cRR within one day.
Conclusion
Extreme meteorological conditions are associated with tinnitus-related EV rates. Further investigation into potential causative links and underlying pathophysiological mechanisms is warranted.
“…20 Fournier et al suggest that the tensor tympani contractions may not be tonic, but measuring changes in the pressure of a sealed external auditory canal could be a reproducible means of testing for middle-ear muscle hyperactivity. 10 The measurement of changing ear pressure in a sealed external auditory canal was not carried out in our retrospective cohort but would be worth exploring in future studies.…”
Section: Discussionmentioning
confidence: 99%
“…suggest that the tensor tympani contractions may not be tonic, but measuring changes in the pressure of a sealed external auditory canal could be a reproducible means of testing for middle-ear muscle hyperactivity. 10 The measurement of changing ear pressure in a sealed external auditory canal was not carried out in our retrospective cohort but would be worth exploring in future studies. Tonic tensor tympani syndrome is a subset of tinnitus that is seen in more than 10 per cent of tinnitus sufferersA central limbic system reaction is involved in the perpetuation of tonic tensor tympani syndrome symptomsSome studies have investigated the prevalence of tonic tensor tympani syndrome, but to date there have been none evaluating the effectiveness of tinnitus management for the syndromeCurrent tinnitus management strategies contribute to the alleviation of the symptoms experienced by tonic tensor tympani syndrome patientsAdditional explanation of tensor tympani muscle function appears to help patients understand the physiology behind and possible psychological influences on their symptomsIt is important to keep a lookout for symptoms of tonic tensor tympani syndrome in tinnitus patients so that treatment can be initiated quickly and expediently…”
Section: Discussionmentioning
confidence: 99%
“…More recently, in 2022, Fournier et al conducted a small study on 11 patients to investigate the possible mechanisms behind tonic tensor tympani syndrome. 10 They used admittancemetry and measurement of air pressure in the sealed external auditory canal to measure middle-ear stiffness and tympanic membrane displacement, respectively. They found that middle-ear muscle contraction could be evoked by acoustic stimulation (n = 3), somatic manoeuvres such as jaw contraction (n = 3) or pressure changes in the ear canal (n = 3).…”
Section: Acoustic Shock Injury and Tonic Tensor Tympani Syndromementioning
Objective
Tonic tensor tympani syndrome is found in a subset of tinnitus patients who experience intra-aural and peri-aural symptoms, in addition to their tinnitus, in the absence of clinically detectable pathology. As the syndrome has not been widely reported, this study aims to determine its prevalence and evaluate the effectiveness of current management.
Methods
The tinnitus management clinic records of patients over the past six years were assessed to identify tonic tensor tympani syndrome patients and track their progress based on patient-reported Tinnitus Handicap Index scores. Patients with reversible ear pathology and temporomandibular joint disorder were excluded.
Results
It was found that 13 per cent of the tinnitus management patients fulfilled the criteria for tonic tensor tympani syndrome and 94 per cent of those who returned for follow up showed an improvement in their Tinnitus Handicap Index grades.
Conclusion
This study suggests that tonic tensor tympani syndrome is a significant problem among tinnitus patients and current tinnitus management strategies contribute effectively to helping such patients habituate to their symptoms.
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