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The auditory ossicles amplify and transmit sound from the environment to the inner ear. The distribution of bone mineral density is crucial for the proper functioning of sound transmission as the ossicles are suspended in an air-filled chamber. However, little is known about the distribution of bone mineral density along the human ossicular chain and within individual ossicles. To investigate this, we analyzed fresh-frozen human specimens using synchrotron-based phase-contrast microtomography. In addition, we analyzed the volume and porosity of the ossicles. The porosity for the auditory ossicles lies, on average, between 1.92% and 9.85%. The average volume for the mallei is 13.85 ± 2.15 mm 3 , for the incudes 17.62 ± 4.05 mm 3 and 1.24 ± 0.29 mm 3 for the stapedes. The bone density distribution showed a similar pattern through all samples. In particular, we found high bone mineralization spots on the anterior crus of the stapes, its footplate, and along areas that are crucial for the transmission of sound. We could also see a correlation between low bone mineral density and holey areas where the bone is only very thin or missing. Our study identified a similar pattern of bone density distribution within all samples: regions exposed to lower forces generally show higher bone density. Further, we observed that the stapes shows high bone mineral density along the anterior crus and its footplate, which may indicate its importance in transmitting sound waves to the inner ear.

This study aimed to compare the functional and anatomical outcomes of ossiculoplasty using an autograft incus or a titanium partial ossicular replacement prosthesis for reconstructing Austin type A ossicular defects. Patients with Austin A ossicular defects were randomly divided into two groups: one group underwent ossiculoplasty with an autologous incus (the autologous incus group) and the other underwent ossiculoplasty with a titanium partial ossicular replacement prosthesis (the titanium prosthesis group). Otoscopic examination and audiological assessment was done pre-operatively and at 3, 6 and 12 months post-operatively. A post-operative average air-bone gap closure of less than 20 dB was seen in 13 patients (65 per cent) in the autologous incus group and 7 (35 per cent) in the titanium prosthesis group. There were fewer post-operative complications in the autologous incus group (20 per cent) than in the titanium prosthesis group (45 per cent). Hearing outcomes and graft take up after ossiculoplasty were significantly better when an autologous incus rather than a titanium partial ossicular replacement prosthesis was used to reconstruct Austin type A ossicular defects. The major disadvantages of the titanium prosthesis were unpredictable results and more post-operative complications.

The aim of this study was to assess the role of virtual otoscopy and 3D ossicular reconstruction in the preoperative assessment of the ossicles in chronic suppurative otitis media. Thirty three patients of chronic suppurative otitis media with conductive deafness (air–bone gap > 35 dB) were included in this prospective study. All patients underwent axial multidetector CT. The axial CT data set was utilized for multiplanar 2D reformations as well as virtual otoscopy (VO) and 3D reconstructions. The imaging findings on these two techniques were read independently by two radiologists with respect to different parts of the ossicular chain by using a three-point scoring system and were compared with surgical findings. Both imaging techniques had comparable accuracy for evaluation of larger ossicular parts. However, for evaluation of stapes superstructure, VO/3D images were more accurate (85.29%) than 2D images (76.97%). Assessment of the lenticular process and incudostapedial joint by HRCT and 2D reformatted images was not reliable ( P  > 0.1); however, significant correlation ( P  < 0.001) was present between VO/3D and the operative findings. Virtual otoscopy improves evaluation of the ossicular chain particularly that of smaller structures such as the lenticular process, incudostapedial joint and stapes superstructure which may influence decisions regarding planning of ossiculoplasty.

Among extant vertebrates, mammals are distinguished by having a chain of three auditory ossicles (the malleus, incus and stapes) that transduce sound waves and promote an increased range of audible—especially high—frequencies 1 . By contrast, the homologous bones in early fossil mammals and relatives also functioned in chewing through their bony attachments to the lower jaw 2 . Recent discoveries of well-preserved Mesozoic mammals have provided glimpses into the transition from the dual (masticatory and auditory) to the single auditory function for the ossicles, which is now widely accepted to have occurred at least three times in mammal evolution 3 – 6 . Here we report a skull and postcranium that we refer to the haramiyidan Vilevolodon diplomylos (dating to the Middle Jurassic epoch (160 million years ago)) and that shows excellent preservation of the malleus, incus and ectotympanic (which supports the tympanic membrane). After comparing this fossil with other Mesozoic and extant mammals, we propose that the overlapping incudomallear articulation found in this and other Mesozoic fossils, in extant monotremes and in early ontogeny in extant marsupials and placentals is a morphology that evolved in several groups of mammals in the transition from the dual to the single function for the ossicles. A fossil of the Middle Jurassic haramiyidan Vilevolodon diplomylos with a well-preserved malleus, incus and ectotympanic sheds light on the evolutionary transition from a dual to a single function for the ossicles in mammals.

Air conduction and bone conduction thresholds in audiograms provide clinically useful information. However, whether bone conduction audiograms can help distinguish between different conductive hearing disorders remains unestablished. This retrospective case-control study included patients with hearing loss (surgically-confirmed ossicular sclerosis, ossicular discontinuity or tympanic membrane perforation) and a group of people with normal hearing (Jikei University School of Medicine, Tokyo, Japan). Data were collected between November 30, 2017 and December 30, 2022. Bone conduction threshold patterns (pure tone audiometry) were compared between groups. All experiments were performed in accordance with the relevant guidelines and regulations. Ossicular fixation was associated with a dip at 2 kHz (57.8% of cases) in the bone conduction thresholds, whereas ossicular discontinuity showed a steep downslope of > 10 dB HL from 1 kHz to 3 kHz (75.0% of cases) with a tendency for a dip at 3 kHz (56.3% of cases). For patients with ossicular fixation, the probability of malleus or incus fixation was higher when the bone conduction thresholds at low frequencies (≤ 1 kHz) exhibited an upslope, whereas the probability of stapes fixation was higher when the pattern was a downslope (likelihood ratio = 4.9, P  < 0.001). For patients with ossicular discontinuity, the probability of incomplete discontinuity was higher when the low-frequency bone conduction thresholds sloped upward, whereas a downslope was associated with a higher probability of complete discontinuity (likelihood ratio = 6.6, P  = 0.018). Analysis of the pattern of the bone conduction thresholds might facilitate the preoperative diagnosis of ossicular sclerosis or ossicular discontinuity in patients with conductive hearing loss.

Recently, computed tomography with photon-counting detector (PCD-CT) has been developed to enable high-resolution imaging at a lower radiation dose. PCD-CT employs a photon-counting detector that can measure the number of incident X-ray photons and their energy. The newly released PCD-CT (NAEOTOM Alpha, Siemens Healthineers, Forchheim, Germany) has been in clinical use at our institution since December 2022. The PCD-CT offers several advantages over current state-of-the-art energy-integrating detector CT (EID-CT). The PCD-CT does not require septa to create a detector channel, while EID-CT does. Therefore, downsizing the anode to achieve higher resolution does not affect the dose efficiency of the PCD-CT. CT is an indispensable modality for evaluating ear ossicles. The ear ossicles and joints are clearly depicted by PCD-CT. In particular, the anterior and posterior legs of the stapes, which are sometimes unclear on conventional CT scans, can be clearly visualized. We present cases of congenital anomalies of the ossicular chain, ossicular chain dislocation, tympanosclerosis, and cholesteatoma in which PCD-CT was useful. This short article reports the usefulness of PCD-CT in the 3D visualization of the ear ossicles.

To compare the results of endoscopic and microscopic ossicular chain reconstruction surgery. Patients undergoing ossicular chain reconstruction surgery via an endoscopic (n = 31) or microscopic (n = 34) technique were analysed for age, gender, Middle Ear Risk Index, ossicular chain defect, incision type, ossicular chain reconstruction surgery material, mean air conduction threshold, air-bone gap, air-bone gap gain, word recognition score, mean operation duration and mean post-operative follow up. Post-operative air conduction, air-bone gap and word recognition score improved significantly in both groups (within-subject p < 0.001 for air conduction and air-bone gap, and 0.026 for word recognition score); differences between groups were not significant (between-subject p = 0.192 for air conduction, 0.102 for air-bone gap, and 0.709 for word recognition score). Other parameters were similar between groups, except for incision type. However, endoscopic ossicular chain reconstruction surgery was associated with a significantly shorter operation duration (p < 0.001). Endoscopic ossicular chain reconstruction surgery can achieve comparable surgical and audiological outcomes to those of microscopic ossicular chain reconstruction surgery in a shorter time.

To compare the diagnostic accuracy of angled otoendoscopy with pure tone audiometry in predicting ossicular discontinuity in patients of mucosal chronic otitis media. Ninety-four patients were included in this prospective study. A 2.7-mm 30° otoendoscope was used to examine ossicular status preoperatively. Hearing thresholds were recorded by pure tone audiometry. Intraoperative ossicular status was recorded as the gold standard. Otoendoscopic findings were recorded as per the criteria has been devised by the authors of this manuscript. Otoendoscopy was conclusive in 56 (59.6 per cent) patients, with 100 per cent sensitivity, 95.56 per cent specificity, 84.62 per cent positive predictive value, and 100 per cent negative predictive value in the conclusive group. Overall (in 94 patients), diagnostic test values of otoendoscopy were 73.33 per cent sensitivity, 97.47 per cent specificity, 84.62 per cent positive predictive value, and 95.06 per cent negative predictive value. As per the ROC curve, air-bone gap > 38.12dB had the optimal diagnostic test values, with 73 per cent sensitivity, 72 per cent specificity, 33.3 per cent positive predictive value, and 93.4 per cent negative predictive value. Angled otoendoscopy has better diagnostic accuracy (93.6 per cent) than pure tone audiometry (72.3 per cent; < 0.001) for preoperative ossicular discontinuity prediction in patients of mucosal chronic otitis media.

The transference of post-dentary jaw elements to the cranium of mammals as auditory ossicles is one of the central topics in evolutionary biology of vertebrates. Homologies of these bones among jawed vertebrates have long been demonstrated by developmental studies; but fossils illuminating this critical transference are sparse and often ambiguous. Here we report the first unambiguous ectotympanic (angular), malleus (articular and prearticular) and incus (quadrate) of an Early Cretaceous eutriconodont mammal from the Jehol Biota, Liaoning, China. The ectotympanic and malleus have lost their direct contact with the dentary bone but still connect the ossified Meckel’s cartilage (OMC); we hypothesize that the OMC serves as a stabilizing mechanism bridging the dentary and the detached ossicles during mammalian evolution. This transitional mammalian middle ear narrows the morphological gap between the mandibular middle ear in basal mammaliaforms and the definitive mammalian middle ear (DMME) of extant mammals; it reveals complex changes contributing to the detachment of ear ossicles during mammalian evolution. The road from jaw to ear The lower jaw of reptiles is made up of several bones. In mammals, however, it consists of just one, the tooth-bearing dentary. Most of the rest have become the ossicles that transmit sound through the middle ear. This transformation is an iconic example of evolutionary change, but direct fossil evidence of the transition has been hard to find. That's why a fossil described by Jin et al . is so important. It is from a triconodont (a type of extinct mammal) from the Cretaceous period in China. In it, the lower-jaw elements have started to resemble middle-ear ossicles, but are still joined to the lower jaw by a sliver of ossified cartilage. This element, Meckel's cartilage, is an important part of the inner surface of the lower jaw; the new fossil shows that it was a vital piece in the evolutionary jigsaw that led to the formation of the mammalian middle ear.

Hearing function in older patients may be related to bone structure. We conducted an experiment to evaluate the effect of zoledronic acid on osteoporotic middle ear ossicles in an animal model. Our subjects were 19 female New Zealand white rabbits (38 ears) weighing 2 to 4 kg. We divided the rabbits into three groups: one group consisted of 6 rabbits with osteoporotic ears that were treated with zoledronic acid; the second group was made up of 8 rabbits with osteoporotic ears that were not treated; a control group included 5 rabbits with normal ears that were untreated. After an oophorectomy, the 6 study rabbits were administered 0.1 ml/kg of zoledronic acid intravenously. All rabbits were sacrificed 16 weeks later, and the middle ear ossicles were removed for investigation under light microscopy. Although osteoporosis enhanced the osteoclastic bone resorption of the ossicles, zoledronic acid enhanced osteoblastic activity on osteoporotic middle ear ossicles. The incidence of osteoporosis was 93.8% in the untreated osteoporosis group and 33.3% in zoledronic acid group—a statistically significant difference (OR: 0.24; 95% CI: 0.09 to 0.58; p < 0.001). Osteoporosis appears to increase the resorption of the middle ear ossicles, a process that can be avoided with zoledronic acid administration. Prevention of the effects of osteoporosis in humans may help decrease the irreversible changes in the middle ear ossicles.