The Effect of Endolymphatic Hydrops and Mannitol Dehydration Treatment on Guinea Pigs.

Background: Endolymphatic hydrops (EH) is considered as the pathological correlate of Menière's disease (MD) and cause of hearing loss. The mechanism of EH, remaining unrevealed, poses challenges for formalized clinical trials. Objective: This study aims to investigate the development of hearing loss, as well as the effect of dehydration treatment on EH animal models. Methods: In this study, different severity EH animal models were created. The laser Doppler vibrometer (LDV) and auditory brainstem responses (ABR) were used to study the effects of EH and the dehydration effects of mannitol. The LDV was used to measure the vibration of the round window membrane (RWM) reflecting the changes in inner ear impedance. ABR was used to evaluate the hearing changes. Furthermore, tissue section and scanning electron microscopy (SEM) observations were used to analyze the anatomical change to the cochlea and outer hair cells. Results: The RWM vibrations decreased with the severity of EH, indicating an increase in the cochlear impedance. The dehydration therapy lowered the impedance to restore acoustic transduction in EH 10- and 20-day animal models. Simultaneously, the ABR thresholds increased in EH models and were restored after dehydration. Moreover, a difference in the hearing was found between ABR and LDV results in severe EH animal models, and the dehydration therapy was less effective, indicating a sensorineural hearing loss (SNHL). Conclusion: Endolymphatic hydrops causes hearing loss by increasing the cochlear impedance in all tested groups, and mannitol dehydration is an effective therapy to restore hearing. However, SNHL occurs for the EH 30-day animal models, limiting the effectiveness of dehydration. Our results suggest the use of dehydrating agents in the early stage of EH.

Finite element simulation of cochlear traveling wave under air and bone conduction hearing.

Besides the normal hearing pathway known as air conduction (AC), sound can also transmit to the cochlea through the skull, known as bone conduction (BC). During BC stimulation, the cochlear walls demonstrate rigid body motion (RBM) and compressional motion (CPM), both inducing the basilar membrane traveling wave (TW). Despite numerous measuring and modeling efforts for the TW phenomenon, the mechanism remains unclear, especially in the case of BC. This paper proposes a 3D finite element cochlea model mimicking the TW under BC. The model uses a traditional "box model" form, but in a spiral shape, with two fluid chambers separated by the long and flexible BM. The cochlear fluid was enclosed by bony walls, the oval and round window membranes. Contingent boundary conditions and stimulations are introduced according to the physical basis of AC and BC. Particularly for BC, both RBM and CPM of the cochlea walls are simulated. Harmonic numerical solutions are obtained at multiple frequencies among the hearing range. The BM vibration amplitude ([Formula: see text]) and its relation with volume displacement difference between the oval and round windows [Formula: see text], as well as the pressure difference at the base of the cochlea ([Formula: see text]), are analyzed. The simulated BM response at 12 mm from the base is peaked at about 3 k Hz, which is consistent with published experimental data. The TW properties under AC and BC are the same and have a common mechanism. (1) [Formula: see text] is proportional to [Formula: see text] at low frequencies. (2) [Formula: see text] is also proportional to [Formula: see text], within 5 dB error at high frequencies such as 16 k Hz. This study partly reveals the common quantitative relations between the TW and related factors under AC and BC hearing.

Ethanol infiltration into the stapedio-vestibular joint reduces low-frequency vibration of the ossicular chain and round window membrane in the guinea pig.

BACKGROUND: The synovial stapedio-vestibular joint (SVJ), which serves as a bridge between the stape and oval window, can be found in guinea pigs and most human adults. Unlike the fibrous SVJs in other animals, the contribution of the synovial SVJ to middle ear sound transmission remains unknown. AIMS/OBJECTIVES: In this study, we investigate whether sclerosis of the synovial SVJ contributes to frequency-dependent vibration of the ossicular chain and round window membrane (RWM). MATERIALS AND METHODS: A model of SVJ sclerosis model was established in the guinea pig using 75% ethanol. A laser Doppler vibrometer was then used to measure vibrations of the RWM and the long process of the incus (LPI) under pure tone sound stimulations of 0.25-16 kHz. The influence of SVJ sclerosis was analysed by comparing structural vibration displacement between the normal and sclerosis groups. RESULTS: Both LPI and RWM vibrations significantly decreased at low frequencies after infiltration of ethanol, which caused SVJ sclerosis. CONCLUSIONS: SVJ sclerosis reduces low-frequency vibration of the ossicular chain and RWM in the guinea pig, which indicates that the synovial SVJ is vital to low-frequency sound transmission in the middle ear. SIGNIFICANCE: Providing useful data for further research regarding middle ear biomechanics.

Feasibility of direct promontory stimulation by bone conduction: A preliminary study of frequency-response characteristics in cats.

BACKGROUND: As an alternative pathway to air conduction, bone conduction is a multipathway process that transmits sound energy to the inner ear through the skull in general. Based on this mechanism, bone conduction devices (BCDs) have been used widely in the rehabilitation of hearing loss. Although great efforts have been devoted to improving BCDs, drawbacks still exist in most categories of BCDs due to the complicated process of bone conduction. We hypothesized that if a bone conduction transducer was placed on the cochlea to stimulate it directly, the attenuation would be minimized, and the frequency dependency would be different from that of the vibratory response induced by traditional BCDs. This study aimed to explore the feasibility of direct promontory stimulation and to investigate its frequency-response characteristics. METHODS: Measurements were conducted in twelve cat ears. To stimulate the promontory directly, the floating mass transducer (FMT) of the Vibrant Soundbridge© (VSB) implant was glued to the promontory coupled with an oval window (OW) coupler. Auditory brainstem response (ABR) and laser Doppler vibrometry (LDV) measurements were used to evaluate the auditory response induced by the FMT. In both measurements, the FMT was driven by direct voltage stimuli. RESULTS: ABR waves could be induced under direct promontory stimulation by the FMT. In the frequency range of 1-12 kHz, the variation in the voltage threshold level were limited to 16 dB SPL with a maximum of 0.2 V at 1 kHz and a minimum of 0.04 V at 10 kHz. In the LDV measurements and the relative motion of the round window membrane (RWM) and the promontory were used to evaluate the cochlear response. The LDV results indicated a weak frequency dependency from 1 to 12 kHz. CONCLUSION: Different from traditional stimulation via transcranial bone conduction, direct promontory stimulation is a new method in which a small bone conduction transducer stimulates the cochlear shell directly. The current experimental data demonstrate that it is feasible to generate sensations through bone conduction by stimulating the cochlea directly. Furthermore, the cochlear response induced by this type of stimulus in cats was weakly frequency dependent at frequencies ranging from 1 to 12 kHz. This study may provide a basis for the design of new transducers that can perform well over a wide range of frequencies.

Experimental research on the therapeutic effect of MMR vaccine to juvenile-onset recurrent respiratory papillomatosis.

OBJECTIVE: To evaluate the efficacy of MMR vaccine in the treatment of juvenile-onset recurrent respiratory papillomatosis as adjuvant therapy by experimental research. METHODS: Thirty-one children with RRP were enrolled and assigned randomly to intervention group or control group. Fifteen subjects in intervention group were treated with local application MMR vaccine on the lesion after surgery; sixteen subjects in the control group were treated with surgical excision alone. The quantity of virus of positive specimens was measured by fluorescence quantitative polymerase chain reaction. RESULTS: After treatment with MMR vaccine, viral load of intervention group was (9.56 ± 11.03) × 108  copies/ml, that of control group was (22.01 ± 17.78) × 108 copies/ml, and there was significant difference between the two groups (P = 0.040). CONCLUSIONS: Local application MMR vaccine as adjuvant therapy can reduce HPV viral load significantly. It is suggested that the MMR vaccine may inhibit replication of HPV DNA, but the curative effect needs further confirmation.

A comparative study of MED-EL FMT attachment to the long process of the incus in intact middle ears and its attachment to disarticulated stapes head.

The Vibrant Soundbridge© (VSB) active middle-ear implant provides an effective treatment for mild-to-severe sensorineural hearing loss in the case of normal middle ear anatomy and mixed hearing loss in middle ear malformation. The VSB floating mass transducer (FMT), with proper couplers, can be installed on various structures of the ossicular chain, e.g., the short and long process of the incus, the stapes head, and the stapes footplate. A long process (LP) coupler is most commonly used for FMT attachment to the long process of the incus with intact ossicular chain, while CliP and Bell couplers are two standardized and reliable methods for FMT attachment to the stapes head with missing incus and malleus. However, the difference and relationship of the vibration properties among these three FMT couplers remain unclear. In the present study, the stapes footplate velocity responses of the LP, CliP, and Bell couplers have been investigated in eight fresh temporal bones (TBs) to evaluate the vibration properties of these three couplers. Normal and reconstructed middle ear transfer functions (METFs) were determined from laser Doppler vibrometer (LDV) measurements. A mastoidectomy and a posterior tympanotomy were performed to expose the ossicular chain. The METFs of the normal middle ear and middle ear with LP-FMT-coupler were compared under acoustic stimulation, thus the mass effect of the FMT with LP coupler was evaluated. Additional comparisons were made between the stapes footplate vibrations of the LP-FMT-coupler (with the intact ossicular chain at the long process of the incus), CliP-FMT-coupler and Bell-FMT-coupler on the stapes head (after incus and malleus removed) under active electromechanical stimulation. After the installation of CliP-FMT-coupler and Bell-FMT-coupler to the middle ear, the average velocity amplitude of the stapes footplate, comparing to the LP-FMT-coupler, was about 15 dB higher between 1 and 6 kHz, and 10 dB lower at about 0.5 kHz. Quantitatively, there was no significant difference between the CliP-FMT-coupler and Bell-FMT-coupler. According to our study, installation of CliP-FMT-coupler or Bell-FMT-coupler on the stapes head provides considerable improvement of the middle ear mechanical and functional responses, comparing with the LP-FMT-coupler in the temporal bone experiments. Moreover, the installation of the Bell-FMT-coupler to the stapes head produces essentially the same footplate velocity responses in comparison to the CliP-FMT-coupler.

The Age-Related Orientational Changes of Human Semicircular Canals.

OBJECTIVES: Some changes are found in the labyrinth anatomy during postnatal development. Although the spatial orientation of semicircular canals was thought to be stable after birth, we investigated the age-related orientational changes of human semicircular canals during development. METHODS: We retrospectively studied the computed tomography (CT) images of both ears of 76 subjects ranged from 1 to 70 years old. They were divided into 4 groups: group A (1-6 years), group B (7-12 years), group C (13-18 years), and group D (>18 years). The anatomical landmarks of the inner ear structures were determined from CT images. Their coordinates were imported into MATLAB software for calculating the semicircular canals orientation, angles between semicircular canal planes and the jugular bulb (JB) position. Differences between age groups were analyzed using multivariate statistics. Relationships between variables were analyzed using Pearson analysis. RESULTS: The angle between the anterior semicircular canal plane and the coronal plane, and the angle between the horizontal semicircular canal plane and the coronal plane were smaller in group D than those in group A (P<0.05). The JB position, especially the anteroposterior position of right JB, correlated to the semicircular canals orientation (P<0.05). However, no statistically significant differences in the angles between ipsilateral canal planes among different age groups were found. CONCLUSION: The semicircular canals had tendencies to tilt anteriorly simultaneously as a whole with age. The JB position correlated to the spatial arrangement of semicircular canals, especially the right JB. Our calculation method helps detect developmental and pathological changes in vestibular anatomy.

A meta-analysis of the long-term hearing outcomes and complications associated with atresiaplasty.

OBJECTIVE: To summarize peer-reviewed literature to evaluate the stability of long-term hearing outcomes with prolonged follow-up, and describe the incidence of complications related to atresiaplasty. DESIGN: A literature search of EMBASE, MEDLINE, PubMed, Google Scholar, and Web of Science was performed to identify studies of congenital aural atresia (CAA). STUDY SAMPLE: Selected studies were published between 1997 and 2014. The 19 studies covered 964 CAA ears. RESULTS: Stenosis and bony regrowth occurred in 14.2% (range from 0% to 30.3%). Lateralization of tympanic membrane (TM) occurred in 7.5% (range from 0% to 18.2%). Facial nerve palsy occurred in 0.5% (range from 0% to 5.0%). Six studies used Air-bone Gap (ABG) to evaluate the short-term and long-term hearing outcomes. The hearing outcomes were performed using meta-analysis, there was no significantly heterogeneity (I(2) = 0%, p = 0.997), and there was a degradation of hearing outcomes with prolonged follow-up (RR = 1.13, 95%CI: 0.98-1.30). CONCLUSION: Nearly all studies focus on postoperative stenosis and bony regrowth, but some studies neglect lateralization of TM. Based on available data, which shows a lack of major complications, such as facial nerve palsy, atresiaplasty is a safe procedure. Our meta-analysis indicated that there was a degradation of hearing outcomes with prolonged follow-up.

The age-related positional and orientational changes of the human cochlea.

CONCLUSION: The cochleae of children over 6 years old and adults displaced more outward, backward, and downward in comparison with those of children under 6 years. However, the cochlear orientation does not significantly change during postnatal development. Adjacent structures correlated with the cochlear position. OBJECTIVE: To test whether the cochlear position and orientation, which are important in cochlea implant surgery, change during postnatal development. METHODS: CT images of both ears of 76 human subjects were studied. They were divided into three groups: group A (1-6 years old), group B (7-18 years old), and group C (>18 years old). RESULTS: The distances from the cochlea to the median sagittal and coronal planes in group A were smaller than those in group B and group C (p < 0.05), but the distance from it to the Frankfurt plane in group A was larger than that in group C (p < 0.05). The volume of the temporal bone pneumatization and the positions of the jugular bulb and the intrapetrous internal carotid artery positively correlated with the cochlear position (p < 0.05). There were no statistically significant differences in the angles between the central axis of the cochlea and these coordinate planes among age groups.

[Morphological changes associated with low-tone hearing loss in guinea pig models of early endolymphatic hydrops].

The present study was to explore the functional and morphological changes in cochleas of guinea pig models of early endolymphatic hydrops. Thirty albino guinea pigs were randomly divided into three groups: control, 4-week model and 8-week model groups. For each group, n = 10. Model groups were operated on the right ears to result in endolymphatic hydrops with the method of slight destruction of endolymphatic sac and duct from extradural posterior cranial fossa approach, and the animals in control group were sham operated. Electrocochleogram recorded by trans-tympanic approach and auditory brainstem response (ABR) were tested in preoperative model groups, control group, 4-week model group and 8-week model group to assess the hearing changes. Histologic morphometry was used to quantify hydrops by testing scala media area (SMA) ratio. Scanning electron microscope was used to assess the changes of cochlea hair cells. The results showed that the summating potential/compound action potential (SP/AP) ratio of electrocochleogram in 4-week model group (0.33 ± 0.14) and 8-week model group (0.43 ± 0.14) increased significantly, compared with that in control group (0.07 ± 0.06). The maximum SMA ratio in 4-week model group (2.64 ± 0.10) and 8-week model group (3.54 ± 0.13) increased significantly, compared with that in control group (1.06 ± 0.08). The results of maximum SMA ratio correlated with SP/AP ratio of electrocochleogram (r = 0.86). The results of hearing threshold of ABR revealed that the operated ears of model groups were higher than the preoperative results at frequencies of 2 kHz and 4 kHz. And the damage of cochlea hair cells in operated ears occurred in apical and subapical turns. These results suggest the increased SP/AP ratio of electrocochleogram can indicate early endolymphatic hydrops. There is low-tone hearing loss in guinea pig models of early endolymphatic hydrops, and it may be associated with the abnormalities of the stereocilia among the outer hair cells in operated ears which occurs in apical and subapical turns.

The site of origin and expansive routes of juvenile nasopharyngeal angiofibroma (JNA).

OBJECTIVE: Juvenile nasopharyngeal angiofibroma (JNA) is a rare vascular tumor of the nasopharynx occurring in young males. The aim of this study was attempt to find out the site of origin and the common expansion routes of JNA. METHODS: The CT examinations of 46 untreated patients with histologically proven JNA were retrospectively analyzed. Evidence of tumor spreading of the locations are those following CT characteristics: (a) expansion and/or erosion of bony wall; (b) obliteration of normal fatty planes. In addition, three dimensional reconstruction technology was used to make further study. RESULTS: The pterygoid canal was affected in all untreated cases and therefore was considered as the origin of JNA. Nineteen patients' tumors (41.3%) originated from the front part of pterygoid canal and the other 27 ones (58.7%) from the post part of pterygoid canal. Pterygoid canal, choanae and nasal cavity are the three most common sites of JNA. CONCLUSION: The possible site of origin is pterygoid canal. After originating from this point, the tumor will invade sphenopalatine foramen, sphenoid sinus and pterygopalatine fossa first, and then into adjacent structure through aforementioned three sites.

Titanium versus non-titanium prostheses in ossiculoplasty: a meta-analysis.

CONCLUSION: The papers collected in our study demonstrated that there were no significant differences in the effectiveness of sound transmission and stability of the prosthesis between the titanium and non-titanium group. However, further randomized controlled trials with large sample sizes are needed to improve the estimation. OBJECTIVE: To compare the effectiveness of sound transmission and stability of the prostheses in the titanium or non-titanium ossiculoplasty groups by meta-analysis for clinical implications and applications. METHODS: Previous studies comparing the hearing status of patients with titanium and non-titanium prostheses were reviewed on PubMed, accompanied by a manual search of all the related references. The eligibility of the investigation was independently confirmed by two reviewers, who extracted all the data from the papers included accordingly for the standard meta-analysis. RESULTS: The study included 12 eligible investigations covering 1388 patients, with the pooled risk ratio (RR) estimating the effectiveness of the postoperational prostheses between the titanium and non-titanium group, with a combined RR of 1.12 (95% confidence interval (CI): 0.98-1.27, p = 0.09), as well as their stability, with a combined RR of 1.47 (95% CI: 0.76-2.84, p = 0.26).

3D image of the middle ear ossicles: three protocols of post-processing based on multislice computed tomography.

The aim of this study was to examine and assess the comparative values of HRCT-based multiplanar reformation (MPR), volume rendering (VR) and virtual endoscope built on three-dimensional shaded-surface display (SSD-based CTVE) for evaluations of the ossicular chain. The normal pure tone audiograms, type-A tympanogram, and normal HRCT characteristics of 32 human ears of 18 patients were reviewed, whose ossicular chains were reconstructed with the three aforementioned protocols and assessed via the 3-point scoring system. The HRCT-based protocols could demonstrate a 3D image of the ossicular chain, except that of the footplate on the SSD-based CTVE. On the qualitative assessment, the efficacy of the MPR and VR, which were both superior to the SSD-based CTVE (P < 0.05), presented no statistical significance among the major and/or hyperdense structures (P > 0.05). As regards the lateral process of the malleus, VR was found to be significantly superior to the MPR and SSD-based CTVE (P < 0.05), both of which, however, showed no significant comparative differences (P > 0.05). Moreover, the three protocols in terms of efficacy were comparatively different in their representations of the anterior crus and footplates of the stapes, respectively (P < 0.05). On the MPR images, not all the images of the lenticular process were ideal; 20 of 32 cases were detected, but not defined. VR could be the more valuable protocol for the 3D reconstruction of the ossicular chain and ought to be more employed in future, especially for the education.

[Analysis of correlation between congenital auricular deformities and middle ear malformations].

OBJECTIVE: To explore the potential value of knowing the relationship between congenital auricular deformities and middle ear malformations. METHODS: A total of 86 patients with congenital auricular deformities and middle ear malformations, including 51 males and 35 females, were admitted from January 2008 to December 2009 to the Eye Ear Nose and Throat Hospital of Fudan University. Fifty-eight patients had unilateral deformities (R:L = 34:24), while 28 were bilateral. One hundred and fourteen ears with congenital auricular deformities were included. High-resolution CT (HRCT) data was obtained from each patient. The auricular deformities were classified into three grades using the Marx H classification system. The modified Jahrsdoerfer grading system was used to score the malformations using HRCT data. The correlation between the grades of auricular deformities and scores of middle ear malformations was analyzed using Spearman rank correlation analysis. RESULTS: The Marx H grades of congenital auricular deformities were 12 patients with grade I, 25 patients with grade II and 77 patients with grade III, while their corresponding Jahrsdoerfer scores were 7.8 ± 2.4, 6.8 ± 2.6 and 6.0 ± 2.8, respectively. The statistical analysis suggested a trend of negative correlation between the Marx H grades of auricular deformities and the Jahrsdoerfer scores of middle ear malformations (r = -0.2386, P = 0.0106). CONCLUSION: There was a trend to a negative correlation between congenital auricular deformities and middle ear malformations.

Three-dimensional reconstruction of C57BL/6 mouse inner ear during development.

PURPOSE: To explore the three-dimensional (3-D) morphological characteristics of the complicated inner ear development of the C57BL/6 mouse. METHODS: Specimens of C57BL/6 mouse embryos on days E7.5, E8.5, E9.5, E10.5, E11.5, E12.5 and E14.5 were collected and sectioned serially in this experiment. After hematoxylin and eosin staining, parts of the inner ear were pictured under the microscope with specific positional control. Using the protocol of 3D-DOCTOR software, we outlined the inner ear margin including the inner and extra face in different colors and put them into the 3-D program to reconstruct the 3-D model. RESULTS: 3-D models of the E9.5, E10.5, E11.5, E12.5 and E14.5 inner ear were obtained and proved to be fine. Different parts of the inner ear were shown clearly in different colors in the 3-D model and significant morphological changes of the inner ear were shown during development between E9.5 and E14.5. CONCLUSION: The new technology of 3-D reconstruction is a useful and important tool to directly observe the complex development of the inner ear, and the development between E9.5 and E14.5 has been proved by the 3-D model to be the most complex and important period of the development of the C57BL/6 mouse inner ear.

Morphological and positional relationships between the sigmoid sinus and the jugular bulb.

The purpose of this study was to determine the quantitative relationships between the positions of the sigmoid sinus (SS) and jugular bulb (JB) and the influence of mastoid pneumatization upon these structures. The investigations were carried out on 116 healthy adult ears based on the axial images of computed tomography (CT). The reference system locating the displacements of the SS and JB was established and the shape and position of the SS and JB were measured. The volume of pneumatization was quantitatively measured based on the serial digital images of CT. The method of partial correlation analysis was used to find the real relationship of two variables from the complicated dependence relationships. There was a tendency for the SS in the males to be situated more laterally and more backwardly, and the JB in the males was situated more laterally with thicker lateral bone wall when compared to the females. When compared to the left side, the SS on the right side tended to protrude more deeply and was situated more laterally and with less thickness of the lateral bone wall. In male, the right SS was situated more anteriorly than the left SS. In female, the right JB was situated more posteriorly than the left JB. There was a tendency for the SS to be situated more medially, to have a thicker lateral bone wall, and to protrude more superficially in the well-pneumatized bones. When the pneumatization was well, the JB tended to be situated more backwards and have a thicker lateral bone wall. However, there was no significant difference of pneumatization between the high JB group and the low JB group. The SS position and JB position changed synchronously in forward-backward or medial-lateral directions. The results suggest that the factors that influence the shape and position of the SS and JB are multiple. The results suggest that the morphological and positional relationships between the SS and the JB are complicated but could be grasped. The development of the cranial base, the temporal bone pneumatization and non-synchronous dural venous development between the right and left sides are considered to contribute to the morphological and positional changes of the SS and JB.

Three-dimensional morphology of the vestibular cleft and its potential application.

HYPOTHESIS: To delineate quantitatively the spatial relationships of the utricle, saccule, and stapedial footplate, to locate the hole on the footplate, and to analyze the insertion depth into the vestibule and the direction of the piston during stapedotomy. BACKGROUND: The quantitative three-dimensional (3D) configuration of the utricle, saccule, and stapedial footplate is undetermined, and the stapedotomy procedures should be improved. METHODS: Four temporal bones were extracted from the fresh cadavers and were undecalcified polymer-embedded. The specimens were sectioned into serial 50-mum-thickness slices. After image processing and 3D reconstruction, a cartesian coordinate system was established to display the spatial relationships of the utricle, saccule, and stapedial footplate in the 3D Studio Max scene. The configuration of the utricle, the saccule, and the "vestibular cleft" was delineated quantitatively with the contour map method. With this contour map, any distance between one point at the surface of the footplate and another point at the surface of the utricle or saccule and its orientation can be measured. RESULTS: There was a V-shaped cleft between the utricle and the saccule named vestibular cleft. The angle of the cleft was 50.30 degrees +/- 19.90 degrees . The apex of the cleft always directed anterosuperiorly, whereas beneath the posteroinferior part of the footplate was an open and deep "seabed." The vertical distances between points on the tympanic surface of the footplate and points on the surface of the utricle or saccule were measured. The vertical distance from the center point of footplate to the vestibular end organs was 2.20 +/- 0.548 mm, the maximum distance being 3.0 mm, whereas the minimum distance was 1.6 mm. CONCLUSION: The posteroinferior area near the central point of the footplate is the optimal position for the fenestra through which the piston can be inserted relatively safely into a depth of 0.8 to 1.0 mm in the vestibule. If the deep end of the piston is inclined inferiorly and posteriorly by 8 to 10 degrees, respectively, the piston will be farther from the vestibular end organs. These manipulations may enhance surgical safety and efficiency in stapedotomy.

[Three-dimensional morphological measurements of the utricle, saccule and stapes footplate].

OBJECTIVE: To determine the optimal drill area on the footplate with the 3D measurements of the stapes and the vestibular end organs. METHODS: Four temporal bones were extracted from the fresh cadavers and undecalcified polymer-embedded. After serially sectioning, image processing and the 3D precisely reconstruction, a local Cartesian coordinates was established in which the tympanic surface of the footplate was supposed to be XY plane and the Z coordinate axis passed through the central point of the footplate and was vertical to the XY plane. The configurations of the utricle and saccule were delineated quantitatively, and then any distance between one point on the surface of the footplate and another point on the surface of the utricle or saccule and its orientation can be measured. RESULTS: There was a "V" shaped cleft between the utricle and the saccule. The angle of the" V" shaped cleft was 50.31 +/- 19.90 (17.00 - 68.00) degrees. The apex of the cleft directed anterosuperiorly and approached the footplate center, while beneath the posteroinferior part of the footplate was an open and deep area. The vertical distance from the center point of the footplate to the vestibular end organs was (2.20 +/- 0.548) mm, the maximum of 3.0 mm and the minimum of 1.6 mm. CONCLUSIONS: The posterior and inferior quadrant of the footplate may be the optimal drill area for the fenestra.