Different Materials for Plugging a Dehiscent Superior Semicircular Canal: A Comparative Histologic Study Using a Gerbil Model.

HYPOTHESIS: The choice of the material for plugging a dehiscence of the superior semicircular canal is based on the ease of use and the success of the procedure to permanently relieve symptoms without adverse side effects. BACKGROUND: Dehiscence of the superior semicircular canal can lead to autophony, conductive hearing loss, and vertigo. Surgical treatment by plugging the canal is a highly effective treatment of the symptoms in many patients, although, the procedure can be associated with some degree of hearing loss in more than or equal to 25% of the patients. The available data indicate that adverse effects may be more frequently observed with bone wax as compared with other materials. METHODS: In the present study we compare the tissue reactions induced by plugging the superior semicircular canal with autologous bone pate/bone chips, muscle, fat, artificial bone wax, and teflon in the gerbil model in an attempt to identify the material leading to successful plugging with the least adverse tissue reactions. RESULTS: Our data show that successful plugging was achieved in 100% of the ears by bone pate/bone chips, teflon, and bone wax while the success rate was significantly lower (<50%) following muscle and fat. The proportion of adverse tissue reactions was significantly more pronounced using bone wax as compared with teflon and bone pate/bone chips. CONCLUSION: The use of teflon or autologous bone as a material for plugging a dehiscent superior semicircular canal should be favored over bone wax, muscle, and fat.

Effect of ageing on the myosin heavy chain composition of the human sternocleidomastoid muscle.

The myosin heavy chain (MyHC) composition of ageing limb muscles is transformed into a slower phenotype and expresses fast-twitch fibre type atrophy, presumably due to age-related motor unit remodelling and a change in the patterns of physical activity. It is not known if ageing affects the sternocleidomastoid muscle (SCM) in a similar way. The goal of the study was to analyze the MyHC composition and the size of muscle fibres in the ageing SCM by immunohistochemical methods and quantitative analysis and stereology using our own software for morphometry. We hypothesize that with ageing the MyHC composition of SCM transforms similarly as in ageing limb muscles, but the size of the muscle fibres is less effected as in limb muscles. The study was performed on the autopsy samples of the SCM in 12 older males. The results were compared with those published in our previous study on 15 young adult males. An ageing SCM transforms into a slower MyHC profile: the percentage of slow-twitch fibres is enhanced (numerical proportion 44.6 vs. 31.5%, P<0.05; area proportion 57.2 vs. 38.4%, P<0.05). The share of hybrid 2a/2x fibres is diminished (numerical proportion 14.1 vs. 26.8%, P<0.05), the area proportion of all fast-twitch fibres expressing MyHC-2a and 2x is smaller (50.6 vs. 63.5%, P<0.05), and the area proportion of fibres expressing the fastest myosin isoform MyHC-2x is smaller too (19.0 vs. 34.5%, P<0.05). The slower phenotype with the preferential reduction of the fibres expressing the fastest MyHC-2x provide circumstantial evidence for: (i) more fast-twitch than slow-twitch motor units being lost; and (ii) reinnervation by the surviving motor units. There appears to be no significant influence on muscle fibre size, which is congruent with relatively unchanged SCM activity during life.

Mastoid Dimensions in Children and Young Adults: Consequences for the Geometry of Transcutaneous Bone-Conduction Implants.

OBJECTIVES: Bone-conduction implants (BCI) are available for adults and children who are aged 5 years or more. Because a transcutaneous bone-conduction implant introduced in 2013 does not completely fit into all adult mastoids, we investigated mastoid dimensions and the possibility of fitting the implant in children. DESIGN: Computed tomography scans of 151 mastoids from 80 children and young adolescents from the age of 5 months to 20 years and 52 control mastoids from 33 adults were retrospectively analyzed. After three-dimensional reconstruction, mastoid volume was measured. The chances of fitting the Bonebridge or a novel BCI were determined as a function of age. Implant diameter and implantation depths were virtually varied to identify the most advantageous dimensions for reducing the minimum age for implantation. RESULTS: Mastoid volume increased to 13.8 ml in female and 16.4 ml in male adult mastoids at ages 18.9 years (male) and 19.0 years (female). Without compromising the middle fossa dura or the sinus and without lifts, the Bonebridge implant fit in 81% of male adult mastoids and 77% of the female adult mastoids. For children, the 50% chance of fitting a Bonebridge in the mastoids was reached at age 12 years; with a protrusion of 4 mm (4-mm lifts), this age was reduced to >6 years. The novel BCI fit in 100% of male and 94% of female adult mastoids. CONCLUSIONS: Casing diameter is the most limiting factor for Bonebridge implantation in children. A modified implant casing with a truncated cone and reduced diameter and volume would increase the number of hearing impaired children who can be rehabilitated with a Bonebridge implant. Radiological planning for Bonebridge implantation is necessary in all children.

Acquired cholesteatoma in children: clinical features and surgical outcome.

OBJECTIVE: In general, cholesteatoma tends to recur more frequently in children than in adults. This has been suggested to be due to immature Eustachian tube function, underdeveloped mastoid air cells, and subsequent repetitive otitis media in children. This study was undertaken to determine the characteristics of acquired cholesteatoma in children by comparison with that in adults. METHODS: We retrospectively evaluated 42 children with acquired cholesteatoma (males, 38; females, 4; age range, 3-15 years) using medical records from January 1999 to December 2009 at the Department of Otolaryngology, Niigata University Hospital. The extent of disease was classified according to the Classification and Staging of cholesteatoma proposed by the Japan Otological Society in 2010. RESULTS: No major differences in stage classification were observed between children and adults. In children with pars flaccida-type cholesteatoma, the epithelium tended to invade from the attic to the mastoid cavity and mesotympanum. In contrast, adult patients with invasion to the mesotympanum were fewer. The rate of disappearance of the stapes superstructure was almost the same in children and in adults. The destruction of the superstructure of the stapes was more common in pars tensa type than pars flaccida type; so it was dependent on the pathology. Postoperative hearing levels were better in children, even in those with widespread lesions. However, the recurrence rate was significantly higher in children. CONCLUSIONS: Acquired cholesteatoma in children showed a wider invasion, and the recurrence rates were higher than that in adults. For patients with a widespread lesion and severe destruction of the ossicles, a two-stage surgery is recommended.

Three-dimensional longitudinal changes in craniofacial growth in untreated hemifacial microsomia patients with cone-beam computed tomography.

INTRODUCTION: The purpose of this study was to evaluate the concept that the affected and contralateral sides do not grow at the same rate in patients with hemifacial microsomia. Changes in the cranial base, maxilla, mandible, and occlusal plane were evaluated on 3-dimensional images from cone-beam computed tomography data in untreated patients. METHODS: Six patients were classified as having mandibular Pruzansky/Kaban type I, IIA, or IIB hemifacial microsomia. Cone-beam computed tomography (MercuRay; Hitachi, Tokyo, Japan) scans were taken before orthodontic treatment during both growth and postpuberty periods. RESULTS: The cranial base as defined by the position of the mastoid process was in a different position between the affected and contralateral control sides. The nasomaxillary length or height was shorter on the affected side for all 6 patients with hemifacial microsomia regardless of its severity, and it grew less than on the contralateral control side in 5 of the 6 patients. The occlusal plane angle became more inclined in 4 of the 6 patients. The mandibular ramus was shorter on the affected side in all patients and grew less on the affected side in 5 of the 6 patients. The mandibular body grew slower, the same, or faster than on the control side. CONCLUSIONS: The cranial base, position of the condyle, lengths of the condyle and ramus, and positions of the gonial angle and condyle can vary between the affected and contralateral control sides of patients with hemifacial microsomia, with the ramus and nasomaxillary length usually growing slower than they grow on the control side. These results suggest that many factors affect the growth rate of the craniofacial region and, specifically, the mandible in patients with hemifacial microsomia.

Effect of otitis media with effusion and its clinical intervention on the development of mastoid in children.

CONCLUSION: Otitis media with effusion (OME) can affect the development of mastoid in children. For younger children (<12 years old), surgical intervention may promote the development of mastoid. It is highly recommended that patients with severe tympanic membrane retraction have tympanostomy tubes to improve the circulation in the middle ear as early as possible. OBJECTIVE: To investigate the effect of OME and its clinical intervention on the development of mastoid in children. METHODS: A total of 46 children with OME were divided into 2 groups according to their ages. In group 1, 26 cases (0-6 years old) were treated for approximately 2 months, while in group 2, 20 cases (7-15 years old) were treated for 10 months. The treatments included tympanic effusion incision or catheterization, and adenoidectomy and/or bilateral tonsillectomy. Before and 6 months after treatments, patients were examined by bilateral temporal bone CT scanning, pure-tone audiometry, and tympanometry. 3-D volumetric reconstruction was then performed to determine the morphological properties of each patient's mastoid. RESULTS: After a 2-month comprehensive treatment, the volume of mastoid was close to that in normal children, indicating that it could return to normal level if the treatment was completed within 2 months. In group 2, the results suggested that if the treatment lasted more than 6 months, the development of mastoid would be stalled.

The developmental characteristics of mastoid pneumatisation in cleft palate children: the genetic influence.

Physiologic and developmental role of mastoid pneumatisation in children with otitis media with effusion (OME) is still controversial. For measuring mastoid pneumatisation and examine developmental characteristics, we used children with orofacial malformation of high risk for long term negative pressure in the middle ear and are expected to have lower rate of size and growth of pneumatisation. Mastoid were measured on Schuller's mastoid X-ray pictures planimetrically in study group of 146 children with bilateral (BCLP), unilateral (UCLP) and isolated (ICP) cleft palate, and control group of non-cleft 52 children, both groups with confirmed otitis media with effusion and no previous otological surgery. The lowest pneumatisation found in BCLE, BCLP and UCLP showed no growth of mastoid with age and lower mastoid size than OME controls. ICP is the only cleft type with growth of mastoid with aging. OME patients has the highest size of mastoid and growth rate with aging.

Three-dimensional morphometric analysis of paranasal sinuses and mastoid air cell system using computed tomography in pediatric population.

OBJECTIVES: To evaluate the volumetric relationship between the mastoid air cell (MAC) and paranasal sinus (PNS) in the pediatric population using three-dimensional reconstruction and the analysis technique of CT. STUDY DESIGN: Retrospective cross-sectional study was conducted at a university-based, secondary referral hospital. METHODS: PNS CT imaging data of 62 children (40 boys and 22 girls; mean age=13.4 ± 4.0 years) was reconstructed to the three-dimensional model with the surface-rendering algorithm (lower threshold of -1024 HU and upper threshold of -318 HU), and subsequently measuring the volume of the three PNSs (frontal, maxillary and sphenoid) and MAC. Hierarchical linear regression analysis was used to control the effect of age. RESULTS: Controlling the effect of age, no significant linear regression relationship was found between the volume of MAC and PNSs. It was observed that PNSs and MAC showed a significant linear relationship with age. The regression slopes of PNSs were larger than that of MAC, especially the growth of maxillary and sphenoid sinuses was faster and larger than that of the frontal sinus and MAC. As the coefficient of determination was extremely small, the aging process itself could not effectively explain the volume variation of PNSs and MAC. CONCLUSION: No interaction was observed in the pneumatization of the three PNSs (frontal, maxillary, and sphenoid) and MAC. It was found that the growths of PNSs and MAC are influenced by age. Further, maxillary and sphenoid sinuses tend to grow faster and become larger than the frontal sinus and mastoid air cell system. Thus, it is verified that environmental factors could be involved in the postnatal pneumatization process of the PNSs and MAC, which might influence MAC to a greater extent than the PNSs.

A cross-sectional study of the change in mastoid geometry with age in children without a history of otitis media.

OBJECTIVES/HYPOTHESIS: This study assessed the normal growth and development of mastoid air-cell system (MACS) geometry from infancy through adolescence. STUDY DESIGN: Cross-sectional study. METHODS: This cross-sectional study evaluated the change with age in MACS volume, surface area, and surface area/volume ratio in 36 (72 ears) individuals aged 1.6 to 18 years with no history of middle ear disease. The three MACS parameters were reconstructed using computed tomography (CT) scans judged by a radiologist to be normal. Linear regression was used to determine the relationship between the left and right values of each parameter, and between those parameters and age for male and female subjects. RESULTS: For all three MACS parameters, the right and left values were highly correlated. MACS volume and surface area for male and female subjects showed an increase between 1 and 18 years. The surface area/volume ratio for males was independent of age but showed a shallow increase for females. When averaged across all ages, the ratio was similar to those previously reported. CONCLUSIONS: The growth trajectory for MACS volume observed in this study was not consistent with other cross-sectional studies employing planimetry or CT of normal subjects that reported inconsistent results. Because of its potential role as a susceptibility factor for otitis media and other otologic problems, it is important to describe the growth and development of MACS geometry. Additional well-controlled studies of this phenomenon are needed to clarify which of the growth trajectories actually describe the growth process for the three parameters of interest.

The growth rate and size of the mastoid air cell system and mastoid bone: a review and reference.

This review suggests a reference to the postnatal growth of mastoid air cells and bone. Information was retrieved from studies having large consecutive age groups, in order to reveal a development pattern. Data regarding origin, gender, and antibiotic treatment was investigated as well. Most measurements were obtained by planimetry. Assessment of the various data sources suggested the antrum to be well developed at birth (1-1.5 cm2), the mastoid cells to be about 3.5-4 cm2 at 1 year, followed by a linear growth till the age of 6 (1-1.2 cm2/year), having a slower increment up to adult size at puberty (approximately 12 cm2). The mastoid bone expansion is about 0.6-0.9 cm/year in length and width and 0.4 cm/year in depth in the first year, followed by half that rate until the age of 6-7. At puberty there was a slower sprout reaching adult size. Different ethnic groups share similar mastoid aeration and bone growth patterns. There were no differences between mastoid aeration measured at the pre-antibiotic era and after its widespread use. In conclusion, there are three distinguishable phases of mastoid pneumatization from birth till reaching final size. Bone and air cell compartments share a similar growth pattern; bone expansion lags behind aeration. Antibiotic treatment for otitis may have no impact upon mastoid aeration.

Histomorphometric estimation of air cell development in experimental otitis media.

OBJECTIVES: The objectives of this study were to examine the effect of acute otitis media on the bony development of the growing middle ear air cell system with a reliable and concise stereologic histomorphometric method and to generate a standard baseline growth plot for the middle ear of the rat. STUDY DESIGN: The authors conducted a histomorphometric analysis of bullar volume during the entire growth period after early induction of unilateral otitis media. METHODS: The authors conducted undecalcified processing of 27 rat skulls sectioned horizontally at various ages from 20 to 83 days after unilateral transtympanic injection of Streptococcus pneumoniae at 19 days postpartum. Stereologic estimation of bullar volume was performed in the experimental and the control ear with Cavalieri's principle. Body mass and air cell volume were plotted as functions of subject age using standard developmental equations on the experimental results. RESULTS: Volumes of the middle ear air cell system were consistently smaller in the otitis ears. Bullar growth was completed at 60 days regardless of otitis history, but body mass was increasing throughout the experimental period. CONCLUSIONS: A single incident of otitis media introduced early in life is sufficient to significantly reduce the final volume of the bulla in rats. This finding may mimic the effect of otitis media contracted in early childhood on the development of the mastoid air cells. The standard growth plot provides a timeframe for studies of signaling molecules responsible for bone modeling in pneumatization.

Acute otitis media and mastoid growth.

CONCLUSIONS: This study implies that the hypothesis that acute otitis media (AOM) in infancy inhibits the growth of the mastoid system cannot be accepted. OBJECTIVE: To establish a relationship between AOM in children and their mastoid pneumatization development. PATIENTS AND METHODS: Lateral Schüller mastoid radiographs (LMRs) were measured in two groups of children at ages 2-11 years. Group A (n=116) had a history of recurrent AOM; group B (n=108) had no such history. Patients were treated in a private clinic. Data were analysed at Tel Aviv University. The patients had their LMR taken and measured planimetrically. LMR areas on left and right sides were compared in each group and age and were tested for possible differences using the paired Student's t test. When no left/right difference was detected, the values were averaged. Groups A and B were compared at different ages using two-tailed two-sample unequal variance and correlation coefficients. RESULTS: The analyses show that the LMR area became gradually and significantly larger with age in group A (R2=0.858; p<0.05). It did not develop significantly in group B.

Relationship between severity of middle ear mucosal lesion and middle ear pneumatic space volume in patients with otitis media with effusion.

If we assume that the state of suppression of pneumatic cells is the result of suppression of pneumatic cell growth by inflammatory stimulation in the middle ear pneumatic space, it is possible to improve the state of suppression by performing sufficient treatment during the growth period of the pneumatic cells. We indwelt a tympanic membrane ventilation tube (hereinafter referred to as tube) for treatment of otitis media with effusion (OME) in child patients aged 3-13 years and investigated the following points: i) relationship between the severity of inflammation of the lamina propria of middle ear mucosal specimens (hereinafter referred to as lamina propria) collected at the time of tube indwelling and the degree of growth of the pneumatic space; and ii) changes in the pneumatic space associated with treatment by tube indwelling, which was studied by comparing the above-described mucosal severity with the pneumatic space area of 2 years after tube indwelling, and with increase in the pneumatic space volume measured periodically after tube indwelling. The results indicated that mastoid cell growth suppression is higher in patients with a higher degree of inflammatory changes in the lamina propria. In association with treatment by tube indwelling, effusion accumulated in the pneumatic space and mucosal swelling disappeared early after the treatment, or 2 months of tube indwelling. After that, in patients with severe mucosal lesion, a long time, 1.5-2 years, was found to be required for repneumatization accompanying regrowth of the temporal bone. We confirmed that the severity of inflammation of the lamina propria is deeply involved in the growth and repneumatization of the pneumatic cells.

Pneumatic processes in the temporal bone of chimpanzee (Pan troglodytes) and gorilla (Gorilla gorilla).

The ontogeny of human temporal bone pneumatization has been well studied from both comparative and clinical perspectives. While a difference in the extent of air cell distribution has been noted in our closest living relatives, chimpanzees and gorillas, the processes responsible have been relatively unexplored. To examine these processes, a large, age-graded series of hominoid skulls was radiographed and the progress of pneumatization recorded. Additionally, a subsample of 30 chimpanzees and 12 gorillas was subjected to high-resolution CT scanning. Neonatal specimens show a well-developed mastoid antrum, as well as a capacious hypotympanum extending into the petrous apex. In African apes, as in humans, the mastoid antrum serves as the focus for air cell expansion into the mastoid and immediately adjacent areas. In chimpanzees and gorillas, however, a pronounced lateral structure, described as the squamous antrum, serves as the focus of pneumatization for anterior structures such as the squamous and zygomatic. The diminution of this structure in Homo sapiens explains the difference in air cell distribution in these regions.

Growth in the external cranial base evaluated on human dry skulls, using nerve canal openings as references.

The purpose of this investigation was to measure on human dry skulls the postnatal widening and lengthening of the external cranial base, including the hard palate, using nerve canal openings as references. Forty-five Indian dry skulls were examined, 36 from children and 9 from adults. The age evaluation was made on the basis of dental development. The dimensions of the external cranial base were determined by direct measurements on the skulls and by measurements from photographs of the skulls. The study showed that growth in width of the external cranial base followed two distinct patterns. The two regions represent different embryologic developmental fields. The study points out that different growth patterns in these fields ought to be taken into account in future investigations of normal and pathologic craniofacial growth.

Imaging findings of the developing temporal bone in fetal specimens.

PURPOSE: To trace the development of the normal fetal temporal bone by means of plain radiography, MR, and CT. METHODS: Eighteen formalin-fixed fetal specimens, 13.5 to 24.4 weeks' gestational age, were examined with a mammographic plain film technique, CT, and MR imaging at 1.5 T. Temporal bone development and ossification were assessed. RESULTS: The membranous labyrinth grows with amazing rapidity and attains adult size by the middle of the gestation period. The cochlea, vestibule, and semicircular canals are very prominent and easily recognized on MR images. The otic capsule develops from a cartilage model. Ossification of the otic capsule proceeds rapidly between 18 and 24 weeks from multiple ossification centers that replace the cartilaginous framework. The mastoid, internal auditory canal, vestibular aqueduct, and external auditory canal continue to grow after birth. CONCLUSION: The study of fetal developmental anatomy may lead to a better understanding of congenital disorders of the ear. Faster MR scanning techniques may provide a method for in utero evaluation of the fetal temporal bone.

Tympanic bulla pneumatization following experimental mastoidectomy in a porcine animal model.

The effect of mastoidectomy on mastoid pneumatization was investigated in an animal model. Experimental mastoidectomy was performed on the air cell system of the tympanic bullae in 10 four-week-old piglets. The developmental process of this structure is very similar to that of the human mastoid air cell system. Two piglets each were decapitated at 1 and 2 weeks, and 1, 3 and 5 months after the operation, and hematoxylin and eosin sections of the bullae were examined histopathologically. The development of the tympanic bulla itself was not affected by the operation. However, inside the bulla, a great amount of bone tissue had proliferated peripheral to the surgical cavity without new formation of normal pneumatized cells. When mastoidectomy was performed in the course of the pneumatization, subsequent pneumatization did not occur in this animal model. This result suggests that mastoidectomy in childhood may arrest the new formation of mastoid air cells in humans.

Postnatal development of the facial canal. An investigation based on cadaver dissections and computed tomography.

The anatomy of the facial nerve canal in the adult and the prenatal development of this canal are well described in the literature. It is divided into three segments (the labyrinthine segment, the tympanic segment and the mastoid segment). However, little is known of the facial canal anatomy in the newborn and almost nothing in the child. Postnatal changes in the development of the facial canal are directly connected with the postnatal development of the temporal bone. Particularly the development of the mastoid process and the bony external ear canal contribute to the development of the third (mastoidal) portion of the facial canal. Therefore, most of the postnatal changes in the facial canal are observed in this segment. However, the second (tympanic) portion also shows some postnatal changes in its direction caused by the changes of the squamous bone. The most significant changes take place during the first four years after birth. Provided with the anatomical description of the entire facial canal in the child, it is also easy to identify the canal on computed tomography scans. In summary, the first and the second part of the facial canal in the child are almost similar to the adult in length and in width; the only change from the newborn to the adult is in the direction of the second part which is more horizontal in the adult than during early childhood. The most significant changes are the changes in the length of the mastoidal part, the change in the position of the stylomastoid foramen and the change of the divergence of the chorda tympani.