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PubMed2002

Temporal bone pathology in fetuses exposed to isotretinoin.

Isotretinoin can be teratogenic, affecting many tissues, including the ear. However, there are only two histopathologic studies of the temporal bone in affected humans, and neither describes the findings in early gestation. We had the opportunity to study both temporal bones in each of two fetuses (22 and 24 weeks) exposed to isotretinoin in early gestation. One of the fetuses had a dilated IVth ventricle and a hypoplastic cerebellar vermis, while no dysmorphic features were seen in the other. In both infants the external ears were not noticeably abnormal. Histologically, anomalies of the middle ear included medial deviation of the malleus, forward displacement of the incus, and a small tympanic cavity (4/4); unilateral absence of the stapes (1/4); single "columella" crus and hypoplastic footplate (3/4); and unilateral dehiscence of the facial canal in one infant. Autolysis limited the examination of the labyrinth, but there was reduction in the number of cochlear spirals, and dilatation of the saccule in both infants. Anomalies of the middle and inner ear can be present without anomalies of the external ear or the central nervous system, and may be found even after relatively short exposures. These anomalies are similar to those detected in experimental exposure to isotretinoin, and are consistent with altered expression of the goosecoid gene.

Abnormalities, Drug-Induced↗
PubMed2006

Rotational and translational reproducibility of newly developed Leksell frame-based relocatable fixation system.

PURPOSE: The aim of this study was to evaluate three-dimensional movement of the cranium in a relocatable frame using positions of anatomical landmarks obtained from repeated quality-assurance (QA) computed tomography (CT) studies. MATERIALS AND METHODS: We analyzed 17 series of QA-CT data representing five patients who underwent stereotactic radiotherapy for treatment of acoustic neurinoma. Helical-CT scans with 1-mm collimation were obtained at the time of treatment planning and during the course of treatment. The right and left short processes of the incus and the top of the crista galli were used as the three anatomical reference points. RESULTS: Fluctuations in distance among the reference points were all <1 mm. The translational displacements for these points were <2 mm, with standard deviations (SD) of <2 mm. A plane that included all three reference points was defined as the reference plane. To investigate the direction of cranial rotation for each QA-CT scan, unit normal vectors of the reference plane were obtained. Three-dimensional analyses indicated that cranial rotation was greatest along the X-axis, followed by the Y-axis, with the least rotation along the Z-axis. CONCLUSION: The result suggested that movement of the craniocaudal axis in the sagittal plane was a major factor behind displacement of the cranium.

Adult↗
PubMed1988

The fate of Meckel's cartilage chondrocytes in ocular culture.

Modulation of the chondrocyte phenotype was observed in an organ culture system using Meckel's cartilage. First branchial arch cartilage was dissected from fetal rats of 16- and 17-day gestation. Perichondrium was mechanically removed, cartilage was split at the rostral process, and each half was grafted into the anterior chamber of an adult rat eye. The observed pattern of development in nonirradiated specimens was the following: hypertrophy of the rostral process and endochondral-type ossification, fibrous atrophy in the midsection, and mineralization of the malleus and incus. A change in matrix composition of the implanted cartilage was demonstrated with immunofluorescence staining for cartilage-specific proteoglycan (CSPG). After 15 days of culture, CSPG was found in the auricular process but not in the midsection or rostral process. In order to mark the implanted cells and follow their fate, cartilage was labeled in vitro with [3H]thymidine [3H]TdR). Immediately after labeling 20% of the chondrocytes contained [3H]TdR. After culturing for 5 days, 20% of the chondrocytes were still labeled and 10% of the osteogenic cells also contained radioactive label. The labeling index decreased in both cell types with increased duration of culture. Multinucleated clast-type cells did not contain label. Additional cartilages not labeled with [3H]TdR were exposed to between 20000 and 6000 rad of gamma irradiation before ocular implantation. Irradiated cartilage did not hypertrophy or form bone but a fibrous region developed in the midsection. Cells of the host animal were not induced to form bone around the irradiated cartilage. Our studies suggest that fully differentiated chondrocytes of Meckel's cartilage have the capacity to become osteocytes, osteoblasts, and fibroblasts.

Animals↗
PubMed1981

Hearing loss in Pfeiffer's syndrome.

A 14-year-old boy with conduction hearing loss, acrocephaly, minimum syndactyly, broad thumbs and big toes is classified as being affected with a form of acrocephalosyndactyly, termed Pfeiffer's syndrome (McK+10160) [12]. It is the first case of this syndrome presented in the otorhinolaryngological literature. During exploratory tympanotomy, the ossicular chain was found to be fixed. The incus seemed to be fixed in the epitympanum and there was ankylosis of the stapes. After antrotomy during a first stage, stapedectomy and teflon interposition during a second stage the air-bone gap disappeared. Multidirectional polytomography of the inner ear, performed preoperatively, was normal with the exception of a markedly local bilateral dilatation of the internal acoustic meatus. Although this case is a sporadic one, the mode of inheritance of this syndrome is autosomal dominant.

Acrocephalosyndactylia↗
PubMedDate not supplied

Implantable hearing aids: changes in the auditory-evoked potential of the monkey in response to increased loading of the stapes.

This study examines the effects on the hearing response in the monkey resulting from an increasing load on the stapes exerted by an implantable middle ear transducer. The transducer was placed on the distal end portion of the long process of the incus in monkeys and progressively advanced in small increments in the direction of the long axis of the stapes. Auditory-evoked potentials were recorded to assess the hearing response induced by the vibration of the transducer at each point. A decrease in response equivalent to a change in stimulus sound pressure level of approximately 20 dB occurred as the load on the stapes increased. Frequency response may also change. Our results imply that, to achieve maximum efficiency, the load placed on the ossicles by a vibrating transducer must be minimized.

Animals↗
PubMed1987

Mixed conductive and sensorineural hearing loss in LP/J mice.

Air and bone conduction thresholds for the detection of a compound action potential response were measured in mice of the LP/J inbred strain, which has been proposed as a possible model for human otosclerosis. Thresholds were compared with control data from CBA/Ca mice. Evidence of a mixed sensorineural and conductive hearing loss was obtained in LP/J mice. Few signs of hair cell degeneration or middle-ear bony lesions were found in 20-day old mice, although they generally showed raised thresholds to both air and bone conducted stimuli. The reason for the observed sensorineural component of the hearing loss at this age is not clear, since endocochlear potentials were normal in mice of this strain. By 225 days of age, hair cell loss was extensive and there was clearly excess bone growth in all middle-ear specimens studied, particularly on the incus and the cochlear wall facing the middle ear. Microbiological analysis of LP/J specimens revealed no evidence of a middle-ear infection specific to these mice which might explain the pathology.

Action Potentials↗
PubMed1993

Displacement of the gerbil tympanic membrane under static pressure variations measured with a real-time differential moire interferometer.

It is thought that chronic middle ear disease ultimately causes changes in the stiffness and elasticity of the tympanic membrane, but it is unknown whether such changes occur early in the course of the disease. In order to analyze mechanical changes in different parts of the tympanic membrane, a full field moire interferometry technique was utilized to measure the shape and real-time displacement in response to positive and negative pressure gradients applied across the tympanic membrane. The measurements were performed on fresh isolated temporal bones from the Mongolian gerbil. In order to gain sufficient visual access to the pars tensa for the moire measurements, the tympanic bulla was opened, the tensor tympani muscle and the incudo-stapedial joint were cut, and part of the medial wall of the tympanic cavity was removed. The malleus and incus and their ligaments were kept intact. The specimens were kept continuously humidified with an evaporator or in a humid chamber, since otherwise the tympanic membrane dries out in a few minutes when its medial surface is exposed. This desiccation reduces the elasticity and cause shrinkage which results in a reduction of the height of the cone constituted by the pars tensa. Profiles of the tympanic membrane at rest and under different pressure conditions were extracted from the moire interferograms. The tympanic membrane and ossicular complex exhibit a hysteresis effect as differences in the displacement patterns under identical pressure gradients during the loading and the unloading phase; a residual displacement of the pars tensa was for instance seen after the pressure gradient across the tympanic membrane was eliminated.

Animals↗
PubMed1995

Scaling of the mammalian middle ear.

This study considers the general question how animal size limits the size and information receiving capacity of sense organs. To clarify this in the case of the mammalian middle ear, I studied 63 mammalian species, ranging from a small bat to the Indian elephant. I determined the skull mass and the masses of the ossicles malleus, incus and stapes (M, I and S), and measured the tympanic membrane area, A1. The ossicular mass (in mg) is generally negatively allometric to skull mass (in g), the regression equation for the whole material (excluding true seals) being y = 1.373 x(0.513). However, for very small mammals the allometry approaches isometry. Within a group of large mammals no distinct allometry can be discerned. The true seals (Phocidae) are exceptional by having massive ossicles. The size relations within the middle ear are generally rather constant. However, the I/M relation is slightly positively allometric, y = 0.554 x(1.162). Two particularly isometric relations were found; the S/(M + I) relation for the ossicles characterized by the regression equation y = 0.054 x(0.993), and the relation between a two-dimensional measure of the ossicles and the tympanic membrane ares, (M + I)2/3 /A1. As in isometric ears the sound energy collected by the tympanic membrane is linearly related to its area, the latter isometry suggests that, regardless of animal size, a given ossicular cross-sectional area is exposed to a similar sound-induced stress. Possible morphological middle ear adaptations to particular acoustic environments are discussed.

Animals↗
PubMedDate not supplied

Locations of congenital cholesteatoma in the middle ear in Japanese patients.

OBJECTIVES: To present clinical features of congenital cholesteatoma treated in our institute and to investigate the locations of congenital cholesteatoma in the middle ear of Japanese patients to verify its pathogeneses. PATIENTS AND METHODS: A retrospective chart review of patients in our institute and a review of articles on congenital cholesteatoma reported by Japanese researchers. Charts of the 25 patients with congenital cholesteatoma treated in our institute were reviewed regarding symptoms, locations of cholesteatoma in the middle ear, and ossicular anomalies. The same points were investigated in the 71 cases in the Japanese literature. RESULTS: Unlike Westerners, more than half of the Japanese cases had posterior-type cholesteatomas, any parts of which did not exist anteriorly beyond the handle of the malleus. Congenital ossicular anomalies, absence of the long process of the incus, and/or the superior structure of the stapes were seen with a high rate in the Japanese patients. CONCLUSIONS: These two findings of the posterior location of cholesteatomas in the middle ear and the high incidence of congenital ossicular anomalies in the Japanese patients suggested that there should be some racial difference in pathogenesis of congenital cholesteatoma. The pathogenesis of congenital cholesteatoma cannot be adequately explained by only one theory alone. It is more appropriate to explain the pathogenesis by using an aggregation of theories.

Asian People↗
PubMed2006

Preoperative evaluation of the congenital aural atresia on computed tomography; an analysis of the severity of the deformity of the middle ear and mastoid.

OBJECTIVE: To compare the development of temporal bone in normal and atretic ears and to assess some radiological landmarks that could be important in the hearing restoration interventions in such patients. MATERIAL AND METHODS: Thirty-five patients with 40 atretic external ears were evaluated with temporal bone CT and compared to a control group of 40 normal ears retrospectively. Using comparable slice levels in all patients, the course and the caliper of the facial canal, the surface area of the incus and malleus, the level of mastoid aeration, the location and anteroposterior diameters of the jugular bulb and sigmoid sinus, the direction and the caliber of the tympanic bony part of the Eustachian tube, area of the middle ear cavity, distance from facial nerve to incudomalleolar joint, to the vestibule and to the jugular bulb were included in the assessment. Non-parametric and parametric statistical tests were used for comparison. RESULTS: In atretic ears middle ear sectional area was found to be smaller at the equivalent plane as compared to control subjects (mean area index: 19.3mm(2) versus 47.4mm(2)). Mastoid aeration was low in general and the ossicles in the atretic ears were hypoplastic (mean ossicular sectional area: 8.3mm(2) versus 11 mm(2)). The distance from the jugular bulb to the facial nerve was significantly lower (mean: 6.2mm versus 6.8mm) (p<0.05) in the atretic ears. Facial canal caliber, distance from the facial canal to the incudomalleolar joint and distance from the facial canal to the vestibule in the atretic ears (means: 1.49, 2.93 and 1.82, respectively) did not show statistically significant difference from the control subjects (means: 1.44, 2.91 and 1.83, respectively) (p>0.05 for all). CONCLUSION: External ear atresia is significantly associated with middle ear and mastoid abnormalities. The ossicles were underdeveloped which always have to be considered during reconstructive surgery. Radiologically, in the atretic ears anterior-posterior length of the temporal bone was more influenced as compared to superior-inferior portion, which justifies abnormal route of the facial nerve canal. However, there is no abnormality in the development of the facial nerve as the caliper is similar to the control subjects.

Adolescent↗
PubMed2005

Topographical anatomy of the guinea pig temporal bone.

Systematic anatomical description of the various structures of the temporal bone have been performed based on dissection of 16 guinea pigs (32 temporal bones). It has been found that besides two main air spaces in the middle ear, the tympanic bulla and dorsal bulla described in literature, there are also additional air cells in the mastoid process and facial nerve region in the temporal bone of a guinea pig. Moreover recesses were found in the walls of the tympanic bulla that formed almost completely separated partitions of tympanic cavity. The malleus head, the body of the incus and the superior and lateral semicircular canals as well as the facial nerve are easily accessible from the dorsal bulla. From the ventral tympanic bulla, one can access both windows and the cochlea. The semicircular canals are relatively large, the lateral canal is largest and the posterior the smallest. The cochlea has thin bony wall, and is composed of 3.5-3.75 turns.

Animals↗
PubMed2005

Experimental ossicular fixations and the middle ear's response to sound: evidence for a flexible ossicular chain.

A human temporal-bone preparation was used to determine the effects of various degrees of artificial ossicular fixation on the sound-induced velocity at the input-side (the umbo of the malleus) and the output-side (the stapes) of the ossicular chain. Construction of various degrees of attachment between an ossicle and the surrounding temporal bone provided a range of reduction in ossicular mobility or "fixations". The results demonstrate different effects of the fixations on the umbo and stapes velocity: fixations of the stapes or incus produce larger reductions in sound-induced stapes velocity (as much as 40-50 dB with extensive stapes fixation), than reductions in umbo velocity (typically less than 10 dB). Fixations of the malleus produce similar-sized changes in both umbo and stapes velocity. These differential effects are consistent with significant flexibility in the ossicular joints (the incudo-malleolar joint and the incudo-stapedial joint) that permits relative motion between the coupled ossicles. The existence of flexibility in the ossicular joints indicates that joints in the ossicular chain can effect a loss of sound-induced mechanical energy between the umbo and the stapes, with a concomitant reduction in the sound-induced motion of the stapes. The introduction of such losses in sound transmission by the joints raises questions concerning the utility of three ossicles in the mammalian ear. The consequences of ossicular flexibility to ossicular-chain reconstruction is discussed. Also, as examined in a more clinically directed paper [Laryngoscope 115 (2005) 147], the different effects of the various ossicular fixations on the motion of the umbo and malleus may be useful in the diagnosis of the site of fixations in humans with conductive hearing losses caused by such pathologies.

Aged↗
PubMed2006

Severe hearing loss in Dlxl mutant mice.

The Dlx homeobox gene family participates in regulating middle and inner ear development. A significant role for Dlxl, in particular,has been demonstrated in the development of the middle ear ossicles, but the functional consequences of Dlx.l gene mutation on hearing thresholds has not been assessed. The present study characterizes auditory brainstem responses to click and tonal stimuli in a non-lethal variant of a Dlxl gene knockout. We found that peripheral hearing thresholds for click and tonal stimuli were significantly elevated in homozygous Dlxl knockout (Dlxl-/ ) compared to both heterozygous (Dlxl+/ ) and wild type (Dlxl+/+) mice. Thus, abnormal mor-phogenesis of the incus and stapes that has been documented previously with histological measures is now known to result in a severe peripheral hearing deficit.

Animals↗
PubMed2004

Recurrent acute otitis media associated meningitis in a patient with a contralateral cochlear implant and bilateral cochleovestibular dysplasia.

OBJECTIVE: To illustrate that a patient with a cochlear implant may be at increased risk of meningitis secondary to developmental anatomic abnormality associated with the underlying sensorineural hearing loss, as opposed to the implant itself. METHODS: Case report. RESULTS: Our 12-year-old patient has bilateral cochlear dysplasia, profound sensorineural hearing loss and no prior history of recurrent acute otitis media or meningitis. He underwent a left cochlear implant at 8 years of age and subsequently experienced three episodes of right acute otitis media and meningitis over the next 4 years. Middle ear exploration revealed a cerebrospinal fluid leak. A right radical mastoidectomy with closure of the external auditory canal, removal of the tympanic membrane, malleus, and incus, closure of the Eustachian tube, and obliteration of the mastoid and middle ear with abdominal fat has prevented further episodes. CONCLUSION: Meningitis in a patient with a cochlear implant is not necessarily related to the implant.

Acute Disease↗
PubMed2006

Aural acquired cholesteatoma in children: surgical findings, recurrence and functional results.

OBJECTIVE: This study was designed to compare clinical features, surgical findings and treatment results from children and adults affected by aural acquired cholesteatoma. METHODS: a retrospective review of 60 children (Group I: mean age 8.8 years, range 3-16 years) and 308 adults (Group II: mean age 45.4 years, range 18-81 years) with aural acquired cholesteatoma who underwent surgery from January 1992 to December 2002, was performed with a follow-up of 5 years. All patients were submitted to single-staged canal wall down tympanoplasty. Variables analysed were otoscopic features, extent of cholesteatoma, surgical findings and the rate of recidivism. RESULTS: The pathologic changes in the tympanic membrane were no different in the two groups. According to Stangerup et al. 40 cases (66.6%) of children were classified as stage III or more, with a significant higher incidence compared to adults (152 cases; 49.3%). Analysis of the ossicular chain state showed, in group I, a significant higher incidence of eroded or absent incus (76.6% versus 61.68%) and malleus (76.6% versus 56.48%), if compared to adults. Children, therefore, had a significantly higher risk of recurrence with a rate of 26.6% in Group I and 6.81% in group II. After surgery the mean gain measured in children group, was 11 dB and 13 dB in adults. CONCLUSION: In our study we found that the behaviour of cholesteatoma in children appears more aggressive than in adults. In fact, we found a greater extension of the cholesteatoma, a worse state of the ossicular chain and a higher incidence of recurrence. Therefore, we obtained acceptable hearing results both in children and in adults.

Adolescent↗
PubMed2006

Tympanoplasty in pediatric patients.

OBJECTIVE: The aim of this study is to analyze the clinical features and follow-up of a series of pediatric patients with chronic otitis media undergoing tymponaplasty surgery and to identify the effect of the factors on the course. METHODS: Forty-one children (mean age 15.1+/-2.62 years, range from 8 to 16 years) who had undergone tympanoplasty with or without ossicular reconstruction were evaluated. Age, gender, size and site of perforation, status of operated ear (dry/discharging), status of the contralateral ear, underlying cause of the perforations, surgical technique, preoperative and postoperative hearing levels, average postoperative follow-up time, and postoperative complications were recorded. RESULTS: Myringoplasty in 28 patients (68.3%), incus interposition in 7 patients (17.1%), partial ossicular replacement prostheses in 4 patients (9.7%) and total ossicular replacement prostheses in 2 patients (4.9%) were performed. In the 37 (90.2%) of patients, intact graft was determined during postoperative follow-up. Surgical success including intact graft and postoperative air-bone gap of less than 25 dB were obtained in 34 (82.9%) cases. CONCLUSIONS: The present study suggested that tympanoplasty was a quite successful method in the appropriate pediatric patients between the ages of 8 and 16 years. In the preoperative evaluation for surgery success, some factors, such as dry middle ear, healthy contralateral ear and concordant to postoperative care should be considered.

Adolescent↗
PubMed2006

Stapedectomy in congenital stapes fixation: are hearing outcomes poorer?

OBJECTIVE: To evaluate outcomes of stapedectomy surgery for congenital stapes fixation. STUDY DESIGN: Retrospective chart review. METHODS: The charts of 463 stapedectomies performed by 1 surgeon from 1996 to 2003 were reviewed. Patients with a history of childhood hearing loss and operative findings consistent with congenital fixation of the stapes were included. Patients with a history of trauma or chronic otitis media and those with otosclerosis were excluded. Thirty-six patients underwent stapedectomy for congenital fixation. Revision cases and those with inadequate postoperative bone or air conduction data were excluded. Inclusion criteria were met for 25 patients. Operative findings and hearing outcomes were evaluated. RESULTS: The study group was comprised of 25 stapedectomies. Closure of the air-bone gap to less than 10 dB was achieved in 48% of cases, and 80% had closure within 20 dB. A gap of more than 30 dB remained in 3 cases. There were 2 cases of sensorineural hearing loss with worsening of the bone conduction thresholds by 15 dB and 30 dB. There were no instances of perilymph gusher. In addition to an excluded case that was not reconstructed because of facial nerve position, 3 of the included patients were found to have a dehiscent facial nerve at surgery. There were no facial nerve injuries, and fixation of the malleus or incus was not found in any of the included patients. When hearing outcomes were compared with our results for otosclerosis over the same time period, rates of closure to within 10 dB and 20 dB were significantly worse in the congenital group. CONCLUSION: Closure of the air-bone gap in this population differs from our results in stapedectomy done for otosclerosis. This difference likely reflects subtle anatomic variations in the congenital group that affect the effectiveness of the prosthesis. Despite the difference in results, stapedectomy for congenital fixation remains an effective method to achieve significant hearing improvement in the majority of patients. EBM RATING: B-3b.

Adolescent↗
PubMed1997

Treatment of conductive hearing loss with ossicular chain reconstruction procedures.

Middle ear infections and ossicular disorders can cause conductive hearing loss. Ossicular disorders include fibrous unions in which scar tissue replaces the long process of the incus; disarticulations caused by previous surgical procedures or cholesteatomas; fixation from otosclerosis, cholesteatomas, or congenital malformations; and dislocations caused by trauma. Surgical reconstruction procedures, with the insertion of partial or total ossicular replacement prostheses, help restore conductive hearing. Patients who undergo these delicate procedures have significant hearing deficits and require sensitive, skilled perioperative nursing care.

Ear↗