Auditory and temporal bone abnormalities in CHARGE association

Understanding the Pathophysiology of Congenital Vestibular Disorders: Current Challenges and Future Directions

In congenital vestibular disorders (CVDs), children develop an abnormal inner ear before birth and face postnatal challenges to maintain posture, balance, walking, eye-hand coordination, eye tracking, or reading. Only limited information on inner ear pathology is acquired from clinical imaging of the temporal bone or studying histological slides of the temporal bone. A more comprehensive and precise assessment and determination of the underlying mechanisms necessitate analyses of the disorders at the cellular level, which can be achieved using animal models. Two main criteria for a suitable animal model are first, a pathology that mirrors the human disorder, and second, a reproducible experimental outcome leading to statistical power. With over 40 genes that affect inner ear development, the phenotypic abnormalities resulting from congenital vestibular disorders (CVDs) are highly variable. Nonetheless, there is a large subset of CVDs that form a common phenotype of a sac-like inner ear with the semicircular canals missing or dysplastic, and discrete abnormalities in the vestibular sensory organs. We have focused the review on this subset, but to advance research on CVDs we have added other CVDs not forming a sac-like inner ear. We have included examples of animal models used to study these CVDs. Presently, little is known about the central pathology resulting from CVDs at the cellular level in the central vestibular neural network, except for preliminary studies on a chick model that show significant loss of second-order, vestibular reflex projection neurons.

Implementing the chick embryo model to study vestibular developmental disorders

Children with congenital vestibular disorders show delayed motor development and challenges in maintaining posture and balance. Computed tomography images reveal that these children have abnormal inner ears in the form of a sac, with the semicircular canals missing or truncated. Little is known about how this inner ear abnormality affects central vestibular development. At present, mice with the chromodomain helicase DNA-binding protein 7 mutation are the most common model for studying congenital vestibular disorders, despite forming multiple diverse inner ear phenotypes and inducing abnormal cerebellar and visual system development. To identify the effects of a sac-like inner ear on central vestibular development, we have designed and implemented a new model, the anterior-posterior axis rotated otocyst (ARO) chick, which forms a sac-like inner ear in 85% of cases. The ARO chick is produced by anterior-posterior rotation of the otocyst at embryonic day 2. Here, we describe for the first time the 15% of ARO chicks that form three small semicircular canals and rename the ARO chicks forming sacs (ARO/s chicks). The basic features of the vestibular sensory organs in ARO/s chicks are similar to those found in patients’ sacs, and ARO/s hatchlings experience balance and walking problems like patients. Thus, ARO/s chicks have a reproducible inner ear phenotype without abnormalities in vestibular-related structures, making the model a relatively simple one to evaluate the relationship between the sac-like inner ear pathology and formation of the central vestibular neural circuitry. Here, we describe unpublished details on the surgical approaches to produce ARO chicks, including pitfalls and difficulties to avoid.

NEW & NOTEWORTHY This paper describes simple techniques for chick otocyst rotation resulting in a sac-like inner ear (85%), the common phenotype in congenital vestibular disorders. We now describe anterior-posterior axis rotated otocyst chicks, which form three small canals (15%), and rename chicks forming a sac (ARO/s chicks). Basic protocols and potential complications of otocyst rotation are described. With the use of ARO/s chicks, it will be possible to determine how the vestibular neural circuit is modified by sac-like inner ear formation.

Cochlear histopathology in human genetic hearing loss: State of the science and future prospects

Sensorineural hearing loss (SNHL) is an extraordinarily common disability, affecting 466 million people across the globe. Half of these incidents are attributed to genetic mutations that disrupt the structure and function of the cochlea. The human cochlea's interior cannot be imaged or biopsied without damaging hearing; thus, everything known about the morphologic correlates of hereditary human deafness comes from histopathologic studies conducted in either cadaveric human temporal bone specimens or animal models of genetic deafness. The purpose of the present review is to a) summarize the findings from all published histopathologic studies conducted in human temporal bones with known SNHL-causing genetic mutations, and b) compare the reported phenotypes of human vs. mouse SNHL caused by the same genetic mutation. The fact that human temporal bone histopathologic analysis has been reported for only 22 of the nearly 200 identified deafness-causing genes suggests a great need for alternative and improved techniques for studying human hereditary deafness; in light of this, the present review concludes with a summary of promising future directions, specifically in the fields of high resolution cochlear imaging, intracochlear fluid biopsy, and gene therapy.

The Modified Rambo Transcanal Approach for Cochlear Implantation in CHARGE Syndrome

OBJECTIVE

CHARGE syndrome is associated with a variety of temporal bone anomalies and deafness. The lack of surgical landmarks and facial nerve irregularities make cochlear implantation in this population a challenging endeavor. This study aims to describe a safe and efficacious transcanal approach for cochlear implantation that obviates the need to perform a mastoidectomy and facial recess.

PATIENTS

Three children with profound hearing loss secondary to CHARGE syndrome.

INTERVENTION

Transcanal cochlear implantation with closure of the ear canal via a modified Rambo meatoplasty.

MAIN OUTCOME MEASURE(S)

Retrospective chart review of temporal bone anomalies associated with CHARGE syndrome, technical nuances of this transcanal approach, and cochlear implant outcomes.

RESULTS

The mean patient age was 2.5 years (range 1.5-3.8 yr). Two were male and two were left ears. All patients had a hypoplastic mastoid, semicircular canal aplasia, and had some degree of cochlear dysplasia. A full cochlear implant insertion was achieved in all cases, even in the presence of grossly abnormal middle ear and facial nerve anatomy. There were no intraoperative or postoperative complications. The mean follow-up was 12.4 months (range, 3.9-25.2 mo). All three patients use their device daily. Their guardians report improved vocalization and environmental awareness.

CONCLUSIONS

The modified Rambo transcanal approach provides a safe corridor for cochlear implantation in patients with CHARGE syndrome. This approach minimizes the anatomical variations associated with the syndrome and may reduce the risk of electrode extrusion. Implant outcomes in this patient population remain highly variable based on the patient's global cognitive capacity.

Outcomes of long-term audiological rehabilitation in charge syndrome

The aim of this paper is to assess the long-term audiological features and outcomes of hearing rehabilitation in a large group of individuals with CHARGE Syndrome. The study has been conducted retrospectively, on a paediatric patient database, at the Audiology Department of the University Hospitals of Ferrara and Padua. The study sample included 31 children presenting with different degrees of hearing impairment associated with CHARGE syndrome. Hearing was assessed using auditory brainstem responses (ABRs) and/or electrocochleography, or conditioned audiometry (visual reinforcement audiometry [VRA] or play audiometry). Auditory-perceptual outcomes in terms of communication skills and expressive language were also recorded. The effects of hearing rehabilitation (with hearing aids or cochlear implants) in this group of children and language outcomes after rehabilitation were monitored during long-term follow-up. The outcomes of rehabilitation measures differed in relation to the heterogeneous and often severe disabilities associated with CHARGE syndrome, e.g. developmental delay, intellectual delay, visual impairment, thin 8^th nerve with retrocochlear auditory dysfunction (as described in cases of auditory neuropathy/dyssynchrony). Oral expressive language was severely impaired in most cases, even after lengthy follow-up, suggesting the need for alternative augmentative communication modes. The early identification of sensorineural hearing loss, and carefully planned rehabilitation treatments, can be of some benefit in children with CHARGE syndrome.

Cochlear Implants in Children Diagnosed with CHARGE Syndrome

Introduction The CHARGE association (coloboma of the eyes; heart disease; atresia of the choanae; retarded growth and development; genital hypoplasia/genitourinary anomalies; ear anomalies and/or hearing loss) was first described in 1979 by Hall, and among its main features is hearing loss. This study presents a case aiming to establish relationships between performance on Infant Toddler Meaningful Auditory Integration Scale (IT-MAIS) and Meaningful Use of Speech Scales (MUSS) tests and the analysis of hearing and language categories of a patient diagnosed with CHARGE syndrome, before and after cochlear implant (CI) surgery.

Case Report A 7-year-old girl was diagnosed with CHARGE. She had severe sensorineural hearing loss and was a prelingual unilateral CI user. We analyzed data from the patient's medical records regarding therapies and video recordings.

Results The patient showed positive results in all evaluations after CI. IT-MAIS rose from 5 to 90% following the use of CI. MUSS also rose, from 75 to 72.5%, after use of CI. Classification of Auditory Skills changed from category 1 before use of CI to category 6 after use of CI. Classification of Language Skills changed from category 1 before use of CI to category 3 after use of CI. The CI is an aid but there are many factors in the therapeutic process, and great heterogeneity in individuals diagnosed with CHARGE should be investigated.

Conclusion The development of listening and language skills after CI use was demonstrated by IT-MAIS and MUSS tests, and categorization of speech and hearing in this child with a diagnosis of CHARGE syndrome shows that CI can be an effective technological resource to provide information on hearing as one source for language construction.

Appearance of ocular vestibular evoked myogenic potential elicited by bone-conducted vibration in a patient with CHARGE syndrome with aplasia of all semicircular canals

We report VEMP results in a patient with aplasia of bilateral semicircular canals and a small vestibular cavity. The patient was a 27-year-old male. The computed tomograph showed absolutely no formation of his semicircular canals, together with hypoplasia of his vestibular cavity and cochlea in both ears. His oVEMP was recorded near the extraocular muscles on the left side when elicited by BCV in the Fz. The clinical profile of this patient suggested that oVEMP elicited by BCV recorded near the extraocular muscles originated from otolithic end organs, and not from semicircular canal afferents.

Congenital incudostapedial anomalies in adult stapes surgery: a case-series review

OBJECTIVES

The management of developmental anomalies of the ossicular chain and otic capsule in stapes surgery tests the otologist's diagnostic skills and flexibility in technique and prosthesis choice. We review our experience in managing various incudostapedial developmental anomalies discovered during middle ear exploration for suspected otosclerosis in adult patients.

DESIGN

A retrospective case-series review was used.

SETTING

The study was set at a military tertiary referral center.

PATIENTS AND OTHER PARTICIPANTS

A review of 185 stapes procedures yielded 8 cases of identified congenital anomalies of the stapes or incudostapedial complex including congenital absence of the oval window with malformed incus and stapes, columellar-type stapes with promontory fixation, stapes superstructure fixation to the fallopian canal, and malformed incus with stapes superstructure fixation to the promontory.

INTERVENTIONS

The developmental anatomy and surgical technique in each case were reviewed. The surgical technique used in each case varied depending on the specific ossicular abnormality found and whether both the stapes and incus were affected.

MAIN OUTCOME MEASURES

Comparison of preoperative and postoperative audiometric testing results was performed.

RESULTS

All 8 ears (7 patients) that underwent a stapes procedure for either an isolated congenital stapes anomaly or a combined incudostapedial anomaly had a favorable hearing outcome, with 7 ears improving to within 10-dB and 1 ear to within 13-dB air-bone gap on postoperative audiometry.

CONCLUSIONS

Despite unanticipated findings of congenital anomalies of the stapes and incus during middle ear exploration for conductive hearing loss, a flexible management approach can lead to successful hearing outcomes.

Mature middle and inner ears express Chd7 and exhibit distinctive pathologies in a mouse model of CHARGE syndrome

Heterozygous mutations in the gene encoding chromodomain-DNA-binding-protein 7 (CHD7) cause CHARGE syndrome, a multiple anomaly condition which includes vestibular dysfunction and hearing loss. Mice with heterozygous Chd7 mutations exhibit semicircular canal dysgenesis and abnormal inner ear neurogenesis, and are an excellent model of CHARGE syndrome. Here we characterized Chd7 expression in mature middle and inner ears, analyzed morphological features of mutant ears and tested whether Chd7 mutant mice have altered responses to noise exposure and correlated those responses to inner and middle ear structure. We found that Chd7 is highly expressed in mature inner and outer hair cells, spiral ganglion neurons, vestibular sensory epithelia and middle ear ossicles. There were no obvious defects in individual hair cell morphology by prestin immunostaining or scanning electron microscopy, and cochlear innervation appeared normal in Chd7(Gt)(/+) mice. Hearing thresholds by auditory brainstem response (ABR) testing were elevated at 4 and 16 kHz in Chd7(Gt)(/+) mice, and there were reduced distortion product otoacoustic emissions (DPOAE). Exposure of Chd7(Gt)(/+) mice to broadband noise resulted in variable degrees of hair cell loss which inversely correlated with severity of stapedial defects. The degrees of hair cell loss and threshold shifts after noise exposure were more severe in wild type mice than in mutants. Together, these data indicate that Chd7(Gt)(/+) mice have combined conductive and sensorineural hearing loss, correlating with changes in both middle and inner ears.

Histology and synchrotron radiation-based microtomography of the inner ear in a molecularly confirmed case of CHARGE syndrome

CHARGE (Coloboma of the iris or retina, heart defects, atresia of the choanae, retardation of growth and/or development, genital anomalies, ear anomalies) syndrome (OMIM #214800) affects about 1 in 10,000 children and is most often caused by chromodomain helicase DNA-binding protein-7 (CHD7) mutations. Inner ear defects and vestibular abnormalities are particularly common. Specifically, semicircular canal (SCC) hypoplasia/aplasia and the presence of a Mondini malformation can be considered pathognomonic in the context of congenital malformations of the CHARGE syndrome. We obtained a temporal bone (TB) of a patient with CHARGE syndrome who died from bacteremia at 3 months of age. The clinical diagnosis was confirmed in the patient by direct DNA sequencing and the detection of a de novo, truncating CHD7 mutation, c.6169dup (p.R2057fs). We assessed changes of the TB and the degree of neural preservation, which may influence the potential benefit of cochlear implantation. The TB was analyzed using synchrotron radiation-based micro computed tomography, and by light microscopy. The vestibular partition consisted of a rudimentary vestibule with agenesis of the SCCs. The cochlea was hypoplastic with poor or deficient interscaling and shortened (Mondini dysplasia). The organ of Corti had near normal structure and innervation. Modiolus and Rosenthal's canal were hypoplastic with perikarya displaced along the axon bundles into the internal acoustic meatus, which may be explained by the arrest or limited migration and translocation of the cell nuclei into the cochlear tube during development.

The cochlea in fetuses with neural tube defects

In this study different malformations of the cochlea could be demonstrated. Nevertheless, we could not delineate a distinct malformation of the inner ear, that can be linked to a neural tube defect. Neural tube defects are a frequent and heterogeneous group of malformations, ranging from the survivable spina bifida to fatal anencephaly. In multiple animal models an involvement of the vestibulocochlear system has been demonstrated. In this article human fetal temporal bones of neural tube defects were analysed in a multimodular work-up. The morphologic study was performed with light microscopy, transmission electron microscopy and synchrotron radiation-based microcomputed tomography. Immunohistochemistry for different neuronal markers such as peripherin, beta-III-tubulin and vimentin helped to evaluate ontogenetic tissue development. Eight fetal temporal bones with neural tube defects and five control temporal bones were included into the morphologic study. The morphologic results of the neural tube defect temporal bones showed six regularly developed cochleas and two with only a single cochlear turn. Three of the neural tube defect temporal bones were further examined with immunohistochemical analysis. No differences in the staining pattern for peripherin, beta-III-tubulin and vimentin were detected.

CHARGE syndrome: relations between behavioral characteristics and medical conditions

The behaviors and medical problems in 27 persons with CHARGE syndrome were studied, because it was hypothesized that their behavior might be partly dependent on the heterogeneous medical status. With the exception of more tics, cardiac surgery was associated with positive behaviors: less withdrawn behavior, better mood, and a more easy temperament. Tube feeding was also related to positive behavior, since participants with a history of tube feeding showed less intense behavior. Cerebral deficits were associated with three problem behaviors: more intense and withdrawn behavior and a worse mood. Deaf-blindness was associated with developmental delays in expressive and overall communication level, and recurrent middle ear infections correlated with delays in written language. Of all medical conditions, only the presence or absence of heart defects and cardiac surgery could differentiate between the participants with regard to the number of behavioral problems. Participants with heart surgery especially, had less behavior problems. The number of operations and hospitalizations was not associated with behavior, but the total length of the hospitalizations was. Long hospital stays were associated with less problem behavior, especially internalizing behaviors. Cerebral and heart problems did not result in longer hospital stays, whereas esophageal reflux did. Age effects were reflected in older participants, who showed more internalizing problems. Heart surgery and hospitalization may be protective factors, but the protection might not be the actual surgery or hospital stay, as there may be other variables that are the actual cause, such as reduced vitality or altered parent child interactions after heart surgery. The study could not confirm a significant association between medical conditions and autism found in previous studies.

CHARGE syndrome: an update

CHARGE syndrome is a rare, usually sporadic autosomal dominant disorder due in 2/3 of cases to mutations within the CHD7 gene. The clinical definition has evolved with time. The 3C triad (Coloboma-Choanal atresia-abnormal semicircular Canals), arhinencephaly and rhombencephalic dysfunctions are now considered the most important and constant clues to the diagnosis. We will discuss here recent aspects of the phenotypic delineation of CHARGE syndrome and highlight the role of CHD7 in its pathogeny. We review available data on its molecular pathology as well as cytogenetic and molecular evidences for genetic heterogeneity within CHARGE syndrome.

Congenital hearing impairment

Establishing the etiology of congenital hearing impairment can significantly improve treatment for certain causes of hearing loss and facilitates genetic counseling. High-resolution CT and MRI have contributed to the evaluation and management of hearing impairment. In addition, with the identification of innumerable genetic loci and genetic defects involved in hearing loss, genetic testing has emerged as an invaluable tool in the assessment of hearing impairment. Some of the common forms of congenital hearing loss are reviewed and their imaging features illustrated.

Multiple mutations in mouse Chd7 provide models for CHARGE syndrome

Mouse ENU mutagenesis programmes have yielded a series of independent mutations on proximal chromosome 4 leading to dominant head-bobbing and circling behaviour due to truncations of the lateral semicircular canal of the inner ear. Here, we report the identification of mutations in the Chd7 gene in nine of these mutant alleles including six nonsense and three splice site mutations. The human CHD7 gene is known to be involved in CHARGE syndrome, which also shows inner ear malformations and a variety of other features with varying penetrance and appears to be due to frequent de novo mutation. We found widespread expression of Chd7 in early development of the mouse in organs affected in CHARGE syndrome including eye, olfactory epithelium, inner ear and vascular system. Closer inspection of heterozygous mutant mice revealed a range of defects with reduced penetrance, such as cleft palate, choanal atresia, septal defects of the heart, haemorrhages, prenatal death, vulva and clitoral defects and keratoconjunctivitis sicca. Many of these defects mimic the features of CHARGE syndrome. There were no obvious features of the gene that might make it more mutable than other genes. We conclude that the large number of mouse mutants and human de novo mutations may be due to the combination of the Chd7 gene being a large target and the fact that many heterozygous carriers of the mutations are viable individuals with a readily detectable phenotype.

Speculations on the pathogenesis of CHARGE syndrome

To be seriously considered, a theory about the pathogenesis of a multiple congenital anomaly syndrome should meet three criteria: (1) it should explain all of the anomalies associated with the syndrome; (2) it should explain why certain anomalies are not associated with the syndrome; and (3) it should predict anomalies that could be associated with the syndrome, but have not yet been described. The theory must eventually pass the ultimate test, that is, molecular confirmation of the proposed mechanism. Several theories about the pathogenesis of CHARGE syndrome have been proposed, but none of these meet the three criteria stated above. In this study, the author proposes that CHARGE syndrome is due to a disruption of mesenchymal-epithelial interaction (epithelial includes ectoderm and endoderm). The theory is tested against the major, minor, and occasional anomalies that are used to make the clinical diagnosis of CHARGE syndrome. Review of the known embryology of the organs and tissues involved in CHARGE syndrome confirms that mesenchymal-epithelial interactions are necessary for proper formation of these organs and tissues. The presence of limb anomalies in approximately one-third of CHARGE syndrome patients fulfills criteria #3 above, in that limb anomalies were not felt to be a part of CHARGE syndrome until relatively recently. It is known that some patients with chromosomal abnormalities have a phenotype that overlaps with CHARGE syndrome. Given that critical developmental pathways must be robust and redundant in order to minimize errors, it may be that disruption of more than one gene is necessary to generate the CHARGE phenotype, as has been proposed for the holoprosencephaly sequence. Mutations and deletions of CHD7 have recently been identified as causing CHARGE syndrome in more than 50% of tested patients. Given this gene classes' putative role as a general controller of developmental gene expression as well as mesodermal patterning, it would fit the hypothesized mechanisms discussed in the study.

Quantitative analysis of limb anomalies in CHARGE syndrome: correlation with diagnosis and characteristic CHARGE anomalies

CHARGE syndrome was initially not thought to involve the limb. Several subsequent reports have shown that limb anomalies are not uncommon. To date, there have been no quantitative studies of limb anomalies in CHARGE syndrome. This study was designed to answer several questions: Do CHARGE patients with limb anomalies represent a subgroup within CHARGE syndrome? Are there correlations between certain CHARGE syndrome anomalies and limb anomalies?Are there differences between the two genders and associated limb anomalies? Are certain types of limb anomalies seen with increased frequency in CHARGE syndrome? All described patients were categorized utilizing the AI/GEN Model 2 Criteria proposed by Mitchell [1985a: J Med Syst 9:425-435]. Patients with chromosomal anomalies or familial CHARGE were excluded, as were patients with inadequate clinical descriptions, and patients in large series where individual characteristics could not be ascertained. Multivariate analysis was performed. One hundred seventy two patients with definite or probable CHARGE syndrome were analyzed. Sixty-four (37.2%) of these patients have at least one limb anomaly. Significant positive associations were seen between limb anomalies and ocular coloboma, urinary tract malformations, and genital anomalies. These associations were not significant when the definite or probable patients were analyzed separately, with the exception of genital anomalies in definite CHARGE. Gender differences were also identified. Females with tracheoesophageal fistula/esophageal atresia, or genital anomalies were more likely to have limb anomalies, while some female subgroups had positive associations between urinary tract malformations, or choanal atresia and limb anomalies. Negative associations were also seen with sensorineural hearing loss and facial paralysis. In contrast, males showed a positive association between coloboma and limb anomalies, while subgroup analysis identified positive associations with DiGeorge sequence or genital anomalies and limb anomalies. Limb anomalies are present in just over one-third of CHARGE syndrome patients. Limb anomalies are seen more frequently in association with certain CHARGE anomalies, and these associations show gender differences. There is not a common limb anomaly seen in CHARGE syndrome.

Protective effect of corticosteroid against the cytotoxicity of aminoglycoside otic drops on isolated cochlear outer hair cells

OBJECTIVES

Otic drops are commonly used not only for otitis externa but also for otorrhea in the presence of tympanic membrane perforation or tympanostomy tube. Many studies demonstrated the ototoxicity of aminoglycoside. In our previous study, we observed that gentamicin (GM), when activated with liver extract, demonstrated significant cytotoxicity. The purpose of this study was to assess the protective effect of corticosteroid against the cytotoxicity of GM and tobramycin drops using isolated cochlear outer hair cells (OHCs) in vitro with liver extract.

METHODS

OHCs from adult chinchilla cochleae were exposed to standard bathing solution, liver extract alone, and aminoglycoside otic drops with and without corticosteroid and liver extract. All experiments were performed at an osmolality of 305 +/- 5 mOsm, at room temperature, and for up to 60 minutes. The images of OHCs were recorded using an inverted microscope and analyzed on the Image Pro-Plus 3.0 program. Time to cell death and change of cell length were measured and analyzed.

RESULTS

The time to cell death and percent change in cell length observed was significantly longer in the GM + liver extract + dexamethasone group than the GM + liver extract group (P <.05). The Tobradex + liver extract group showed an insignificant increase in percent change of cell length (P >.05) and significantly increased time to cell death than the tobramycin + liver extract group (P <.05).

CONCLUSION

This study demonstrated that dexamethasone significantly reduced aminoglycoside cytotoxicity.

Temporal bone histopathology in CHARGE association

Three temporal bones obtained at autopsy from 2 patients with CHARGE association (Coloboma, congenital Heart disease, Atresia of choanae, mental Retardation and/or central nervous system anomalies, Genital hypoplasia, and Ear anomalies) were examined histopathologically. Both temporal bones from 1 patient showed multiple anomalies in the middle ear, inner ear, and facial nerve. However, the temporal bone obtained from the other patient showed almost normal structures in the inner ear, middle ear, and eustachian tube. These results are different from those of 2 previous reports of temporal bone histopathology regarding CHARGE association. This difference suggests that CHARGE association may arise not from one etiopathogenetic factor, but from complex factors. Special attention to dehiscent facial canal and perilymphatic gusher during otologic surgery in patients with CHARGE association is discussed.

Further clinical and sensorial delineation of Schinzel-Giedion syndrome: report of two cases

Schinzel-Giedion syndrome is a rare multiple congenital malformation syndrome defined by an evocative midfacial retraction, kidney and urinary malformations and multiple skeletal abnormalities associated to a recently described neurodegenerative process. Two children with SGS are reported with identical clinical findings: megacalycosis, progressive neurodegeneration with infantile spasms and hypsarrhymtic activity. Ocular investigations revealed alacrimia and corneal hypoesthesia. Computed tomography of the temporal bone showed a tuning-fork malformation of the stapes for both children. These features may contribute to further delineation of SGS as additional clinical criteria.

Vestibular abnormalities in congenital disorders

This paper reviews the histopathologic features of vestibular abnormalities in congenital disorders affecting the inner ear, based upon a comprehensive literature survey and a review of cases in our temporal bone collection. The review proceeds in three systematic steps. First, we surveyed associated diseases with the major phenotypic features of congenital abnormalities of the inner ear (including the internal auditory canal and otic capsule). Second, the vestibular anomalies are examined specifically. Finally, the anomalies are discussed from a developmental perspective. Among vestibular anomalies, a hypoplastic endolymphatic duct and sac are observed most frequently. Anomalies of the semicircular canals are also often observed. From embryological and clinical viewpoints, many of these resemble the structural features from fetal stages and appear to be associated with vestibular dysfunction. It is expected that progress in genetic analysis and accumulation of temporal bone specimens with vestibular abnormalities in congenital diseases will provide crucial information not only for pathology of those diseases, but also for genetic factors that are responsible for the specific vestibular abnormalities.

Past history of otitis media and balance in four-year-old children

OBJECTIVES/HYPOTHESIS

To obtain normative data for a population of children 4 years of age with respect to standard vestibular and balance test protocols and to determine, in the absence of concurrent middle ear effusion (MEE), the possible changes caused by a history of recurrent or persistent MEE.

STUDY DESIGN

Comparative studies of the results of vestibular and balance tests in a cohort of young children with and without a history of MEE.

METHODS

Seventy-one children, 4 years of age, with a well-documented history since early infancy regarding the presence or absence of MEE were evaluated using pneumatic otoscopy, tympanometry, audiometry, and vestibular and balance (rotational and moving platform posturography) tests. For the results of the vestibular and balance tests, comparisons were made between the group of 31 children (43.7%) without and the group of 40 children (56.3%) with a history of recurrent or persistent MEE, when a positive disease history was defined as at least a 10% cumulative percentage of time with MEE between early infancy and time of testing.

RESULTS

When compared with children with a negative history of significant MEE, children with a positive history had a lower average gain to a rotational stimulus of 0.1 Hz, 150 degrees/s (0.57 vs. 0.44; P = .007). There were no significant differences between groups with respect to other measures.

CONCLUSIONS

These results suggest that a history of recurrent or persistent MEE affects the vestibular and/or balance function of 4-year-old children when tested in the absence of a concurrent episode of MEE. The possible sequelae of the disease should be weighed in future considerations of early intervention for MEE.

Growth failure and pituitary function in CHARGE and VATER associations

Growth failure and anterior pituitary dysfunction are clinical features of the CHARGE and VATER associations. This study investigated pituitary dysfunction as a potential cause of poor growth in a series of four and three patients with the CHARGE and VATER associations, respectively, who had height standard deviation scores (SDS) less than-2. Five of the seven patients had associated subnormal growth velocity SDS. Patients were investigated with a combination of dynamic and basal endocrine tests. All patients were found to be normonatraemic and to have normal basal thyrotroph and stimulated corticotroph function. The one peripubertal patient had evidence of biochemical gonadotroph dysfunction. Although two patients had marginally low stimulated serum growth hormone responses to glucagon stimulation testing, this was associated with either normal growth velocity or normal serum insulin-like growth factor binding protein 3 (IGFBP-3) concentrations. Thus, somatotroph dysfunction could not be demonstrated unequivocally in any patient. Poor childhood linear growth in the CHARGE and VATER associations does not appear to be associated with pituitary dysfunction.

Patients with CHARGE association: a model to study saccular function in the human

The term CHARGE association refers to a combination of congenital malformations, the mnemonic CHARGE designating the most frequently occurring anomalies in the constellation. "C" indicates coloboma of the retina, "H" heart defects, "A" choanal atresia, "R" retarded growth and/or central nervous system anomalies, "G" genital hypoplasia, and "E" ear anomalies and/or deafness. The inner ear anomaly consists of a specific form of labyrinthine dysplasia that includes Mondini dysplasia of the pars inferior (cochlea and saccule) and complete absence of the pars superior (utricle and semicircular canals). We observed the development of a child with CHARGE association up to the age of 10 years. There was complete absence of nystagmic response to bithermal caloric and rotatory pendular stimuli. A nystagmic reaction was elicited by the off-vertical axis rotation test, indicating stimulation of the saccular macula, the sole remaining vestibular sense organ in this dysplasia. This reaffirms that the saccule is a vestibular organ, even though it is located in the pars inferior. In spite of the severe bilateral vestibular deficit and coloboma of the retina, the child was able to walk at the age of 2 years. The delay in the development of walking was not due to central nervous system anomalies, as suggested by the "R" of the acronym CHARGE, but rather, to the severe sensorineural visual and vestibular deficits.

Otological manifestations of CHARGE association

The combined findings of abnormalities of the incus and stapes, absence of the oval window, absence of the stapedius muscle (with absent pyramidal eminence and tympanic sinus in most cases), and abnormalities of different parts of the inner ear (dysplastic cochlea, hypoplastic or dysplastic vestibule, and absent semicircular canals) are characteristic of the CHARGE association. Computed tomography and magnetic resonance imaging using 1-mm-thick contiguous slices proved useful in demonstrating the broad spectrum of temporal bone abnormalities in patients with the CHARGE association.

Temporal bone CT findings in the CHARGE association

Ten out of 20 cases with the CHARGE association and two CHARGE-like cases underwent temporal bone CT scanning and/or MRI: they all showed bilateral aplasia of the semicircular canals and obliteration of the oval windows. Vestibular examination was performed in nine CHARGE cases and the two CHARGE-like cases, which disclosed vestibular areflexia in all of them. Of the 16 evaluable CHARGE cases, eight had bilateral mixed hearing impairment, while eight had sensorineural hearing impairment which was bilateral in six and unilateral in two cases. Temporal bone CT scanning is therefore indicated in suspected CHARGE cases, even if they show normal hearing or a relatively good bone conduction threshold in one or both ears.

Otologic management in children with the CHARGE association

OBJECTIVES

To characterize otologic management of two patient groups, those with the CHARGE association and those not strictly labeled as CHARGE but with several features of the disorder (CHARGE-like), in order to determine: (1) the clinical validity and utility of managing CHARGE-like children in a similar manner to patients with the strictly defined CHARGE association, (2) the progression and prognosis of hearing loss and (3) the identification of factors that may predict the degree of hearing loss.

DESIGN

Case series.

SETTING

Tertiary care urban children's hospital.

PATIENTS

37 children, 22 in the CHARGE group and 15 in the CHARGE-like group.

INTERVENTIONS

Otorhinolaryngologic and audiologic management.

MAIN OUTCOME MEASURES

Otorhinolaryngologic and audiologic evaluation.

RESULTS

All patients required otologic and/or audiologic care. Bilateral hearing loss was found in 32 patients (86%) and unilateral hearing loss in five patients (14%) when hearing was assessed in the absence of otitis media. Among the 32 patients with bilateral hearing loss, 31 (97%) were able to be fit with useful hearing aids. External ear anomalies were present in 25/37 (68%) patients, and middle ear and ossicular anomalies were identified in four cases (4/37, 11%), 36/37 (97%) patients required surgical management of otitis media. Three patients (3/37, 8%) exhibited radiographic evidence of inner ear deformity. Facial nerve dysfunction was noted in the records of 14/37 (38%) patients. No statistically significant difference was found when CHARGE and CHARGE-like patients were compared for degree of hearing loss (P = 0.5964), type of hearing loss (P = 0.2657), worsening of hearing level (P = 0.7908), or anomalies of the external ear (P = 0.6921), ossicles (P = 0.7908), inner ear (P = 0.7908) or facial nerve (P = 0.6409). Patients with external ear anomalies did not exhibit statistically different degrees (P = 0.3125) or types (P = 0.1515) of hearing loss from patients without auricular anomalies. The presence of facial nerve anomaly correlated significantly (P = 0.0021) with profound hearing loss.

CONCLUSIONS

Children who are CHARGE-like may be may be considered equivalent in terms of otologic and audiologic management to children strictly defined as CHARGE patients. These children all require otologic care due to the high prevalence of middle ear disease and the underlying permanent hearing loss that is both stable and aidable. The degree of hearing loss cannot be predicted by external ear morphology, but may be predicted by facial nerve palsy.

Histologic demonstration of glycosaminoglycans in inner ear fluids

Hyaluronic acid is a glycosaminoglycan (GAG) which has been demonstrated by biochemical and histochemical methods to be present in inner ear fluids and tissues. However, consistent labeling of hyaluronic acid or other GAGs in inner ear fluid compartments in histologic sections has not been previously reported. Staining and characterization of GAGs in the normal inner ear fluids of humans and guinea pigs are described in this report. It was initially observed that alcian blue produces dense staining of the endolymphatic and perilymphatic fluid compartments in celloidin embedded material. Results obtained with alcian blue were subsequently compared to staining obtained with hematoxylin/eosin and periodic acid/Schiff base. Enzyme digestion was also performed with testicular hyaluronidase (bovine and ovine), streptomyces hyaluronidase, chondroitase ABC, and alpha-amylase. Results of the differential staining and enzyme digestion studies suggest that the substances in inner ear fluids that stain with alcian blue are a combination of chondroitin sulfate-4, -5 and/or -6 and hyaluronic acid.

CHARGE syndrome: report of 47 cases and review

The acronym CHARGE refers to a syndrome of unknown cause. Here we report on 47 CHARGE patients evaluated for the frequency of major anomalies, namely coloboma (79%), heart malformation (85%), choanal atresia (57%), growth and/or mental retardation (100%), genital anomalies (34%), ear anomalies (91%), and/or deafness (62%). In addition, we comment on anomalies observed very frequently in neonates and infants with the CHARGE syndrome, including, minor facial anomalies, neonatal brain stem dysfunction with cranial nerve palsy, and, mostly, internal ear anomalies such as semicircular canal hypoplasia that were found in each patient that could be tested. We propose several criteria for poor survival including male gender, central nervous system and/or oesophageal malformations, and bilateral choanal atresia. No predictive factor regarding developmental prognosis could be identified in our series. A significantly higher mean paternal age at conception together with concordance in monozygotic twins and the existence of rare familial cases support the role of genetic factors such as de novo mutation of a dominant gene or subtle sub-microscopic chromosome rearrangement. Finally, the combination of malformations in CHARGE syndrome strongly supports the view that this multiple congenital anomalies/mental retardation syndrome is a polytopic developmental field defect involving the neural tube and the neural crests cells.

Vestibular areflexia as a cause of delayed motor skill development in children with the CHARGE association

Six cases of the CHARGE association are described that were encountered consecutively at an institute for the deaf. Five of them showed external ear anomalies and according to expectations all of them showed some degree of hearing impairment: two had moderate mixed hearing loss; three had severe to profound sensorineural hearing loss; and one was completely deaf. In addition, they all had vestibular areflexia and the five cases examined with computer tomography of the petrosal bones showed aplasia of the semicircular canals. One case with poor visual acuity also showed subnormal optokinetic responses and horizontal pendular nystagmus during visual fixation. All these children were initially diagnosed as having severe psychomotor retardation, because of their failure to acquire speech and their delayed motor skill development. Given the fact that (mild) mental retardation was found in only one case, the delayed development could at least in part have been caused by vestibular areflexia. The vestibular findings support previously reported temporal bone findings that indicate dysplasia or aplasia of the superior part of the labyrinth. Early detection of the full extent of (multiple) sensory deficits is necessary in children with the CHARGE association who have similar abnormalities, because aggressive intervention and special educational support are likely to be of great benefit to sensorimotor development.

Vestibular abnormalities in charge association

We report the vestibular abnormalities in 5 patients with the CHARGE association (Coloboma, Heart disease, Atresia of choanae, Retarded growth and development and/or central nervous system anomalies, Genital hypoplasia, and Ear anomalies). All patients had absent vestibular function as indicated by absent vestibulo-ocular reflexes and severe imbalance on simultaneous deprivation of proprioception and vision, as well as delayed motor development. All 6 semicircular canals were aplastic in each of the patients. While cochlear function was severely reduced in 6 of the 10 ears, it was absent only in 3 ears and was actually intact below 3 kHz in 1 ear. All 10 bony cochleas were present on computed tomography, and although 7 appeared abnormal, 3 appeared normal. This study confirms that absence of the bony semicircular canals in the presence of a bony cochlea is a characteristic finding in CHARGE association. It also demonstrates that these disproportionate structural abnormalities are reflected in the functional abnormalities: absent vestibular function with preservation of some cochlear function.

Clinical manifestations of CHARGE Association

The clinical literature regarding CHARGE Association is mostly retrospective in nature and deals largely with non-auditory issues related to the care and management of these patients with multisystem involvements. In this paper, we describe the clinical findings in 24 patients evaluated in the Division of Audiology and Electrophysiology at the University of Michigan Medical Center from 1983 to 1993. We report on the clinical manifestations of CHARGE Association in these patients with particular attention paid to their audiologic status. We discuss the relationships between auditory, ear, and craniofacial anomalies. Our review of these previously unreported cases suggests the following: (1) a variety of audiologic outcomes is possible, however, if a sensorineural or mixed hearing loss exists, it tends to be severe in degree; (2) progressive hearing loss does not appear to occur, but recurring otitis media is a probable confounding factor in the early identification of hearing loss; (3) congenital unresolved facial weakness may serve as a reliable predictor of sensorineural hearing loss; and (4) amplification use may be poor due to a number of factors. We hope to offer guidance to the professionals from assorted disciplines who participate in the care of these children.

Cranial nerve abnormalities in CHARGE association

Many children with the CHARGE association have facial paralysis and feeding and swallowing difficulties. Indeed, facial paralysis and pharyngeal incoordination may be important diagnostic indicators of CHARGE association [Davenport et al., 1986a; Mitchell et al., 1985]. We describe an individual with dysfunction of multiple cranial nerves (Möbius sequence) and CHARGE association, a previously unrecognized combination. Our review of 150 patients from the literature and 13 patients from this center with CHARGE association documented that dysfunction of cranial nerves is frequent in CHARGE association, and that often cranial nerve abnormalities are multiple. Such multiple cranial nerve abnormalities may be the primary underlying cause for the facial paralysis, feeding difficulties and sensorineural hearing loss seen in many individuals with CHARGE association.

Apparent CHARGE association and chromosome anomaly: chance or contiguous gene syndrome

This report concerns 2 unrelated patients with apparent CHARGE association and a chromosome abnormality, resulting from different unbalanced familial translocations involving chromosomes 2 and 18 in one family, and chromosomes 3 and 22 in the other. Although the identification of two different chromosome abnormalities might be due to chance, the observation of a long arm deletion of chromosome 22 in patients 2 and of the frequent coexistence of CHARGE association and DiGeorge anomaly raise the possibility of a contiguous gene syndrome in at least some CHARGE cases.

CHARGE association: clinical manifestations and developmental outcome

Mental retardation and growth failure are considered integral manifestations in the CHARGE association, reported to be present in as many as 90% of cases. Recent studies have reported a better than expected outcome in some patients; however, the conclusions of these studies have been confounded to some extent by their inclusion criteria. We report follow-up of 17 patients with CHARGE association in whom the diagnosis was based on clinical findings present in early infancy, before developmental patterns were established. Of the 7 survivors, all had motor delay, and 6 had feeding difficulties during infancy. Psychometric assessment at follow-up (age range 2 years, 10 months, to 15 years) showed that 2 were functioning in the normal range, 3 had specific language delay, one had moderate mental retardation, and one had severe mental retardation. Feeding problems persisted in only the 2 youngest patients. After initial failure to thrive, normal height was reached in 4 of 5 children older than age 3 years. The effects of visual and hearing deficits, their management, and the effects of physical illness are discussed with respect to developmental outcome. Our results suggest that some infants with CHARGE association who survive early infancy have a better prognosis for feeding difficulties, growth, and mental development than may be expected from early performance and better than that generally predicted from the current literature. The prompt management of sensory deficits is emphasized.

Central nervous system malformations in the CHARGE association

Of 144 patients with the CHARGE association (literature 136, new patients 8), 47 (33%) had either a postmortem examination (30) or computerized axial tomography scan (17) of the head. Twenty-six of 47 (55%) had definite central nervous system (CNS) malformations; arhinencephaly, with or without other defects (11), holoprosencephaly (2), holoprosencephaly with arhinencephaly (1), other forebrain defects (3), hindbrain defects (3), or other defects (6). The presence of CNS malformation was most strongly associated with choanal atresia. This review demonstrates a predominance of forebrain anomalies, particularly arhinencephaly and holoprosencephaly, which may provide a clue to the mechanism of abnormal morphogenesis involved in CHARGE association.