A Pilot Study to Assess the Vestibular Apparatus Function with Videonystagmography During Chronic Otitis Media with Effusion

OBJECTIVE

To assess the effect of chronic middle ear effusion (CMEE) on balance and equilibrium.

MATERIAL AND METHODS

Prospective study controlling two groups of children. The active arm consisted of children having a unilateral or bilateral CMEE that persisted for at least 3 months. The control group consisted of children presenting with normal middle ear. Children and parents in both groups were questioned about any symptom of vertigo, dizziness, disequilibrium or child's tendency to fall. ENT exam included an assessment with pneumatic and microscopic otoscopy, evaluation of the vestibular system with the Romberg test, the Fukuda test, the head-shaking test and the Starwalk test.

RESULTS

The study group consisted of 15 children (mean = 6.5 years, SD = 2; 10 females and 5 males). The control group consisted also of 15 children (mean = 7.2 years, SD = 1.8; 8 females and 7 males). The duration of MEE was between 3 and 12 months (mean = 8 months). Three children (20%) in the study group had a history of vertigo, imbalance, disequilibrium and/or tendency to fall. None of the children in the control group had such a history (p = 0.22); Five children in the study group had abnormal head-shaking test, Fukuda and/or Starwalk tests (33.33%). Two children in the control group had such a finding (13.33%) (p = 0.39). Romberg test was normal in all children in both groups. In the study group, one child showed positional and spontaneous nystagmus on VNG testing. Another one showed positional nystagmus. Hence, 2 children had abnormal findings on VNG (13.33%). In the control group, VNG was normal in all children (p = 0.46). Tympanometry showed a type B curve in 26 ears, a type C curve in 3 ears and type A in one ear. In the control group all patients presented a type A curve.

CONCLUSION

This paper describes the first study using VNG in a population of children with CMEE. The presence of balance disturbances associated or not with hearing loss is of paramount importance to the clinician as to the indications of myringotomy with a tube intervention.

Down syndrome: an electrophysiological and radiological profile

OBJECTIVES/HYPOTHESIS

To assess the hearing status of trisomy 21 patients by analyzing electrophysiological and radiological findings of any correlation between hearing impairment and major or minor inner ear malformations.

STUDY DESIGN

Prospective radiological and electrophysiological study.

METHODS

A group of 34 ears of Down syndrome subjects and 20 ears of a volunteer age- and sex-matched control group of 10 normal subjects were studied electrophysiologically by means of otoacoustic emissions and auditory brainstem response. Temporal bone computed tomography (CT) scans were carried out in both groups; radiological findings were compared. Inner ear structure measurements were applied attempting to disclose subtle bony labyrinthine anomalies. The findings from both groups were statistically analyzed employing the t test.

RESULTS

The rate of sensorineural hearing loss (SNHL) in Down syndrome group was 41%. Temporal bone CT scans showed no ossicular malformation in all Down syndrome cases. Major inner ear abnormalities were disclosed in 5.8%; they corresponded to two cases of lateral semicircular canal dysplasia detected on CT images by visual inspection. The application of various inner ear structure measurements increased the overall detection rate of common inner ear malformations to 47%. A statistically significant correlation was found between hearing level and vestibule length (P = .009) and internal auditory canal length (P = .028). Vestibular aqueduct width was correlated to different otic abnormalities.

CONCLUSIONS

SNHL is mainly secondary to the underestimated subtle inner ear malformations that are adequately demonstrated by adopting standardized inner ear structure measurements on petrous bone imaging. Vestibular height and internal auditory canal length were correlated to SNHL.

LEVEL OF EVIDENCE

3b.

A mutation in OTOF, encoding otoferlin, a FER-1-like protein, causes DFNB9, a nonsyndromic form of deafness

Using a candidate gene approach, we identified a novel human gene, OTOF, underlying an autosomal recessive, nonsyndromic prelingual deafness, DFNB9. The same nonsense mutation was detected in four unrelated affected families of Lebanese origin. OTOF is the second member of a mammalian gene family related to Caenorhabditis elegans fer-1. It encodes a predicted cytosolic protein (of 1,230 aa) with three C2 domains and a single carboxy-terminal transmembrane domain. The sequence homologies and predicted structure of otoferlin, the protein encoded by OTOF, suggest its involvement in vesicle membrane fusion. In the inner ear, the expression of the orthologous mouse gene, mainly in the sensory hair cells, indicates that such a role could apply to synaptic vesicles.

An alpha-tectorin gene defect causes a newly identified autosomal recessive form of sensorineural pre-lingual non-syndromic deafness, DFNB21

In our efforts to identify new loci responsible for non-syndromic autosomal recessive forms of deafness, DFNB loci, we have pursued the analysis of large consanguineous affected families living in geographically isolated areas. Here, we report on the study of a Lebanese family comprising nine members presenting with a pre-lingual severe to profound sensorineural isolated form of deafness. Linkage analysis led to the characterization of a new locus, DFNB21, which was assigned to chromosome 11q23-25. Already mapped to this chromosomal region was TECTA. This gene encodes alpha-tectorin, a 2155 amino acid protein which is a component of the tectorial membrane. This gene recently has been shown to be responsible for a dominant form of deafness, DFNA8/12. Sequence analysis of the TECTA gene in the DFNB21-affected family revealed a G to A transition in the donor splice site (GT) of intron 9, predicted to lead to a truncated protein of 971 amino acids. This establishes that alpha-tectorin mutations can be responsible for both dominant and recessive forms of deafness. Comparison of the phenotype of the DFNB21 heterozygous carriers with that of DFNA8/12-affected individuals supports the hypothesis that the TECTA mutations which cause the dominant form of deafness have a dominant-negative effect. The present results provide genetic evidence for alpha-tectorin forming homo- or heteromeric structures.

Prelingual deafness: high prevalence of a 30delG mutation in the connexin 26 gene

Prelingual non-syndromic (isolated) deafness is the most frequent hereditary sensory defect. In >80% of the cases, the mode of transmission is autosomal recessive. To date, 14 loci have been identified for the recessive forms (DFNB loci). For two of them, DFNB1 and DFNB2, the genes responsible have been characterized; they encode connexin 26 and myosin VIIA, respectively. In order to evaluate the extent to which the connexin 26 gene (Cx26) contributes to prelingual deafness, we searched for mutations in this gene in 65 affected Caucasian families originating from various countries, mainly tunisia, France, New Zealand and the UK. Six of these families are consanguineous, and deafness was shown to be linked to the DFNB1 locus, 10 are small non consanguineous families in which the segregation of the trait has been found to be compatible with the involvement of DFNB1, and in the remaining 49 families no linkage analysis has been performed. A total of 62 mutant alleles in 39 families were identified. Therefore, mutations in Cx26 represent a major cause of recessively inherited prelingual deafness since according to the present results they would underlie approximately half of the cases. In addition, one specific mutation, 30delG, accounts for the majority (approximately 70%) of the Cx26 mutant alleles. It is therefore one of the most frequent disease mutations so far identified. Several lines of evidence indicate that the high prevalence of the 30delG mutation arises from a mutation hot spot rather than from a founder effect. Genetic counseling for prelingual deafness has been so far considerably impaired by the difficulty in distinguishing genetic and non genetic deafness in families presenting with a single deaf child. Based on the results presented here, the development of a simple molecular test could be designed which should be of considerable help.

A gene responsible for a sensorineural nonsyndromic recessive deafness maps to chromosome 2p22-23

The recessive mode of transmission accounts for approximately 75% of inherited non syndromic deafness cases. We have previously designed the conditions for linkage studies of this highly heterogeneous disorder [Guilford et al. (1994) Nature Genet. 6, 24-28]. Here, using a similar approach, we have studied the segregation of a gene responsible for congenital, profound and fully penetrant sensorineural deafness in a consanguineous family living in an isolated region of Lebanon. A maximum lod score of 8.03 (theta = 0.00) was detected with a new polymorphic marker, AFMa052yb5 (D2S2144). Observed recombinants and homozygosity mapping define a maximum interval of 2 cM for this gene, DFNB6, which lies between AFMb346ye5 (a new polymorphic marker) (D2S2303) and AFM254vc9 (D2S174) on chromosome 2p22-23.