Asymmetrical internal auditory canals. A normal variant

Enlarged vestibular aqueducts and other inner-ear abnormalities in patients with Down syndrome

BACKGROUND

Histopathological anomalies of inner-ear structures in individuals with Down syndrome have been well documented; however, few studies have examined the radiological features.

METHODS

A retrospective study was conducted of temporal bone computed tomography images in 38 individuals (75 ears) with Down syndrome to evaluate the prevalence of inner-ear abnormalities and assess vestibular aqueduct widths.

RESULTS

Inner-ear anomalies were identified in 20 of the 38 individuals (52.6 per cent). Seven of the 75 temporal bones (9.3 per cent) were found to have higher than previously reported. A dilated internal auditory canal and vestibule were more common among the present study group, while prior studies have demonstrated internal auditory canal stenosis and decreased vestibule size.

CONCLUSION

Down syndrome patients exhibit a high prevalence of dysplastic inner-ear features that confer substantial risk of sensorineural hearing loss. Computed tomography is a useful screening aid to detect inner-ear abnormalities, particularly enlarged vestibular aqueducts, which cause preventable sensorineural hearing loss in this population.

Hearing loss and enlarged internal auditory canal in children

INTRODUCTION

Among the temporal bone abnormalities that can be found in the etiological study of paediatric sensorineural hearing loss (SNHL) by imaging techniques, those related to the internal auditory canal (IAC) are the least frequent. The most prevalent of these abnormalities that is associated with SNHL is stenotic IAC due to its association with cochlear nerve deficiencies. Less frequent and less concomitant with SNHL is the finding of an enlarged IAC (>8mm).

METHODS

Retrospective and descriptive review of clinical associations, imaging, audiological patterns and treatment of 9 children with hearing loss and enlarged IAC in the period 1999 to 2012.

RESULTS

Two groups of patients are described. The first, without association with vestibulocochlear dysplasias, consisted of: 2 patients with SNHL without other temporal bone or systemic abnormalities, one with bilateral mixed HL from chromosome 18q deletion, one with a genetic X-linked DFN3 hearing loss, one with unilateral hearing loss in neurofibromatosis type 2 with bilateral acoustic neuroma, and one with unilateral hearing loss with cochlear nerve deficiency. The second group, with association with vestibulocochlear dysplasias, was comprised of: one patient with moderate bilateral mixed hearing loss in branchio-oto-renal syndrome, one with profound unilateral SNHL with recurrent meningitis, and another with profound bilateral SNHL with congenital hypothyroidism.

CONCLUSIONS

The presence of an enlarged IAC in children can be found in different clinical and audiological settings with relevancies that can range from life-threatening situations, such as recurrent meningitis, to isolated hearing loss with no other associations.

A screening protocol used for the detection of acoustic neuromas: a clinical evaluation

Screening for acoustic neuromas in large numbers of patients in whom the possibility exists should effectively select out the small proportion who have a tumour, prior to more definitive but costly radiological scanning techniques. A suitable screening protocol has been suggested using a combination of caloric testing, tomography of the internal auditory meati and evoked response audiometry. The protocol was applied retrospectively from the records of 64 patients with proven acoustic neuromas and found to predict correctly the presence of a tumour in 97% of cases. It is concluded that this combination of investigations constitutes an effective method of screening patients in whom an acoustic neuroma confined to the 8th nerve is suspected. The great importance of early diagnosis is that the operative mortality and morbidity is much less when the tumour removed is small.

Cerebellopontine pantopaque cisternography and tomography of the internal acoustic meatus in the diagnosis of angle tumors

The results of 106 consecutive Pantopaque cisternographies performed at the neuro-radiological department, Rigshospitalet, are presented. 41 positive and 65 negative examinations were found. Good accordance between radiological tumor size estimation and size of actual, surgically verified tumor was noted. A comparison between tomography of the internal auditory canal and pantopaque cisternography of the posterior fossa has been made, and we found 6 cases with normal tomography and positive cisternography. Furthermore 17 cases (26%) with pathological tomographic examination of internal auditory canal as well as a negative finding at Pantopaque cisternography, were encountered. Therefore we conclude that asymmetry of the radiological appearance of the internal auditory canal at tomography is not of decisive importance in the indication for cisternography, but the examination should be included in the test battery in search for cerebellopontine angle pathology. We agree with other authors that Pantopaque cisternography is without any doubt the final and most conclusive examination available for the diagnosis of cerebellopontine angle tumors. A system of grading the different objective findings giving indication for Pantopaque cisternography has been made.