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Genomics and Hearing Loss: Toward a New Standard of Care?
Published in Stavros Hatzopoulos, Andrea Ciorba, Mark Krumm, Advances in Audiology and Hearing Science, 2020
The initial evaluation for the differential diagnosis of hearing loss usually includes a detailed family history, clinical examination, comprehensive audiology test, imaging studies before genetic testing. When possible, a three-generation family history with attention to other relatives with hearing loss and associated findings is obtained. The search of relevant findings in relatives is accomplished either through direct examination or through review of their medical records, including audiology testing and molecular genetic testing, if performed previously. The clinical examination of patients with hearing loss of unknown cause aims at evaluating the presence of features associated with syndromic deafness. Because variable expressivity is common among several syndromes with deafness, the correct diagnosis may depend on molecular genetic testing. The audiology testing includes tympanometry, middle ear muscle reflexes, otoacoustic emissions, behavioral testing, and auditory evoked potentials. Individuals presenting with progressive hearing loss should be evaluated for several syndromes, such as Pendred and Stickler syndromes. Imaging studies of the temporal bone should be considered to evaluate for the presence of an enlarged vestibular aqueduct, cochlear nerve deficiency or other inner ear anomalies. Finally, in cases of apparent nonsyndromic sensorineural hearing loss, genetic testing should be obtained.
Balance Disorders in Children
Published in John C Watkinson, Raymond W Clarke, Christopher P Aldren, Doris-Eva Bamiou, Raymond W Clarke, Richard M Irving, Haytham Kubba, Shakeel R Saeed, Paediatrics, The Ear, Skull Base, 2018
Louisa Murdin, Gavin A.J. Morrison
Enlarged vestibular aqueduct syndrome is a rare congenital anomaly; vestibular disturbance is uncommon but is seen in 4% of children. Fluctuant and progressive sensorineural hearing loss is the norm and is bilateral in 87% of cases. A vestibular aqueduct radiologically wider than 1.5 mm at its midpoint or wider than 2 mm at the operculum is defined as enlarged.28 Most patients maintain stable hearing in at least one ear over a 4-year period. It can occur in non-syndromic conditions but is also found in 50% of patients with Waardenburg syndrome (types 1 and 2), in which there may be significant widening of the vestibular aqueduct at its midpoint together with other temporal bone anomalies.29 These children tend to have profound or severe hearing loss. Up to 30% of children with Waardenburg syndrome have vestibular impairment and some experience episodic vertigo. Enlarged vestibular aqueduct syndrome is also seen in Pendred and the branchio-otorenal syndromes, often with an associated Mondini deformity in the former. Patients with enlarged vestibular aqueduct syndrome may show an autosomal recessive inheritance (see Chapter 10, Management of the hearing impaired child).30
Case 40
Published in Simon Lloyd, Manohar Bance, Jayesh Doshi, ENT Medicine and Surgery, 2018
Simon Lloyd, Manohar Bance, Jayesh Doshi
Several conditions can cause a conductive hearing loss with preserved stapedial reflexes. The simplest cause is a calibration error in the bone or air conduction transducers. In this situation, the stimulation level of the bone or air conduction transducer is not accurately reported on the audiometer reading, and it can artefactually appear that the air and bone conductions thresholds are different, when in fact they are not. Calibration errors typically manifest as a milda mild conductive hearing loss, and miscalibration seen to the extent shown here would be very unusual. Other causes are fracture or loss of the stapes suprastructure medial to the insertion of the stapedius tendon. In this case, stapedius contraction is able to cause stiffening of the incus/malleus/eardrum but the loss of suprastructure results in failure of transmission of this stiffening to the stapes footplate. A more common cause to consider in clinical practice is superior canal dehiscence (SCD). This can cause a conductive hearing loss which can be marked and can resemble the audiogram in otosclerosis. Most often, however, SCD cause a “pseudoconductive” hearing loss only in the low frequencies on audiometry, partly caused by better than normal bone conduction hearing thresholds (e.g. thresholds at −10dB HL), and slightly reduced air conduction hearing thresholds. Other inner ear abnormalities such as x-linked stapes gusher syndrome and enlarged vestibular aqueduct can cause a non-middle ear related hearing loss. In these cases it is thought that the pressure in the vestibule exerted on the stapes footplate acts to stiffen it and increase its mechanical input impedance, similar to stiffening of the annular ligament in otosclerosis. Non-organic hearing loss, in which a subject is falsifying their true hearing thresholds can also cause a mismatch in the air and bone conduction hearing thresholds manifesting as an air-bone gap. Sometimes this can even be a reversed air-bone gap, with air conduction better than bone conduction.
Longitudinal assessment of listening skills in UK infants with hearing aids using the LittlEARS® auditory questionnaire
Published in International Journal of Audiology, 2023
Anisa Sadru Visram, Suzanne Carolyn Purdy, Jack Kelly, Kevin James Munro
In total eight infants showed scores that decreased, in absolute terms, over time. Of these, four had profound losses, and could perhaps represent over-optimistic scoring at the initial time point. Two infants (one mild-moderate and one severe loss) were within/above the normative range at both time points. Of the remaining two cases, one had a mild underlying loss, and has been discussed above as a case significantly affected by otitis media with conductive overlay. The remaining case had a mild-moderate loss with their score decreasing by 3 points, to outside the normative range. This infant was diagnosed with enlarged vestibular aqueduct which is associated with progressive/variable loss. Clinical audiometric results did not indicate a progressive loss between the two test sessions, but it is possible that the infant was negatively impacted by variable loss.
Is routine preoperative computed tomography imaging justified in otosclerosis? A retrospective single-centre analysis
Published in Hearing, Balance and Communication, 2022
Mohamed Bassiouni, Hans-Christian Bauknecht, Katharina Stölzel, Steffen Dommerich, Heidi Olze
Nevertheless, it is undeniable that preoperative CT scanning is useful for surgical planning, which explains its increasingly widespread use even in straightforward cases. CT imaging may help to avoid complications, since it can detect rare anatomical variants preoperatively (such as persistent stapedial artery, enlarged vestibular aqueduct, or dehiscent jugular bulb) [15]. This is especially relevant in cases of superior canal dehiscence or enlarged vestibular aqueduct, since the history may not always provide clues of the underlying diagnosis, but a preoperative scan may greatly influence the decision to operate. However, the main question here is whether its value in those rare cases justifies routine preoperative imaging in every case, especially when taking into account the associated risks of radiation exposure. We propose that preoperative CT imaging should not be routinely recommended for all cases, but rather selectively performed. We suggest that preoperative imaging should still be offered to patients, even in straightforward cases, to provide them with the best preoperative counselling. For instance, the surgical treatment of otosclerosis is markedly different from that of epitympanic incus ankylosis, and some patients would understandably wish to know the underlying diagnosis before surgery, because of the considerably different counselling and consent details regarding the audiological outcomes and complication rates of those two surgical procedures. Such patients should be offered a preoperative CT scan, but should be made aware of the added risks of ionising radiation exposure.
Enlargement of the vestibular aqueduct at cone-beam CT: ELST or EVA?
Published in Hearing, Balance and Communication, 2020
Davide Brotto, Federica Sartorato
First described by Cotunnius in 1761 [1], the vestibular aqueduct (VA) is a bone canal localized in the temporal bone and is considered a part of the bony labyrinth. Its orifice can be found at the hinder part of the medial wall of the vestibule. With a posterosuperior direction, the VA extends towards the posteromedial surface of the petrous portion of the temporal bone [2]. The canal is known to host an outpouch of the membranous labyrinth, the ductus endolymphaticus, ending in a cul-de-sac between the layers of the dura mater within the cranial cavity, the endolymphatic sac [2]. On the contrary, the belief that a vessel is hosted in the canal is quite widespread, although it was proven to be false [3]. As a matter of fact, the vein of the vestibular aqueduct (VVA) was correctly described by Cotugno in 1761 [1] and by Siebenmann in 1894 [4]: the VVA takes an individual bony course parallel to the VA [3]. As a consequence of the above mentioned anatomical relationships, pathologies causing abnormalities of the VA are the abnormal embryological development or the acquired degeneration of the ductus endolymphaticus and/or the endolymphatic sac. The congenital bulging of the endolymphatic sac is supposed to cause the enlarged vestibular aqueduct (EVA), the most frequent malformative cause of hearing loss [5]. On the other hand, a neoplastic degeneration of the cells of the endolymphatic sac is the cause of the development of the endolymphatic sac tumor (ELST) [6].