The enlarged vestibular aqueduct is more common among inner ear malformations, and is often combined with cochlear or vestibular malformations, but there are also cases with simple enlargement of the vestibular aqueduct, the latter being called large vestibular aqueduct syndrome, which is mostly seen with bilateral enlargement of the vestibular aqueduct.
I. Diagnostic criteria.
1, clinical manifestations
(1) Medical history: hearing loss, delayed speech development, sudden hearing loss, progressive or fluctuating hearing changes, bilateral hearing loss is often asymmetric. It may be accompanied by episodes of vertigo. Some patients have a history of aggravation of deafness induced by shock or trauma to the head.
(2) , Signs and symptoms.
① , Deafness is mostly in early childhood. It is a progressive aggravation that appears later in life, often with fluctuating hearing loss, mostly bilateral. Hearing variability ranges from normal to profound deafness, and severe cases may have speech impairment.
②, About 1/3 of patients complain of vestibular symptoms, vertigo attacks with balance disorders and ataxia.
2.Auxiliary examinations.
(1), Audiological examination.
(1) Pure tone audiometry: usually sensorineural deafness.
(2) Acoustic conductance: to determine whether there are abnormalities in the middle ear.
③, ABR, 40Hz AERP: for uncooperative people and infants.
(2) , Vestibular function examination: low or no response to cold and heat realization of nystagmography.
(3) , Imaging examinations.
(1) High-resolution thin-layer CT scan of temporal bone: axial CT scan shows the diameter of the vestibular aqueduct, the maximum canal width >1.5mm at the midpoint between the common vestibular pedicle and the opening of the vestibular aqueduct; the horizontal semicircular canal or common pedicle level shows a deep and large triangular-shaped obvious bone defect shadow at the posterior edge of the valley; the triangular base is the anterior and posterior lip of the opening of the vestibular aqueduct “bone defect shadow “The edges are clear and sharp, and the inner mouth is mostly in direct communication with the vestibule or common pedicle.
②, inner ear MRI: endolymphatic sac is found to be enlarged in T2-weighted image, and when there is a bar arc or ellipsoid on the surface of bilateral cerebellar hemispheres, the enlarged vestibular aqueduct should be noted.
II. Treatment principles.
(1), the hearing occurs when the rapid decline can be used conservative treatment, as far as possible to restore hearing, and strive for the child to have a longer period of time to maintain a better hearing stage, so that the child’s language development is beneficial.
(2), the general use of comprehensive treatment, mainly to improve the inner ear microcirculation metabolism and membrane permeability, commonly used low-molecular dextrose, geranium to improve the inner ear microcirculation, also used prednisone or dexamethasone anti-inflammatory, anti edema treatment, the course of treatment for several weeks.
(3) Wear hearing aids for moderate to severe hearing, and perform cochlear implantation for very severe hearing.
(4) Strengthen speech training.
(5) Prevent head trauma.