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) 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 shocks 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 speech impairment may be present.
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: generally sensorineural deafness.
② Acoustic conduction resistance: to determine whether there is abnormality in the middle ear.
③ ABR, 40Hz AERP: for uncooperative people and infants.
(2) Vestibular function examination: Nystagmography with low or no response to cold and heat realization.
(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 >1.5 mm at the midpoint between the common vestibular pedicle and the opening of the vestibular aqueduct; the horizontal semicircular canal or the level of the common pedicle shows a deep and large triangular distinct bone defect shadow at the posterior edge of the rock valley; the triangular bottom is the anterior and posterior lip of the opening of the vestibular aqueduct “bone defect shadow “The edges are clear and sharp, and the internal opening is mostly in direct communication with the vestibule or common pedicle.
② MRI of the inner ear: when the enlarged endolymphatic sac is found in the T2-weighted image, and when there is a bar arc or ellipse on the surface of the bilateral cerebellar hemispheres, the enlarged vestibular aqueduct should be noted.
II. Treatment principles.
(1) Conservative treatment can be used when a rapid decrease in hearing occurs, to restore hearing as much as possible, and to strive for a longer period of time for the child to maintain a better hearing stage, which is beneficial to pediatric language development.
(2) Generally, comprehensive treatment is used, mainly to improve the inner ear microcirculation metabolism and membrane permeability, commonly used low-molecular dextrose, geranium to improve inner ear microcirculation, also used prednisone or dexamethasone anti-inflammatory, anti-edema treatment, the course of treatment for several weeks.
(3) Wearing hearing aids for moderate to severe hearing, and cochlear implants for very severe hearing.
(4) Strengthen speech training.
(5) Prevent head trauma.