Large vestibular aqueduct syndrome (LVAS) is an increasingly recognized recessive hereditary hearing disorder that accounts for approximately 1-12% of sensorineural deafness in children and adolescents and presents as an enlarged vestibular aqueduct malformation, a relatively common malformation of the inner ear. Most scholars now believe that it is the result of arrested development of the vestibular aqueduct during the late fetal period and after birth. The large vestibular aqueduct syndrome was first studied and described by Valvassori and Clemis in 1978 as an autosomal recessive familial lesion. The disease is becoming more widely recognized with the increasing level of detection technology. It occurs in infants and children, and its main clinical manifestation is fluctuating sensorineural hearing loss, which may be accompanied by vertigo or tinnitus. Infants or toddlers often have hearing within the first few years of life, hearing loss has not yet appeared, cascade hearing loss occurs a few years after birth, i.e., hearing can heal spontaneously when it is mild or improve or get better after treatment, hearing is progressive over a longer period of time, progressive sensorineural deafness can be accelerated by minor head trauma or cold or fever most cases are bilateral sensorineural deafness, both ears The hearing loss is mostly asymmetrical and the degree of hearing loss is mostly moderately severe and very severe sensorineural hearing loss, so large vestibular conduction canal syndrome is a congenital inner ear malformation but manifests as acquired sensorineural deafness. CT and MRI are currently the main basis for the diagnosis of large vestibular aqueduct syndrome. I. Normal vestibular aqueduct CT imaging Under normal circumstances, at the level of the horizontal semicircular canal or the emergence of the common bony foot, small and shallow bony indentation or fine tubular hypointense shadow can be seen at the posterior edge of the rock cone, which is basically parallel to the posterior semicircular canal alignment (Figure 1), the outer mouth of the vestibular aqueduct is flattened and fissured, and the proximal segment of the vestibular aqueduct, i.e., the part close to the posterior medial part of the common bony foot, is more difficult to show on CT, and the distal inner diameter of the normal vestibular aqueduct The width of the distal end of the normal vestibular aqueduct is 0.4~1.0mm. The normal vestibular aqueduct shows a thin linear hypointense shadow (pointed by white arrow) Second, the CT manifestation of the enlarged vestibular aqueduct Some scholars believe that the measurement of the enlarged VA can be taken at two locations: the width of the inner diameter of the aqueduct at the midpoint (mp) between the external orifice of the vestibular aqueduct and the foot of the common bone, i.e. the maximum width of the middle segment of the vestibular aqueduct MDVA>1.5mm; or The width of the outer opening (op) of the vestibular aqueduct, i.e., the vertical distance from the bony crest of the vestibular aqueduct to the posterior lateral wall of the common bony pedicle ODVA >2.0 mm, can be diagnosed as enlarged vestibular aqueduct EVA (Figure 2). The midpoint of the vestibular aqueduct (mp) and the external opening (op) were considered as the threshold values for diagnosing EVA when the maximum width of the middle segment of the anterior aqueduct, MDVA, was 1.0-1.4 mm and the width of the external opening, ODVA, was 1.5-1.9 mm. When the maximum width of the mid vestibular aqueduct MDVA is less than 1.0 mm and the outer orifice width ODVA is less than 1.5 mm, the vestibular aqueduct can be diagnosed as normal. When the vestibular aqueduct is enlarged, a flared or conical bone defect with sharp and clear margins is seen at the posterior edge of the rock cone at the level of the horizontal semicircular canal or common pedicle, and the intra-periodic opening is mostly connected to the vestibule. Bilateral enlargement of vestibular aqueduct in the form of fissure Bilateral enlargement of vestibular aqueduct in the form of wide triangle with sharp and smooth edges C. CT manifestations of several special types of enlarged vestibular aqueduct 1. 4.The enlarged vestibular aqueduct was in the shape of “inverted fishhook” 5.The width of vestibular aqueduct was <1.5 mm, but the vestibular aqueduct could be observed to be connected with the common foot of the semicircular canal