Usher syndrome
Introduction
Introduction to Usher Syndrome Usher syndrome is also known as hereditary deafness - retinitis pigmentosa syndrome, retinitis pigmentosa - sensorineural deafness syndrome, deafness with retinitis pigmentosa syndrome. It is an autosomal recessive hereditary disease characterized by congenital sensorineural hearing loss, progressive retinitis pigmentosa, and visual impairment. It is genetically heterogeneous. In 1858, VonGraefe first discovered cases of deaf-mute retinitis pigmentosa. In 1914, British eye scientist Charles Usher investigated the incidence of deafness in people with retinitis pigmentosa, and first proposed that deafness-retinal pigmentation is associated with genetic factors. In 1972, Holland et al. officially named the disease as Usher syndrome. basic knowledge The proportion of illness: 0.0001--0.0005% Susceptible people: no specific population Mode of infection: non-infectious Complications: cataract
Cause
Cause of Usher syndrome
Pathogenesis
The pigment cells of the ear and retina are derived from the optic nerve, and the cochlea and vestibule have a common source of embryos. Therefore, it is speculated that the pathogenic gene system causes blindness by affecting the matrix necessary for hearing, balance, and vision. Immunological localization revealed that myoVIIA protein was expressed in the retinal pigment epithelium of guinea pig Corti inner and outer hair cells and adult rats. In situ hybridization revealed that the mRNA of myoVIIA was restricted to the sensory cells of the inner ear (cochlear and vestibular), while the supporting cells and cochlear nerve and vestibular nerve were supported. Then no mRNA of myoVIIA was found. In the hair cell development and function studies, the effects of myoVIIA were found to be: 1 involved in the development and maintenance of the villous hair bundle; 2 affecting the inner hair cells. Therefore, the mutation of myoVIIA gene causes development and dysfunction of the inner ear, which is characterized by sensorineural hearing loss and vestibular dysfunction.
pathology
The pathology of the humerus: In 1975, Belal found a cochlear basal vascular stenosis in a USIII type sacral autopsy. The hair cells were completely degenerated within 15 mm of the basal turn, and the spiral ganglia in the corresponding area was significantly reduced or even completely absent. Balloon sacs and elliptic sacs. The ampullary sputum cells were significantly reduced and the capsular membrane was normal. In 1984, Shinkawa and Nadol also found degeneration of basal transcranial cells in a USIII type tibia autopsy. The spiral ganglion was significantly reduced, the cochlear nerve was extensively degenerated, and the Corti support cells were also degenerated, but the vascular pattern, the cap membrane, and the ampullary sputum were all normal. Observation of the Usher syndrome mouse model confirmed that the inner ear felt epithelial ciliated bundles arranged irregularly.
Ocular pathology: retinal rod cells, cone cells were significantly reduced, nerve synapses were reduced, and autophagic vacuoles and autophagic filaments were found in the residual rod cells. Hunter et al. observed ultrastructural changes of retinal cilia in 10 patients with Usher syndrome (1 US I, 9 US II). The microtubule bipolar abnormalities of the recipient axis were 60%, and Barrong et al observed 1 US. II found that the number of ciliated microtubules accounted for 86%. Patients with retinitis pigmentosa have not found abnormal cilia structure. The sperm structure and function of patients with Usher syndrome showed that the sperm axis structure was abnormal, the sperm movement was reduced, and the movement speed was slowed down.
Prevention
Usher syndrome prevention
No relevant information.
Complication
Usher syndrome complications Complications cataract
1. Retinal pigmentation.
2. Cataracts.
Symptom
Usher syndrome symptoms common symptoms mental disorder vertigo deafness blind gait instability field of view narrowing visual field defect visual impairment green blind night blindness
Ear performance
Congenital binaural sensorineural hearing loss, some manifestations of sputum or hoarseness, accompanied by symptoms of vestibular dysfunction such as dizziness and gait instability. Romberg levies eyes (+), wide step base gait. The inner ear is generally normal. Mol observation of 25 patients with Usher syndrome by Moller et al showed that all patients developed normal inner ear and no brain stem or cerebellar atrophy. There was no bone abnormality in the CT scan of the tibia.
Ophthalmic performance
Clinically, night blindness is often the first symptom. The patient is slow to adapt to darkness, and it is difficult to walk under dark light or at night. The binocular vision gradually shrinks toward the center of the heart, and the early field of view has a ring-shaped defect, which gradually develops into a tube or a blind. Vision is progressively declining, early visual acuity is generally normal, and the visual field is still significantly reduced after the visual field is severely reduced. As the disease progresses further, the central vision is impaired, and half of the patients are completely blind after middle age. Late complicated cataract. Due to visual impairment in childhood, the macula loses its fixation function, and nystagmus often occurs. Some patients may also have red-green blindness and glaucoma.
Other performance
A small number of patients may also experience loss of olfactory or loss, mental retardation, abnormal EEG, and schizophrenia.
Examine
Usher syndrome check
Fundus examination: vaginal wax yellow atrophy, retinitis pigmentosa, typical pigmentation is osteoblast-like, atypical can be round or irregular. Retinal pigmentation begins in the equator and gradually expands to the periphery and center of the fundus; retinal vascular stenosis, especially in arterial stenosis.
Visual field examination: the early field of view of the annular defect, the blind spot range gradually expanded, the surrounding visual field degeneration, only 5 to 10 ° central field of view. Eventually the central field of vision is gradually lost, leading to total blindness.
Electroretinogram: In the early stage, there was dark adaptation abnormality, the threshold was increased, and most of the waveforms were not recorded. Low waves can be recorded with strong light stimulation and superimposed averaging techniques.
Electrooculogram: Reduce or even disappear.
Diagnosis
Diagnosis and differentiation of Usher syndrome
A typical congenital sensorineural deafness with progressive retinitis pigmentosa can diagnose Usher syndrome. Among them, progressive retinitis pigmentosa is necessary for the diagnosis of Usher syndrome. According to the hearing impairment, the vestibular response is different. The clinical classification of Usher syndrome is divided into three types. The difference in vestibular reaction is the most reliable standard for distinguishing type I and type II. The age of onset of retinitis pigmentosa and the age of diagnosis overlap in US I and US II, and cannot be used as an indicator to identify type I and type II. It has been observed that almost all patients with Usher syndrome have diffuse pigmentation, hypopigmentation, or coexistence in the retina after infancy. When retinal pigmentation is not found in ophthalmoscopy, electroretinogram must be performed. The electroretinogram should show a decrease in retinal response consistent with retinal dystrophy. Several authors have observed that patients with Usher syndrome between the ages of 2 and 3 have abnormal electroretinograms when their ophthalmoscopy has not been found abnormal. Clinically, when the Usher syndrome is highly suspected, the electroretinogram of preschool children can not completely rule out Usher syndrome even if it is normal. The electroretinogram should be reviewed after 6-12 months. With the development of retinal dystrophy, electroretinogram Gradually not recorded. If retinal degeneration is not found in both ophthalmoscopy and electroretinogram, the diagnosis of Usher syndrome cannot be made.
