Congenital degenerative cochleopathy: causes, symptoms, diagnosis, treatment

Congenital degenerative cochleopathy (congenital deafness) is caused by prenatal or intranatal pathogenic factors, manifested by deafness from the moment of birth. In most cases, the etiology of congenital deafness is not established, however, among the identified causes of this disease, the following are distinguished:

1. progenetic, or hereditary, deafness, accompanying many genetic anomalies of a somatic, humoral (metabolic) and functional nature (Dolowitz-Aldous, Edwards, Gardner-Turner, Nance, Richards-Randell, Wildervanck (I), Wolfe-Dolowitz-Aldous, Tsiprovski syndromes, etc.);
2. Metagenetic syndromes caused by:
   1. embryopathies of the first three months, during which the embryo's organs and systems are laid down, the causes of which may be intoxication and illness of the mother, especially infection with the rubella virus;
   2. embryopathies from the beginning of the 4th month of intrauterine life, caused by early congenital syphilis or Rh-conflict between the fetus and the pregnant mother, as a result of which degenerative-dystrophic changes may occur in many organs and systems of the body, including in the cochlear sac;
3. intranatal complications associated with pathological births, which may result in intracranial trauma to the newborn.

According to various authors, hereditary hearing loss in various genetically determined syndromes accounts for 40 to 60% of cases; cochleopathies caused by intranatal trauma - 11-15%, Rhesus conflict - 3-10%, rubella - 1-5%.

Hereditary hearing loss (deafness) is usually detected very early, when parents notice that the child does not respond to sounds and the mother's voice; sometimes several months pass before this defect manifests itself. The disease is more common in boys. The anatomical substrate is the nervous apparatus of the cochlea, while the bony capsule of the labyrinth remains normal. The SpO may be completely absent or preserved in a rudimentary form, the integumentary plate does not cover the receptor cells, the cochlear duct and saccule are flattened and reduced or, on the contrary, sharply enlarged. Degenerative changes in the spiral ganglion, nerve trunk and even auditory centers may also be observed. Usually, these pathological changes are bilateral. The vestibular apparatus remains intact, the function of the organ of balance is not changed.

Hearing loss (deafness) is perceptual in nature and irreversible. It is usually followed by dumbness. As a rule, hereditary forms of deafness are accompanied by other genetic anomalies, such as debility, amaurotic idiocy, pigment retinitis, albinism, etc. In some patients with idiocy, the ear labyrinth may be completely absent.

Intranatal trauma may be caused by a discrepancy between the size of the fetus and the size of the birth canal, the use of birth forceps, the occurrence of an intracranial hematoma, the overlapping of cranial bones and compression of the brain, etc., including “external” trauma to the abdomen of a pregnant woman.

Birth trauma to the fetus manifests itself in three forms:

1. the fetus is born in a state of clinical death (apnea, anoxia with dysfunction of the nerve centers);
2. detect fractures and cracks in the bones of the skull with damage to the membranes, brain matter and temporal bone (ear labyrinth);
3. The presence of an intracranial hematoma may manifest itself in signs of increased intracranial pressure, collapse, cyanosis, convulsions, and impaired thermoregulation. As a rule, intracranial hematomas end in death, otherwise many different encephalopathies develop subsequently. The resulting hearing loss is usually profound, does not progress, and causes muteness.

Rhesus conflict in 1/3 of cases leads to bilateral perceptual hearing loss of varying severity in the absence of recruitment. Threshold tonal audiograms have a descending type. Vestibular reactions can be normal, reduced or completely absent on one or both sides.

Deafness caused by rubella virus is a component of Gregg syndrome (congenital cataract, retinal anomalies, optic nerve atrophy, microphthalmos, nystagmus, deafness, various anomalies of the outer and middle ear, etc.) and is caused by a cessation of development of the cochlea structures, while the vestibular apparatus remains normal. Deafness is bilateral and irreversible. If hearing is partially preserved, early hearing aids are indicated to prevent mutism.

Prevention consists of isolating pregnant patients from other women in labor and conducting specific and non-specific immunotherapy.

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