Injuries of the inner ear: causes, symptoms, diagnosis, treatment

Inner ear injuries occur both in peacetime and in wartime. They are divided into gunshot wounds, caused by cold arms and sharp household objects (knitting needles, pins, etc.), as well as injuries that occur when accidentally falling on a sharp object that penetrates the tympanic cavity and injures its medial wall. A special category of violations of the anatomical integrity of the ear labyrinth is intraoperative trauma, provided for by the treatment process or committed through negligence (the so-called iatrogenic trauma).

Pathological anatomy and pathogenesis. Inner ear wounds usually occur with gunshot and shrapnel wounds. Due to the fact that the ear labyrinth is located deep at the base of the skull, its wounds are accompanied by significant destruction of the surrounding anatomical structures, most often incompatible with life. In shrapnel wounds, this destruction is especially extensive and traumatic. Bullet wounds are deeper and often reach the deepest parts of the skull.

A bullet passing through the ear labyrinth can cause combined damage to the internal carotid artery, vestibulocochlear and facial nerves, brainstem, cerebellum, etc. In these cases, the overall severe clinical picture masks specific labyrinthine disorders. Isolated gunshot wounds to the ear labyrinth are extremely rare. They are characterized by complete shutdown of the auditory and vestibular functions, which may not manifest itself in the first hours against the background of traumatic shock. However, when restoring nervous activity and contact with the wounded, signs of destruction of the ear labyrinth are clearly visible: complete deafness in one ear, repercussion hearing loss in the contralateral ear, pronounced vestibular shutdown syndrome (spontaneous nystagmus in the healthy side, dizziness, impaired coordination of movements, ataxia, nausea, vomiting).

When a shot is fired into the ear for murder or suicide, the wound channel passes through the eardrum, the medial wall of the tympanic cavity, the ear labyrinth and reaches the deep sections of the pyramid. With significant kinetic energy, the bullet can penetrate the middle cranial fossa. The wound channel with a bullet wound can take different directions, in which the phenomenon of ricochet can play a certain role. When the wounding projectile gets stuck in the thickness of the pyramid, the mastoid process or in other parts of the temporal bone, without causing damage to large vessels and vital centers, the wounds are most often not fatal.

Symptoms. In the first hours after the injury, the victim is in a comatose state. Upon examination, pale skin with an earthy tint, soporous breathing, a rare irregular pulse, dilated pupils that react weakly to light, blood clots in the auricle area, and bleeding from the external auditory canal are revealed. When shot at close range (less than 1 m), there are traces of soot, powder particles, and scorch marks on the skin of the lateral surface of the face. The walls of the external auditory canal are bruised, partially crushed, the tissues surrounding the external opening of the external auditory canal are pale-blue, edematous, and partially damaged.

Symptoms of injury to the ear labyrinth appear when the victim comes out of unconsciousness and the reflex activity of the central nervous system is restored. In the first hours, complete deafness and pronounced vestibular symptoms of labyrinth shutdown may be observed, which, however, do not indicate the degree of damage to the ear labyrinth. In the absence of anatomical damage to the cochlea, but in the presence of its contusion or contusion, varying degrees of hearing loss or even deafness are observed, the dynamics of which can subsequently be directed either towards hearing deterioration, up to its complete shutdown, or towards some improvement with stabilization at a certain degree of hearing loss. In the appropriate condition of the patient, hearing is examined using live speech, tuning forks and tonal threshold audiometry.

Injury to the vestibular apparatus leads to its complete shutdown with the development of a violent vestibular-vegetative syndrome, which develops gradually as the victim emerges from the soporous state and reflex activity is restored. In this case, spontaneous nystagmus and dizziness directed toward the healthy ear are detected, as well as missing the pointer in the direction of the injured ear. Provocative vestibular tests using gentle rotational techniques are allowed only after 2-3 weeks if the patient's condition is satisfactory. Caloric tests are possible only by the air calorization method with the corresponding condition of the external auditory canal.

With a favorable course of the wound process and the absence of damage to vital centers and large vessels, the clinical recovery of the victim occurs within 1 to 3 months. The patient's condition deteriorates sharply in the presence of complications of the injury to the ear labyrinth. These complications, according to the time of occurrence, can be immediate, delayed, late and remote.

Complications. Direct: bleeding from large vessels (internal carotid artery, jugular bulb, sigmoid sinus), facial nerve paralysis, injuries to the nerves of the auditory-facial bundle in the MMU.

Delayed: chondroperichondritis of the auricle and membranous-cartilaginous part of the external auditory canal, purulent meningitis and meningoencephalitis, labyrinthitis, thrombosis of the sigmoid sinus, abscess of the temporal and occipital lobes, early osteomyelitis of the temporal bones, purulent inflammation of the parotid salivary gland.

Late: chronic post-traumatic otomastoiditis, osteomyelitis of the temporal bone, arachnoiditis of the temporomandibular joint, arthrosis of the temporomandibular joint, fistulas of the parotid salivary gland.

Remote: various anatomical defects in the area of the outer, middle and inner ear, persistent disorders of the auditory and vestibular analyzers such as hypofunction, post-traumatic neuritis of the nerves of the auditory-facial bundle and caudal group.

Treatment of injuries to the ear labyrinth is a complex, lengthy process, and in the vast majority of cases, unsuccessful in terms of hearing function.

First aid consists of applying a dry sterile dressing to the wound or injured ear area. In case of disruption of vital functions - administration of appropriate drugs, as well as the use of means aimed at combating traumatic shock. Urgent evacuation to a neurosurgical hospital, where the wounded person is given resuscitation assistance and a diagnosis is established. If there is a wounding projectile in the area of the temporal bone, not penetrating the cranial cavity (established by the CT method), and in the absence of contraindications from the general condition, the victim is given specialized otosurgical care in an ENT hospital, the main goal of which is to remove the foreign body. As for the further tactics of surgical intervention, it is dictated by the nature of the injury. Its main principle is the prevention of intracranial complications (open wound management, its effective drainage and massive use of antibiotics).

Intraoperative labyrinth trauma. Intraoperative labyrinth traumas are divided into "planned", or intentional, and accidental. The former are intended for therapeutic purposes, for example, in the surgical treatment of Meniere's disease, the latter occur unintentionally, through carelessness, as a result of an accidental error by the doctor.

Accidental intraoperative injuries are a relatively rare occurrence that occur during various surgical interventions on the middle ear and during paracentesis of the tympanic membrane. Possible complications during paracentesis include injury to the high jugular bulb, the medial wall of the tympanic cavity and the facial nerve passing through it, disruption of the integrity of the incudostapedial joint, and subluxation of the base of the stapes. In the latter case, a sharp noise in the ear and sudden deafness to it occur, as well as severe dizziness, spontaneous nystagmus and imbalance. When the protruding part of the lateral semicircular canal is injured, for example, when manipulating a chisel or burr on the end of a "spur" during surgery under local anesthesia, severe dizziness and a motor reaction occur due to the patient suddenly feeling as if he or she is falling from the operating table, with spontaneous nystagmus of grade III being detected towards the ear being operated on. The occurrence of the above symptoms during paracentesis or other manipulations on the middle ear certainly indicates the penetration of the wounding instrument into the perilymphatic space or, if a chisel was used, the occurrence of a crack in the area of the promontory or arch of the lateral semicircular canal.

Most often, intraoperative injuries occur during the so-called reposition of fragments when removing the lateral wall of the epitympanic recess, the "bridge" formed when opening the mastoid cave and being part of the posterior wall of the external auditory canal, removing the "Bochon tooth", smoothing the facial nerve spur. The occurrence of intraoperative injuries should not be a reason to stop the operation, on the contrary, the intervention carried out for purulent inflammation of the middle ear must be completed, since this is what minimizes the possibility of complications from the inner ear. Often, in the presence of chronic phlegmon and ingrowth of cholesteatoma, granulation or fibrous tissue, active manipulation with suction or ear forceps can lead to a rupture of the membranous labyrinth fused with the said pathological tissues.

If intraoperative labyrinth injuries occur during surgery on a “purulent” ear, four rules must be followed:

1. radical removal of pathological tissue;
2. isolation of the injured area of the labyrinth with autoplastic material;
3. effective drainage of the postoperative cavity.
4. intensive use of antibiotics.

Intentional intraoperative labyrinth injuries are caused by the purpose of surgical intervention to achieve a certain therapeutic effect. Such intraoperative injuries include, for example, opening the lateral semicircular canal during fenestration, perforation of the base of the stapes during stapedoplasty, a number of effects (mechanical, ultrasound, alcohol, etc.) aimed at destroying the labyrinth in Meniere's disease.

Treatment of intraoperative labyrinth injuries is determined by the specific clinical case and is aimed primarily at relieving the acute labyrinthine traumatic syndrome and preventing the development of labyrinthitis and intracranial complications.

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