Inner ear injuries: causes, symptoms, diagnosis, treatment

Injuries to the inner ear occur both in peacetime and in wartime. They are divided into gunshots, caused by cold weapons and sharp household items (knitting needles, pins, etc.), as well as injuries that occur by accidentally falling on a sharp object penetrating the drum cavity and injuring its medial wall. A special category of violations of the anatomical integrity of the ear maze is the intraoperative trauma prescribed by the treatment process or committed by negligence (the so-called iatrogenic trauma).

Pathological anatomy and pathogenesis. Injuries to the inner ear occur, as a rule, with gunshot and fragmentation wounds. Due to the fact that the ear maze is located deep at the base of the skull, its injuries are accompanied by significant destruction of the surrounding anatomical formations, most often incompatible with life. At shrapnel wounds, these disruptions are especially extensive and traumatic. Bullet wounds are deeper and often reach the deepest parts of the skull.

A bullet, passing through the ear maze, can cause a combined damage to the internal carotid artery, pre-collateral and cochlear nerves, brainstem, cerebellum, etc. In these cases, the general severe clinical picture masks specific labyrinthine disorders. Isolated gunshot wounds of the ear maze are extremely rare. With them, a complete deactivation of auditory and vestibular functions is observed, which in the first hours against a background of traumatic shock may not manifest itself. However, with the restoration of nervous activity and contact with the wounded, the signs of destruction of the ear maze manifest themselves clearly: complete deafness in one ear, repercussion loss of hearing on the contralateral ear, pronounced vestibular exclusion syndrome (spontaneous nystagmus in a healthy way, dizziness, coordination of movements, ataxia, nausea, vomiting).

When shot in the ear, produced for murder or suicide, the wound channel passes through the tympanic membrane, the medial wall of the tympanum, the ear maze and reaches the deep sections of the pyramid. With considerable kinetic energy, the bullet can penetrate into the middle cranial fossa. The wound channel can acquire various directions in a bullet wound, in which the phenomenon of rebound can play a role. When a wounding projectile sticks in the thickness of a pyramid, mastoid process or in other parts of the temporal bone, without harming large vessels and vital centers, injuries are usually not fatal.

Symptoms. In the first hours after injury, the victim is in a coma. On examination, paleness of the skin with an earthy tinge, co-respiration, a rare irregular pulse, dilated pupils slightly reacting to light, palpable blood clots, and bleeding from the external auditory canal are revealed. When shooting from a close distance (less than 1 m) on the skin of the side face there are traces of soot, powder particles, burn marks. The walls of the external auditory canal are bruised, partially crushed, the tissues surrounding the external aperture of the external auditory canal, pale blue, edematous, partially damaged.

Symptoms of injuring the ear maze are manifested when the victim leaves the unconscious state and restores the reflex activity of the central nervous system. In the first hours there may be complete deafness and pronounced vestibular symptoms of the maze turning off, which, however, do not indicate a degree of damage to the ear maze. In the absence of anatomic damage to the cochlea, but with its concussion or concussion, there is a different degree of deafness or even deafness, the dynamics of which can later be directed either to deterioration of the hearing, to its complete shutdown, or to some improvement with stabilization on some degree of deafness. With the appropriate condition of the patient, a hearing test is conducted with live speech, tuning forks and tonal threshold audiometry.

The wounding of the vestibular apparatus leads to its complete exclusion with the development of a turbulent vestibulo-vegetative syndrome, which gradually develops as the patient leaves the co-morbid state and restores reflex activity. In this case, spontaneous nystagmus and dizziness directed to the healthy ear, misses when pointing toward the wounded ear, provocative vestibular tests with sparing rotational techniques are allowed only after 2-3 weeks with a satisfactory state of the patient. Caloric samples are possible only by air calorization with the corresponding state of the external auditory canal.

With a favorable course of the wound process and no damage to the vital centers and large vessels, the clinical recovery of the affected person occurs within a period of 1 to 3 months. The patient's condition deteriorates sharply in the presence of complications injuring the ear maze. These complications can be immediate, delayed, late and distant.

Complications. Immediate: bleeding from large vessels (internal carotid artery, jugular vein bulb, sigmoid sinus), paralysis of the facial nerve, wounds of nerves of the scrotal fascicule 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, occipital lobes, early osteomyelitis of the bones of the temporal bone, purulent inflammation of the parotid salivary gland.

Late: chronic posttraumatic otomastoiditis, temporal bone osteomyelitis, arachnoiditis of MMU, arthrosoarthritis of temporomandibular joint, fistulas of parotid salivary gland.

Remote: various anatomical defects in the area of the external, middle and inner ear, persistent disturbances of auditory and vestibular analyzers by type of hypofunction, posttraumatic neuritis of nerves of the scrotal fasciculus and caudal group.

Treatment of wounds of the ear maze is a complex, lengthy process, in the overwhelming majority of cases, unsuccessful with respect to the auditory function.

First aid is to apply a dry sterile dressing to the wound or wounded ear area. In case of violation of vital functions - the introduction of appropriate drugs, as well as the use of funds designed to combat traumatic shock. Urgent evacuation to the neurosurgical hospital, in which the wounded are provided with a reanimation aid and diagnosed. In the presence of a wounding projectile in the temporal bone region that does not penetrate into the cranial cavity (it is established by the CT method), and in the absence of contraindications from the general condition, the victim is provided with specialized otosurgical assistance in an ENT hospital whose main purpose is to remove the foreign body. As for the further tactics of surgical intervention, it is dictated by the nature of the wound. Its main principle is to prevent intracranial complications (open wound management, effective drainage, and massive use of antibiotics).

Intraoperative trauma of the labyrinth. The intraoperative lesions of the labyrinth are divided into "planned", or intentional, and random. The first pursue therapeutic goals, for example, in the surgical treatment of Ménière's disease, the latter arise unintentionally, through carelessness, as a result of an accidental doctor's mistake.

Accidental intraoperative trauma is a relatively rare phenomenon that occurs with various surgical interventions in the middle ear and in the paracentesis of the tympanic membrane. Of the possible complications of paracentesis, it should be noted the wounding of the bulb of the jugular vein, the medial wall of the tympanic cavity and the facial nerve that passes through it, the violation of the integrity of the anvil, the subluxation of the stapes. In the latter case, there is a sharp noise in the ear and sudden deafness to it, as well as severe dizziness, spontaneous nystagmus and imbalance. When the protruding part of the lateral semicircular canal is injured, for example, when manipulating the chisel or milling cutter at the end of the "spur" when operated under local anesthesia, there is a sharp dizziness and motor reaction due to a sudden feeling of falling from the operating table, while a spontaneous nystagmus of the third degree in the direction of the operated ear. The appearance of these symptoms during paracentesis or other manipulations in the middle ear certainly indicates the penetration of the wounding instrument into the perilymphatic space, or, if a chisel was applied, about the occurrence of a crack in the cape or arc of the lateral semicircular canal.

Most often, intraoperative injuries occur during the so-called repositioning of fragments when removing the lateral wall of the above-drum depression, the "bridge" formed at the opening of the cavernous mastoid and forming part of the back wall of the external auditory canal, removing the "Bohona tooth", and smoothing the spurs of the facial nerve. The emergence of intraoperative injuries should not serve as an excuse for stopping the operation, on the contrary, the intervention to purulent inflammation of the middle ear should be completed, as this minimizes the possibility of complications from the inner ear. Often, in the presence of chronic phlegmon and the ingrowth of cholesteatoma, granulation or fibrous tissue into it, active manipulation of suction or ear root can lead to rupture of the membranous labyrinth, which is welded to these pathological tissues.

If intraoperative labyrinthine injuries occur during the operation on the "purulent" ear, four rules must be observed:

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

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

The treatment of intraoperative labyrinthine traumas is determined by a specific clinical case and is aimed primarily at arresting an acute labyrinthine traumatic syndrome and preventing the development of labyrinthitis and intracranial complications.

[1], [2], [3]