Injuries to the Middle and Inner Ear: Symptoms, Diagnosis, and Treatment

Injuries of the middle and inner ear are anatomical and functional damage to the structures of the middle and/or inner ear caused by a pathological force and resulting in hearing loss or vestibular disorders. A common cause of these conditions is mechanical, acoustic, or pressure-related trauma. The pathological process may involve the tympanic membrane, ossicular chain, oval and round windows, bony labyrinth capsule, and temporal bone. Clinically, these injuries manifest as conductive, sensorineural, or mixed hearing loss, tinnitus, and vestibular disturbances.

Main types of middle and inner ear injuries:

• Traumatic perforation of the tympanic membrane — disruption of the integrity of the tympanic membrane caused by external impact and accompanied by hearing loss;
• Ossicular chain injury — a pathological condition in which the integrity of the ossicular chain is disrupted, leading to impaired sound transmission to the structures of the inner ear;
• Hemotympanum — accumulation of blood in the tympanic cavity with an intact tympanic membrane;
• Temporal bone petrous portion fracture — disruption of the anatomical integrity of the temporal bone caused by mechanical force, resulting in damage to the structures located within the petrous portion;
• Posttraumatic mastoiditis — inflammatory changes in the mucous membrane and bone tissue of the mastoid process developing as a consequence of trauma.

Classification of Middle and Inner Ear Injuries

Middle ear injuries

The following types of injuries are classified as middle ear injuries:

• Traumatic perforation of the tympanic membrane:

• central;
• marginal;
• total;

• hemotimpanum;
• damage to the chain of the auditory ossicles:
• fracture of the anvil-stem joint;
• Incudostapedial joint disruption;
• Stapes dislocation;
• hammer fracture;
• anvil fracture;
• Stapes fracture.

Injuries to the inner ear

Inner ear injuries include:

• Fractures of the petrous portion of the temporal bone:

• longitudinal;
• transverse.

Other Injuries

Other injuries include posttraumatic mastoiditis.

Etiology

All middle and inner ear injuries occur as a result of exposure to an external pathological factor. The most common causes are motor vehicle accidents, as well as injuries caused by the use of inappropriate objects for cleaning the ear canal or by foreign body penetration. Tympanic membrane perforation and ossicular chain injury may result from a sudden changes in pressure within the ear canal — known as barotrauma (a blow to the ear, a kiss, rapid submersion underwater, or rapid ascent), as well as from the head striking hard objects. Cases of ossicular chain dislocation during middle ear surgery or paracentesis are extremely rare.

Hemotympanum may be triggered by severe coughing or sneezing due to rupture of small blood vessels in the mucosa of the tympanic cavity. This condition can also occur after posterior nasopharyngeal tamponade for massive bleeding or adenotomy. In addition, hemotympanum may be a manifestation of a temporal bone petrous portion fracture.

Temporal bone fractures are a specific type of skull base fracture. In addition to road traffic accidents, the leading cause is fights, beatings. Longitudinal fractures occur when force is applied to the temporal region on the affected side, whereas transverse fractures occur with mechanical impact to the frontal or occipital region. It should be noted that all the mentioned types of injuries may occur in combination.

If diagnosis is insufficient or delayed, or adequate treatment is not provided in the presence of the above conditions, posttraumatic mastoiditis may develop. This occurs due to the introduction of pathogenic microflora from the nasopharynx or through a perforated tympanic membrane.

Anatomy

Traumatic Perforation of the Tympanic Membrane

Traumatic perforation of the tympanic membrane is characterized by disruption of the integrity of all of its layers: epithelial, fibrous, and mucosal. A hole is formed at the site of the lesion, along the edges of which hemorrhagic drips are determined, and blood is found in the external auditory canal. In cases of temporal bone injury, leakage of cerebrospinal fluid (otoliquorrea) may also be observed.

The location and size of the perforation are important to select the appropriate patient management strategy.

Based on location, perforations are classified as:

• Central — located in the tense portion of the tympanic membrane (most commonly in the anteroinferior quadrant) and do not involve the tympanic annulus;

• Marginal — located in the flaccid portion of the tympanic membrane (posterosuperior quadrant) and extend to the tympanic annulus. They may be round or slit-like;
• Total — the defect involves almost the entire area of the tympanic membrane, while small flaps usually remain at the periphery and are typically folded inward into the middle ear cavity.

Even with small tympanic membrane injuries, ossicular dislocations may occur. Traumatic perforation in the posterosuperior quadrant is frequently associated with disruption of the ossicular chain.

Hemotimpanum

In hemotympanum, the tympanic membrane remains intact, while hemorrhagic fluid accumulates within the tympanic cavity. Consequently, the tympanic membrane may appear cyanopurplish and even protrude into the auditory canal lumen.

Sources of hemorrhage:

• Traumatized vessels of the tympanic cavity mucosa;
• Blood entering the middle ear through the auditory tube from the nasal cavity or nasopharynx (after surgical procedures or nasal bleeding);
• Blood entering the tympanic cavity due to a temporal bone fracture.

Damage to the chain of the auditory ossicles

Disruptions of the ossicular joints occur more frequently than fractures and may develop either in combination with traumatic perforation of the tympanic membrane or independently.

The most common ossicular chain injuries:

• Incudostapedial joint disruption (most commonly occurs after blunt or penetrating trauma to the middle ear);
• Incudomalleolar joint dislocation (ranks second in frequency among injuries; this joint is better protected by the epitympanic recess);
• Stapes dislocation from the oval window of the vestibule (with rupture of the annular ligament that fixes the stapes to the bony labyrinth).

The incus is the heaviest of the three middle ear ossicles and is supported by two weak ligaments; therefore, it is more commonly subject to dislocation and fracture than the other ossicles.

The malleus is maximally protected from injury and dislocation due to its fixation to the tympanic membrane, the tensor tympani muscle, and the presence of three ligaments (anterior, posterior, and superior).

Ossicular fractures are rare and may occur at any location. The most common are fractures of the long process of the incus and fractures of the stapes crura. Fracture of the malleus handle has also been described in isolated cases. In fractures, displacement of the intact ossicular chain occurs toward the sites of ligament attachment.

Fractures of the Petrous Portion of the Temporal Bone

Fractures of the petrous portion of the temporal bone are classified according to the axis of injury:

• Longitudinal (approximately 80% of cases) — extend along the petrous portion. The inner ear structures remain intact, but the ossicular chain is damaged. There is also a rupture of the tympanic membrane and a fracture of the bony wall of the ear canal. In addition, the canal of the facial nerve may be traumatized with the subsequent development of edema. Leakage of cerebrospinal fluid or blood from the external auditory canal is frequently observed (otoliquorrhea or otohematorrhea);
• Transverse — extend across the petrous portion of the temporal bone. The cochlea or semicircular canals are damaged, resulting in the formation of a perilymphatic fistula. The internal auditory canal and facial nerve canal are also affected. The tympanic membrane usually remains intact; however, hemotympanum may occur.

Combined fractures are also encountered in clinical practice.

Posttraumatic Mastoiditis

Posttraumatic mastoiditis is an inflammatory condition developing against the background of traumatic changes in the middle ear, most commonly in the presence of pathological contents (blood) within the mastoid air cells. The inflammatory process spreads to the mucous membrane and bone tissue of the tympanic cavity and temporal bone.

As the condition progresses, bone caries develops with formation of sequestra surrounded by purulent contents. In the presence of perforation in the tympanic membrane is determined by the oozing of pus into the external ear canal. The tympanic membrane may remain intact, but its bulging is observed, and the identifying signs are smoothed. The posterior wall of the ear canal may also be overhanging.

Clinical Manifestations

General symptoms of middle and inner ear injuries:

• Hearing loss;
• Tinnitus;
• Sensation of ear fullness;
• Pain (at the time of injury and afterward).

The type of hearing loss depends on the type of injury: conductive hearing loss is characteristic of tympanic membrane and middle ear injuries, whereas sensorineural or mixed hearing loss is observed with inner ear involvement.

Features of the clinical presentation in various injuries:

• Tympanic membrane injury — minor bleeding from the ear canal, hearing loss;
• Middle ear injury — increased amount of hemorrhagic discharge, hearing loss up to deafness, pulsatile tinnitus that worsens with nose blowing;
• Stapes dislocation from the oval window — vestibular symptoms (dizziness, nausea, vomiting, imbalance);
• Longitudinal temporal bone fractures — mild conductive hearing loss, leakage of blood or cerebrospinal fluid from the auditory canal through the damaged tympanic membrane, temporary facial nerve paresis, brief episodes of dizziness;
• Transverse temporal bone fractures — sensorineural hearing loss up to deafness, severe labyrinthine disturbances (prolonged and intense dizziness, nausea, vomiting), spontaneous nystagmus toward the healthy ear, facial nerve paralysis occurring immediately after trauma, leakage of cerebrospinal fluid into the nasopharynx through the Eustachian tube;
• Traumatic mastoiditis — elevation of body temperature to febrile levels, persistent pulsating postauricular pain that worsens with palpation of the mastoid process, swelling in the postauricular region, and, in cases of tympanic membrane perforation, purulent discharge from the auditory canal.

In both types of temporal bone fractures, Battle’s sign may be present — postauricular hematomas. Fractures of the temporal bone are also associated with early and late complications, the most serious of which include damaged carotid artery, facial nerve damage, mastoiditis, and meningitis.

Diagnosis

Diagnosis is based on findings from an otolaryngologic examination and a carefully collected medical history. An important stage of diagnosis is otomicroscopy.

Vestibular function must be assessed; audiometry, tympanometry, tuning fork tests, and vestibular tests are performed, as well as hearing assessment using whispered and conversational speech.

Among instrumental diagnostic methods, computed tomography (CT) of the temporal bones with thin sections is mandatory to determine the extent of injury. In some cases, consultation with a neurologist, neurosurgeon and ophthalmologist is recommended. Electroneuromyography is used to assess facial nerve function.

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Treatment

Treatment Approaches for Tympanic Membrane Perforations

For tympanic membrane perforations, a watchful waiting approach is the most justified, since even large perforations are capable of spontaneous closure. If the perforation is suspected to have been infected at the time of injury, topical antibacterial medications in the form of ear drops are prescribed. An important condition for optimal healing is prevention of secondary infection, including restricting water entry into the external auditory canal and ensuring proper function of the Eustachian tube.

If healing does not occur within 2–3 months, as well as in cases where the perforation is located in the flaccid portion of the tympanic membrane or extends to the tympanic annulus, myringoplasty is performed. When the tympanic membrane is infected, either systemic or local antibacterial drugs are prescribed. After myringoplasty, follow-up with an ENT physician is recommended for at least 2 years, because the risk of cholesteatoma formation remains.

Treatment of Hemotympanum

In case of hemotympanum, oral antibacterial therapy and topical nasal medications (nasal decongestants) are prescribed to improve Eustachian tube function; autoinsufflation of the Eustachian tube is also recommended. With a favorable outcome, the blood undergoes lysis within 7–10 days.

If the contents of the tympanic cavity become infected, puncture of the cavity is performed, pathological discharge is aspirated, and bacteriological examination is carried out. Antibacterial therapy is prescribed according to the results of susceptibility testing.

Restoration of the Ossicular Chain

To restore the ossicular chain, revision of the tympanic cavity and tympanoplasty are performed 3–6 months after the injury. This delay is intentional, as spontaneous hearing improvement may occur during this period when scar tissue bridges the ruptures.

Management Strategy for Patients with Temporal Bone Fractures

Conservative therapy includes the use of systemic corticosteroids to prevent delayed facial nerve paresis and systemic antibacterial therapy to prevent bacterial complications. Regarding surgical treatment, a watchful waiting approach is considered appropriate.

Early surgical intervention is necessary in the following cases:

• Facial nerve paralysis;
• Presence of a perilymphatic fistula with progressive vestibular symptoms;
• Severe sensorineural hearing loss.

If facial nerve edema develops during the delayed period despite conservative therapy, decompression of the facial nerve canal is performed. In case of continued liquorrhea for more than 14 days, surgical treatment with closure of the defect is also indicated.

For inflammatory complications (mastoiditis, meningitis), antromastoidotomy with revision of the tympanic cavity and mastoid air cells is performed, and broad-spectrum antibacterial medications are prescribed.