OVERVIEW

Which part of the human body does the mastoid refer to in acute mastoiditis?

The mastoid is part of the temporal bone, which forms the base of the skull and the lateral part of the cranial cavity. At birth, the mastoid contains only one air cell, the mastoid antrum, which connects to the middle ear through a narrow passage called the aditus ad antrum. As a child grows, the mastoid bone gradually becomes pneumatized, forming a series of interconnected air cells lined with modified respiratory epithelium.

The mastoid, eustachian tube, and middle ear are central to the pathogenesis of mastoiditis. The mastoid's proximity to the facial nerve, semicircular canals, sternocleidomastoid muscle, jugular vein, internal carotid artery, sigmoid sinus, brain, and meninges is a critical factor in the development of complications.

What is acute mastoiditis?

Acute mastoiditis is the most common suppurative complication of acute otitis media, referring to a suppurative infection of the mastoid air cells with symptoms lasting less than 1 month. It primarily affects children and is rare in adults, also known as acute suppurative otomastoiditis. With the routine use of antibiotics to treat otitis media, its incidence has significantly decreased.

SYMPTOMS

What are the manifestations of acute mastoiditis patients?

The symptoms of acute mastoiditis can range from mild to severe, with some cases being asymptomatic and resolving spontaneously, while others may progressively worsen and lead to life-threatening complications. The specific clinical manifestations depend on age, stage of infection, and the pathway of pus drainage.

Generally, patients may exhibit tenderness, erythema, and swelling behind the ear. The postauricular sulcus may disappear, show fluctuance or a draining fistula, or present as a mass, with the auricle protruding outward. Ear pain is nonspecific and may manifest as irritability in young children. Other symptoms may include lethargy, abnormal tympanic membrane, fever, and narrowing of the external auditory canal.

Why can acute mastoiditis lead to cranial complications?

Complications of acute mastoiditis are related to the spread of infection or inflammation from the middle ear or mastoid to adjacent structures. Pus accumulates in the mastoid cavity, and as pressure increases, the thin bony septa between air cells may be destroyed, leading to coalescent mastoiditis and the possible formation of an abscess. Eventually, pus may spread to neighboring areas.

What types of intracranial and extracranial complications can acute mastoiditis cause?

Extracranial complications:

• Subperiosteal abscess: Presents with erythema, fluctuance, and a tender mass over the mastoid bone. This complication occurs in 58% of acute mastoiditis cases.

• Facial nerve palsy: Caused by compression of the facial nerve due to infection or inflammation as it passes through the narrow canal in the petrous part of the temporal bone. Symptoms include unilateral facial paralysis, reduced forehead movement, drooping eyebrow, inability to close the eye, loss of the nasolabial fold, and deviation of the mouth to the unaffected side.

• Hearing loss: Temporary hearing loss due to obstruction of the external auditory canal or middle ear effusion; permanent hearing loss may result from damage to the ossicles or cochlea due to suppurative labyrinthitis.

• Labyrinthitis: Inflammation or infection of the bony labyrinth can lead to labyrinthitis, causing tinnitus, hearing loss, nausea, vomiting, dizziness, vertigo, and nystagmus.

• Osteomyelitis: Spread of mastoid infection to other parts of the skull, leading to osteomyelitis. Petrous bone osteomyelitis may cause facial nerve palsy and Gradenigo's syndrome, characterized by otorrhea, retro-orbital pain, and ipsilateral abducens nerve palsy, possibly including other cranial nerve dysfunctions. Osteomyelitis of the calvarium is called Citelli's abscess.

• Bezold's abscess: Refers to an abscess deep to the sternocleidomastoid and digastric muscles in the neck, presenting with swelling and tenderness below the mastoid and deep to the sternocleidomastoid muscle.

Intracranial complications:

• Meningitis: Symptoms include nausea, vomiting, irritability, anorexia, headache, confusion, back pain, and neck stiffness. Infants may exhibit hypothermia, lethargy, respiratory distress, jaundice, feeding difficulties, diarrhea, bulging fontanelle, restlessness, and irritability.

• Temporal lobe or cerebellar abscess: Symptoms include headache, neck stiffness, lethargy progressing to coma, and vomiting.

• Epidural or subdural abscess: Presents with symptoms of increased intracranial pressure and papilledema, along with fever, headache, lethargy, nausea, and vomiting. Patients with concurrent sinus infection may exhibit nasal or ear discharge.

• Venous sinus thrombosis: Symptoms include headache, fever, and periorbital edema, initially affecting one eye but spreading to the other within 24–48 hours via the intercavernous sinus, causing bilateral swelling. Diplopia occurs when eye movement is impaired. Altered mental status, such as lethargy, confusion, or coma, may also develop.

CAUSES

Who is prone to acute mastoiditis?

Patients with low resistance, or those accompanied by acute infections, chronic diseases, inadequate or incomplete antibiotic treatment, highly virulent pathogens, or the presence of drug-resistant strains are all more likely to develop acute mastoiditis.

DIAGNOSIS

What tests are needed for the diagnosis of acute mastoiditis?

• Peripheral white blood cell count may be normal or elevated, often with a left shift. Erythrocyte sedimentation rate or C-reactive protein may also be elevated, but these laboratory findings are nonspecific.

• Imaging studies are required for otitis media with intracranial or extracranial complications, severe conditions, toxic manifestations, or ineffective antibiotic treatment. Contrast-enhanced CT can reveal changes in the temporal bone. For patients suspected of having intracranial complications, perform a head CT with intravenous contrast or contrast-enhanced head MRI.

What diseases can acute mastoiditis be easily confused with?

Acute mastoiditis needs to be differentiated from other causes of postauricular inflammation or swelling.

• Postauricular lymphadenopathy: For example, scalp infections can cause postauricular lymphadenopathy. The swelling is usually well-defined and mobile, whereas in acute mastoiditis, it is poorly defined and immobile. Additionally, in lymphadenopathy, the auricle is in a normal position, the postauricular sulcus is visible, and the tympanic membrane appears normal.

• Postauricular cellulitis: The distinction between postauricular cellulitis and mastoiditis lies in the normal appearance of the tympanic membrane in the former, which often occurs after insect or spider bites.

• Auricular perichondritis: Presents with swelling and erythema of the auricle, which may spread to the postauricular periosteum. Unlike acute mastoiditis, the postauricular sulcus is visible, and the tympanic membrane appears normal.

• Parotitis: Causes swelling of the parotid gland located anterior and inferior to the auricle.

• Tumors: Benign or malignant tumors of the mastoid bone, such as aneurysmal bone cysts, acute lymphoblastic leukemia, or Langerhans cell histiocytosis, may exhibit clinical features suggestive of mastoiditis. In these patients, the tympanic membrane examination is typically normal.

TREATMENT

Do patients with acute mastoiditis require hospitalization?

Patients with acute mastoiditis should be hospitalized and started on intravenous antibiotic therapy.

What are the treatment options for acute mastoiditis?

• Antibiotic therapy and drainage of the middle ear and mastoid are the foundation of treatment for acute mastoiditis.

• For uncomplicated acute mastoiditis, intravenous antibiotics should be administered, along with myringotomy and, if necessary, tympanostomy tube placement. Antibiotic therapy must be sufficient, especially in later stages of the disease, as achieving adequate antibiotic levels in bone tissue may otherwise be difficult. However, this still cannot completely prevent complications.

• Mastoiditis complicating chronic otitis media requires antibiotic coverage for Staphylococcus aureus, Pseudomonas, enteric Gram-negative bacilli, as well as Streptococcus pneumoniae and Haemophilus influenzae.

• If conservative treatment with intravenous antibiotics is ineffective, further intervention is needed. This includes mastoidectomy to remove necrotic bone. Myringotomy may be performed alongside mastoidectomy for acute mastoiditis. In cases of cholesteatoma, tympanomastoidectomy is performed to remove necrotic bone and cholesteatoma.

When is mastoidectomy required in the treatment of acute mastoiditis?

Indications for mastoidectomy may include:

• Subperiosteal abscess, such as postauricular fluctuance or mass;

• CT findings suggestive of coalescent mastoiditis;

• Other suppurative complications of acute mastoiditis;

• Acute mastoiditis occurring in children with chronic suppurative otitis media or cholesteatoma;

• Persistent or progressive postauricular swelling or fluctuance, fever, ear pain, or discharge despite intravenous antibiotics and tympanocentesis.

What are the serious consequences if acute mastoiditis is left untreated?

If acute mastoiditis is untreated or not managed promptly and effectively, the infection may spread. Intracranial extension can lead to permanent neurological deficits or death.

Can acute mastoiditis be cured?

Most patients with acute mastoiditis who receive appropriate treatment early in the course of the disease recover without complications or long-term sequelae, such as hearing loss.

DIET & LIFESTYLE

Will there be any sequelae after acute mastoiditis is cured?

Possible sequelae of acute mastoiditis are mostly hearing loss. During the patient's recovery period, hearing tests should be conducted to determine if there is hearing loss. If present, it should be assessed whether it is conductive or sensorineural.

Can acute mastoiditis recur after being cured?

Untreated or ineffective treatment of acute otitis media can lead to a recurrence of acute mastoiditis.

PREVENTION

How to prevent acute mastoiditis?

• Early and adequate treatment of acute otitis media can reduce the risk of mastoiditis but cannot completely prevent it.

• Pneumococcal vaccination also has a preventive effect.

• Prompt treatment of acute mastoiditis and early evaluation of persistent ear discharge, ear pain, or acute otitis media unresponsive to antibiotic therapy can reduce the risk of mastoiditis complications.

How to prevent recurrence of acute mastoiditis?

• Smaller daycare groups lower exposure to respiratory pathogens and reduce the risk of acute mastoiditis.

• Smoke exposure: This is a risk factor and should be avoided.

• Breastfeeding: At least 3 months of breastfeeding protects infants from acute otitis media in the first year of life, thereby reducing the incidence of acute mastoiditis.

• Pacifiers: Pacifier use after 6 months of age increases the risk of recurrent acute otitis media, thereby raising the incidence of acute mastoiditis, and should be avoided.