Various causes lead to defects in the bone of the tympanomastoid portion, causing the cerebral membrane or brain parenchyma to herniate into the tympanic cavity or mastoid cavity. This condition is relatively rare, with fewer than 10 cases reported domestically by Cheng Shaoguang, Shi Chunhua, and others.

bubble_chart Etiology

It is commonly seen in otogenic intracranial complications such as extensive bone destruction caused by sebaceous cysts and severe intracranial infections, including meningitis, brain abscess, and lateral sinus thrombophlebitis. These conditions lead to persistently increased intracranial pressure, causing the temporal lobe of the brain or the lateral cerebellum to herniate into the tympanic cavity or mastoid cavity through bone defects. The resulting infarction and necrosis of brain tissue further exacerbate intracranial infection and high intracranial pressure, creating a vicious cycle. Improper surgical management, such as excessive removal of the mastoid tegmen or sigmoid sinus plate, excessive incision of the meninges during brain abscess drainage, or prolonged inadequate drainage of abscesses, can also induce this condition.

bubble_chart Clinical Manifestations

Brain abscess or meningitis that does not heal soon presents with low-grade fever and headache. The ear is filled with meningeal and brain tissues in the tympanic cavity and mastoid cavity, which become necrotic and discharge pus, potentially even forming a cerebrospinal fluid fistula. Intracranial complex infections may soon develop, leading to death.

bubble_chart Treatment Measures

First, administer broad-spectrum antibiotics in large doses to control the infection, and use mannitol to reduce intracranial pressure. Then, make an incision inside or behind the ear to remove residual lesions in the tympanic mastoid cavity, such as sequestra, sebaceous cysts, and granulation tissue. Next, excise the herniated brain membrane and brain tissue without attempting to reposition them into the cranial cavity, as necrotic and degenerated brain tissue can form abscesses and worsen the infection. Subsequently, harvest fascia lata or temporal fascia to suture and repair the defect in the brain membrane. Additionally, use a pedicled temporal muscle flap or sternocleidomastoid muscle flap to fill the surgical cavity. If the cranial defect is large, autologous muscle grafts or costal cartilage grafts can be used. This repair procedure must only be performed after the infection is completely controlled. In recent years, intracranial complications have significantly decreased, and it is expected that this complication will soon be eradicated.