Temporal bone fracture is often caused by car accidents, occipitotemporal impacts, and falls, and is often accompanied by intracranial, thoracic, or abdominal tissue and organ injuries. About 1/3 of skull base fractures invade the petrous part of the temporal bone. In the injuries to the petrous, squamous, and mastoid parts of the temporal bone, petrous fracture is most common. Because the bone at the junction of the petrous and squamous parts is weak, the middle ear is more affected than the inner ear after fracture. Temporal bone fracture can affect the middle ear, inner ear, and facial nerve. According to the relationship between the fracture line and the long axis of the petrous bone, temporal bone fracture is usually divided into longitudinal fracture, transverse fracture, mixed fracture, and petrous apex fracture; sometimes, more than two types of fractures can exist simultaneously.
Clinical manifestations
Longitudinal fracture
Longitudinal fracture is most common, accounting for 70% - 80%, and is mostly caused by impacts on the temporal and parietal regions. The fracture line is parallel to the long axis of the petrous bone, often starts from the squamous part of the temporal bone, passes through the posterior superior wall of the external auditory canal and tegmen tympani, and extends along the carotid canal to the vicinity of the foramen lacerum or foramen spinosum at the base of the middle cranial fossa. Because the fracture line often passes through the front or outside of the bony labyrinth, the inner ear is rarely injured. It is often accompanied by damage to the structure of the middle ear. The manifestations are ear hemorrhage and conductive hearing loss or mixed hearing loss. About 20% of patients have facial paralysis, which can gradually recover. If the dura mater is ruptured, there may be cerebrospinal fluid leakage. Longitudinal fracture can occur on both sides simultaneously, and occasionally involve the temporomandibular joint.
Figure 1 Schematic diagram of temporal bone fracture
The dashed line is the fracture line
Figure 2 Longitudinal fracture of temporal bone
Transverse high-resolution CT shows a longitudinal lucent line (↗) on the right temporal bone, which extends inward and involves the incudomallear joint; opacities of soft tissue density can be seen in the tympanic cavity and mastoid pneumatization, representing hemorrhage.
Transverse fracture
Transverse fracture is less common, accounting for about 20%, mainly caused by violence in the occipital region. The fracture line is perpendicular to the long axis of the petrous bone, mostly starts from the foramen magnum of the occipital bone in the posterior cranial fossa and crosses the petrous pyramid to the middle cranial fossa, but also passes through the hypoglossal nerve foramen and the foramen of the petrous part (jugular foramen) and passes through the internal auditory canal and labyrinth to the vicinity of the foramen lacerum or foramen spinosum. Because the fracture line can pass through the internal auditory canal or bony labyrinth, and the inner wall of the tympanic cavity, vestibular window, and cochlear window can be fractured, there are often symptoms of damage to the cochlea, vestibule, and facial nerve, such as sensorineural hearing loss, vertigo, spontaneous nystagmus, facial paralysis, and hemotympanum. Facial paralysis has an incidence of about 50%, and is not easy to recover.
Mixed fracture
Mixed fracture is rare, and is often caused by multiple skull fractures. Temporal bone longitudinal and transverse fractures can occur simultaneously, causing tympano-labyrinthine fracture, and middle ear and inner ear symptoms occur.
Petrous apex fracture
Petrous apex fracture is rare, and can damage the cranial nerve II - VI. The manifestations include amblyopia, reduced palpebral fissure, ptosis, mydriasis, ocular motility disorder, diplopia, strabismus, and trigeminal neuralgia or facial sensory disturbance. Petrous apex fracture can damage the internal carotid artery, causing fatal massive hemorrhage. Petrous apex fracture should be differentiated from brainstem injuries and brain herniation.
All types of temporal bone fractures may be accompanied by meningeal damage and cerebrospinal fluid leakage. Cerebrospinal fluid flowing out of the external auditory canal through ruptured tympanic membrane is termed cerebrospinal fluid otorrhea; if the tympanic membrane is intact, cerebrospinal fluid flowing out of the nasal cavity through the eustachian tube is termed cerebrospinal fluid rhinorrhea; cerebrospinal fluid flowing out of the external auditory canal and nasal cavity simultaneously is termed cerebrospinal fluid otorrhea and rhinorrhea. The cerebrospinal fluid is light red due to blood mixture in the early stage, and gradually clear; Laboratory test shows that the fluid contains sugar (test strips for diabetes can be used). Temporal bone fracture is often part of skull base fractures, and systemic symptoms, such as post-traumatic headache, coma, and shock, are apparent. If patients seek medical attention due to hearing deterioration and aural fullness, attention should be paid to whether patients have systemic symptoms, because some symptoms such as coma in some patients occur several hours after trauma. If the condition permits, imaging examination of the skull base should be performed. High-resolution CT can show the direction of the fracture line and intracranial hemorrhage and pneumocephalus.
Treatment
Temporal bone fracture often occurs in craniocerebral trauma. If there are symptoms of increased intracranial pressure, cranial nerve signs, and massive hemorrhage in the ear or nose, patients should be rescued. If necessary, tracheotomy should be performed to keep the airway open. Hemorrhage should be controlled, rehydration or blood transfusion should be conducted to prevent hemorrhagic shock and maintain the normal function of the circulatory system. If the condition permits, detailed examination, including cranial CT and neurological examination, should be performed.
Antibiotics and other drugs should be used to prevent intracranial or ear infections, and attention should be paid to ear disinfection. If the general condition permits, the accumulated blood in the external auditory canal should be removed under aseptic conditions. If there is cerebrospinal fluid otorrhea, the external auditory canal should not be filled, and only sterilized cotton ball should be placed at the opening of the external auditory canal. If the condition permits, cerebrospinal fluid leakage can mostly stop spontaneously in head-up or semi-sitting positions. If the leakage cannot stop in more than 2 - 3 weeks, the defect of the dura mater can be repaired with the temporal muscle or fascia through the ear approach to control cerebrospinal fluid leakage.
In peripheral facial paralysis caused by transverse fracture of the temporal bone, as long as the condition permits, surgical decompression should be as early as possible. If conservative treatment fails in 2 - 6 weeks and the general condition permits, facial nerve decompression can be performed. After the condition is completely stable, tympanoplasty or facial nerve surgery can be performed to treat the sequelae such as tympanic membrane perforation, ossicular rupture, conductive hearing loss, and facial nerve paralysis.
Prognosis
Longitudinal fracture has the best prognosis. Conductive hearing loss can often be restored through tympanoplasty or myringoplasty, transverse fracture has a poor prognosis, and sensorineural hearing loss is often difficult to improve. Vestibular function loss can still be gradually compensated. After the head trauma heals, the fracture gap may still exist, and there is a risk of meningitis when the middle ear is infected in the future. Children have better prognosis than adults.