The neurosurgical management of lateral skull base trauma

The lateral skull base is comprised of the squamous and petrous temporal bones. Fractures through the petrous pyramid account for approximately 20% of all traumatic skull fractures. They can be classified into two types, based upon the involvement of the otic capsule, otic capsule sparing, and otic capsule disrupting. The eloquent structures within and surrounding the petrous temporal bone lead to significant morbidity associated with these fractures. They can lead to cerebrospinal fluid (CSF) leak, facial nerve injury, hearing loss (both conductive and sensorineural), and cerebrovascular injury. Early recognition of a lateral skull base fracture, based upon clinical signs (e.g., Battle's sign) and imaging, is key to further management. Examination of the external ear for CSF leak or extruded brain parenchyma and examination of facial movement are the most important physical exam findings to determine need for early surgical intervention. Facial weakness is treated conservatively for the first 7 days after injury. Acute-onset, complete facial weakness, though, is a poor prognostic sign and can be an indication for early surgical intervention to decompress the nerve. Most CSF leaks will resolve spontaneously within the first week after injury and will not require surgical intervention. Hearing loss is managed conservatively with delayed audiogram. Sensorineural hearing loss has a poor prognosis for recovery. Persistent conductive hearing loss for more than 6 months can be treated with exploratory tympanotomy. Cerebrovascular injury is treated with antithrombotic therapy. In conclusion, the timing of onset of facial weakness is the most important determining factor in surgical intervention, while most sequelae of lateral skull base trauma can be treated conservatively.