Summary of Temporal Bone and Skull Fractures

## Introduction This study aid summarizes key information regarding skull fractures and temporal bone fractures, focusing on classifications, complications, diagnostic features, and practical scenarios. This material is designed for self-study and does not include details on "Temporal Bone Fractures" or "Head Trauma Imaging," which are discussed elsewhere. > Definition: A skull fracture is a disruption of the continuity of the calvarium or skull base due to mechanical injury; a temporal bone fracture involves the bones in the temporal region and can affect ear structures and nerve pathways. ## Basic Classification of Skull Fractures ### Linear (Nondisplaced) Fractures - Most common type of skull vault fracture - Can be difficult to detect on CT, especially if parallel to the imaging plane - Isolated linear fractures typically do not require treatment ### Depressed and Comminuted Fractures - Depressed: bone fragment is driven inward, often with contusion of the cerebellum or brain beneath the fracture - Comminuted: multiple fragments - Surgical intervention is often indicated for depressed and compound (open) fractures > Definition: A depressed fracture is a type of fracture where a bone fragment is pushed inward towards the brain tissue; a compound fracture means a breach of skin integrity with communication to the fracture site. ### Skull Base Fractures (General) - Critical locations: skull base region, orbits, facial bones - For evaluating the degree of comminution and depression, thin-slice CT scans with bone algorithms and multiplanar reconstructions are recommended ## Temporal Bone Fractures — Key Types and Consequences Note: This material focuses on general classifications related to functional outcomes, rather than a detailed description of "Temporal Bone Fractures" themselves. ### Longitudinal vs. Transverse Fractures - Longitudinal: run parallel to the long axis of the petrous bone; often associated with middle ear dysfunction and ossicular dislocation - Transverse: run perpendicular to the long axis of the petrous bone; more frequently lead to inner ear damage, sensorineural hearing loss, significant vertigo, and perilymphatic leak > Definition: A transverse temporal bone fracture is a fracture perpendicular to the long axis of the petrous bone and is often the result of an impact to the occipital or frontal region. Practical Example: A patient who has fallen from a height reports intense vertigo and sudden hearing loss in one ear — consider a transverse temporal bone fracture with possible inner ear injury. ### Otic capsule–sparing vs. otic capsule–violating - Otic-sparing: the fracture runs anterolateral to the otic capsule, typically following a localized impact to the temporoparietal region - Otic-violating: the fracture involves the otic capsule (cochlea, semicircular canals) Comparison of Consequences (Table): | Feature | Otic-sparing | Otic-violating | |---|---:|---:| | Risk of Facial Nerve Injury | Lower | 2–5x Higher | | Risk of CSF Leak | Lower | 4–8x Higher | | Risk of Hearing Loss | Lower | 7–25x Higher | | Risk of Intracranial Complications | Lower | Higher (epidural hematoma, subarachnoid hemorrhage) | Practical Implications: Otic-violating fractures require more intensive monitoring for CSF leak, hearing preservation, and assessment of facial nerve function. ### Complications Associated with Temporal Bone Fractures - Sensorineural hearing loss - Severe vertigo and nystagmus - Perilymphatic fistula (CSF or perilymphatic leak into the middle ear) - Facial nerve palsy (30–50%, often complete) - Vascular injury (carotid arteries, jugular veins), especially with transverse fractures Did you know that a perilymphatic fistula can cause a combination of fluid leakage, hearing reduction, and significant vestibular symptoms, including rotatory vertigo? ## Soft Tissue and Scalp Assessment - When evaluating CT/MR scans for head trauma, begin by reviewing extracerebral structures. - Scalp swelling o