Skull vault fractures are generally classified into two types: linear fractures and depressed fractures. The former category also includes diastasis of cranial sutures, while the latter includes comminuted fractures. Most linear fractures involve the entire thickness of the skull, though a minority affect only the inner table. The fracture lines are typically single, linear, or radiating. The width of the fracture line is usually a narrow gap or a few millimeters, occasionally reaching 1 cm. Depressed fractures mostly involve full-thickness indentation of the skull, with a minority showing inward depression of the inner table. The fracture lines around the depressed bone fragments appear circular or radiating. In infants and young children, the soft skull may exhibit a "ping-pong ball" depression at the impact site.
Clinical Presentation and Diagnosis
Linear fractures may be accompanied by scalp injuries (lacerations, hematomas) and often require X-ray plain films or CT scans (bone window images). High-resolution CT (HRCT) can detect fine fracture lines. For larger, visibly depressed fractures with minimal scalp soft tissue bleeding, the fracture can be identified by palpation. However, shallow depressions may be confused with firm-edged scalp hematomas and require CT for differentiation. When depressed bone fragments intrude into the intracranial space, they may compress underlying brain tissue or cause cerebral contusions, intracranial hematomas, leading to corresponding neurological deficits, elevated intracranial pressure, and/or epilepsy. If depressed fragments penetrate a venous sinus, significant hemorrhage may occur.
Treatment
Linear fractures themselves do not require surgical intervention. However, if the fracture line crosses a meningeal vascular groove or venous sinus, vigilance for epidural hematoma is essential. Indications for surgery in depressed fractures remain debated. Generally, surgical intervention is recommended if the depression causes neurological deficits (e.g., paralysis, aphasia) or epilepsy, under the following conditions:
- Depression depth >1 cm
- Location in eloquent brain areas
- Bone fragments penetrating brain tissue
Surgery involves elevating and reducing the bone fragments or removing debris followed by cranioplasty. Mild depressions in non-eloquent areas or venous sinus depressions without cerebral compression may be managed conservatively.