Cranial vault and skull base fractures in children are distinctly different from those seen in adults. Pediatric skull fractures have the benefit of greater capacity to remodel; however, the developing pediatric brain and craniofacial skeleton present unique challenges to diagnosis, natural history, and management. This article discusses the role of surgical treatment of these fractures, its indications, and techniques.
Key points
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Growth and development of the pediatric cranial vault and skull base play a significant role in the patterns of injury seen in pediatric craniofacial trauma.
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The cranial vault grows in a cephalocaudal vector, with 95% of growth completed by age 5.
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Most pediatric vault and skull base fractures can be treated conservatively. Surgical repair may be indicated for fronto-basilar injuries with associated cerebrospinal fluid leak, depressed skull fractures, orbital roof and sphenoid wing fractures, and growing skull fractures.
Introduction
Head trauma in the pediatric population is extremely common, accounting for 600,000 emergency department visits annually among American children with an incidence of 250 per 100,000 per year. Among all children with head injuries, skull fractures are identified up to 30% of patients. Most pediatric skull fractures can be managed conservatively. Of those requiring surgical intervention, fewer than half of surgeries are performed for skull fracture repair only. Surgical intervention on initial injury is largely performed in cases of skull fracture depression, underlying hemorrhage/mass lesion, frontal or basilar injury with venous sinus involvement or cerebrospinal fluid (CSF) leak. Frontal bone fractures with depression, CSF leak, or cortical injury is the most likely to require repair.
Although the pediatric skull has the advantage over the adult skull of improved capacity to remodel and heal, the developing skull places unique challenges such as growing skull fractures (GSFs) and the essential role of the anterior cranial base in orbital development. This article discusses the normal development of the cranial vault, the role of surgical treatment of pediatric skull fractures and its technical challenges even for experienced multidisciplinary teams.
Normal development of the cranial vault
A thorough understanding of normal growth and development of the pediatric skull base and craniofacial structures is important to understand skull fracture patterns. In contrast to the midface (eg, maxilla, zygoma, and nasal complex), and lower face (mandible), cranial vault growth is largely complete by the time children reach mixed dentition.
Craniomaxillofacial growth follows a cephalocaudal vector such that the cranial vault and upper face are relatively prominent in infants and small children ( Fig. 1 A). , Enlow discusses 2 main morphologic events that direct craniofacial growth including (1) basal cranium growth and (2) development of pharyngeal and facial airway structures. The first phase occurs as a response to rapid growth of the brain and orbit during the first year of life resulting in growth of the cranium, orbit, and upper third of the face.
The cranium is composed of the chondrocranium and the neurocranium. The chondrocranium, or the cranial base, is initially formed as a cartilage model from occipital somites, which eventually becomes bone by endochondral ossification. During the first few months of life, there is progressive ossification of the cribiform plate, roof of the nasal cavities, and crista galli. These ossification centers form the bones of the base of the skull including occipital, sphenoid, temporal, and ethmoid bones. Most growth of the cranial base occurs at articulations called synchondroses. The most significant synchondrosis is called the spheno-occipital synchondrosis, which remains patent until teenage years. Once ossified, the bone can also grow via remodeling, a process called appositional growth. Before the age of 4 years, the anterior skull base is not completely ossified. Normal variant lucencies in the pediatric skull base can be confused for traumatic injuries, so experienced clinical expertise is required in the initial evaluation.
The neurocranium, or cranial vault, is made up of curved, flat bones formed intramembranously from neural crest cells. The growth of these bones occurs at the fibrous articulations, or the sutures. Appositional growth also occurs on the endocortical and ectocortical surfaces. The growth velocity of the cranial vault is rapid in the first few years of life and plateaus between 5 and 7 years of age. Measurement of head circumferences shows that 86% of growth occurs within the first year and 94% of growth within 5 years of age ( Fig. 1 B).
Knowledge of normal paranasal sinus development also guides management of cranial fractures in children. Frontal sinus fracture is not an issue for children who have not yet developed aeration of the frontal air cells. The frontal sinus is the last of the paranasal sinuses to develop, coming from the anterior ethmoid air cells. Earliest frontal sinus pneumatization occurs at the age of 2. By 4 years of age, the frontal sinus reaches half the height of the orbit, and by 10 years of age, the frontal sinuses extend into the frontal bone.
The development of the orbital wall influences the types of fractures seen in young children. Infants typically have relative frontal bossing, which protects the orbital structures but results in orbital roof fractures being more common than orbital floor fractures in younger aged children. Isolated orbital fractures are relatively rare in children younger than age 5. The frequency of orbital floor fractures does not exceed upper orbit fractures until after age 7.
Types of skull fractures
The patterns of skull fractures in older children and adolescents are frequently identical to those found in adults ( Figs. 2–6 ). However, the patterns of craniofacial injuries in younger children differ from those in adults, primarily reflecting changes in anatomy and physiology of the developing skull as well as extent of sinus pneumatization.
The location of the fracture on the skull determines treatment strategy. Parietal bone fractures are the most common fracture managed nonoperatively. Frontal bone fractures are more likely to require surgical intervention. These fractures are more likely to involve the frontal sinus, skull base, and orbit as well as have an increased chance of causing a CSF leak, ocular complications, cortical contusion, and cosmetic deformity. Children with aerated frontal sinuses are at higher risk of requiring surgical repair. Other fractures that are more likely to require surgical management include depressed skull fractures (DSFs), orbital fractures, and GSFs.
Growing Skull Fractures
Children aged younger 3 years with skull fractures are at risk of developing diastatic enlargement of the fracture line as brain growth proceeds. This phenomenon is called a growing skull fracture (GSF). In a series of 897 pediatric patients with skull fractures, only 1 patient (0.1%) developed a growing fracture requiring a delayed repair. GSF is thought to result from a dural tear through which the leptomeninges and brain parenchyma herniate. This forms a cystic sac, which manifests as a soft, nontender swelling at the site of the fracture. , Surgery is recommended in almost all cases and involves dural repair with or without cranioplasty. , , Early surgical intervention is recommended, regardless of the GSF location, to yield a good cosmetic result and cortical integrity. , Delay in repair of GSF can result in seizures and focal neurologic deficits. , , ,
Skull Base Fractures
Fracture of the skull base may involve several bones such as temporal, occipital, sphenoidal, and spheno-ethmoidal complex as well as orbital portion of the frontal bone. The most common skull base fracture is temporal bone fracture. Skull base fractures may cause associated injuries such as hearing loss, facial nerve injury, and CSF leak.
Dural tears leading to CSF leak are common among skull base fractures due to tight adherence between the skull base and dura, especially in the anterior skull base fractures. The clinical signs of a skull base fracture include retroauricular and/or periorbital bruising, hemotympanum, CSF otorrhea, and rhinorrhea. Dural tears leading to CSF leak are common among skull base fractures due to tight adherence between the skull base and dura, especially in the anterior skull base fractures. , Most traumatic CSF leaks resolve spontaneously within 1 week. CSF leakage in the setting of a temporal bone fracture ceases more often spontaneously compared with a CSF leak associated with the fracture of the anterior cranial fossa.
Surgical repair is required for persistent CSF leaks. Untreated CSF leakage may lead to meningitis, hydrocephalus, subdural fluid collections, and neurocognitive abnormalities. Meningitis develops among 10% to 27.5% of these patients and is associated mortality rate of up to 10%. , Persistent CSF leak may be managed either by diversion via lumbar drainage or with extracranial repair. In a series of 63 pediatric patients with skull base fractures, 25% of patients required operative treatment with intracranial, extracranial, or combined approach.
Depressed Skull Fractures
Most isolated nondepressed linear skull fractures can be managed conservatively, and numerous studies have favored discharge rather than observation for these patients. Depressed skull fractures (DSFs) DSFs are more likely to be associated with intracranial pathologic condition and morbidity. , DSFs account for 15% to 25% of children with skull fractures. The term “compound fractures” is used to described contaminated skull fractures where the skin integrity is impaired. In a series of 530 pediatric patients with DSFs, 66% had compound fractures. Compound fractures were more likely to be associated with underlying brain injury than simple fractures alone.
One subtype of DSFs occurring in young children is so called “ping-pong” fractures (see Fig. 4 ). This subtype of DSF occurs when the skull is relatively soft and able to indent without a break in the bone. Ping-pong fractures occur in newborns and young infants and have been reported to spontaneously elevate with growth of the skull, particularly among newborns after birth trauma. In general, select DSFs may be managed conservatively except in cases of underlying intracranial hematoma, severe cosmetic defects, compound fractures, and in cases where the bone depression is greater than 1 cm and are associated with cortical deformation (see Fig. 5 ).
Orbital Roof and Sphenoid Fractures
Orbital roof fractures are more common among children than adults. Orbital fractures in children represent a unique subset of fractures with the risk of adjacent intracranial injury. These fractures can also result in entrapment of orbital soft tissues even without significant displacement of the fracture.
There is also the potential for sequelae not seen with fractures elsewhere in the orbit such as pulsatile proptosis and encephaloceles leading to “growing” roof fractures. Similar to GSFs as described previously, the orbitocranial variant of GSF involves herniation of tissue through the fracture line. Due to their proximity to the globe, these injuries can cause proptosis, which may lead to amblyopia in infants. ,
Orbitocranial GSFs are associated with specific visual and cosmetic complications as well as the risk of CSF rhinorrhea through communications with the ethmoid sinus.
Fractures of the greater sphenoid wing, including the lateral orbital wall, can result in decreased orbital volume, with associated proptosis and/or vision changes. These fractures frequently require surgical repair to prevent orbital dystopia and, in cases of acute vision compromise, decompression of the globe.
Surgical management
Growing Skull Fracture
The basic surgical principal in the management of GSFs is to repair the defects in both the dura and the cranium (see Fig. 2 ). , , , Liu and colleagues argued that duraplasty alone may suffice in GSF with cranial defects less than 3 cm. Cranioplasty is required for larger defects to prevent recurrence. The procedure involves raising the craniotomy flap around the defect, resecting the herniated dural sac, gently repositioning the herniated cortex in the cranium, followed by watertight dural closure and cranioplasty. Duraplasty may be useful as the dural edges often retract following a tear. Pericranial graft or temporalis fascia may be used for repair.
Skull Base Fracture with Cerebrospinal Fluid Leak
The coronal flap approach provides excellent extracranial exposure for the repair of anterior skull base CSF leaks (see Fig. 3 ). A robust pericranial flap should be harvested at the time of the coronal approach. This flap is utilized to line the skull base and occlude the nasofrontal recess.
Surgical management of frontal sinus fractures involves techniques such as repair (open reduction and internal fixation of the anterior table), obliteration (ablation), and cranialization. A standard coronal incision may be used for all these techniques. The goal of repair of the frontal sinuses is to preserve the sinus anatomy including the nasofrontal duct, sinus mucosa, and anterior and posterior tables. The anterior table is reduced and then stabilized with titanium or resorbable plates and screws. Obliteration involves eliminating the frontal sinus cavity while maintaining the anterior and posterior tables. This technique involves the removal of the anterior table followed by meticulous removal of all mucosa as well as the inner cortex of the sinus wall and the occlusion of the frontonasal duct.
Frontal sinus cranialization is similar to obliteration but the posterior table is removed instead of the anterior table. Often, the frontal sinuses may be cranialized, which means removing the bony wall between the skull’s posterior table and opposing dura through an existing frontal bone fracture. However, sometimes this technique requires a frontal craniotomy to approach the posterior table. This technique also allows repair of dural lacerations and the ability to attend to any underlying hemorrhage. A pericranial flap is rotated into the defect to isolate the cranium from the frontal sinus. The obstructed duct is sealed with fibrin glue. The anterior table is then reconstructed and stabilized with plates and screws.
Depressed Skull Fracture
Standard surgical management of DSFs involves (1) elevation of the depressed bone fragment, (2) removal of free bone fragments driven into the cerebral cortex, (3) repair of dural defects, (4) evacuation of underlying hematoma, and (4) debridement of wound. Titanium mesh and screws may be used for cranial reconstruction in cases where the bone fragments may be contaminated or if the free fragments are unable to be used. Performing an immediate cranioplasty with titanium mesh instead of leaving the bone defect may improve the child’s quality of life with low risk of implant-associated complications. In patients with extensive hemicraniectomy defects, secondary alloplastic reconstruction with customized alloplastic implants may be indicated (see Fig. 8 ).
Orbital Roof and Sphenoid Fractures
Surgical approaches to orbital roof fractures involve a multidisciplinary team of neurosurgeons, plastic surgeons, and ophthalmologists. Several approaches exist for obtaining access to the anterior skull base for these injuries including a lateral eyebrow incision, upper eyelid incision, and coronal incision. A coronal incision with frontal craniotomy provides wide exposure for dural repair and orbital roof reconstruction ( Figs. 6 and 7 ). Reconstruction of the orbit following intracranial exploration and dural closure may be performed using titanium mesh, plates, and screws. Autogenous substances such as calvarium, rib, and ilium can be considered for internal orbital reconstruction but may be difficult to contour to the precise anatomy of the internal orbit and have unpredictable resorption rates.
