Pediatric Considerations In Craniofacial Trauma
Pediatric Considerationsi n C r a n i o f a c i a l Tr a u m aBernadette L. Koch, MDKEYWORDS Pediatric craniofacial trauma Pediatric facial fractures Pediatric normal skull base Pediatric craniofacial development Pediatric facial trauma Toppled furniture All-terrain vehicle pediatric injuries Impalement injuriesKEY POINTS Mechanism of injury and growth and development of the pediatric face play a role in the type andpattern of injury in pediatric craniofacial trauma. Normal variant lucencies in the pediatric skull base are important to recognize, so as not to misdiagnose fractures. Lack of complete ossification of the anterior skull base, before the age of 4 years, should not bemistaken as a posttraumatic or congenital anomaly. Trapdoor orbital floor fractures are more common in children than adults, and can result in entrapment of orbital soft tissues, without significant displacement of fracture fragments. Beware of toppled furniture, especially the television, as a cause of significant craniofacial and skullbase trauma in children. Most pediatric craniofacial impalement injuries are treated conservatively. However, imaging is veryhelpful to define the extent of injury and assess for retained foreign bodies.Craniofacial trauma in children is in many respectsvery similar to that in adults. The patterns of fractures and associated injuries in older childrenand adolescents are frequently identical to thosefound in adults. However, the patterns of facialinjury in younger children differ from those inadults, primarily reflecting changes in anatomyand physiology of the developing face, extent ofparanasal sinus pneumatization, and phase ofdentition. The frequency of different types of fractures is, therefore, also variable depending on theage of the child. In addition to understanding hownormal growth and development of the pediatricskull base and craniofacial structures affect thepatterns of injury in children, it is important forthe imager to recognize multiple normal variant lucencies in the pediatric skull base that may mimicfractures. Furthermore, a few types of injurydeserve special attention in children, includinginjuries related to toppled furniture, nonaccidentaltrauma, all-terrain vehicle (ATV) accidents, andimpalement injuries.NORMAL GROWTH AND DEVELOPMENTGrowth and development play a role in the types ofcraniofacial fractures that occur at differing ages.Because many of the structures are still in the process of growing and maturing, and dentition maybe incomplete, pediatric maxillofacial injuries carrywith them the risk of altering the function and ultimate growth of the affected structures. Therefore,timely diagnosis and prompt management areimportant to prevent disturbances in future growththat may affect function, dental occlusion, andcosmetic appearance. By the end of the first yearof life, the mandibular halves are fused at thesypmphysis. The condyle contributes to theDisclosures and Conflict of Interests: None.Department of Radiology, Cincinnati Children’s Hospital Medical Center, University of Cincinnati College ofMedicine, 3333 Burnet Avenue, Cincinnati, OH 45229, USAE-mail address: Bernadette.koch@cchmc.orgNeuroimag Clin N Am 24 (2014) 021052-5149/14/ – see front matter Ó 2014 Elsevier Inc. All rights reserved.neuroimaging.theclinics.comINTRODUCTION
514Kochvertical growth of the mandible. Most growth of thezygoma and maxilla is complete by 7 years, mostorbital growth is completed by 5 to 7 years ofage, but cranial vault and craniofacial structurestypically do not achieve growth maturity until 14to 16 years of age.1 The bones of the craniofacialskeleton grow and develop by remodeling anddisplacement throughout young life. Remodelingoccurs secondary to local factors that result inchange in size and shape of each component,and displacement occurs secondary to bonesmoving apart at joints, sutures, and articular surfaces. The cranium and orbits grow in responseto the growth of the brain and globes early duringthe first year of life and growth of the zygoma andmaxilla is initially slower than the cranio-orbital region. Therefore, the cranio-orbital complex islarger than the maxilla-mandibular complex in infancy. Over time, the young child’s craniofacialdevelopment is altered by central nervous system,optic pathway, and speech/swallowing development and use and development of muscles offacial expression and mastication, paranasal sinuspneumatization, and normal phases of dentition.Deciduous teeth begin to erupt at approximately6 months of age, mixed dentition is noted at about6 years of age, and adult dentition is reached by 12or 13 years of age.Features unique to the young pediatric facethat affect outcome of injuryCranio-orbital complex is larger than themaxilla-mandibular complex in infancyIncomplete development of the paranasal sinuses: increases stability and decreases incidence of midface fracturesIncomplete dentition: increases stability and decreases incidence of mandible fractures, rare ininfantsNORMAL VARIANT LUCENCIES IN THE SKULLBASEThe postnatal development of the anterior andcentral skull base is complex, and beyond thescope of this article. The central skull base (chondrocranium) is composed of at least 25 separateossification centers in the embryo that ultimatelycontribute to the mature sphenoid and occipitalbones.2 Throughout childhood, there are manynormal skull base sutures, fissures, synchondroses, vascular channels, and clefts that canroutinely be identified on head and neck computedtomography (CT) imaging in children. Knowledgeof the normal developmental anatomy of the skullbase is important to prevent misinterpretation ofthese findings as fractures, osseous lesions, andcephaloceles.A large number of normal lucencies are identified in the central skull base, including but notlimited to the spheno-occipital synchondrosis, olivary eminence, craniopharyngeal canal, canalisbasilaris medianus, median raphe of the basiocciput, and coronal clefts of the basiocciput. In addition, there are normal variant lucencies in theocciput that should not be confused with fractures. These include remnants of the anteriorintraocciptial synchondrosis, and posterior lucencies related to variant fusion of Kerckringossicle.At birth, there are multiple separate ossification centers that ultimately form the mature sphenoid bone, all of which are initially separatedfrom the adjacent centers by a nonossified synchondrosis. The most commonly visualizedsynchondrosis related to the sphenoid bone onpostnatal CT is the spheno-occipital synchondrosis. Most skull base growth occurs at thespheno-occipital synchondrosis, which separates the postsphenoid ossification center fromthe basiocciput and remains patent until teenageyears (Fig. 1). During closure, small ossifiedbodies may be identifiable within the sphenooccipital synchondrosis (Fig. 2). After closure iscomplete, there are frequently small divots,clefts, or fissures on one or both sides of thespheno-occipital synchondrosis.In infants, the sphenoid body frequently contains two visible midline foramina, an anteriortriangular-shaped lucency and a round posteriorforamen. The anterior cartilage-containing structure is called the olivary eminence (Fig. 3) andis not identifiable in most older children, butmay be visible as a sclerotic remnant in 11.2%of children older than 9 months of age.2 Theround posterior foramen, the craniopharyngealcanal, is a tubular lucency extending from thefloor of the sella turcica to the roof of the nasopharynx (Fig. 4). The craniopharyngeal canal isvisible on CT in 8.5% of children, and as a partialcanal or sclerotic remnant in 20% of children.Rarely, this canal is pathologically widened secondary to the presence of cephaloceles thatfrequently contain ectopic adenohypophysis(Fig. 5).3Most normal-variant lucencies in the occipitalbone involve the basiocciput or the region of theKerckring ossicle. Occasionally, midline lucencyin the basiocciput, called the canalis basilarismedianus, is identified posterior to the sphenooccipital synchondrosis (Fig. 6). This structure
Pediatric Considerations in Craniofacial TraumaFig. 1. Spheno-occiptal synchondrosis. (A) Sagittal reformatted CT image in a 4 year old demonstrates a patentspheno-occipital synchondrosis (arrow). (B) Axial bone window CT image in the same child shows the horizontallucency between the postsphenoid and the basiocciput (arrow).may be variable in shape, and complete or incomplete.4,5 The canalis basilaris medianus is thoughtto represent a remnant of the cephalic end of thenotochordal canal, most frequently is an incidental finding, but is rarely associated with nasopharyngeal cysts (Fig. 7).5,6 The anteriorintraoccipital synchondrosis has a variableappearance over time, and during fusion mayprogress from a somewhat cross-shaped appearance to a small well-corticated round lucency(Fig. 8). Coronal clefts involving the basiocciputmay also occur. Finally, lucencies related tovariant fusion of Kerckring ossicle include unfused and partially fused Kerckring ossicles(Fig. 9), both of which, if not recognized as normalvariants, may be misinterpreted as fracture. Whenfracture is suspected on axial imaging, threedimensional reconstructions in these childrenare frequently very helpful to better define the lucencies as normal variants related to KerckringFig. 2. Remnants of the spheno-occipital synchondrosis. (A) Axial and (B) sagittal bone window images in a13 year old show normal variant small ossified bodies (arrows) within the closing spheno-occipital synchondrosis.515
516KochFig. 3. Olivary eminence. Axial CT image in a 1 day oldshows the typical triangular-shaped anterior foramen,called the olivary eminence, located posterior to thepresphenoid and anterior to the paired main sphenoid ossification centers. This is only identifiable in infants, but may be present as a sclerotic remnant inchildren older than 9 months. Also easily identifiableis the posterior foramen, called the craniopharyngealcanal.ossicle rather than fracture lines. Threedimensional reconstructions are also helpful inproving that lucencies related to intrasuturalbones, when they occur anywhere in the skull,are not fractures.Fig. 4. Craniopharyngeal canal. Sagittal reformattedCT image in a 4-month-old child shows the normalcraniopharyngeal canal (arrow), extending from thefloor of the sella turcica to the roof of the nasopharynx, anterior to the patent spheno-occipital synchondrosis (arrowhead).NORMAL ANTERIOR SKULL BASEOSSIFICATIONImagers must also recognize several additionalpotential pitfalls related to the complex ossificationpattern of the anterior skull base in order not toMost common normal variant sutures andlucencies in the skull baseSpheno-occipital synchondrosis: may seeremnant clefts, fissures, or small ossified bodiesOlivary eminence: only identifiable in infantsCraniopharyngeal canal: floor of sella to roof ofnasopharynx, completely fuses in most children,rarely contains cephaloceleCanalis basilaris medianus: usually incidentalfinding, rarely associated with nasopharyngealcystsMedian raphe of the basiocciputCoronal clefts of the basiocciputAnterior intraocciptial synchondrosis: changesshape over time from somewhat cross-shapedto well-corticated round lucencyUnfused or partially fused Kerckring ossicle:may be confused with fractureFig. 5. Craniopharyngeal canal cephalocele containing adenohypopyhsis. Sagittal T1-weighted MR imagein a 10-day-old boy demonstrates a wide, primarilycerebrospinal fluid–containing cephalocele (arrows),extending through the floor of the sella, into the posterior nasopharynx. Notice posterior pituitary brightspot along the dorsal aspect of the cephalocele andpatent spheno-occipital synchondrosis.
Pediatric Considerations in Craniofacial TraumaFig. 6. Canalis basilaris medianus. Sagittal reformatted images from a temporal bone CT in a 4 year oldshow the patent canalis basilaris medianus (arrow),posterior to the patent spheno-occipital synchondrosis (arrowhead).mistake such items as incomplete or multiple ossification centers as a defect from trauma, or as acephalocele. Anterior skull base ossification occurs in a fairly predictable fashion, but with varyingrates in young children. Most of the skull base atbirth is composed of cartilage (Fig. 10). Duringthe first few months of life, there is progressiveossification of the cribriform plate, roof of the nasalFig. 7. Canalis basilaris medianus associated withnasopharyngeal cyst. Sagittal reformatted CT in thesame child as Fig. 6, at 13 years of age, shows intervalfusion of the spheno-occipital synchondrosis (arrowhead) and narrowing but persistent patency of the canalis basilaris medianus (arrow). Notice also the nowvisible nasopharyngeal mass just beneath the canalisbasilaris medianus.cavities, and crista calli. Ossification of the cribriform plate begins near the region where the superior and middle turbinates attach and extendsmedially to reach the crista galli by about 2 monthsof age. Ossification extends from the cribriformFig. 8. Anterior intraoccipital synchondrosis. (A) Axial CT image in a 2 year old demonstrates somewhat crossshaped lucencies, which represent the incompletely fused intraoccipital synchondroses (arrows). (B) Axial CT image at 7 years of age in a different child demonstrates small, foramen-like remnants of the fused intraoccipitalsynchondrosis (arrows).517
518KochFig. 9. Kerckring ossicle variants. (A) Sagittal CT in a newborn demonstrates unfused Kerckring ossicles (arrows).(B) Three-dimensional reformatted CT image in the same child demonstrates unfused duplicated Kerckring ossicles (arrows) at the posterior aspect of the foramen magnum.plate, and proceeds posteriorly more quickly thananteriorly, therefore a nonossified gap is frequentlypresent anterior to the crista galli in very youngchildren. Only 4% of children in a study by Hughesand colleagues7 had complete ossification of theanterior skull base by 2 years of age, whereas allpatients had a fully ossified anterior skull base bythe age of 3 years, 10 months (Fig. 11). After4 years of age, the only unossified normal structurethat remains in the midline anterior cranial fossa isthe foramen cecum, just anterior to the crista galli(Fig. 12), which may transmit a small vein.Anterior skull base ossificationMajority is unossified at birth4% of children have completely ossified anterior skull base by 2 years of ageAll children fully ossified anterior skull base by4 years of ageAfter 4 years, only unossified portion of anterior skull basea is foramen cecumPARANASAL SINUS DEVELOPMENTKnowledge of normal paranasal sinus development is helpful to understand the impact andoutcome of craniofacial injuries in children. Forexample, concern for frontal sinus fracture andits associated complications is not an issue in children who have not yet developed aeration of thefrontal air cells. In addition, lack of sinus pneumatization is thought to provide increased stabilityand resultant decreased incidence of midfacefractures in younger children. Paranasal sinusdevelopment follows a fairly predictable pattern;however, the ultimate degree of pneumatizationof each sinus is variable between individuals. Themaxillary sinus is formed, but rudimentary at birth.Lateral extension of the maxillary sinus to reachthe maxillary bone and inferior extension to thelevel of the hard palate are usually achieved by9 years of age, with progressive pneumatizationsometimes occurring until early adulthood. Theanterior ethmoid air cells are also present at birthand grow until late puberty. Ethmoid pneumatization progresses in the posterior, inferomedial,and inferolateral directions until early adulthood.The sphenoid bone initially contains red marrowat birth, and conversion to fatty marrow occursduring the first 2 years of life. Subsequently, thesphenoid sinus becomes progressively pneumatized until it reaches adult size by approximately14 years of age. The frontal sinus is the last todevelop, developing from the anterior ethmoid aircells. The earliest frontal sinus pneumatization occurs around 2 years of age, by 4 years of age thefrontal sinus reaches half of the height of the orbit,and by 10 years of age the frontal sinuses extendinto the vertical portion of the frontal bone.8Orbital fracture types vary with age, in part secondary to normal variant development of the paranasal sinuses and nasal cavities. The height of thelateral nasal wall depends on the development ofthe ethmoid and maxillary sinuses, and the heightof the lateral nasal wall determines the height ofthe orbit.9 The infant typically has relative frontal
Pediatric Considerations in Craniofacial TraumaFig. 10. Normal anterior skull base ossification at birth. (A, B) Coronal CT images in a newborn demonstrate thenormal unossified appearance of the anterior skull.bossing, which protects the orbital structures, butresults in orbital roof fractures being more common than orbital floor fractures in the youngeraged children. Furthermore, fractures of the supraorbital rim, with or without extension across theanterior cranial floor or orbital roof, are more common in younger children, and as the frontal sinusesdevelop, there is increased frequency of isolatedfrontal bone and frontal sinus fractures.9Paranasal sinus developmentEthmoid sinuses present at birth, mature size byyoung adulthoodMaxillary sinuses present at birth, mature sizeby early teenage yearsSphenoid sinus absent at birth, begins development around 2 years of age, mature size byearly teenage yearsFrontal sinus last to develop, begins aeration at2 years of age, mature size by early teenageyearsDISTRIBUTION AND CAUSES OF PEDIATRICFACIAL FRACTURESOverall, facial fractures are less common in children than adults, with less than 15% of all facialfractures occurring in children. The lowest prevalence of pediatric facial fractures occurs in infants.10 The prevalence of pediatric facialfractures, therefore, increases with age. There aretwo peaks of facial fracture, one at 6 to 7 years ofage, correlating with the time when many childrenstart attending school, and the other at 12 to14 years of age, thought to be related to increasingphysical activity and participation in sports.10,11 Inaddition, there is a predominance of boys affectedby facial fractures, with a ratio of up to 8.5:1.10,12The primary causes of pediatric facial fractures indescending order of frequency are motor vehicleaccidents; sports-related injury; and accidentalcauses, such as falls, and violence.12The frequency of different types of facial fractures in children varies in the literature, with moststudies showing that mandible and nasal fracturesare the most common, followed by maxillary/zygoma fractures. Although nasal fractures arecommon, septal hematomas remain rare, but ofsignificant importance because when they occur,they require immediate surgical drainage to prevent septal cartilage necrosis, saddle nose deformity, and, in the young child, midface growthretardation.10 The low incidence of mandible fractures in children younger than the age of 4 years isthought to be secondary to the relative increase instrength of the mandible at this age, which is atleast in part secondary to the presence of unerrupted dentition. Incomplete dentition, with toothbuds still present within the maxilla and mandible,provides stability and resistance to fracture. Inaddition, children are thought to be relatively resistant to facial fractures because of more flexiblesuture lines, greater elasticity/flexibility of theosseous structures of the face, and a thicker layerof protective subcutaneous fat typically present inthe pediatric face.10,12When mandibular fractures occur in children,they are more likely to be unilateral fractures thanin their adult counterparts. In children younger519
520KochFig. 11. Normal anterior skull base ossification
Pediatric Considerations in Craniofacial Trauma Bernadette L. Koch, MD INTRODUCTION Craniofacial trauma in children is in many respects very similar to that in adults. The patterns of frac-tures and associated injuries in older children and adolescents are frequently identical
LEVEL I PEDIATRIC TRAUMA CENTER The Level I Regional Pediatric Trauma and Burn Center at Children’s Hospital Colorado is a large, multi-disciplinary program. We provide timely, comprehensive, cost- . Trauma/Burn Medical Director Trauma/Burn Program Manager Trauma Coordinators Trauma Registrars Staff Assi
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