Skull fracture vs. accessory sutures: how can we tell the difference?

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1 Emerg Rdiol (2010) 17: DOI /s PICTORIAL ESSAY Skull frcture vs. ccessory sutures: how cn we tell the difference? Thoms Snchez & Deorh Stewrt & Mtthew Wlvick & Leonrd Swischuk Received: 23 Mrch 2010 /Accepted: 12 My 2010 /Pulished online: 23 My 2010 # The Author(s) This rticle is pulished with open ccess t Springerlink.com Keywords Skull frctures. Accessory sutures. CT scn Introduction Plin film rdiogrphy remins the most cost effective method in evluting skull frctures nd cn esily differentite mjor sutures nd common vsculr grooves from frctures. However, in children this cn e complicted due to the presence of numerous synchondroses nd unusul ccessory sutures. Plin film evlution is especilly chllenging not only ecuse of vrious rtifcts tht cn degrde the study ut lso the inility to visulize intrcrnil processes, such s contusions nd hemorrhge, tht cn sustntite clvril finding. From the Deprtments of Rdiology nd Peditrics, University of Cliforni Dvis, Scrmento CA nd University of Texs Medicl Brnch, Glveston TX T. Snchez (*) University of Cliforni Dvis, Scrmento, CA, USA e-mil: thoms.snchez@ucdmc.ucdvis.edu D. Stewrt CAARE Dignostic nd Tretment Center, Deprtment of Peditrics, University of Cliforni Dvis, Scrmento, CA, USA M. Wlvick Deprtment of Internl Medicine, University of Cliforni Sn Frncisco, Fresno, CA, USA L. Swischuk Deprtment of Rdiology, University of Texs Medicl Brnch, Glveston, TX, USA Miniml soft tissue swelling cn e difficult to see even with olique views. Superimposition of norml suture lines like the metopic suture cn mimic frcture if one is not creful to otin dditionl views [1]. During the pst decde, the incresing use of spirl nd multidetector CT hve led to the ility of worksttions to generte threedimensionl (3D) reconstructions of the skull. Therefore if crnil CT is deemed cliniclly necessry in trum ptients, questionle frctures cn e confidently differentited from unusul ccessory sutures using these dditionl worksttion cpilities. Norml ossifiction centers The prietl nd occipitl ones in prticulr re common regions for ccessory sutures ecuse of their multiple ossifiction centers. The prietl one ossifies from two centers while the occipitl one ossifies from six centers [2, 3]. An ccessory intrprietl or susgittl suture is rre ut cn e seen dividing the prietl one (Fig. 1). They cn e explined on the sis of incomplete union of the two seprte ossifiction centers [4]. These re usully ilterl nd firly symmetricl ut cn t times e unilterl. The occipitl one hs more complex development. The formen mgnum is surrounded y four ossifiction centers. On ech side re the exoccipitls, ventrlly locted is the soccipitl nd dorslly, the suproccipitl center contins the midline occipitl fissure which cn sometimes persist ntentlly (Fig. 2). This pttern of development cn therefore give rise to numerous ccessory sutures tht could e mistken for frctures especilly with plin film evlution lone. CT scn with 3D reconstruction is vitl in the further chrcteriztion of questionle frcture.

2 414 Emerg Rdiol (2010) 17: Fig. 1 Accessory intrprietl or susgittl suture (rrow) Rdiogrphic differentition of skull frcture nd ccessory suture Simple non-depressed skull frctures re shrp lucencies with non-sclerotic edges. In contrst, ccessory sutures usully will show zigzg pttern with interdigittions nd sclerotic orders similr to mjor clvril sutures (Fig. 3). When frctures extend into mjor suture, there could e widening of the frcture line s it pproches the suture or there is ssocited distsis of the djcent synchodrosis or suture. (Fig. 4). An ccessory suture will usully not produce this ppernce. High impct frctures cn cross suture lines or extend from one mjor suture to nother, wheres ccessory sutures join nd merge with the mjor suture (Fig. 5). In terms of ilterlity, ccessory sutures re often present on oth sides nd re firly symmetric especilly in the prietl ones [2]. Occipitl ccessory sutures cn e complex nd multiple ut re lso frequently ilterl [5]. However, skull frctures cn e lso ilterl. When they re, these frctures re lmost lwys ssocited with high impct injuries nd thus will often show comminution, depression, nd mrked symmetry. Hence, these complex nd high impct frctures re lmost never confused with developmentl vrints [6, 7]. Finlly, soft tissue swelling or hemtom is frequently ssocited with cute skull frctures. One study hs shown tht t lest 4 mm of soft tissue swelling ws present on the crnil CT scn in ll cses of cute skull frctures tht they reviewed [8]. However, sence of suglel hemtom or swelling does not entirely rule out frcture especilly if the injury is remote or imging ws performed severl dys fter the trum [9]. Its presence though is highly suggestive of n cute trumtic event. (Fig. 6). Knowledge of the norml ntomy, development nd timing of suturl closure re lso importnt in the evlution of questionle frctures. The occipitl nd innominte sutures re no longer pprent y ge 4 while Fig. 2 Three-dimensionl reconstruction of the occipitl one outlining the six ossifiction centers including the remnnt of the midline occipitl fissure (rrow). Two interprietl ossifiction centers (yellow), single suproccipitl center (red), two exoccipitls (violet), nd single soccipitl (green). FM formen mgnum

3 Emerg Rdiol (2010) 17: Fig. 3 This shrp lucency (rrow) with djcent mild soft tissue swelling represents frcture. In contrst, this occipitl ccessory suture (rrow) hs sclerotic order with irregulr interdigittions similr to the djcent lmdoid sutures (smller rrows). Note the sence of soft tissue swelling Fig. 4 Notice how the frcture line is nrrow proximlly ut progressively widens s it extends into the sgittl suture. In different ptient, the left occipitl one frcture (rrow) extends into nd slightly widens the posterior introccipitl synchondrosis (smll rrow) Fig. 5 High impct injury with non-depressed frcture line extending from oth lmdoid sutures nd crossing over into the left prietl one. Accessory sutures will not produce this ppernce the mendosl suture completely fuses y 6 yers of ge [10]. An exmple of n ccessory suture tht cn e misleding is the norml persistent occipitl suture. It extends from the dorsl spect of the formen mgnum nd cn pper wide nd shrp. However, it should extend no more thn 2 cm from the edge of the formen mgnum. A longer fissure would e inconsistent with its norml emryogenesis nd therefore represents frcture [3] (Fig.7). In some cses where lucency is shorter thn 2 cm, the ge of the ptient would help in deciding if this is frcture or just suturl remnnt. As noted previously, this suture closes y 4 yers nd persistent lucency eyond this ge is indictive of frcture. In some cses, definite differentition etween frcture nd ccessory suture cn still e elusive. This is illustrted y recent cse where 2-yer-old oy cme in with mild frontl soft tissue swelling fter fll. Plin

4 416 Emerg Rdiol (2010) 17: Fig. 6 Shrp lucency representing frcture in the right prietl region is ccompnied y lrge suglel hemtom (rrow). In different ptient, the right temporl one frcture is ssocited with more sutle 3 mm soft tissue swelling (rrow) rdiogrph showed shrp lucency in the left occipitl one tht ws thought to represent frcture. CT scn with 3D reconstruction ws performed nd showed well-defined lucency extending into the lmdoid suture. There is no ssocited distsis or widening nd it does not extend into the formen mgnum posteriorly. Soft tissue swelling or hemtom ws lso sent. A one scn ws performed which showed no evidence of rdiotrcer uptke. It ws therefore felt tht this is more consistent with n ccessory suture. Follow-up study fter 3 months however showed sclerosis of this lucency indicting tht this ws indeed frcture. (Fig. 8). Clinicl experience hs consistently demonstrted tht one scn is much less sensitive in detecting skull frctures. In one study, less thn 40% of skull scintigrms were positive in ptients with clerly visulized frctures in skull rdiogrphs [11, 12]. The ove cse lso demonstrtes tht in difficult cses, follow-up study mightetheonlywytodifferentitefrcturefromn ccessory suture. A frcture usully will show evidence of heling or sclerosis in two or three months. Conclusion In summry, frctures nd ccessory sutures cn e differentited in most cses y oserving its chrcteristics Fig. 7 This midline occipitl frcture extending into the formen mgnum is esily differentited from norml persistent midline occipitl fissure ecuse of its length, extending 3 cm from the dorsl lip of the formen mgnum

5 Emerg Rdiol (2010) 17: Fig. 8 Occipitl frcture tht ws mistken for n ccesory suture. Plin rdiogrph showed left occipitl lucency. Nucler medicine study did not show ny norml uptke of rdiotrcer. c Together with the CT scn chrcteristics, it ws felt tht this lucency is more comptile with n ccesory suture. d Follow-up CT scn fter 3 months however showed sclerosis of this lucency indicting heling of the frcture c d such s ilterlity, symmetry, ssocited distsis, nd presence of soft tissue swelling (Tle 1). Knowledge of the norml ntomy, development, nd timing of suturl closure re lso necessry to decipher the vried nd sometimes complex nture of these ccessory sutures especilly in the occipitl region. However, in difficult cses, it is prudent to request for follow-up study to look for signs of heling. Tle 1 Differentition etween skull frcture nd ccessory suture Skull frcture Shrp lucency with non-sclerotic edges Widens s is pproches suture Cn cross djcent suture lines Often unilterl nd symmetric if ilterl Associted with some soft tissue swelling Accessory suture Zigzg pttern with sclerotic orders No ssocited distsis Merges with the djcent suture Often ilterl nd firly symmetric No soft tissue swelling

6 418 Emerg Rdiol (2010) 17: Open Access This rticle is distriuted under the terms of the Cretive Commons Attriution Noncommercil License which permits ny noncommercil use, distriution, nd reproduction in ny medium, provided the originl uthor(s) nd source re credited. References 1. Chsler C (1967) The neworn skull: the dignosis of frcture. Am J Roentgenol Rdium Ther Nucl Med 100(1): Weir P, Suttner NJ, Flynn P, McAuley D (2006) Norml skull suture vrint mimicking intentionl injury. BMJ 332(7548): Frnken EA Jr (1969) The midline occipitl fissure: dignosis of frcture versus ntomic vrints. Rdiology 93(5): Allen WE 3rd, Kier EL, Rothmn SL (1973) Pitflls in the evlution of skull trum. A review. Rdiol Clin N Am 11(3): Nkhr K, Miysk Y, Tkgi H, Kn S, Fujii K (2003) Unusul ccessory crnil sutures in peditric hed trum cse report. Neurol Med Chir 43(2): Meservy CJ, Towin R, McLurin RL, Myers PA, Bll W (1987) Rdiogrphic chrcteristics of skull frctures resulting from child use. Am J Roentgenol 149(1): Hos CJ (1984) Skull frcture nd the dignosis of use. Arch Dis Child 59(3): Kleinmn PK, Spevk MR (1992) Soft tissue swelling nd cute skull frctures. J Peditr 121(5): Fernndo S, Oldo RE, Wlsh IR, Lowe LH (2008) Neuroimging of nonccidentl hed trum: pitflls nd controversies. Peditr Rdiol 38(8): Nkhr K, Utsuki S, Shimizu S, Iid H et l (2006) Age dependence of fusion of primry occipitl sutures: rdiogrphic study. Childs Nerv Syst 22(11): Kemp AM, Butler A, Morris S, Mnn M et l (2006) Which rdiologicl investigtions should e performed to identify frctures in suspected child use? Clin Rdiol 61(9): Sty JR, Strshk RJ (1983) The role of one scintigrphy in the evlution of the suspected used child. Rdiology 146(2):