Retroclival collections associated with abusive head trauma in children

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1 Peditr Rdiol (2014) 44 (Suppl 4):S621 S631 DOI /s SPECIAL ISSUE: ABUSIVE HEAD TRAUMA Retroclivl collections ssocited with busive hed trum in children V. Michelle Silver & Amy R. Dnehy & Alice W. Newton & Ctherine Stmoulis & Chir Crducci & P. Ellen Grnt & Celeste R. Wilson & Pul K. Kleinmn Received: 14 Februry 2014 /Revised: 7 June 2014 /Accepted: 20 August 2014 # Springer-Verlg Berlin Heidelberg 2014 Abstrct Retroclivl collections re rre lesions reported lmostexclusivelyinchildrenndstronglyssocitedwithtrum. We exmine the incidence nd imging chrcteristics of retroclivl collections in young children with busive hed trum. We conducted dtbse serch to identify children with busive hed trum 3 yers of ge with brin imging performed between 2007 nd Clinicl dt nd brin imges of 65 children were nlyzed. Retroclivl collections were identified in 21 of 65 (32%) children. Ten (48%) were subdurl, 3 (14%) epidurl, 2 (10%) both, nd 6 (28%) indeterminte. Only 8 of 21 retroclivl collections were identifible on CT nd most were low or intermedite in ttenution. Eighteen of 21 retroclivl collections were identifible on MRI: 3 followed cerebrl spinl fluid in signl intensity nd 15 were bloody/ proteinceous. Additionlly, 2 retroclivl collections demonstrted fluid-fluid level nd 2 enhnced in the 5 children who received contrst mteril. Sgittl T1-weighted imges, sgittl fluid-sensitive sequences, nd xil FLAIR (fluid-ttenuted inversion recovery) imges showed the retroclivl collections best. Retroclivl collections were significntly correlted with V. M. Silver (*): A. R. Dnehy : C. Stmoulis : C. Crducci : P. E. Grnt: P. K. Kleinmn Deprtment of Rdiology, Boston Children s Hospitl, Hrvrd Medicl School, 300 Longwood Ave, Boston, MA, USA e-mil: michelle.silver@tch.hrvrd.edu A. W. Newton Child Protection Progrm, Deprtment of Peditrics, Msschusetts Generl Hospitl, Hrvrd Medicl School, Boston, MA 02114, USA C. Stmoulis Deprtment of Neurology, Boston Children s Hospitl, Hrvrd Medicl School, Boston, MA 02115, USA C. R. Wilson Division of Generl Peditrics, Deprtment of Medicine, Boston Children s Hospitl, Hrvrd Medicl School, Boston, MA 02115, USA suprtentoril nd posterior foss subdurl hemtoms nd were not sttisticlly correlted with skull frcture or prenchyml brin injury. Retroclivl collections, previously considered rre lesions strongly ssocited with ccidentl injury, were commonly identified in this cohort of children with busive hed trum, suggesting tht retroclivl collections re n importnt component of the imging spectrum in busive hed trum. Retroclivl collections were better demonstrted on MRI thn CT, were commonly identified in conjunction with intrcrnil subdurl hemtoms, nd were not significntly correlted with the severity of brin injury or with skull frctures. Keywords Child buse. Brin. Trum. Mgnetic resonnce imging. Peditric. Clivus. Computed tomogrphy. Child. Abusive hed trum Introduction Abusive hed trum is mjor cuse of deth nd disbility in infnts nd young children [1]. In the pproprite clinicl context, imging findings such s multifocl, thin subdurl hemtoms nd prenchyml brin injury my suggest dignosis of busive hed trum. Retroclivl hemtoms were first described by Orrison et l. [2] in 1986 nd hve been subsequently noted in occsionl cse reports [2 19] nd smll series [20 23]. Most retroclivl epidurl nd subdurl hemtoms occur in children, nd these collections re lmost lwys reported in the context of ccidentl trum, prticulrly motor vehicle ccidents [19, 24 27]. We found no specific reference to retroclivl hemtoms in the context of busive hed trum. Given the strong correltion between retroclivl hemtoms nd ccidentl peditric hed trum, we hypothesized tht these lesions would be observed in children with busive hed trum. As such, this study ws performed to determine

2 S622 the incidence nd imging chrcteristics of retroclivl collections in cohort of young children with busive hed trum. Mterils nd methods This study ws pproved by the hospitl s institutionl review bord nd ws complint with the Helth Informtion Portbility nd Accountbility Act. Informed consent ws wived. Ptient cohort nd clinicl dt In this retrospective study, ll children younger thn 36 months with busive hed trum who were treted t lrge urbn peditric tertiry-cre hospitl between 2007 nd 2013 nd who hd dignostic-qulity hed CT or MRI were identified through serch of the hospitl s Child Protection Progrm dtbse nd the multidisciplinry child buse conference list. The ge threshold of 36 months ws chosen becuse busive hed trum is most often noted in infnts nd toddlers. Abusive hed trum ws considered present if the dignosis ws estblished through multidisciplinry evlution, including ssessment by child buse peditricin. Fctors considered in this ssessment included the clinicl presenttion, imging findings (including hed CT nd brin MRI), dmission by the perpetrtor, nd buse independently witnessed (Tble 1). If cse ws considered suspicious for buse but ws not confirmed, it ws excluded. Clinicl dt were bstrcted from medicl records by child buse peditricin to determine ptient demogrphics nd clinicl detils. Children included in this study hd one or more of the following imging findings: skull frcture, intrcrnil hemorrhge, nd prenchyml brin injury. Children with isolted sclp hemtoms or isolted fcil bruising were excluded from the study. The time intervl between the onset of symptoms nd imging ws determined from chrt review. A totl of 65 children (29 girls nd 36 boys, ge rnge 1 36 months, men 5.2 months, stndrd devition [SD] 5.5 months) met ll inclusion criteri for this study. Imge review Peditr Rdiol (2014) 44 (Suppl 4):S621 S631 CT nd MRI were used to determine the presence or bsence of retroclivl collection. Retroclivl epidurl collections were defined s fluid collections long the clivus deep to the tectoril membrne. Retroclivl subdurl collections were defined s fluid collections superficil to the tectoril membrne nd deep to the rchnoid membrne (Fig. 1). Retroclivl collections were defined s indeterminte if the collection ws identified on CT only (nd no MRI ws performed or if the retroclivl collection hd resolved by the time MRI ws performed) or if the tectoril membrne could not be definitively identified on MRI. If retroclivl collection ws identified on either modlity, it ws deemed present. CT imging ws performed on LightSpeed 16 Slice CT or Optim CT660 (Generl Electric Helthcre, Milwukee, WI) or SOMATOM Senstion 64 (Siemens, Erlngen, Germny) with the use of non-helicl 5-mm contiguous xil imges. In the ltter prt of the study period, hed CTs were routinely reconstructed into mm xil dtsets nd reformtted into 3-mm-thick sgittl nd coronl imge sets using stndrd lgorithm. MR imging ws performed on 3T Mgnetom Skyr or Trio scnner (Siemens, Erlngen, Germny) or 1.5T Sign Excite (Generl Electric Helthcre, Milwukee, WI). Stndrd pulse sequences cquired on the 3T MRI system included sgittl 3D volumetric T1-weighted spoiled grdient echo imges (0.9-mm section thickness) reformtted into xil nd coronl plnes (0.9-mm section thickness, 0-mm gp), xil nd coronl fst spin echo (FSE) T2-weighted imges (2.5-mm section thickness, 0-mm gp), xil T2-weighted fluid-ttenuted inversion recovery (FLAIR) imges (4-mm section thickness, 0-mm gp), nd xil diffusion tensor imging (DTI) imges (2-mm section thickness, 0-mm gp). Imging on the 1.5 T MRI system consisted of sgittl T1-weighted spin echo Tble 1 Clinicl fctors in estblishing buse Number who met criteri Children with busive hed trum 65 Abuse independently witnessed 4 Abuse cknowledged/confessed 1 Dignosis estblished by multidisciplinry 63 ssessment child protection tem Dignosis of buse greed upon by 65 multispecilty providers Direct cre tem, child protection MD, hospitlists, neurosurgery, neurology, ophthlmology nd rdiology, s pplicble Fig. 1 Illustrtion of retroclivl collection in the sgittl plne. The tectoril membrne is blck, the rchnoid membrne yellow; the blue str defines the epidurl spce, the blck str the subdurl spce

3 Peditr Rdiol (2014) 44 (Suppl 4):S621 S631 S623 imges (4-mm section thickness, 0-mm gp), xil nd coronl FSE T2-weighted imges (4-mm section thickness, 0-mm gp), xil T2-weighted FLAIR imges (5-mm section thickness, 1.0-mm gp), nd DTI imges (5-mm section thickness, 0- mm gp). Vribly obtined sequences included xil susceptibility-weighted imges (SWI) (1.25-mm thick section, 0-mm gp), xil stedy-stte grdient echo imges (4-mm section thickness, 0-mm gp), xil or sgittl T2-weighted 3D vrible-flip-ngle FSE imges (0.5-mm section) reformtted in 0.5-mm-thick sections in orthogonl plnes, xil or sgittl fst imging employing stedy-stte cquisition imges (0.8-mm section thickness) reformtted in 0.8-mmthick sections in orthogonl plnes, sgittl FSE inversion recovery imges (3-mm section thickness, 0-mm gp) nd xil T1-weighted spin echo post-gdolinium (5-mm section thickness, 0-mm gp) or sgittl 3D volumetric T1-weighted spoiled grdient echo post-gdolinium imges (0.9-mm section thickness) reformtted into xil nd coronl plnes. Vrible sequences were vilble in individul ptients becuse imging protocols for busive hed trum evolved over time. In prticulr, fluid-sensitive sequences, defined s T2-weighted 3D vrible-flip-ngle FSE, fst imging employing stedy-stte cquisition or FSE inversion recovery imges, were more commonly dded to the imging protocol in the ltter prt of the study period. Moreover, buse ws not lwys the initil clinicl considertion t the time of first imging, e.g., child my hve been imged for new-onset seizures before buse ws contemplted. Findings were therefore expressed s percentges of findings positively identified reltive to the totl number of ptients in whom specific finding could be ssessed bsed on the vilble imging sequences. MR imging sequences vilble for ech ptient with retroclivl collection re listed in Tble 2. All imging ws independently nlyzed nd clssified by two bord-certified fellowship-trined peditric neurordiologists with 15 nd 8 yers of experience. Interobserver differences were resolved nd clssified by consensus following greement between the reders. Chrcteristics of retroclivl collections such s loction, ttenution, signl intensity, enhncement, nd the presence of Tble 2 MRI sequences performed in the children with retroclivl collection nd busive hed trum Cse 1.5 T 3.0 T Sg T1 Sg or xil T1 post contrst Axil T2 Axil FLAIR Axil GRE/ SWI Axil DTI Sg FSEIR Sg or xil T2- weighted 3D vrible-flip-ngle FSE Sg or xil fst imging employing stedy-stte cquisition b No MRI performed b RCC Retroclivl collection DTI diffusion tensor imging, FLAIR Fluid-ttenuted inversion recovery, FSE fst spin echo in footer, FSEIR fst spin echo inversion recovery, GRE grdient echo, Sg sgittl, SWI susceptibility-weighted imging

4 S624 Peditr Rdiol (2014) 44 (Suppl 4):S621 S631 fluid-fluid levels were exmined. If more thn one hed CT or MRI ws performed during the sme hospitl dmission, the first hed CT nd the first MRI were used to determine the ttenution nd signl chrcteristics of the retroclivl collection. Retroclivl collections were ctegorized s subdurl, epidurl, both subdurl nd epidurl, or indeterminte. Becuse xil FLAIR imges cn show flow-relted rtifct in the retroclivl region, the sequence ws not used to determine the presence or bsence of retroclivl collection. Additionl neuroimging findings including skull frcture, subdurl hemtom nd prenchyml brin injury were identified. Suprtentoril subdurl hemtoms were defined s one or more subdurl hemtom in the suprtentoril spce, unilterl, bilterl, or interhemispheric in loction. Posterior foss subdurl hemtoms were defined s one or more subdurl hemtom long the occipitl squm. Prenchyml brin injury ws defined s ny re of prenchyml tissue ltertion tht ws bright on T2-weighted MR imges nd correspondingly bright on the diffusion trce-weighted mp nd drk on the pprent diffusion coefficient (ADC) mp. Imges were not seprtely nlyzed for prenchyml edem without restricted diffusion or bridging vein thrombosis. Detils of retinl hemorrhges nd skeletl frctures were bstrcted from the medicl record. Sttisticl methods Interobserver greement ws ssessed using Cohen s kpp sttistic. Correltions between retroclivl collection nd either skull frcture, supr- or infrtentoril prenchyml injury; nd supr- or infrtentoril subdurl hemtoms were ssessed using simple contingency tbles nd the Fisher exct test or chi-squred test. Results Interobserver greement There ws excellent interobserver greement (Cohen s kpp κ=0.96, 95% confidence intervl [0.89,1])) for identifying the presence of retroclivl collection in this cohort of children Tble 3 Demogrphics nd imging chrcteristics of retroclivl collections (RCC) Cse Age (mos) Gen-der RCC Loction CT vilble Dy of CT since symptom onset CT sgittl reformtted imges vilble CT density MRI vilble Dy of MRI since symptom onset RCC signl intensity RCC enhncing RCC fluidfluid level 1 2 F EDC Yes Dy 1 No Not seen Yes Dy 2 No No 2 3 M SDC Yes Dy 1 Yes Not seen Yes Dy 1 No Gd No 3 1 F Both b Yes Dy 1 Yes Not seen Yes Dy 2 Yes Yes 4 3 M SDC Yes Dy 1 No Not seen Yes Dy 5 CSF No No 5 1 M SDC Yes Dy 1 Yes Not seen Yes Dy 3 CSF No Gd No 6 5 F ID Yes Dy 1 No Not seen Yes Dy 2 No No 7 2 M ID Yes Dy 1 Yes Intermed No No MRI NA NA No 8 16 F ID Yes Dy 1 Yes Intermed Yes Dy 1 Resolved No Gd No 9 36 M SDC Yes Dy 1 Yes Intermed Yes Dy 1 No Gd No M SDC Yes Dy 1 No Not seen Yes Dy 1 Yes No 11 7 F SDC Yes Dy 2 Yes Intermed Yes Dy 4 No Gd No 12 7 F SDC Yes Dy 2 Yes Not seen Yes Dy 4 No Gd No 13 8 M ID Yes Dy 4 Yes Not seen Yes Dy 9 No Gd No 14 3 M SDC Yes Dy 2 Yes Not seen Yes Dy 3 No Gd No 15 1 M EDC Yes Dy 1 No Not seen Yes Dy 2 No Gd No 16 4 F SDC Yes Dy 1 Yes Low Yes Dy 2 No Gd No M EDC No No CT NA NA Yes Dy 16 No Gd No 18 1 M ID Yes Dy 1 No Not seen Yes Dy 3 No Gd Yes 19 4 M SDC Yes Dy 1 Yes Intermed Yes Dy 2 CSF No Gd No 20 6 M ID Yes Dy 1 Yes High No No MRI NA NA No F Both b Yes Dy 1 No Intermed Yes Dy 2 No Gd No Intermedite or drk signl on T2-weighted imges, or intermedite or bright signl on T1-weighted imges, or mixed signl intensity on T1- or T2- weighted imges, or intermedite signl on fluid-ttenuted inversion recovery imges b Both epidurl nd subdurl collections present CSF cerebrospinl fluid, EDC epidurl collection, F femle, Gd gdolinium, ID indeterminte, M mle, mos months, NA not pplicble, SDC subdurl collection

5 Peditr Rdiol (2014) 44 (Suppl 4):S621 S631 S625 Tble 4 Additionl findings in children with retroclivl collections (RCC) nd busive hed trum (AHT) Cse Posterior foss SDH Posterior foss cerebellr injury Suprtentoril findings nd skull frcture (SFX) Retinl hemorrhge Skeletl survey 1 SDH Absent SDH, PI Yes, B Ribs, CML humerus, CML tibi, femur 2 SDH Present SDH, PI, IVH, SAH Yes, B Negtive 3 SDH Absent SDH, PI, SFX No Negtive 4 SDH Absent SDH, PI, SFX No Ribs 5 SDH Absent SDH, PI Yes, B Ribs, rdius, CML femur, CML tibi, clvicle 6 SDH Absent SDH Yes, B Negtive 7 No NA SDH, SFX N.E. Negtive 8 SDH Present SDH, PI Yes, B Negtive 9 SDH Absent SDH, PI Yes, B Rdius 10 SDH Absent SDH, PI Yes, B Fibul, multiple thorcic vertebrl bodies 11 SDH Absent SDH, PI Yes, B Negtive 12 SDH Absent SDH, SFX No Negtive 13 SDH Absent SDH Yes, B Negtive 14 SDH Absent SDH Yes, B Negtive 15 SDH Absent SDH Yes, U Clvicle, CML femur, CML tibi, CML fibul 16 SDH Absent SDH Yes, B Negtive 17 SDH Absent SDH, PI Yes, B Negtive 18 SDH Absent SDH, PI No Ribs, CML femur, CML tibi 19 SDH Present SDH, PI Yes, B CML tibi 20 SDH NA SDH, PI Yes, B Negtive 21 SDH Absent SDH Yes, U Negtive no MRI performed; B, Bilterl; CML, clssic metphysel lesion; IVH, intrventriculr hemorrhge; NA, not pplicble; no MRI, vilble; N.E., not exmined; PI, prenchyml injury; SAH, subrchnoid hemorrhge; SDH, subdurl hemtom; U unilterl with busive hed trum, with one discrepnt red, which ws resolved by consensus. Imging findings Retroclivl collections were identified in 21/65 (32%) children (ge rnge 1 36 months, men 8.7 months, SD 10.5 months). Ptient demogrphics, clinicl determintion of retinl hemorrhge, imging nd ssocited findings in children with busive hed trum nd retroclivl collections re summrized in Tbles 3 nd 4. Of the 65 children in this cohort, 62 children (95%) hd hed CTs; 43 of those 62 (69%) children hd sgittl reformtted imges nd 19 (31%) did not. Almost ll of the 65 ptients (58 children, 89%) underwent MRI imging of the brin. Retroclivl collections were identified in 8/62 (13%) children on hed CT nd 18/57 (32%) by MRI. In 5 children retroclivl collection ws identified on both modlities (4 subdurl collections nd 1 epidurl collection with subdurl collection). Of the 18 children with retroclivl collections identified on MRI, 12 (67%) (2 epidurl collections, 6 subdurl collections, 1 subdurl with epidurl collection, 3 indeterminte collections) could not be identified on the preceding hed CT; 5 were seen on the prior hed CT; nd 1 child (epidurl collection) hd brin MRI exmintion but no hed CT. Seven of the 8 (88%) children in whom retroclivl collection ws detected on hed CT hd sgittl reformtted imges vilble for interprettion. In three children, retroclivl collections were identified only by hed CT; in two of these, CT ws the only imging modlity utilized nd in one child retroclivl collection initilly present on the CT performed t 1.5 h post injury ws resolved on the CT t 6 h post injury (Fig. 2)ndtheMRI performed 7 h post injury confirmed resolution. The loction, CT ttenution nd MRI signl chrcteristics of the retroclivl collections re listed in Tble 3. Of the 21 retroclivl collections, subdurl collections (10 of 21; 48%) (Fig. 3) weremorecommonlyobservedthnepidurlcollections (3 of 21; 14%), nd combined epidurl nd subdurl collections (2 of 21; 10%) (Fig. 4) were lest common. Six collections (6 of 21; 28%) could not be ctegorized nd were clssified s indeterminte for the following resons: two children did not hve n MRI following their hed CT nd thus by definition were indeterminte in loction; in one child the retroclivl collection hd resolved by the time the MRI ws performed nd therefore only hed CT ws vilble for clssifiction; in two cses the collections were well seen, but the lck of sgittl fluid-sensitive sequence precluded ccurte locliztion of the collections (Fig. 5); nd in one cse the

6 S626 Peditr Rdiol (2014) 44 (Suppl 4):S621 S631 Fig. 2 CT in 16-month-old girl with retroclivl collection (cse 8, indeterminte). Sgittl reformtted CT imge 1.5 h post symptom onset shows n intermedite-density retroclivl collection (rrows). b Sgittl reformttedctimge6hpost symptom onset shows resolution of the retroclivl collection. Resolution ws confirmed on brin MRI performed 7 h post symptom onset (not shown) Fig. 3 CT nd MRI in 7-month-old girl with retroclivl subdurl collection (cse 11). Sgittl reformtted CT imge performed 2 dys post symptom onset shows the subdurl collection (long rrows) s intermedite in density. Note the retroclivl collection is superficil to the tectoril membrne (short rrow). b Sgittl reformtted CT imge membrne overlying the collection ws well seen nd likely represented the rchnoid membrne, but the ngle of the membrne reltive to the clivus ws considered typicl (cse 18). performed 3 dys post symptom onset shows tht the collection is incresed in size nd density. c Sgittl T1-weighted spin echo MR imge 4 dys post symptom onset shows the collection (white rrow) s bright in signl nd superficil to the tectoril membrne (blck rrow) The erliest point t which retroclivl collection ws identified on imging ws 1.5 h post symptom onset. The erliest point t which retroclivl collection resolved ws 6 h post symptom onset. The ltest point t which retroclivl collection Fig. 4 MRI in 30-month-old girl with combined retroclivl epidurl nd subdurl collection (cse 21). Sgittl fst spin echo inversion recovery imge shows smll epidurl collection (long blck rrows) deep to the tectoril membrne (short blck rrow). A subdurl collection (white rrows) overlies the tectoril membrne. Note the subdurl hemtom long the occipitl squm (rrowheds). b Sgittl fst imging employing stedy-stte cquisition sequence shows the subdurl collections long the clivus (white rrow) nd occipitl squm (blck rrows)

7 Peditr Rdiol (2014) 44 (Suppl 4):S621 S631 S627 Fig. 5 MRI in n 8-month-old boy with retroclivl collection (cse 13, indeterminte). Sgittl T1-weighted imge shows hyperintense retroclivl collection. The tectoril membrne is not clerly visulized ws identified on imging during the sme hospitl dmission ws 19 dys post symptom onset. Ten children with retroclivl collections identified on MRI underwent second MRI exmintion during the sme hospitl dmission nd of these 10 children, retroclivl collections could still be identified in 9 (rnge 2 19 dys, men 10.8 dys). Of children with retroclivl collection, 19 underwent brin MRI, on which 18 retroclivl collections were identified. The sgittl sequences employed in the MRI exmintions tht detected retroclivl collections were s follows: 18 children were imged with sgittl T1-weighted sequence nd 9 children with sgittl fluid-sensitive sequences. Retroclivl collections were identified on sgittl T1-weighted imges in 16/18 (89%), nd on sgittl fluid-sensitive sequences in 9/9 (100%). In regrd to xil brin imging, of the 18 children with retroclivl collection identified by MRI, 18 hd T2-weighted sequences, 16 hd susceptibility sequences (SWI or stedy-stte grdient echo imges), nd 11 hd FLAIR imges (xil FLAIR imging is not typiclly included in our infnt brin imging protocol nd ws therefore not consistently vilble for interprettion). Retroclivl collections were visulized on xil T2- weighted imges in 7/18 (39%), xil susceptibility imges in 4/ 16 (25%) nd xil FLAIR imges in 9/11 (82%). Five children hd gdolinium-enhnced MRIs nd in two cses the retroclivl collections enhnced (Fig. 6). A fluid-fluid level ws observed in 2 of 18 children with RCCs (Fig. 7). Other posterior foss nd impct injuries Subdurl hemtoms were concurrently noted within the posterior foss long the occipitl squm by CT or MRI in 20/21 (95%) children with retroclivl collections (Figs. 4 nd 6). Fig. 6 MRI in 30-month-old boy with n enhncing retroclivl subdurl collection (cse 10). The sgittl T1- weighted imge shows retroclivl subdurl collection (white rrows) nd n occipitl squm subdurl hemtom (blck rrow). b Sgittl T1- weighted post-contrst imge shows enhncement of the retroclivl subdurl collection (white rrows) nd the occipitl squml subdurl hemtom (blck rrow). c Axil FLAIR imge shows the retroclivl collection long the clivus (rrow), wheres the xil T2- weighted imge (d) does not. FLAIR fluid-ttenuted inversion recovery

8 S628 Peditr Rdiol (2014) 44 (Suppl 4):S621 S631 Fig. 7 MRI in 1-month-old boy with retroclivl collection (cse 18, indeterminte). Sgittl T1- weighted nd (b) sgittlfst imging employing stedy-stte cquisition imges show retroclivl collection with fluidfluid level (rrows) representing the interfce between sediment nd superntnt Imging resolution did not llow for ssessment for continuity between occipitl squm subdurl hemtoms nd retroclivl collections. In 3/21 (14%) children with retroclivl collections, prenchyml injury of the cerebellum ws lso present. Of those children without retroclivl collection (n=44), 28/ 44 (64%) hd subdurl hemtoms long the occipitl squm nd 8/44 (18%) hd prenchyml injury of the cerebellum. Skull frctures were present in 4/21 children (19%) with retroclivl collection nd in 15/44 (34%) children without retroclivl collection. There ws sttisticlly significnt correltion between retroclivl collections nd occipitl squm subdurl hemtoms (P=0.0066); there ws no sttisticlly significnt correltion between retroclivl collections nd skull frcture (P=0.21) or cerebellr prenchyml injury (P=0.69). Finlly, no child ws found to hve focl contusion of the brinstem or cerebellum, brinstem compression, epidurl hemtom long the occipitl squm, or clivl frcture. In ddition, no child hd evidence of ruptured tectoril membrne s hs beendescribedinchildrenwithretroclivlepidurlhemtoms occurring with ccidentl trum [28]. Discussion Retroclivl collections were reltively common (32%) in our cohort of young children with busive hed trum. This finding contrsts with the generl consensus tht these collections re rre [4, 6, 10, 11, 22]. Retroclivl collections were best visulized on CT in children with sgittl reformtted imges nd on MRI in the sgittl plne on T1-weighted, T2- weighted 3D vrible-flip-ngle FSE, fst imging employing stedy-stte cquisition, nd FSE inversion recovery imges, nd in the xil plne on FLAIR imges. A retroclivl collection cn be subdurl or epidurl in loction nd occsionlly combintion of both is identified. To scertin the loction of retroclivl collection, the tectoril membrne, thin sheet-like structure tht is continuous Additionl findings The dditionl neuroimging, clinicl nd skeletl survey findings re detiled in Tble 4. Thirteen children with retroclivl collection hd prenchyml injury of the suprtentoril brin prenchym, nd ll (n=21) hd suprtentoril subdurl hemtoms. There ws sttisticlly significnt correltion between retroclivl collections nd suprtentoril subdurl hemtoms (P=0.018) but no significnt correltion with prenchyml injury of the cerebrl hemispheres (P=0.16). No retroclivl collection demonstrted enough mss effect in the posterior foss to cuse obstructive hydrocephlus from loclized brinstem compression. In one child, retroclivl collection ws contiguous with subdurl collection in the cervicl nd thorcic spinl cnl (cse 12, Fig. 8). No child underwent surgicl evcution of retroclivl collection. Fig. 8 MRI in 7-month-old girl with retroclivl subdurl collection extending into the spinl cnl (cse 12). Sgittl T1-weighted imge shows thin but extensive subdurl collection extending from the mid clivus into the spinl cnl (white rrows). The tectoril membrne is well seen (blck rrow)

9 Peditr Rdiol (2014) 44 (Suppl 4):S621 S631 with the intrcrnil dur mter nd extends from the midclivus to the bse of C2, hs to be identified [29]. Fluid collections deep to the tectoril membrne re epidurl in loction nd those superficil to the tectoril membrne re subdurl [30]. In this study, the most common type of retroclivl collection ws locted in the subdurl comprtment (48%). Less common were retroclivl epidurl collections (14%) or combined retroclivl epidurl nd subdurl collections (10%). Approximtely one-third (28%) of collections were ctegorized s indeterminte for the following resons: the retroclivl collection ws identified on CT only nd no brin MRI ws performed; the retroclivl collection resolved (on CT) prior to the MRI being performed; nd MRI detil/ vilble sequences did not permit relible identifiction of the tectoril membrne nd therefore limited ctegoriztion of the retroclivl collection. Severl mechnisms hve been proposed for the formtion of clivl epidurl hemtoms which include stripping of the tectoril membrne from the surfce of the clivus from hyperextension injury resulting in trumtic injury to the tectoril membrne nd bleeding from the injured dur; trumtic disruption of the locl vsculture such s the meninohypophysel trunk or bsilr plexus; nd clivl frcture or distsis of the spheno-occipitl synchondrosis with durl bleeding [4, 5, 8]. Clivl subdurl hemtoms re rrely reported nd the source of bleeding is not clerly understood becuse there re few vessels in the clivl subdurl spce [30, 31]. We hypothesize tht fluid within the subdurl spce cn ccumulte secondry to (1) durl injury, resulting in bleeding; (2) trumtic rchnoid ter llowing cerebrospinl fluid to enter the subdurl spce, which would explin the three CSF-intensity subdurl collections seen in this cohort, nd (3) redistribution of subdurl fluid/blood from subdurl hemtoms locted long the occipitl squm or middle crnil foss. The clinicl presenttion of children with retroclivl collections vries. Children with retroclivl epidurl hemtoms occurring in the setting of ccidentl trum often present with neurologicl deficits rnging from lower crnil nerve presis to tetrplegi nd loss of spontneous respirtion [21 23, 28]. Children with retroclivl subdurl hemtoms rising from ccidentl injury my present with hemipresis nd respirtory rrest but children cn lso be symptomtic [27, 30, 32]. Neurologicl bnormlities observed in ccidentlly injured children with retroclivl collections my be relted to loclized injury to posterior foss contents with stretching, direct compression or contusion of nerves nd brin tissue. In ddition, deficits my reflect broder injury to the centrl nervous system [33]. Correlting neurologicl deficits in bused infnts to retroclivl epidurl or subdurl collections cn be especilly chllenging, prticulrly when there is polytrum with dditionl intrcrnil injuries in sedted/intubted ptient. In this S629 study, correltion of retroclivl collections with neurologicl bnormlities ws not possible bsed on lck of detiled neurologicl findings documented in the medicl records. The imging ppernces of retroclivl subdurl nd epidurl collections differed in this study. Retroclivl subdurl collections were either low or intermedite in ttenution on the first CT exmintion. This resulted in subtle ppernce of these collections in the xil plne, which ws further compounded by volume verging with the clivus nd bem hrdening rtifct rising from the clvrium. Sgittl reformtted imges were helpful in identifying some but not ll retroclivl subdurl collections. Interestingly, no retroclivl subdurl collection ws of high or mixed ttenution on the first CT exmintion, n ppernce tht is considered common for suprtentoril subdurl hemtoms in children with busive hed trum [34 36]. On MRI, one-third of retroclivl subdurl collections pproximted cerebrl spinl fluid in signl intensity. These collections represented either subdurl hygroms, possibly relted to n rchnoid ter with lekge of CSF into the subdurl spce [34, 36, 37], hemtohygroms or chronic subdurl hemtoms. The remining two-thirds of retroclivl subdurl collections followed signl intensities consistent with hemorrhgic/proteinceous fluid content. By contrst, retroclivl epidurl collections followed signl intensities consistent with bloody/proteinceous fluid. Furthermore, retroclivl epidurl hemtoms were not esily detected on hed CT, nd ll isolted retroclivl epidurl collections were identified on MRI only. This is of potentil clinicl significnce becuse retroclivl epidurl hemtoms seen in ccidentlly injured children re usully ssocited with crniocervicl junction injuries [4, 21, 28]. We detected more thn twice s mny retroclivl collections with MRI thn with CT, which suggests superior sensitivity of MRIcompredtoCT.SgittlT1-weightedimges,sgittl fluid-sensitive nd xil FLAIR imges showed the collections best, demonstrting the collections in 89%, 100% nd 82% of cses, respectively. Axil T2-weighted MR imges nd susceptibility sequences did not show the collections well, positive in only 37% nd 25% of cses, respectively. In some imging centers, sgittl fluid-sensitive sequences re not incorported into peditric brin trum protocols, nd xil FLAIR sequences re omitted in infnts. Thus, supplementtion of brin imging with these potentilly helpful sequences should be considered when ssessing children for busive hed trum. Severl interesting imging fetures of retroclivl collections were observed in this study. Two children with retroclivl collections demonstrted fluid-fluid levels within the collection, representing seprtion of blood components into sediment nd superntnt. Additionlly, 2 of 5 children who received gdolinium on MRI showed enhncement of the retroclivl collection. The mechnism of enhncement of subdurl collections is not known. Hypotheses put forwrd

10 S630 include pssive diffusion of contrst gent into the subdurl spce similr to ccumultion of contrst gent in pinel cysts nd contrst lekge from neovsculture in children with preexistent subdurl collections [38]. One child demonstrted continuity of retroclivl subdurl collection with cervicl nd thorcic subdurl collection. This observtion suggests tht it is possible tht posterior foss subdurl hemtoms resolve, t lest in prt, by redistribution of blood from the posterior foss into the spinl subdurl spce [39]. This mechnism would explin the rpid resolution of the retroclivl collectionseenincse8,whichresolvedwithin6hofinjury. Rpid resolution of retroclivl subdurl hemtom into the spinl comprtment hs lso been reported in child with ccidentl trum [19]. In our cohort, some retroclivl collections resolved quickly, while others remined evident dys fter the initil symptom onset. About hlf were visible on MRI t n verge of 10 dys fter symptom onset nd one ws still visible on dy 19. Therefore, even if brin MRI is delyed for severl dys fter dmission, retroclivl collection my still be detectble. In ddition to retroclivl collections, other posterior foss bnormlities were identified, such s subdurl hemtoms long the occipitl squm, common finding in children with busive hed trum, s well s cerebellr prenchyml injury, which is less commonly observed in these children nd ssocited with poor neurodevelopmentl outcomes [40]. Retroclivl collections were significntly correlted with posterior foss subdurl hemtoms but not with prenchyml injury of the cerebellum. No child in this study hd retroclivl collection lrge enough to cuse brinstem compression or hydrocephlus from loclized brinstem compression. Nor did ny child hve evidence of brinstem or cerebellr contusion or clivl frcture, ll findings previously reported in children with retroclivl hemtoms occurring with ccidentl trum [2, 7, 8, 10]. The spectrum of tectoril membrne bnormlities described in ccidentlly injured children rnges from bowing/ elevtion of the tectoril membrne to prtil nd complete tectoril membrne ters with frnk disruption. We did not identify ny child with prtil or complete ter of the tectoril membrne, findings seen t the most severe end of theinjuryspectruminchildrenwithccidentltrum[28, 41]. Furthermore, ll children with retroclivl collections in this cohort were mnged expectntly, s opposed to children with ccidentl trum who re occsionlly treted surgiclly [7, 9, 11, 20]. In regrd to suprtentoril hed injury, retroclivl collections were significntly correlted with suprtentoril subdurl hemtoms but not with prenchyml brin injury or skull frcture. This suggests tht in cses of busive hed trum, retroclivl collections re not necessrily ssocited with more severe brin injury ptterns or injuries tht involve blunt force trum. This study is limited by its retrospective nture nd modest cohort size. Results need to be vlidted in lrger prospective study. Also, s with most studies of busive hed trum, we cnnot be certin of the exct timing of injury in our cses nd cn only drw inferences bsed on when ptients presented for cre nd histories provided by cretkers regrding the onset of symptoms. Imging findings on hed CT nd MRI were tken into considertion in the clinicl multidisciplinry ssessment of the children in this cohort. Although the presence of n intrcrnil subdurl hemtom or retroclivl collection on imging did not constitute n inclusion criterion for dignosing buse, knowledge of the presence of these findings in the clinicl ssessment represented confounding fctor. Nevertheless, these findings were but two of mny dditionl dt points considered in the finl determintion of busive injury. CT nd MRI were not both vilble for ll ptients with identified retroclivl collections, nd thus in few cses modlities with differentil sensitivities for retroclivl collections were used. In ddition, children were dmitted to the hospitl on n emergent bsis nd the institution is tertiry cre center. Therefore, the cohort my hve been skewed towrd the more severe end of the spectrum of busive hed trum. Finlly, lck of detiled neurologicl ssessments vilble in the medicl chrts limited our bility to correlte retroclivl collections to specific neurologicl deficits. Conclusion Our study shows tht retroclivl collections re reltively common in children with busive hed trum nd suggests tht these collections re n importnt component of the busive hed trum imging spectrum. Retroclivl collections cn be subtle in ppernce, re better demonstrted on MRI thn on CT, nd cn be overlooked if cre is not tken with imge cquisition nd interprettion. Retroclivl collections were commonly identified in conjunction with multifocl subdurl hemtoms, which re considered hllmrk findings in busive hed trum, but were not significntly correlted with brin prenchyml injury or skull frcture. 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