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Table 1. Subject Demographics A g e B o y s Number of Subjects G i r l s <03 mo 03 00 <06 mo 04 02 <12 mo 03 04 <02 yrs 09 06 <04 yrs 06 09 <06 yrs 12 04 <10 yrs 19 08 <16 yrs 14 06 T o t a l 7 0 3 9 Fig. 1. Components of the occipital bone at birth with corresponding sutures and synchondroses. Basiocc = basioccipital bone, Exocc = exoccipital bone, Supraocc = supraoccipital bone, Temp = temporal bone, BES = basioccipital-exoccipital synchondrosis, ESS = exoccipital-supraoccipital synchondrosis, KSS = Kerckring-supraoccipital synchondrosis, OMS = occipitomastoidal suture, POS = petro-occipital synchondrosis, SOS = spheno-occipital synchondrosis. A B Fig. 2. Components of the sphenoid bone at birth with corresponding sutures and synchondroses at level of middle orbit (A) and upper orbit (B). The superomedial extension of the orbitosphenoid (B) extends across the superior aspect of the anterior accessory center of the presphenoid to form a prejugum ridge. Alisph=alisphenoid, Basiocc=basioccipital bone, Orbitosph=orbitosphenoid, Postsph= postsphenoid, Presph = presphenoid, A- POS=anterior presphenoido-orbital synchondrosis, BAS=basisphenoidalalisphenoidal synchondrosis, FSS= frontosphenoidal suture, IPOS=intrapostsphenoidal synchondrosis, IPRES=intrapresphenoidal synchondrosis, IPS=inter-planum sphenoidale, ISS=intersphenoidal synchondrosis, LMPS=lateromedial postsphenoidal synchondrosis, PPOS=posterior presphenoido-orbital synchondrosis, ROB=rostrum-ossicles of Bertin synchondrosis, SSS=sphenosquamal suture, SES=sphenoethmoidal suture. 2 1 6

Fig. 3. Five-tier scheme for grading sutural or synchondrosal closure is illustrated along the basioccipital-exoccipital synchondrosis on CT scans. (A) Grade 1. Margins of the synchondrosis(suture) are clearly separated on all sections. (B) Grade 2. Clear separation of the synchondrosis is seen on most sections, but some areas are indistinct or suspicious for osseous bridge (arrow). (C) Grade 3. Area of fusion or bridging (arrow) across a portion of the synchondrosis is definitely seen. (D) Grade 4. Complete fusion of the synchondrosis with remnant sclerotic margins is seen. (E) Grade 5. Complete closure is seen with no apparent vestige r e m a i n i n g. Table 2. Prevalence of Low Grade and High Grade Fusion in Boys* Sutures or s y n c h o n d o r o s e s 2 1 7 Number of subjects < 3 m o ( n = 3 ) < 6 m o ( n = 4 )< 1 2 m o ( n = 3 ) < 2 y r s ( n = 9 ) < 4 y r s ( n = 6 ) < 6 y r s ( n = 1 2 )< 1 0 y r s ( n = 1 9 )< 1 6 y r s ( n = 1 4 ) l o w h i g h l o w h i g h l o w h i g h l o w h i g h l o w h i g h l o w h i g h l o w h i g h l o w h i g h Related to occipital bone K e r c k r i n g - s u p r a o c c i p i t a l 2 1 1 3 0 3 0 9 0 6 00 12 00 19 00 14 E x o c c i p i t a l - s u p r a o c c i p i t a l 3 0 4 0 3 0 9 0 4 2 00 12 00 19 00 14 O c c i p i t o m a s t o i d a l 3 0 4 0 3 0 9 0 6 0 12 00 18 01 13 01 B a s i o c c i p i t a l - e x o c c i p i t a l 3 0 4 0 3 0 9 0 6 0 12 00 08 11 00 14 P e t r o - o c c i p i t a l 3 0 4 0 3 0 9 0 6 0 12 00 19 00 14 00 S p h e n o - o c c i p i t a l 3 0 4 0 3 0 9 0 6 0 12 00 19 00 12 02 Related to sphenoid bone Anterior p r e s p h e n o i d o - o r b i t a l 1 2 0 4 1 2 0 9 0 6 00 12 00 19 00 14 Posterior p r e s p h e n o i d o - o r b i t a l 0 3 0 4 0 3 0 9 0 6 00 12 00 19 00 14 I n t e r s p h e n o i d a l 0 3 0 4 0 3 0 9 0 6 00 12 00 19 00 14 I n t r a p r e s p h e n o i d a l 2 1 1 3 2 1 2 7 3 3 01 11 00 19 00 14 I n t r a p o s t s p h e n o i d a l 1 2 0 4 0 3 2 7 1 5 01 11 00 19 00 14 Rostrum-ossicle of Bertin 3 0 4 0 3 0 7 2 1 5 00 12 00 19 00 14 Lateromedial p o s t s p h e n o i d a l 2 1 0 4 0 3 0 9 0 6 00 12 00 19 00 14 B a s i s p h e n o i d a l - a l i s p h e n o i d a l 3 0 2 2 1 2 1 8 1 5 00 12 00 19 00 14 S p h e n o s q u a m o s a l 3 0 4 0 3 0 9 0 6 0 12 00 19 00 14 00 S p h e n o e t h m o i d a l 3 0 4 0 3 0 9 0 5 1 12 00 10 09 02 12 F r o n t o s p h e n o i d a l 3 0 4 0 3 0 9 0 6 0 12 00 11 08 02 12 Inter-planum sphenoidale 3 0 2 2 1 2 0 9 0 6 00 12 00 19 00 14 *Low grade fusion consists of grade 1,2, and 3, and high grade fusion consists of grade 4 and 5. Grade of fusion was determined by fivetier scheme for grading sutural or synchondrosal closure.

Table 3. Prevalence of Low Grade and High Grade Fusion in Girls* Sutures or s y n c h o n d o r o s e s 2 1 8 Number of subjects < 3 m o ( n = 0 ) < 6 m o ( n = 2 ) < 1 2 m o ( n = 4 ) < 2 y r s ( n = 6 ) < 4 y r s ( n = 9 ) < 6 y r s ( n = 4 ) < 1 0 y r s ( n = 8 ) < 1 6 y r s ( n = 6 ) l o w h i g h l o w h i g h l o w h i g h l o w h i g h l o w h i g h l o w h i g h l o w h i g h l o w h i g h Related to occipital bone K e r c k r i n g - s u p r a o c c i p i t a l 1 1 0 4 1 5 0 9 0 4 0 8 0 6 E x o c c i p i t a l - s u p r a o c c i p i t a l 2 0 4 0 6 0 7 2 1 3 2 6 0 6 O c c i p i t o m a s t o i d a l 2 0 4 0 6 0 9 0 4 0 8 0 6 0 B a s i o c c i p i t a l - e x o c c i p i t a l 2 0 4 0 6 0 9 0 4 0 2 6 0 6 P e t r o - o c c i p i t a l 2 0 4 0 6 0 9 0 4 0 8 0 6 0 S p h e n o - o c c i p i t a l 2 0 4 0 6 0 9 0 4 0 8 0 6 2 Related to sphenoid bone Anterior p r e s p h e n o i d o - o r b i t a l 0 2 0 4 0 6 0 9 0 4 0 8 0 6 Posterior p r e s p h e n o i d o - o r b i t a l 0 2 0 4 0 6 0 9 0 4 0 8 0 6 I n t e r s p h e n o i d a l 0 2 0 4 0 6 0 9 0 4 0 8 0 6 I n t r a p r e s p h e n o i d a l 2 0 1 3 1 5 0 9 0 4 0 8 0 6 I n t r a p o s t s p h e n o i d a l 0 2 1 3 1 5 1 8 0 4 0 8 1 5 Rostrum-ossicle of Bertin 2 0 3 1 3 3 0 9 0 4 0 8 0 6 Lateromedial postsphenoidal 1 1 0 4 0 6 0 9 0 4 0 8 0 6 B a s i s p h e n o i d a l - a l i s p h e n o i d a l 0 2 0 4 0 6 0 9 0 4 0 8 0 6 S p h e n o s q u a m o s a l 2 0 4 0 6 0 9 0 4 0 8 0 6 0 S p h e n o e t h m o i d a l 2 0 4 0 6 0 9 0 4 0 5 3 0 6 F r o n t o s p h e n o i d a l 2 0 4 0 6 0 9 0 4 0 6 2 1 5 Inter-planum sphenoidale 1 1 0 4 0 6 0 9 0 4 0 8 0 6 *Low grade fusion consists of grade 1,2, and 3, and high grade fusion consists of grade 4 and 5. Grade of fusion was determined by fivetier scheme for grading sutural or synchondrosal closure.

Table 4. Average Scores of Sutural or Synchondrosal Closure in Boys According to Each Age Groups CT scores (averagestandard deviation) Sutures or synchondoroses < 3 m o ( n = 3 ) < 6 m o ( n = 4 )< 12 m o ( n = 3 )< 2 y r s ( n = 9 ) < 4 y r s ( n = 6 )< 6 y r s ( n = 12 )< 10 y r s ( n = 19 )< 16 y r s ( n = 14 ) Related to occipital bone K e r c k r i n g - s u p r a o c c i p i t a l 3. 001. 00 4. 000. 82 4. 670. 58 5. 000. 00 4. 830. 41 5. 000. 00 5. 000. 00 5. 000. 00 e x o o c c i p i t a l - s u p r a o c c i p i t a l 1. 000. 00 1. 000. 00 1. 000. 00 1. 670. 53 3. 001. 41 4. 270. 45 4. 630. 51 4. 930. 28 O c c i p i t o m a s t o i d a l 1. 000. 00 1. 000. 00 1. 000. 00 1. 000. 00 1. 170. 40 1. 830. 38 2. 210. 63 2. 330. 52 b a s i o c c i p i t a l - e x o c c i p i t a l 1. 000. 00 1. 000. 00 1. 000. 00 1. 110. 33 1. 170. 41 2. 170. 83 3. 630. 76 4. 290. 47 Petro-occipital 1. 000. 00 1. 000. 00 1. 000. 00 1. 000. 00 1. 000. 00 1. 000. 00 1. 370. 49 2. 140. 36 S p h e n o - o c c i p i t a l 1. 000. 00 1. 000. 00 1. 000. 00 1. 000. 00 1. 000. 00 1. 000. 00 1. 160. 37 2. 250. 93 Related to sphenoid bone Anterior p r e s p h e n o i d o - o r b i t a l 3. 670. 58 4. 250. 58 3. 670. 58 4. 560. 52 4. 830. 40 5. 000. 00 5. 000. 00 5. 000. 00 Posterior p r e s p h e n o i d o - o r b i t a l 4. 000. 00 4. 750. 50 4. 670. 58 4. 670. 50 4. 670. 51 4. 920. 28 5. 000. 00 5. 000. 00 I n t e r s p h e n o i d a l 4. 000. 00 4. 250. 50 4. 000. 00 4. 330. 50 4. 330. 51 4. 920. 28 5. 000. 00 5. 000. 00 Intrapresphenoidal 3. 001. 00 4. 251. 50 3. 330. 58 4. 110. 78 3. 50. 54 4. 830. 57 5. 000. 00 5. 000. 00 I n t r a p o s t s p h e n o i d a l 4. 001. 73 5. 000. 00 5. 000. 00 4. 560. 88 4. 670. 81 5. 000. 00 4. 950. 45 5. 000. 00 Rostrum-ossicle of Bertin 1. 330. 58 1. 500. 58 2. 330. 58 2. 781. 05 4. 670. 81 5. 000. 00 5. 000. 00 5. 000. 00 Lateromedial postsphenoidal 3. 330. 58 4. 400. 89 4. 670. 58 4. 780. 44 5. 000. 00 4. 750. 45 4. 950. 45 5. 000. 00 B a s i s p h e n o i d a l - a l i s p h e n o i d a l 2. 330. 58 3. 250. 95 3. 670. 58 4. 220. 66 4. 830. 38 4. 830. 32 4. 890. 32 4. 870. 36 S p h e n o s q u a m o s a l 1. 330. 58 1. 250. 50 1. 670. 58 2. 000. 50 2. 000. 00 2. 170. 39 2. 500. 51 2. 710. 49 S p h e n o e t h m o i d a l 1. 330. 58 1. 50. 58 2. 000. 00 2. 000. 00 2. 500. 83 2. 880. 38 3. 530. 61 4. 570. 75 F r o n t o s p h e n o i d a l 1. 330. 58 1. 750. 50 2. 000. 00 2. 330. 50 2. 500. 54 2. 500. 52 3. 530. 69 4. 360. 74 Inter-planum sphenoidale 1. 330. 58 3. 501. 29 4. 001. 00 4. 500. 44 5. 000. 00 5. 000. 00 4. 950. 22 5. 000. 00 Table 5. Average Scores of Sutural or Synchondrosal Closure in Girls According to Each Age Groups CT scores (averagestandard deviation) Sutures or Synchondoroses < 3 m o ( n = 0 ) < 6 m o ( n = 2 )< 12 m o ( n = 4 )< 2 y r s ( n = 6 ) < 4 y r s ( n = 9 ) < 6 y r s ( n = 4 ) < 10 y r s ( n = 8 ) < 16 y r s ( n = 6 ) Related to occipital bone K e r c k r i n g - s u p r a o c c i p i t a l 3. 001. 41 4. 500. 58 4. 500. 83 4. 900. 33 5. 000. 00 5. 000. 00 5. 000. 00 e x o o c c i p i t a l - s u p r a o c c i p i t a l 1. 500. 71 1. 250. 50 1. 830. 75 3. 110. 60 3. 750. 50 4. 120. 83 4. 830. 41 O c c i p i t o m a s t o i d a l 1. 000. 00 1. 000. 00 1. 170. 41 2. 000. 00 2. 000. 00 2. 250. 46 2. 830. 41 b a s i o c c i p i t a l - e x o c c i p i t a l 1. 000. 00 1. 000. 00 1. 000. 00 1. 440. 53 2. 750. 50 3. 750. 46 4. 170. 41 Petro-occipital 1. 000. 00 1. 000. 00 1. 000. 00 1. 000. 00 1. 000. 00 1. 750. 46 2. 500. 54 S p h e n o - o c c i p i t a l 1. 000. 00 1. 000. 00 1. 000. 00 1. 000. 00 1. 250. 50 1. 250. 52 2. 500. 54 Related to sphenoid bone Anterior presphenoido - o r b i t a l 4. 500. 70 4. 500. 54 4. 330. 54 4. 860. 37 5. 000. 00 5. 000. 00 5. 000. 00 Posterior presphenoido - o r b i t a l 4. 500. 70 4. 750. 50 4. 670. 52 4. 780. 44 5. 000. 00 4. 870. 35 5. 000. 00 I n t e r s p h e n o i d a l 4. 000. 00 4. 000. 00 4. 330. 52 4. 780. 44 5. 000. 00 5. 000. 00 5. 000. 00 Intrapresphenoidal 4. 000. 00 4. 001. 41 4. 330. 81 4. 890. 33 5. 000. 00 5. 000. 00 5. 000. 00 Intrapostsphenoidal 5. 000. 00 4. 250. 95 4. 500. 83 4. 670. 71 5. 000. 00 5. 000. 00 4. 600. 89 Rostrum-ossicle of Bertin 2. 500. 70 2. 501. 00 3. 171. 15 5. 000. 00 5. 000. 00 5. 000. 00 5. 000. 00 Lateromedial postsphenoidal 3. 500. 70 4. 50. 58 4. 830. 41 4. 890. 33 4. 750. 50 4. 750. 46 4. 830. 41 B a s i s p h e n o i d a l - a l i s p h e n o i d a l 4. 000. 00 4. 000. 00 4. 670. 52 4. 710. 48 5. 000. 00 4. 750. 46 5. 000. 00 S p h e n o s q u a m o s a l 1. 500. 70 1. 500. 57 1. 830. 41 2. 110. 35 2. 500. 58 2. 870. 35 2. 830. 41 S p h e n o e t h m o i d a l 2. 000. 00 2. 000. 00 2. 000. 00 2. 890. 33 3. 000. 00 3. 380. 52 4. 670. 52 F r o n t o s p h e n o i d a l 2. 000. 00 2. 000. 00 2. 000. 00 2. 560. 52 2. 220. 50 3. 120. 64 3. 830. 41 Inter-planum sphenoidale 3. 001. 41 3. 751. 50 4. 500. 54 4. 890. 33 5. 000. 00 5. 000. 00 5. 000. 00 2 1 9

4 5 6 Fig. 4. Axial CT scan of the occipital bone in a 5-month-old female infant. All sutures and synchondroses are widely open, including Kerckring-supraoccipital synchondrosis (long arrows), exoccipital-supraoccipital synchondrosis (double arrows), occipitomastoidal suture (arrowheads), basioccipital-exoccipital synchondrosis (large arrows), petro-occipital synchondrosis (double arrows), and spheno-occipital synchondrosis (triple arrows). Note the Kerckring ossicle (single arrow) located in the middle of the posterior aspect of the foramen magnum. Fig. 5. Axial CT scan of the occipital bone in a 9-month-old female infant. Kerckring-supraoccipital synchondrosis has already fused (long arrow). The exoccipital-supraoccipital synchondrosis (small double arrows) and occipitomastoidal suture (single arrows) are still open. Basioccipital-exoccipital synchondrosis(large arrows) is also widely open. Fig. 6. Axial CT scan of the sphenoid bone in same infant as in Fig. 5. The posterior presphenoido-orbital synchondrosis (small single arrows) shows early high grade fusion with some sclerotic remnants. The intersphenoidal synchondrosis(small double arrows) and intrapostsphenoidal synchondrosis (long arrow) have completely fused without remnant. However, the intrapresphenoidal synchondrosis (large double arrows) remains partially open (grade 3), which fuses last among three synchondroses within the sphenoidal body. Note the widely open spheno-occipital synchondrosis (large single arrows) posterior to the postsphenoid. 7 8 9 Fig. 7. Axial CT scan shows grade 4 fusion of the anterior presphenoido-orbital synchondrosis (arrows) in a 3-year-old boy. Fig. 8. Axial CT scan of the sphenoid body in a 1-month-old male infant. The intersphenoidal synchondrosis (single arrows) fuses earlier than the other synchondroses in the sphenoidal body. The intrapostsphenoidal synchondrosis (long arrow) and intrapresphenoidal synchondrosis (double arrows) show low grade fusion (grade 2). Fig. 9. Axial CT scan in a 1 year-old boy. The rostrum-ossicle of Bertin synchondrosis (long arrow) shows low grade fusion (grade 2). Note the paired ossicles of Bertin (small arrows). The sphenosquamosal suture (arrows) shows its complex and interwoven appearance with the sclerotic remnants along the suture. 2 2 0

A B Fig. 10. The lateromedial postsphenoidal synchondrosis and basisphenoidal-alisphenoidal synchondrosis. A. Axial CT scan in a 2-month-old male infant shows fusion of the lateromedial postsphenoidal synchondrosis (arrows) earlier than that of the basisphenoidalalisphenoidal synchondrosis (small double arrows). B. Axial CT scan in a 3-year-old girl shows complete fusion of both sync h o n d r o s e s. Fig. 11. Axial CT scan shows grade 2 fusion of the sphenoethmoidal suture (short arrows) and interplanum sphenoidale (long arrow) in a 5-month-old female infant. Fig. 12. Axial CT scan shows grade 2 fusion of the frontosphenoidal suture (arrows) in a 5-month-old female inf a n t. 1 1 1 2 2 2 1

2 2 2 Fig. 13. Schematic representation of the skull base of a new born. This drawing depicts the relationship of the sphenoidal and occipital centers to their neighboring structures.

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1. Madeline LA, Elster AD. Suture closure in the human chondrocranium: CT assessment. R a d i o l o g y 1995 ; 196 : 747-756 2. Madeline LA, Elster AD. Postnatal development of the central skull base: normal variants. R a d i o l o g y 1995 ; 196 : 757-763 3.,,,,,,. CT. 1999 ; 41 : 1209-1214 4. David DJ, Poswillo D, Simpson D. The craniosynostoses: causes, natural history, and management. New York, NY:Springer-Verlag,1982: 18-19 5. Furuya Y, Edwards MS, Alpers CF, Tress BM, Ousterhout DK, Norman D. Computerized tomography of cranial sutures, part I: comparison of suture anatomy in children and adults. J Neurosurg 1984 ; 61 : 53-58 6. Belden CJ, Mancuso AA, Kotzur IM. The developing anterior skull base: CT apperance from birth to 2 year of age. AJNR 1997 ; 18 : 811-818 7. Shapiro R, Robinson F. Embryogenesis of the human occipital b o n e. AJR 1976 ; 126 : 1063-1068 8. Okamoto K, Ito J, Tokiguchi S, Furusawa T. High resolution CT findings in the development of the sphenooccipital synchondrosis. A J N R 1995 ; 17 : 117-120 9. Melsen B. Time and mode of closure of the spheno-occipital synchondrosis determined on human autopsy material. Acta Anat 1972;83:112-118 10. Shopfner CE, Wolfe TW, O Kell RT. The intersphenoid synchondrosis. AJR 1968 ; 104 : 184-193 11. Hoyte DAN. A critical analysis of the growth in length and the cra- nial base. Birth Defects 1975 ; 11 : 255-282 2 2 4

Normal Development of Sutures and Sy n c h o n d roses in the Central Skull Base : CT Study 1 Hong Gee Roh, M.D., Hyung-Jin Kim, M.D., Jee Hee Kang, M.D., Kyung-Hee Lee, M.D., Myung Kwan Lim, M.D., Young Kuk Cho, M.D., Cheol Su Ok, M.D., Chang Hae Suh, M.D. 1 Department of Radiology, Inha University College of Medicine Purpose : To evaluate the developmental patterns of the sutures and synchondroses in the central skull base. Materials and Methods : We evaluated the CT scans of 109 children(age range, 29 days to 15 years) with no skull base abnormality who had undergone axial CT of the skull base with 1-mm collimation. Using a five-tier scheme, we analyzed the developmental patterns of the 18 sutures and synchondroses related to the sphenoid and occipital bones. Results : Fusion of the sutures and synchondroses related to the sphenoid bone progressed rapidly during the first two years. Thereafter, changes in the sphenoid bone were dominated by pneumatization of the sphenoid sinus. Fusion of the synchondroses within the sphenoid body, including intersphenoidal, intrapresphenoidal, and intrapostsphenoidal synchondrosis occurred early and in most cases was graded 4. Fusion of the sphenosquamosal, sphenoethmoidal, and frontosphenoidal sutures was delayed, and residual sclerosis was a common finding. Except for Kerckring-supraoccipital synchondrosis, fusion of the six sutures and synchondroses related to the occipital bone occurred more gradually than that of those related to the sphenoid bone. Among these, fusion of the occipitomastoidal suture and petro-occipital synchondrosis was the last to occur. Conclusion : A knowledge of the developmental patterns of sutures and synchondroses can help differentiate normal conditions from those such as fracture, osseous dysplasia, or congenital malformation, which are abnormal. Our results provide certain basic informations about skull base maturity in children. Index words : Skull, anatomy Skull, CT Skull, growth and development Address reprint requests to : Hyung-Jin Kim, M.D., Department of Radiology, Inha University Hospital 7-206, 3rd Street, Shinheung-dong, Choong-gu, Inchon, 400-103, Korea. Tel. 82-32-890-3402 Fax. 82-32-890-3097 2 2 5

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