craniofacial morphology in - university of pittsburgh

Craniofacial Morphology in Shunt-Treated.Hydrocephalic Children

JAN A. Hugaaare, Lic. Opont.Tuomo J. Kantomaa, Dr. ODboNT.OLLI V. Ronining, Dr. Opont.WiILLy S. SERLO, M.D.

Craniofacial morphology was studied in a sample of 37 hydrocephalicsubjects, 7 to 18 years of age, most of whom had had their first shuntoperation performed in early childhood and were presently undergo-ing shunt treatment. The patients were grouped according to age andsex, and cephalometric radiograms were made. Similar radiogramsfrom a north Finnish population and pretreatment radiograms from chil-dren having orthodontic cure were used as controls. The cephalo-gramswere analyzed using linear, angular, and proportional measurements.

Both cranial and facial morphological deviations were observedamong the shunt-treated patients. The calvarium was thickened andthe neurocranium enlarged; the cranial base flexure was increased,particularly among the older boys; and increased facial prognathismwas observed. These craniofacial aberrations seemed to be exacer-bated by a prolonged shunting time.A class I dental interrelation was found in all but two patients.

The essential factor in controlling hydrocepha-lus is maintenance of adequate subdural pressure(Hakim and Hakim, 1984). The introduction ofa valve-regulated shunt device to ensure unidirec-tional cerebrospinal fluid (CSF) circulation (Nul-sen and Spitz, 1952) has made shuntingprocedures the main treatment modality in themanagement of childhood hydrocephalus(Choux, 1982). The cranial (proximal) end of theshunt is inserted into the lateral ventricle by anoccipital or frontal approach and the distal endinto the peritoneal cavity or into the right atri-um of the heart. The pressure regulating valveis situated outside the bony cranium. Althougha marked improvement in the prognosis ofhydrocephalic children is achieved with the shunttreatment, it is prone to various complications

The authors are all affiliated with the University of Oulu,Oulu, Finland. Mr. Huggare (Assistant Professor) and Drs.Kantomaa (Assistant Professor) and Ronning (Professor) arewith the Department of Oral Development and Orthodon-tics in the Institute of Dentistry. Dr. Serio is Pediatric Sur-geon in the Department of Pediatrics and Surgery.

This paper was presented in part at the meeting of the Nor-dic Orthodontic Society in Jonkoping, Sweden, 1984.

261

such as shunt obstructions, mechanical failures,infections, and overdrainage of CSF (Serlo,1985). An extended period of shunting may alsobe associated with change in the configurationof the sella turcica, planum sphenoidale, and cli-vus, thickening of the cribriform plate and cal-varium, and premature fusion of cranial sutures(Anderson, 1966; Anderson et al, 1970; Kauf-man et al, 1970, 1973; Serlo et al, 1985).According to the classification of Forrester et

al (1966), a child is considered to have uncon-trolled hydrocephalus if the occipitofrontal cir-cumference exceeds the norm for his age by twostandard deviations. Hydrocephalus is judged tobe controlled if the occipitofrontal circumferenceis within two standard deviations. Thus, thereare no statistically significant differences betweenyoung controlled hydrocephalic and healthy, nor-mal children (Forrester et al, 1966).

Skull form is associated with the shape of thecranial base in that a dolichocephalic head formtends to be associated with a relatively flat cranialbase, whereas the brachycephalic head form isassociated with a more closed cranial base flex-ure (Enlow, 1975). The cranial base flexure in

262 Cleft Palate Journal, October 1986, Vol. 23 No. 4

turn provides the basis for the topographic

characteristics of the face. Bjork (1947) found

the most influential changes in the degree of fa-

cial prognathism to be attributable to the shape

and size of the cranial base.

The purpose of this study was to evaluate pos-

sible deviations in the craniofacial skeleton and

the interrelation between facial and cranial struc-

tures in shunt-treated hydrocephalic children.

SUBJECTS AND METHODS

The 37 patients,7 to 18 years of age, who par-

ticipated in the study had been treated at the

Department of Pediatrics, University of Oulu,

Finland during the period 1968 to 1983. Most

of the subjects had developed hydrocephalus dur-

ing the first or second postnatal year and had the

first shunt operation immediately after diagno-

sis. Revisions were common, since there had

been an average of 3.9 operations per patient.

The subjects generally cooperated, and many of

them managed well in normal school grades.

Their motor performance skills were, however,

somewhat disturbed (Serlo, 1985).

Since the cranial changes in shunt-treated

hydrocephaly patients have been found to be age

'dependent (Huggare et al, 1984), the subjects

were divided into four groups by age and sex

- (Table 1). Group I comprised seven boys, 7 to

9 years of age; group II, 12 boys, 11 to 18 years

of age; group III, eight girls, 7 to 10 years of

age; and group IV, 10 girls, 11 to 18 years of

age.

Control subjects were selected randomly for

each of the groups, partly from a sample from

northern Finland (Huggare, unpublished) and

partly from pretreatment roentgenocephalometric

data obtained from children reporting for or-

thodontic treatment at the Institute of Dentistry,

University of Oulu. The control groups were

twice as large as the corresponding shunt-treated

groups.

The hydrocephaly patients and the controls

were examined and roentgenographed in a

cephalostat (Lumex, Tagarno, A/S) at the Insti-

tute of Dentistry, University of Oulu.

The cephalograms were analyzed, using eight-

een linear and nineteen angular measurements

characterizing both cranial and dentoalveolar

structures (Figs. 1 to 4). In addition, a method

based on concentric circles drawn on the

cephalogram with the posterior rim of the fora-

men magnum (point opisthion) as the center

TABLE 1 Size, Age, and Sexual Distribution of the Groups

Group I Group II Group III Group IV

- Control Treated Control Treated Control Treated > Control Treated

N 14 7 24 16 8 20 10Mean age 7.6 7.7 14 8.6 8.4 14.7 14.7Age range 5-9 7-9 11-17 11-18 7-9 7-10 11-20 11-18

Sex M M M F F F F

Ww

SAA

~\&

IE

FIGURE 1 Linear measure-

ments for cranial variables 1-7

(shown in Tables 4-7).

Huggare, CRANIOFACIAL MORPHOLOGY IN HYDROCEPHALIC CHILDREN 263

T

y fi\ ia

FIGURE 3 Angular measure-ments for craniofacial variables19-23 (shown in Tables 4-7).


(Koski, 1953) was employed for analysis of fa-

cial proportions (Fig. 5). The reference points,

lines, and planes are given in Tables 2 and 3.

Student's t-test for small samples was used for

statistical analysis of the differences between the

groups of shunt-treated subjects and controls.

In addition, the sagittal relationship between

the upper and lower dentition was recorded either

from plaster casts or clinically according to the

classification of Angle (1899).

RESULTS

Analysis of data from tracing the cephalomet-

ric radiograms revealed two consistent findings:

a thickened calvarium (Calv) and an increased

distance from sella to bregma (S-Br) in all shunt-

treated groups. The other craniofacial deviations

showed some inconsistency between the groups.

The 7- to 9-year-old shunt-treated boys (group

I) did not show any radiographic differences rela-

tive to control subjects other than a distinctly en-

larged neurocranium (G1-OpC, Na-La, S-Br),

a slightly increased thickness of the calvarium

FIGURE 5 Proportional (cir-cle) analysis for the estimation offacial proportions, variables38-43 (shown in Tables 4-7).

FIGURE 4 Angular measure-ments for craniofacial variables34-37 (shown in Tables 4-7).

(Calv), and an increased distance between

opisthion and the sella turcica point (Op-St) (Ta-

ble 4).

The 11- to 18-year-old treated boys (group II)

showed notable deviations in craniofacial con-

figuration. The neurocranium was larger

(G1-OpC, N-La, S-Br), the calvarium (Calv)

thickened, the cranial base (N-Ba) reduced in

length and more flexed (N-S-Ba, N-S-Ar,

Cliv/Sph), the inclination of the clivus with

regard to the foramen magnum plane (For/Cliv)

and orbital plane (Cliv/Orb) was steeper, and the

angle indicating the depth of the bony

nasopharynx (Pm-S-Ba) was slightly decreased.

Both the maxilla and mandible were more prog-

nathic (S-Ss, S-Pgn, Pt-Ss, Pt-Pgn, S-N-Ss, S-

N-Pg), and the lower face height (Ac-Gn), the

distance from the sella to articulare (S-Ar), and

the length of the mandible (Pgn-Cd) were slightly

increased. There were also some dentoalveolar

changes in that the occlusal plane was more

parallel to the nasal plane (OL/NL) and the up-

per incisors were more labially inclined in the

shunt-treated group (IL/NL; Table 5). The

\4u) 30

38

yacsh


TABLE 2 Reference Points Used for Dimensional and Angular Measurements on the Roentgenocephalograms.

Abbreviation Reference Point Location

Ac Acanthion Tip of the anterior nasal spine -Ar Articulare Intersection between the external contour of the cranial base and the dorsal contour of the

condylar head or neckBa Basion Extreme posteroinferior point on the anterior margin of the foramen magnumBr Bregma Midpoint of the coronal suture on the external cranial contourCd Condylion Extreme superoposterior point on the condylar headGI Glabelia Extreme anterior point of the frontal boneGn Gnathion Extreme inferior point on the mandibular symphysisId Infradentale Extreme anterosuperior point on the lower alveolar marginLa Lambda Midpoint of the lamboid suture on the external cranial contourN Nasion Extreme anterior point of the frontonasal sutureOp Opisthion Extreme posterior point of the bony margin of the foramen magnumOpC Opisthokranion Extreme posterior point of the occipital bonePg Pogonion Extreme anterior point on the mandibular symphysisPgn Prognathion Point on the mandibular symphysis furthest from CdPm Pterygomaxillare Intersection between the nasal floor and the posterior contour of the maxillaPr Prosthion Extreme anteroinferior point on the upper alveolar marginPt Pterygoid point Crest of bone seen at the lower lip of the foramen rotundumS Sella Centre of the sella turcica. The upper limit of the sella turcica is defined as the line joining

the tuberculum and dorsum sellae.Ss Subspinale Extreme posterior point on the anterior contour of the upper alveolar processSt Sella turcica point Anteroposterior midpoint of the lower bony margin of the hypophyseal fossa

TABLE 3 Reference Lines and Planes Used for Dimensional and Angular Measurements ontheRoentgenocephalograms

Abbreviation Line/Plane Definition

Calv Calvarium line Shortest distance between the outer and inner surface of the calvarium at the region ofthe opisthion

Cliv Clivus plane Tangent line to the clivus, excluding the dorsum sellaeCL Chin line Line through Id and PgFor Foraminal plane Line from the basion through the opisthionIL; Lower incisor line Line from the tip of the most labial lower incisor through its apexIL, Upper incisor line Line from the tip of the most labial upper incisor through its apexMBL Mandibular base line Line through Pgn and CdML Mandibular line Tangent to the lower border of the mandible through GnNL Nasal line Line through Ac and PgNSL Nasion-sella line Line through N and SOrb Orbital roof plane Line tangential to the orbital roofOL Occlusal line Line from the tip of the upper incisor to the distal cusp of the first permanent molar or, if

not erupted, to the distal cusp of the second deciduous molarRL Ramus line Tangent to the posterior border of the mandibleSph Sphenoidal plane Tangent to the planum sphenoidale


TABLE 4 Mean Values and Standard Deviations forDifferent Craniofacial Variables in Boys 7 to 9 Years

TABLE 5 Mean Values and Standard Deviations forDifferent Craniofacial Variables in Boys 11 to 18 Years

of Age (Group D*

Control (N=14) Treated (N=7)

Variables X SD X SD Difference

1. G1-OpC 192.9 4.7 204.1 5.6 +11.2t2. N-La 186.4 5.1 198.9 5.3 +12.5t3. S-Br 108.6 4.9 115.9 5.10 + 7.3%4. Calv 6.1 1.0 7.6 1.6 + 1.5§5. N-Ba 100.3 4.8 100.0 5.2 - 0.36. S-N 68.4 2.9 69.0 4.2 + 0.67. S-Ba 42.6 2.8 42.6 1.7 + 08. S-Ar 31.3 3.0 31.7 22.1 + 0.49. S-Pm 43.8 3.3 43.0 2.250 - 0.2

10. S-Ss 79.0 4.2 77.4 2.2 - 1.611. S-Pgn 111.5 7.7 109.4 5.4 - 2.112. Pt-Ss 57.9 3.4 56.4 1.8 - 1.513. Pt-Pgn 90.8 6.2 88.7 4,4 - 2.114. Pm-Ba 43.1 2.3 43.1 3.0 + 015. N-Ac 46.1 4.2 43.9 223 - 2.216. Ss-Pm 46.17 2.6 45.7 1.7 - 1.017. Ac-Gn 61.5 4.0 63.9 5.9 + 2.418. Pgn-Cd 103.8 5.6 101.9 5.0 - 1.919. N-S-Ba 130.9 3.4 130.6 5.4 - 0.320. N-S-Ar 122.7 3.7 121.7 6.0 - 1.021. Pm-S-Ba 61.2 4.4 61.7 2.9 + 0.522. S-N-Ss 81.5 2.4 79.6 3.5 - 1.923. S-N-Pg 78.1. 3.7 76.3 2.9 - 1.824. NSL/NL 5.6 2.9 4.6 2.3 - 1.025. NSL/ML 33.6 4.8 36.6 4.9 + 3.026. NSL/MBL 55.4 3.6 55.6 5.50 + 0.227. NL/ML 28.0 4.4 32.0 5.3 + 4.028. ML/RL 129.6 5.3 133.1 2.30 + 3.529. CL/ML 70.0 6.4 72.0 3.4 + 2.030. OL/NL 15.50 3.2 17.1 5.9 + 1.631. IL 106.9 7.0 103.4 10.8 - 3.532. IL,/ML 93.6 5.3 91.9 6.1 - 1.733. IL/IL; 129.4 8.7 131.9 124 + 2.534. For/Cliv 121.0 4.7 123.0 3.3 + 2.035. Cliv/Sph 112.7 6.6 112.7 9.7 +036. Cliv/Orb 139.4 5.4 139.1 5.8 - 0.337. Sph/Orb 28.2 5.4 28.9 7.3 + 0.738. Op-Ac 100.0 0.0 100.0 0.039. Op-St 53.3 1.8 55.0 1.70 + 1.7840. Op-N 104.4 1.7 105.7 2.50 4+ 1.341. Op-Pr 98.4 1.0 98.0 0.8% - 0.442. Op-Id 97.5 2.1 97.0 1.5 - 0.543. Op-Pg 100.4 2.8 98.1 2.1 - 2.3 * Variables 1-18 in millimetres, 19-37 in degrees, and 38-43

in percentagesf p <0.001+p <0.01§ p <0.05

analysis of facial proportions showed the distance

between opisthion and nasion to be markedly

reduced.

Thetreated younger girls, 7 to 10 years of age

(group III), showed deviations from the control

subjects with regard to the neurocranium and

cranial base. The distances from glabella to

opisthocranion (G1-Opc), from nasion to lamb-

da (N-La), and from the sella midpoint to breg-

ma (S-Br) were all increased; the cranial vault

(Calv) was thickened, the cranial base (N-S-Ba,

N-S-Ar) more flexed, and the angle between the

foraminal and clival planes (For/Cliv) was steep-

er. The distances from sella and pterygoid point

to subspinale and prognathion were increased,

of Age (Group ID*



1. GIl-OpC 193.6 6.1 202.2 8.9 +2.. N-La 188.5 6.2 197.6 7.9 + 9.1%3. S-Br 107.8 3.0 112.8 6.17 + 5.084. Calv 6.1 1.7 10.1 3.7 + 4.0%5. N-Ba 108.1 3.9 104.0 4.0 - 4.1%6. S-N 72.2 2.7 71.7 4.4 - 0.57. S-Ba 46.17 2.3 48.2 2.6 + 1.58. S-Ar 35.1 2.8 37.9 4.0 + 2.8§9. S-Pm 47.9 3.0 50.4 4.5000 + 2.5

10. S-Ss 84.2 4.1 89.1 5.6 + 4.9%11. S-Pgn 122.8 5.8 130.0 9.0 + 7.2§12. Pt-Ss 62.0 3.1 65.5 2.80 + 3.5%13. Pt-Pgn 100.2 5.6 107.0 7.0 + 6.8%14. Pm-Ba 46.0 2.9 45.3 4.1 - 0.715. N-Ac 51.50 3.7 51.4 3.6 - 0.116. Ss-Pm 51.3 2.0 51.7 2.29 + 0.417. Ac-Gn 67.0 4.2 71.5 4.9 + 4.5%18. Pgn-Cd 115.0 4.8 120.2 8.50 0+ 5.2$§19. N-S-Ba 132.2 5.4 124.3 4.9 - 7.9120. N-S-Ar 124.2 5.3 117.4 4.6 - 6.8121. Pm-S-Ba 59.3 4.5 55.3 5.2 - 4.0822. S-N-Ss 81.3 3.5 85.8 3.0 + 4.5t23. S-N-Pg 78.5 3.4 82.1 2.9 + 3.6%24. NSL/NL 5.5 2.4 4.8 3.0 - 0.725. NSL/ML 32.3 4.8 32.7 3.2 + 0.426. NSL/MBL 56.0 3.5 55.1 3.2 - 0.927. NL/ML 26.8 3.6 27.9 4.8 + 1.128. ML/RL 125.3 6.4 128.3 6.8 + 3.029. CL/ML 73.3 7.1 72.5 4.6 - 0.830. OL/NL 14.6 - 2.0 11.2 4.2 - 3.4%31. IL,/NL 107.2 6.0 113.2 6.1 + 6.0%32. IL,/ML 98.8 6.3 95.2 5.8 - 3.633. IL/IL,; 126.0 9.8 124.0 10.7 - 2.034. For/Cliv 122.2 5.0 116.8 5.6 - 5.4435. Cliv/Sph 111.3 8.1 103.0 7.2 - 7.7436. Cliv/Orb 142.7 6.7 135.6 5.9 - 7.1%37. Sph/Orb 31.6 5.1 29.7 6.3 - 1.938. Op-Ac 100.0 0.0 100.0 0.039. Op-St 52.4 2.0 51.9 2.6 - 0.540. Op-N 104.2 2.3 101.3 1.7 - 2.9t41. Op-Pr 99.9 1.2 99.8 1.6 - 0.142. Op-Id 98.5 1.6 99.3 3.0 + 0.843. Op-Pg 102.3 2.5 103.4 4.7 + 1.1 * Variables 1-18 in millimetres, 19-37 in degrees, and 38-43

in percentages -t p <0.001+ p <0.01§ p <0.05

significantly so between sella and subspinale (S-

Ss) (Table 6).Group IV, girls aged 11 to 18 years of age,

displayed increased flexure of the cranial base

(N-S-Ar, Cliv/Sph) and slight morphological

deviations of the neurocranium; the distance

from the sella midpoint to bregma (S-Br) was in-

creased and the calvarium (Calv) thickened.

Maxillary and mandibular prognathism (Pt-Pgn,

S-N-Ss, S-N-Pg) was significantly increased, as

were the lower facial height (Ac-Gn, NL/ML)

and the gonial angle (ML/RL). The angle be-

tween the nasal floor and the nasion-sella line

(NSL/NL) was reduced, and the proportional

analysis showed the distances from opisthion to


the infradentale and pogonion (Op-Id, Op-Pg) to

be slightly increased. The upper incisors

(IL,/NL) were more protruded, and the interin-

cisal angle (IL,/IL;) steepened (Table 7).

Analysis of the occlusion showed one shunt-

treated subject to have bilateral Angle class II

intercuspation and another unilateral class I in-

tercuspation. Two children had an end-to-end oc-

clusion. All others had a normal class I

occlusion.

DISCUSSION

The present study is based on a group of ac-

tively shunt-treated hydrocephalic patients and

TABLE 6 Mean Values and Standard Deviations forDifferent Craniofacial Variables in Girls 7 to 10 Yearsof Age (Group ID*

Control (N= 16) Treated (N=8)


1. G1-OpC 187.0 5.4 194.1 11.6 + 7.182. N-La 180.9 5.4 190.0 10.7 + 9.1§3. S-Br 102.5 3.7 114.9 6.8 +12.4t4. Calv 5.3 1.5 8.3 1.9 + 3.0f5. N-Ba 98.8 3.1 97.4 2.8 - 1.46. S-N 66.0 2.0 67.4 2.8 + 1.47. S-Ba 41.4 1.5 41.8 2.6 + 0.48. S-Ar 29.50 2.2 31.3 2.9 + 1.89. S-Pm 42.4 1.2 44.6 4.2 + 2.2

10. S-Ss 75.6 2.3 78.8 5.10 4+ 3.2811. S-Pgn 105.9 3.4 109.8 6.6 + 3.912. Pt-Ss 55.9 2.5 58.0 4.6 + 2.113. Pt-Pgn 87.2 3.7 90.0 6.2 0+ 2.814. Pm-Ba 43.8 2.2 43.0 2.3 - 0.815. N-Ac 45.9 2.4 44.6 3.1 - 1.316. Ss-Pm 45.4 2.2 44.8 217 - 0.617. Ac-Gn 59.3 3.3 61.6 4.4 + 2.318. Pgn-Cd 100.4 3.7 101.3 6.1 + 0.919. N-S-Ba 134.7 3.4 129.3 6.17 - 5.4§20. N-S-Ar 125.6 3.9 119.5 5.2 - 6.13%21. Pm-S-Ba 63.4 4.0 60.6 4.7 - 2.822. S-N-Ss 79.6 3.3 82.3 4.2 + 2.723. S-N-Pg 76.1 2.1 78.6 3.9 + 2.524. NSL/NL 6.1 2.9 5.5 2.8 - 0.625. NSL/ML 35.4 4.3 36.0 6.1 + 0.626. NSL/MBL 57.0 3.2 55.6 4.6 - 1.427. NL/ML 29.4 4.3 30.5 4.2 0+ 1.28. ML/RL 128.4 6.1 133.1 5.4 + 4.729. CL/ML 73.8 4.5 73.4 4.8 - 0.430. OL/NL 15.4 2.1 15.6 22.1 + 0.231. IL,/NL 111.0 5.7 107.4 7.9 - 3.632. IL;/ML 98.0 5.3 92.5 7.0 - 5.533. IL/IL; 122.0 6.8 126.6 10.7 + 4.634. For/Cliv 125.9 5.9 121.8 3.6 - 4.1§35. Cliv/Sph 112.0 8.7 114.0 10.3 + 2.036. Cliv/Orb 141.8 4.3 138.6 6.2 - 3.237. Sph/Orb 31.6 8.0 26.6 6.6 - 5.038. Op-Ac 100.0 0.0 100.0 0.039. Op-St 53.4 1.5 52.5 2.0 - 0.940. Op-N 105.0 1.9 104.0 2250 - 1.041. Op-Pr 98.8 1.7 99.0 1.7 + 0.242. Op-Id 96.8 1.8 97.8 2.0 + 1.043. Op-Pg 98.7 2.6 99.4 2.3 + 0.7 * Variables 1-18 in millimetres, 19-37 in degrees, and 38-43

in percentagest p <0.001£ p <0.01§ p <0.05

age- and sex-matched controls. No conspicuous

morphological changes were noted in the youn-

- ger groups as compared to the controls; however,

marked morphological deviations were observed

after a longer shunting period, representing long-

term effects, which are of greater clinical im-

portance. 'The facial prognathismobserved in the shunt-

treated subjects seems to support the hypothesisof an association between cranial base flexureand facial prognathism (Anderson and Popovich,1983). When facial prognathism is estimated interms of the sella-nasion-subspinale and sella-nasion-pogonion angles, however, any change inthe position of either sella or nasion can alter

TABLE 7 Mean Values and Standard Deviations forDifferent Craniofacial Variables in Girls 11 to 18 Yearsof Age (Group IV)*



1. G1-OpC 193.2 6.3 191.1 13.3 - 2.12. N-La 187.6 6.1 187.2 13.9 - 0.43. S-Br 105.9 3.3 111.1 7.9 + 5.284. Calv 5.9 1.2 9.0 1.8 + 3.115. N-Ba 105.9 3.7 102.5 6.2 - 3.46. S-N 70.9 2.8 68.6 3.6 - 2.37. S-Ba 45.3 2.6 45.5 3.2 + 0.28. S-Ar 33.8 2.2 35.5 3.7 + 1.79. S-Pm 46.2 2.2 48.1 4.500 + 1.9

10. S-Ss 83.1 3.7 83.1 4.9 + 011. S-Pgn 119.50 3.8 123.3 7.50 + 3.812. Pt-Ss 61.6 3.0 62.2 3.1 + 0.613. Pt-Pgn 98.2 3.4 101.8 5.9 + 3.6§14. Pm-Ba 45.6 2.9 45.2 4.4 - 0.415. N-Ac 51.3 3.0 48.7 3.0 - 2.6§16. Ss-Pm 50.0 2.8 49.9 2.1 - 0.117. Ac-Gn 64.0 3.6 69.2 6.1 + 5.2418. Pgn-Cd 114.4 3.5 116.0 6.2 + 1.619. N-S-Ba 132.6 3.3 129.4 6.9 - 3.220. N-S-Ar 125.2 3.2 120.9 7.17 - 4.3§21. Pm-S-Ba 60.7 3.1 58.3 4.9 - 2.422. S-N-Ss 81.0 2.7 85.2 5.2 + 4.2%23. S-N-Pg 78.9 2.7 81.7 3.4 + 2.8§24. NSL/NL 8.0 2.5 3.7 2.8 -.4.3125. NSL/ML 31.8 6.7 33.5 4,4 + 1.726. NSL/MBL 56.1 3.4 55.5 2.6 - 0.627. NL/ML 23.8 6.4 29.8 4.17 + 6.0%28. ML/RL 125.9 8.4 130.9 5.9 + 5.0§29. CL/ML 72.4 5.7 71.5 5.0 - 0.930. OL/NL 12.9 3.2 11.5 227 - 1.431. IL,/NL 110.3 4.3 116.5 6.2 + 6.2%32. IL,;/ML 98.0 7.4 96.8 4.2 - 1.233. IL/IL; 126.4 8.8 117.3 6.9 - 9.1%34. For/Cliv 120.8 3.8 122.3 4.8 + 1.535. Cliv/Sph 111.9 4.5 102.0 11.8 - 9.9%36. Cliv/Orb 143.3 5.4 138.50 11.7 - 4.837. Sph/Orb 31.3 5.4 31.8 7.3 + 0.538. Op-Ac 100.0 0.0 100.0 0.039. Op-St 51.2 1.9 51.6 3.1 + 0.440. Op-N 104.0 1.9 103.2 3.5 - 0.841. Op-Pr 99.9 1.7 101.7 1.3 + 1.842. Op-Id 99.1 1.1 101.0 2.2 00+ 1.9843. Op-Pg 103.2 2.1 105.1 2.4 00+ 1.9§ * Variables 1-18 in millimetres, 19-37 in degrees, and 38-43

in percentagesf p <0.001+ p <0.01§ p <0.05


these angles without any actual change in the

sagittal position of the facial structures in rela-

tion to the cranial base proper. Since many of

the shunt-treated subjects showed a deviant con-

figuration of the structures involving the sella

region, a possible superior displacement of sel-

la (Kantomaa et al, 1985) could explain the en-

larged values for both the angles indicating facial

prognathism and those pertaining to the cranial

base flexure. Such a tendency for a superiorly

displaced sella may be seen as the increase in the

distance from the sella midpoint to the articulare

(S-Ar) in all groups, being statistically signifi-

cant in group II. Furthermore, as the distance

from the pterygomaxillare to basion (Pm-Ba) was

the same in the treated subjects and the controls,

the reduced Pm-S-Ba angle supports the assump-

tion of a superiorly displaced sella.

The reliability of nasion as a reference point

can be questioned in pathological conditions in-

fluencing the volumetric growth of the brain. Ac-

cording to previous findings, premature closure

of sutures is a common complication arising for

shunt treatment (Andersson, 1966; Kaufman et

al, 1973). If premature synostosis occurs in su-

tures involved in the normal growth of the an-

terior cranial base, nasion will remain in a

posterior position in relation to the rest of the

face, thus causing an increase in the sella-nasion-

subspinale angle.

In order to overcome the problems associated

with a possibly displaced sella, nasion, or both,

cranial base flexure was measured in terms of

the angle between the clival and sphenoidal

planes (Cliv/Sph) which, according to Varjanne

and Koski (1982), should be preferable to the

more commonly used nasion-sella-basion and

nasion-sella-articulare angles. This angle has

been found to remain almost unchanged during

the growth period (Aantaa and Koski, 1962), as

was also the case in the controls included in the

present study. However, this angle was signifi-

cantly smaller in the older shunt-treated children

as compared with the younger ones (girls 9.7

degrees, boys 12 degrees). Among the older boys

(group II) the angles between the foramen and

the clivus (For/Cliv) and those between the cli-

vus and the orbital plane (Cliv/Orb) as well as

the distance between the nasion and basion were

all reduced, indicating a change in the inclina-

tion of the clivus. These data imply that the rea-

son for increased cranial base flexure in the

treated subjects was not merely a positional

change in nasion and sella as cephalometric

landmarks.

In order to reach more reliable conclusions on

maxillary and mandibular prognathism, the dis-

tances from the sella midpoint to the subspinale

(S-Ss) and the prognathion (S-Pgn) and from the

pterygoid point to the subspinale (Pt-Ss) and

prognathion (Pt-Pgn) were measured. The results

consistently indicated that the facial structures

were located more forward in relation to the an-

terior cranial base in those groups where the

cranial base angle (N-S-Ba) was reduced. The

distances from the facial structures to sella had

increased more than those to the pterygoid point,

which may also lend support for the hypothesis

of a superiorly displaced sella.

The apparent differences between boys and

girls with regard to the effect of shunt treatment

are confusing. The enlarged state of the cranial

vault in the younger subjects, for instance, had

been completely corrected at an older age in the

girls but not in the boys, and the same was true

of the changes in the thickness of the cranial

vault. No explanation for this condition can be

offered at present. However, this study was

limited to a two-dimensional, lateral cephalomet-

ric study of the cranium. It is possible that there

are transverse variations among the cranial vaults

that were not described in this study.

One interesting finding probably related to the

cranial base flexure was the rare occurrence of

Angle class II occlusion among the shunt-treated

subjects, since its frequency among Finnish chil-

dren with mixed dentition is reported to be about

20 percent (Myllarniemi, 1970).

In conclusion, this study shows that prolonged

shunt treatment is associated with craniofacial

aberrations, particularly among boys. The most

evident deviations from normal cranial morphol-

ogy were changes in the calvarium and the skull

base. The facial structures of the shunt-treated

subjects seemed to be more prognathic (Fig. 6).

FIGURE 6 Roentgenocephalogram of a 13-year-old boyafter prolonged shunting. Note the increased thicknessof the calvarium, the increased cranial base flexure, andthe prognathic face.


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