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Fontanels: Range of normal size
May, 1972 T h e Journal of P E D I A T R I C S
749
Fontanels: Range of normal size Normal dimensions for fontanel size are provided from birth through the first year of life in order to assist the clinician in utilizing abnormal fontanel size, without increased intracranial pressure, as a possible clue to the recognition of alterations in morphogenesis.
Gregory A. Poplch and David W. Smith, M.D., Seattle, Wash.
EXAMINATION of the fontanels has been utilized for evidence of altered intracranial pressure and less consistently as an index of the rate of development and ossification of the calvarium, which may be altered in a wide variety of disorders affecting morphogenesis. In order to properly utilize fontanel size as a clue to altered morphogenesis it is necessary to have normal age-related standards. T h e purpose of this paper is to provide a range of normal fontanel dimensions from birth through the first year and a partial listing of conditions in which altered development of the calvarium, as indicated by abnormal sized fontanels for age, occurs as one aspect of the disorder. METHODS Measurements were taken of both the anterior and posterior fontanels of 201 fullterm newborn infants (104 males and 97 females), and of the anterior fontanel in 110 infants from 2 weeks of age to 12 months From the Dysmorphology Unit, Department of Pediatrics, University of Washington School of Medicine. Supported by a grant from the Children's Bureau. Reprint address: Dysmorphology Unit Department of Pediatrics, Univers~'tv o[ Washington ~chool o] Medidne, Seattle, Wash. 98103.
of age (54 males and 56 females). The subjects, all Caucasian, were studied in newborn nurseries, private offices, and private homes. Those with obvious disease or malformation were excluded from the study; otherwise there was no conscious selection of the subjects. See related article p. 753. The fontanel dimensions were recorded in terms of length (anterior-posterior dimension) and width (transverse dimension) rather than by the alternative techniques described by El~isser 1 or S c a m m o n and AdairY The anterior-posterior and lateral extent of the fontanels were identified and marked on the skin surface with a water color pen. The length and width were then measured with a steel tape and recorded to the closest millimeter. T h e average of the length plus width was utilized as mean fontanel size. Any fontanel that was too small to measure accurately was for the purposes of this study judged to be closed. Newborn infants weer studied within one or two days of birth. The measurements of infants from 2 weeks to 12 months of age were averaged for periods of three months. Vol. 80, No. 5, pp. 749-752
7 50
Popich and S m i t h
- 2 S.D. 0.6
Mean 2 .I
The Journal of Pediatrics May 1972
+ 2 S. D. 3.6
,, ,\\\-~
1
.,~
0
0
I
Types o[ disorders Skeletal disorders
~\\\-,
"\\" I
i
z Mean anterior fontanel
Table I. Disorders in which large fontanel for age may be one feature s, 4
4 size in cm
Fig. 1. Mean anterior fontanel sizes in 201 newborn infants. RESULTS
The anterior fontanel normally is quite variable in size and shape. As shown in Fig. 1 the mean anterior fontanel size of the newborn infants was 2.1 cm., with 2 standard deviations above and below the mean being at 0.6 and 3.6 cm., respectively. There was no significant difference between the mean values of male and female newborn infants. Fig. 2 depicts the ranges in size of the anterior fontanel at intervals of three months, from birth to 12 months of age. The mean values for males tended to be higher than those for females during the first six months (Fig. 3). Although there was wide individual variability in the shape of the fontanel, there was no significant difference between the mean length and width of the anterior fontanel at any given age (Fig. 4). Only 6 of the 201 full-term newborn infants had a posterior fontanel larger than 0.5 cm. in size, the largest of these being 2.0 by 2.1 cm. DISCUSSION The tendency for the anterior fontanel to enlarge during the first few postnatal months has been previously noted s and need not necessarily raise concern about the presence of increased intiracranial pressure. With the help of the normal range of fontanel dimensions, the clinician should be able to identify those individuals having either an abnormally large or small fontanel for
Achondroplasia Aminopterin-induced syndrome Apert's syndrome Cleidocranial dysostosis Hypophosphatasia Kenny's syndrome Osteogenesis imperfecta Pyknodysostosis Vitamin D deficiency rickets Chromosomal abnormalities
Down's syndrome 13 Trisomy syndrome 18 Trisomy syndrome Other conditions
Athyrotic hypothyroidism Hallerman-Streiff syndrome Malnutrition Progeria Rubella syndrome Russell-Silver syndrome
age. The presence of an unusually large fontanel without increased intracranial pressure can be a valuable clue in the recognition of a variety of disorders (Table I ) . For exampie, in any condition with early lag in the ossification of the calvarium, the fontanels tend to be abnormally large. One such condition is athyrotic hypothyroidism. ~ In this disorder the increased size of the fontanel correlates with the degree of retardation of bone age and can thus serve as a useful index of the delayed osseous maturation and potentially as an early postnatal clue towards the diagnosis. However, caution shouId be used in ascribing more significance to the sole finding of an enlarged fontanel than that Of a minor sign; an enlarged fontanel alone is not pathognomonic for any condition. Furthermore, the ranges of normal variability in size and shape of the anterior fontanel are broad. An ianusually small anterior fontanel for age may be a secondary feature in disorders which affect brain growth such as primary microcephaly, it may be due to craniosynostosis ir~volving the sagittal a n d / o r coronal
Volume 80 Number 5
Fontanels
+Z S.D.
: :::::::::::::::::::::
:7:i: (..!~;<:};~ ~ i'-s ,..
!iiiii!i'iii@it:t::i'i:i:! i }
1~=========================================== 2 - : ? ~:::::::::::::::::::::::::::::::::::: ~?)t:"::
NB
tSii;; " IIlit: j :1: :1:~I
g
i
g
;2
Age in months F~g, 2. Mean anterior fontanel size during the first postnatal year, Beyond the newborn period (NB) the data are averaged at 3 month intervals with the number of individuals in each group
indicated.
3-
~MALE
ii t
at 9
2:
O~
0
NB
3
& Age in months
9
1'2
Fig. 3. Mean anterior fontanel size in males versus females at birth and at 3 month intervals during the first year.
t 3-
WIDTH l/
2-
~
'
i
Age
in
months
Fig. 4. Mean length and width of the anterior fontanel at birth and at 3 month intervals during the first year.
75l
752
Popich and Smith
sutures; or it m a y be caused by accelerated osseous m a t u r a t i o n such as has occurred with hyperthyroidism in early life2 However, given a n otherwise n o r m a l i n f a n t with norm a l size and shape of the c a l v a r i u m a n d no palpable ridging along the sagittal or coronal sutures, there should be no concern about a n unusually small fontanel since the age of "closure" of" the anterior fontanel is highly variable. We give thanks to University of Washington Hospital, Children's Orthopedic Hospital and Medical Center, Overlake Memorial Hospital, and Northwest Hospital for making their patients available to us. We also thank Drs. J. Owens, H. Hilgers, B. Joslin, T. Cock, F. Van Paasschen, and L. Vincent for providing access to their patients; also M. Pearlman for secretarial assistance and L. Harrah for her assistance as research librarian. Special thanks to Mr. D. Abrams of the Baby Diaper Service of Seattle for pro-
The Journal of Pediatrics May 1972
viding us with a population of children under one year of age. REFERENCES 1. Els~isser, C. L.: Der Weiche Hinterkopf. Ein Beitragzu Physiologle and Pathologic der ersten Kinderheit, S. 9 et. seq. Stuttgart und Tiiblgen, 1843. 2. Scammon, R. E., and Adair, F. L.: The geometric relationships of the frontal fontanelle in infancy, Anat. Rec. 46: 349, 1930. 3. Nelson, W. E., Vaughan, V. D., III, and McKay, R. C., editors: Textbook of pediatrics, ed. 9, Philadelphia, 1969, W. B. Saunders Company, p. 23. 4. Smith, D. W.: Recognizable patterns of human malformation, Philadelphia, 1970, W. B. Saunders Company. 5. Smith, D. W., and Popich, G. A.: Large fontanels in congenital hypothyroidism: A potentim clue toward its earlier recognition, J. PEDIATR. 80: 753, 1972. 6. Robinson, D. C., Hall, R., and Munro, D. S.: Grave's disease, an unusual complication : Raised intracranlal pressure clue to premature fusion of skull sutures, Arch. Dis. Child. 44: 252, 1969.
749
Fontanels: Range of normal size Normal dimensions for fontanel size are provided from birth through the first year of life in order to assist the clinician in utilizing abnormal fontanel size, without increased intracranial pressure, as a possible clue to the recognition of alterations in morphogenesis.
Gregory A. Poplch and David W. Smith, M.D., Seattle, Wash.
EXAMINATION of the fontanels has been utilized for evidence of altered intracranial pressure and less consistently as an index of the rate of development and ossification of the calvarium, which may be altered in a wide variety of disorders affecting morphogenesis. In order to properly utilize fontanel size as a clue to altered morphogenesis it is necessary to have normal age-related standards. T h e purpose of this paper is to provide a range of normal fontanel dimensions from birth through the first year and a partial listing of conditions in which altered development of the calvarium, as indicated by abnormal sized fontanels for age, occurs as one aspect of the disorder. METHODS Measurements were taken of both the anterior and posterior fontanels of 201 fullterm newborn infants (104 males and 97 females), and of the anterior fontanel in 110 infants from 2 weeks of age to 12 months From the Dysmorphology Unit, Department of Pediatrics, University of Washington School of Medicine. Supported by a grant from the Children's Bureau. Reprint address: Dysmorphology Unit Department of Pediatrics, Univers~'tv o[ Washington ~chool o] Medidne, Seattle, Wash. 98103.
of age (54 males and 56 females). The subjects, all Caucasian, were studied in newborn nurseries, private offices, and private homes. Those with obvious disease or malformation were excluded from the study; otherwise there was no conscious selection of the subjects. See related article p. 753. The fontanel dimensions were recorded in terms of length (anterior-posterior dimension) and width (transverse dimension) rather than by the alternative techniques described by El~isser 1 or S c a m m o n and AdairY The anterior-posterior and lateral extent of the fontanels were identified and marked on the skin surface with a water color pen. The length and width were then measured with a steel tape and recorded to the closest millimeter. T h e average of the length plus width was utilized as mean fontanel size. Any fontanel that was too small to measure accurately was for the purposes of this study judged to be closed. Newborn infants weer studied within one or two days of birth. The measurements of infants from 2 weeks to 12 months of age were averaged for periods of three months. Vol. 80, No. 5, pp. 749-752
7 50
Popich and S m i t h
- 2 S.D. 0.6
Mean 2 .I
The Journal of Pediatrics May 1972
+ 2 S. D. 3.6
,, ,\\\-~
1
.,~
0
0
I
Types o[ disorders Skeletal disorders
~\\\-,
"\\" I
i
z Mean anterior fontanel
Table I. Disorders in which large fontanel for age may be one feature s, 4
4 size in cm
Fig. 1. Mean anterior fontanel sizes in 201 newborn infants. RESULTS
The anterior fontanel normally is quite variable in size and shape. As shown in Fig. 1 the mean anterior fontanel size of the newborn infants was 2.1 cm., with 2 standard deviations above and below the mean being at 0.6 and 3.6 cm., respectively. There was no significant difference between the mean values of male and female newborn infants. Fig. 2 depicts the ranges in size of the anterior fontanel at intervals of three months, from birth to 12 months of age. The mean values for males tended to be higher than those for females during the first six months (Fig. 3). Although there was wide individual variability in the shape of the fontanel, there was no significant difference between the mean length and width of the anterior fontanel at any given age (Fig. 4). Only 6 of the 201 full-term newborn infants had a posterior fontanel larger than 0.5 cm. in size, the largest of these being 2.0 by 2.1 cm. DISCUSSION The tendency for the anterior fontanel to enlarge during the first few postnatal months has been previously noted s and need not necessarily raise concern about the presence of increased intiracranial pressure. With the help of the normal range of fontanel dimensions, the clinician should be able to identify those individuals having either an abnormally large or small fontanel for
Achondroplasia Aminopterin-induced syndrome Apert's syndrome Cleidocranial dysostosis Hypophosphatasia Kenny's syndrome Osteogenesis imperfecta Pyknodysostosis Vitamin D deficiency rickets Chromosomal abnormalities
Down's syndrome 13 Trisomy syndrome 18 Trisomy syndrome Other conditions
Athyrotic hypothyroidism Hallerman-Streiff syndrome Malnutrition Progeria Rubella syndrome Russell-Silver syndrome
age. The presence of an unusually large fontanel without increased intracranial pressure can be a valuable clue in the recognition of a variety of disorders (Table I ) . For exampie, in any condition with early lag in the ossification of the calvarium, the fontanels tend to be abnormally large. One such condition is athyrotic hypothyroidism. ~ In this disorder the increased size of the fontanel correlates with the degree of retardation of bone age and can thus serve as a useful index of the delayed osseous maturation and potentially as an early postnatal clue towards the diagnosis. However, caution shouId be used in ascribing more significance to the sole finding of an enlarged fontanel than that Of a minor sign; an enlarged fontanel alone is not pathognomonic for any condition. Furthermore, the ranges of normal variability in size and shape of the anterior fontanel are broad. An ianusually small anterior fontanel for age may be a secondary feature in disorders which affect brain growth such as primary microcephaly, it may be due to craniosynostosis ir~volving the sagittal a n d / o r coronal
Volume 80 Number 5
Fontanels
+Z S.D.
: :::::::::::::::::::::
:7:i: (..!~;<:};~ ~ i'-s ,..
!iiiii!i'iii@it:t::i'i:i:! i }
1~=========================================== 2 - : ? ~:::::::::::::::::::::::::::::::::::: ~?)t:"::
NB
tSii;; " IIlit: j :1: :1:~I
g
i
g
;2
Age in months F~g, 2. Mean anterior fontanel size during the first postnatal year, Beyond the newborn period (NB) the data are averaged at 3 month intervals with the number of individuals in each group
indicated.
3-
~MALE
ii t
at 9
2:
O~
0
NB
3
& Age in months
9
1'2
Fig. 3. Mean anterior fontanel size in males versus females at birth and at 3 month intervals during the first year.
t 3-
WIDTH l/
2-
~
'
i
Age
in
months
Fig. 4. Mean length and width of the anterior fontanel at birth and at 3 month intervals during the first year.
75l
752
Popich and Smith
sutures; or it m a y be caused by accelerated osseous m a t u r a t i o n such as has occurred with hyperthyroidism in early life2 However, given a n otherwise n o r m a l i n f a n t with norm a l size and shape of the c a l v a r i u m a n d no palpable ridging along the sagittal or coronal sutures, there should be no concern about a n unusually small fontanel since the age of "closure" of" the anterior fontanel is highly variable. We give thanks to University of Washington Hospital, Children's Orthopedic Hospital and Medical Center, Overlake Memorial Hospital, and Northwest Hospital for making their patients available to us. We also thank Drs. J. Owens, H. Hilgers, B. Joslin, T. Cock, F. Van Paasschen, and L. Vincent for providing access to their patients; also M. Pearlman for secretarial assistance and L. Harrah for her assistance as research librarian. Special thanks to Mr. D. Abrams of the Baby Diaper Service of Seattle for pro-
The Journal of Pediatrics May 1972
viding us with a population of children under one year of age. REFERENCES 1. Els~isser, C. L.: Der Weiche Hinterkopf. Ein Beitragzu Physiologle and Pathologic der ersten Kinderheit, S. 9 et. seq. Stuttgart und Tiiblgen, 1843. 2. Scammon, R. E., and Adair, F. L.: The geometric relationships of the frontal fontanelle in infancy, Anat. Rec. 46: 349, 1930. 3. Nelson, W. E., Vaughan, V. D., III, and McKay, R. C., editors: Textbook of pediatrics, ed. 9, Philadelphia, 1969, W. B. Saunders Company, p. 23. 4. Smith, D. W.: Recognizable patterns of human malformation, Philadelphia, 1970, W. B. Saunders Company. 5. Smith, D. W., and Popich, G. A.: Large fontanels in congenital hypothyroidism: A potentim clue toward its earlier recognition, J. PEDIATR. 80: 753, 1972. 6. Robinson, D. C., Hall, R., and Munro, D. S.: Grave's disease, an unusual complication : Raised intracranlal pressure clue to premature fusion of skull sutures, Arch. Dis. Child. 44: 252, 1969.