Trigonocephaly is the third most common single suture synostosis which is seen as bulging of the forehead due to early fusion of themetopic suture. It is linked with an increased level of neurodevelopmental delays. On imaging, multidetector computed tomographyshows anterior fontanelle ossification, hypoteliorism, narrowing of the anterior cranial fossa, and compensatory increase of themiddle cranial fossa with atrophic features of brain. Its reported incidence is 1 in 700-15,000 live births. Operative multipleosteotomies were done and imaged in follow-up

Adarsh, E

Basu, Sabyasachi

Chakrabarty, Dibanath

Shankar, K R

Shukla, Anil Kumar

Talwade, Rahul

English

Atharva Scientific Publications (E-Jounals)

Vol 3 | Issue 3 | Jul - Sep 2017 Indian J Case Reports 156
Case Report
Trigonocephaly pre- and post-operative evaluation by multidetector computed 
tomography
Rahul Talwade1, Sabyasachi Basu2, E Adarsh3, Anil Kumar Shukla1, K R Shankar1, Dibanath Chakrabarty2
From Departments of 1Radiodiagnosis, 2Neurosurgery, 3Paediatrics, Raja Rajeswari Medical College and Hospital, Bengaluru, Karnataka, India
Correspondence to: Dr. Anil Kumar Shukla, Department of Radiodiagnosis, Raja Rajeswari Medical College and Hospital, 
Bengaluru - 560 074, Karnataka, India. Phone: +91-9342508923. E-mail: shookla2007@yahoo.co.in
Received – 11-April 2017 Initial Review – 07-May 2017 Published Online – 19-July 2017
Premature closure of the metopic suture results in a growth restriction of the frontal bones, which leads to a skull malformation known as trigonocephaly (metopic 
synostosis). Over the course of recent decades, its incidence has 
been rising, currently making it the third most common type of 
craniosynostosis. Treatment consists of a cranioplasty, usually 
performed before the age of 1 year. It is linked with an increased 
level of neurodevelopmental delays. The imaging findings range 
from a reduced volume of the anterior cranial fossa to intrinsic 
malformations of the brain [1]. This case report aims to provide 
an overview and roadmap of this entity by pre- and post-operative 
multidetector computed tomography (MDCT) which also plays a 
vital role in follow-ups.
CASE REPORT
A 3-month-old female baby was brought to hospital in view of 
bony midline frontal ridge noted by her mother. There was no 
history of seizures or delayed milestones. Clinical inspection 
showed triangular shape of the forehead and midline frontal 
ridge. The ridging metopic suture could be palpated and temporal 
narrowing was noted (Fig. 1a and b). Swelling was non-
compressible and no signs of inflammation were noted. Central 
nervous system examination revealed normal reflexes, and there 
was no neurological deficit. The patient was referred to the 
department of radiology for MDCT. Written informed consent 
was obtained from the father of the child, and multidetected 
computed tomography was performed.
We used a 128 slice Siemens perspective CT machine 
and images obtained at sub mm sections in the axial, coronal, 
and sagittal planes in both bone and soft tissue windows. 
Post-processing techniques such as shaded surface displays and 
volume rendering technique (VRT) were used. In bone window, 
there was complete closure of the metopic suture (Fig. 1c). Axial 
sections showed triangular anterior fossa and triangular frontal 
lobes of brain with minimal atrophy and prominent adjacent sulcal 
spaces (Fig. 1d). Ratio of interparietal and intercoronal distance 
(ICD) is increased (Fig. 2a). Frontal angle was decreased to 97° 
(Fig. 2b). Orbits show decreased interorbital distance suggestive 
of hypoteliorism (Fig. 2c and d). VRT images showing prominent 
gyral impressions on calvaria in bilateral parieto-occipital regions 
(Fig. 3a-d).
Child underwent decompressive craniotomies with sutural 
release involving frontal bone and was stable post procedure. 
Follow-up CT scan was done 1 month after surgical correction 
and it appearing as “floating forehead” (Fig. 4a and b). Few 
overlapping bony fragments noted with adequate distance 
between other fragments (Fig. 4). However, orbits did not show 
significant changes compared to pre-operative images. The 
cosmetic appearance was improved, and no neurological deficit 
was noted on follow-up.
DISCUSSION
Craniosynostosis or craniostenosis is the premature fusion of 
cranial sutures. It can be isolated or associated with craniofacial 
syndrome with alteration of shape of the cranial vault. Broad 
categories include “simple craniosynostosis,” involving only 
one suture, or “compound craniosynostosis,” where two or more 
sutures are involved [2]. By etiology, it is primary - due to intrinsic 
defect in suture or secondary - due to premature closure of normal 
sutures and deficient brain growth [3]. Trigonocephaly is derived 
ABSTRACT
Trigonocephaly is the third most common single suture synostosis which is seen as bulging of the forehead due to early fusion of the 
metopic suture. It is linked with an increased level of neurodevelopmental delays. On imaging, multidetector computed tomography 
shows anterior fontanelle ossification, hypoteliorism, narrowing of the anterior cranial fossa, and compensatory increase of the 
middle cranial fossa with atrophic features of brain. Its reported incidence is 1 in 700-15,000 live births. Operative multiple 
osteotomies were done and imaged in follow-up.
Key words: Craniosynostosis, Hypoteliorism, Metopic synostosis, Multi detector computed tomography, Trigonocephaly
Talwade et al. Trigonocephaly road map by MDCT
Vol 3 | Issue 3 | Jul - Sep 2017 Indian J Case Reports 157
from the Greek word “trigon on,” which means triangle, and 
“kephale,” which means head. Forehead is triangular, or wedge-
shaped due to premature fusion and subsequent ossification of 
the metopic suture (Greek “metopon” = forehead). The term 
trigonocephaly was first proposed by Walker in 1862 [1].
The metopic suture separates the two frontal bones at birth 
and is the first skull suture to close physiologically, starting 
at 3 months and completely fused at the age of 8 months [4]. 
Premature fusion shows a ridge over the midline of the forehead 
due to ossification of the suture and lateral growth restriction of 
the frontal bones. According to the theory of Virchow, this wedge 
shape is even further enhanced by the increased compensatory 
growth of the remaining skull sutures while the skull keeps 
expanding [1]. This can occur from in utero fusion, and one-
third of the cases are syndrome and may be associated with other 
midline anomalies involving the brain or palate [5].
Due to MDCT, many imaging features are observed in our 
patient such as a triangular, pointed forehead with flattened frontal 
bones, and bossing of the parieto-occipital regions. Our patient 
had hypoteliorism, narrow anterior cranial fossa, hypoplasia of 
the ethmoid sinuses and “quizzical” orbits. Inferior angle of the 
anterior fontanel is elongated with frontal notching and tight 
anterior extraaxial subarachnoid spaces. Temporal shortening 
and parietal widening with normal cephalic index were also 
observed [6].
Synostosis of this kind is the third most common type followed 
by unicornal and sagittal and has an incidence of 1:700 to 1:15,000 
of newborns, having male to female ratio of 3:1 [1]. On clinical 
evaluation, there is reduction in skull size, lengthening, and 
ridging of the skull along the fused suture. Due to stenosed suture, 
there is growth restriction with compensatory more of growth at 
the other open sutures sites. By fetal ultrasonography, it can also 
be identified after 9 week of gestation [7]. Due to mainly bony 
changes submillimeter slices by MDCT is very accurate, and it 
also shows features of brain growth, deformities and ventricular 
volumes. MDCT is very useful in planning of surgical correction 
and subsequent post-operative follow-ups [8].
By MDCT supraorbital retrusion, classical feature of 
trigonocephaly can be classified as - Frontal angle: It is the angle 
between the two lines drawn through pterion (bilaterally) and 
nation. Trigonocephaly is classified as: (1) Severe with an angle 
of <89°, (2) moderate between 90°and 95°, (3) mild between 
96° and 103°, our case was in this category as angle is 97°, and 
Figure 1: (a and b) Photographs of the baby showing midline frontal 
ridge (arrows). Multidetector computed tomography showing 
(c) complete closure of metopic suture (arrow) and (d) frontal lobe 
minimal atrophy
dc
ba
Figure 2: Multidetector computed tomography showing (a) increased 
ratio of interparietal and intercoronal distance (b) showing decreased 
frontal angle (c and d) decreased interorbital distance
dc
ba
Figure 3: Multidetector computed tomography volume rendering 
technique images showing (a and b) midline frontal eminence (white 
arrow) and bitemporal indentations (blue arrows) (c and d) gyral 
impressions on calvarial and bilateral parieto-occipital regions 
(arrows)
dc
ba
Figure 4: (a and b) Post-operative multidetector computed 
tomography volume rendering technique and bone window images 
showing multiple osteotomies appearing as “floating forehead”
ba
Talwade et al. Trigonocephaly road map by MDCT
Vol 3 | Issue 3 | Jul - Sep 2017 Indian J Case Reports 158
(4) normal when 104° or more (Fig. 2b) [1]. Frontal stenosis, It is 
defined as the increased ratio of the interparietal distance (IPD) to 
the ICD. The IPD/ICD to be 1.21 in normal children in our case it 
is increased 1.37 with small anterior fossa (Fig. 2a) [1].
Any craniosynostosis leads to high incidence of poor 
scholastic and mental development. Diagnosed patient should be 
operated as soon as possible as it has very good prognosis and 
it also improves the cosmetic appearance and developmental 
milestones. For surgical treatment, timing and extent are directed 
by the severity of the frontal changes with normalization of the 
forehead with reconstitution of the normal supraorbital rim if 
necessary. Individuals presenting solely with a prominent midline 
keel may be best served by simple contouring of the frontal bone 
or by removal of the frontal bone flap followed by reconfiguration. 
Patients with significant trigonocephaly and hypertelorism need 
orbital reconstruction and may also require lateral expansion of 
the orbits at the same time. The type and timing of the correction 
must be tailored to the individual patient, and long-term results 
are excellent with minimal complications [9]. In our case, 
decompressive craniotomies with sutural release were done 
and are seen by post-operative follow-up MDCT as “floating 
forehead” (Fig. 4a and b).
CONCLUSION
MDCT is the imaging modality of choice in trigonocephaly in the 
initial pre-operative stage to take various measurements and in 
post-operative status to assess osteotomies and to assess bony and 
cerebral components in the further follow-ups. Regular pediatric 
clinical, neurological and whenever required MDCT follow-ups 
are recommended in these cases. Our patient had no underlying 
neurological deformity; however, in later follow-ups, we will 
assess improvement in the cognition.
REFERENCES
1. van der Meulen J. Metopic synostosis. Childs Nerv Syst. 2012;28(9):1359-67.
2. Ocal E, Sun PP, Parsing JA. Craniosynostosis. In: Albright AL, Pollack IF, 
Adel-Son PD, editors. Principle and Practice of Pediatric Neurosurgery. 
New York: Thieme Medical; 2007. p. 265-85.
3. Kimonis V, Gold JA, Hoffman TL, Panchal J, Boyadjiev SA. Genetics of 
craniosynostosis. Semin Pediatr Neurol. 2007;14(3):150-61.
4. Weinzweig J, Kirschner RE, Farley A, Reiss P, Hunter J, Whitaker LA, et al. 
Metopic synostosis: Defining the temporal sequence of normal suture fusion 
and differentiating it from synostosis on the basis of computed tomography 
images. Plast Reconstr Surg. 2003;112(5):1211-8.
5. Kirmi O, Lo SJ, Johnson D, Anslow P. Craniosynostosis: A radiological and 
surgical perspective. Semin Ultrasound CT MR. 2009;30(6):492-512.
6. Khanna PC, Thapa MM, Iyer RS, Prasad SS. Pictorial essay: The many faces 
of craniosynostosis. Indian J Radiol Imaging. 2011;21(1):49-56.
7. Kotrikova B, Krempien R, Freier K, Mühling J. Diagnostic imaging in the 
management of craniosynostoses. Eur Radiol. 2007;17(8):1968-78.
8. Attaya H, Thomas J, Alleman A. Imaging of craniosynostosis from diagnosis 
through reconstruction. Neurographics. 2011;1:121-8.
9. Rengachary SS, Ellenbogen RG, editors. Principles of Neurosurgery. 
Edinburgh: Elsevier Mosby; 2005.
Funding: None; Conflict of Interest: None Stated.
How to cite this article: Talwade R, Basu S, Adarsh E, Shukla AK, 
Shankar KR, Chakrabarty D. Trigonocephaly pre- and post-operative 
evaluation by multidetector computed tomography. Indian J Case Reports. 
2017;3(3):156-158.


Trigonocephaly pre- and post-operative evaluation by multidetector computed tomography

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Trigonocephaly pre- and post-operative evaluation by multidetector computed tomography

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