The significance or insignificance of prematurely fused bilateral squamosal sutures

Vybhav Deraje; Anisha Sawkar Tandon

doi:10.4103/jclpca.jclpca_28_21

CASE REPORT

Year : 2022 | Volume : 9 | Issue : 1 | Page : 82-84

The significance or insignificance of prematurely fused bilateral squamosal sutures

Vybhav Deraje¹, Anisha Sawkar Tandon²
¹ Department of Plastic and Reconstructive Surgery, Sakra World Hospital, Bengaluru, Karnataka, India
² Department of Radiology and Imaging, Sakra World Hospital, Bengaluru, Karnataka, India

Date of Submission	14-Jul-2021
Date of Acceptance	17-Aug-2021
Date of Web Publication	01-Jan-2022

Correspondence Address:
Dr. Vybhav Deraje
Room 2, Multi-OPD, Sakra World Hospital, Sy No 52/2 and 52/3, Devarabeesanahalli, Varthur Hobli, Opp Intel, Outer Ring Rd, Marathahalli, Bengaluru - 560 103, Karnataka
India

Source of Support: None, Conflict of Interest: None

Check

DOI: 10.4103/jclpca.jclpca_28_21

Abstract

We report a case of a patient with premature fusion of bilateral squamous sutures and perform a literature review of similar cases. We have noted in our case and in other reports that bilateral squamous synostosis does not lead to significant clinical effects such as deformed shape of the skull or raised intracranial pressure.

Keywords: Craniosynostosis, scaphocephaly, squamosal suture fusion

How to cite this article:
Deraje V, Tandon AS. The significance or insignificance of prematurely fused bilateral squamosal sutures. J Cleft Lip Palate Craniofac Anomal 2022;9:82-4

How to cite this URL:
Deraje V, Tandon AS. The significance or insignificance of prematurely fused bilateral squamosal sutures. J Cleft Lip Palate Craniofac Anomal [serial online] 2022 [cited 2022 Jan 25];9:82-4. Available from: https://www.jclpca.org/text.asp?2022/9/1/82/333643

Introduction

Squamous suture synostosis is a rare condition where there is premature fusion of squamous suture (the suture between the parietal and temporal bones). It has been rarely reported in the literature probably because of its mild effects on the skull shape and growth. We report one such case of bilateral squamous suture synostosis who presented to us at a relatively late age of 4 years. We performed a literature search of similar cases with special emphasis on the clinical presentation and management of squamous suture synostosis.

Case Report

A 4-year-old girl presented to our clinic with parents concerned regarding abnormal shape of the head and speech and learning difficulties. She was the first child of the parents and there was no family history of craniofacial anomalies. The antenatal period was uneventful and she was born at term by normal delivery. The parents noticed delay in the development of speech when compared to her peers and also alleged learning difficulties at day school. In addition, the parents also noticed that the shape of her skull was narrow and had mild depressions on both sides of the skull just above the ears.

On examination, the head shape was unremarkable on inspection. On palpation, there was mild flattening on the parietotemporal region and mild parietal bulge on both sides but appeared generally normal. There was no occipital bullet or frontal bossing. The cephalic index was 0.81. A fine metopic ridge was noticed, but no trigonocephaly was noted.

Computed tomography (CT) scan of the head showed fused temporosquamosal suture on both sides [Figure 1], while the sphenosquamosal suture was unfused. The frontosphenoid and sphenotemporal were patent. All the major sutures were also patent, except the metopic suture. The cerebral parenchyma was normal, and there were no signs of raised intracranial pressure. There were no other anomalies noted.

Figure 1: Bilateral squamous suture synostosis, mainly involving the parietotemporal part (anterior two-third) of the suture

Click here to view

We advised a conservative approach for the management of the patient. Surgical treatment was not advised since there was no indication for such a procedure (cosmetic or raised intracranial pressure). The parents were reassured. The patient was already undergoing speech and behavioral therapy and was making good progress according to the parents.

Discussion

Isolated premature fusion of minor cranial sutures is rare. This is probably due to under reporting because the phenotypical manifestations of such synostoses are very subtle. Eley et al.^[1] have proved this point in a study of 422 CT scans of children below 16 years of age, where they found squamosal synostosis (isolated or combined with other suture synostosis) in 9% of the scans that were studied, who were originally not diagnosed with squamous synostosis. Murphy et al.^[2] have reported even higher rates (20.8%, n = 125) in their report, but majority were in combination with other suture synostosis. It requires an extremely concerned or curious parent to flag such an issue with their child (which was the case in our patient) combined with an in-depth analysis of the CT scans to diagnose these isolated synostoses.

If we apply the Virchow's law to bilateral squamosal synostosis, we should have a phenotype which is similar to sagittal synostosis (scaphocephaly) patients. However, in practice, this has not been found to be true, which is also supported in a review article by Chieffe et al.,^[3] where they found that only 1 out of 33 patients had a cranial morphology that was consistent with Virchow's law. Authors around the world have struggled to describe the phenotype of bilateral squamosal synostosis and differentiate it from the accepted “normal.” Diab et al.,^[4] in their case report of a similar bilateral squamosal synostosis, have also described the shape as “bi-temporal saddle-like deformity” but have not found it severe enough to warrant a surgical correction. In our case, there was mild flattening of the parietotemporal region and mild parietal bulge [Figure 2], which was obvious only on palpation because the child had a head full of hair. It was definitely not severe enough to categorize the deformity as scaphocephaly, owing to a cephalic index in the normal range. Law et al.^[5] have reported anterior plagiocephaly in their case who had unilateral squamosal synostosis in addition to other sutural fusions around the pterion, which they named “pterional craniosynostosis.” In our case, the frontosphenoid, sphenotemporal, and coronal sutures were patent. Even the posterior one-third of the squamosal suture (parietomastoid part) and the sphenosquamosal suture were patent. Smartt et al.,^[6] who presented a large series of 14 patients, have also noted significant deformity in patients who had multisuture involvement or unilateral involvement. In patients with isolated unilateral squamosal involvement, there was some degree of occipital flattening and ipsilateral parietal bossing. This emphasizes the fact that multiple sutural fusions, especially unilateral, may translate to a more obvious deformity when compared to isolated bilateral squamosal synostosis.

Figure 2: Mild flattening of the parietotemporal region (red arrows) and mild parietal bulge on both sides (green arrows)

Click here to view

Chaisrisawadisuk et al.^[7] presented a case of bilateral squamosal synostosis in a girl who had global developmental delay and chromosome 1p12–1p13.3 deletion. Our patient had mild speech delay and learning difficulties but was progressing well with speech and behavioral support. We did not conduct genetic studies in our patient. In general, midline suture craniosynostoses (metopic and sagittal) are the ones that have been associated with speech and learning difficulties. Our patient had a fine metopic ridge but no evidence of true metopic synostosis. It is difficult to attribute the speech delay to either squamosal synostosis or metopic ridge due to lack of scientific evidence to support this.

Treatment of bilateral squamosal synostosis is primarily conservative. The usual indication of craniosynostosis surgery is either a significant cosmetic disfigurement or raised intracranial pressure. Ranger et al.^[8] reported two cases, one unilateral and the other bilateral, who both required cranial remodeling surgery. All other authors, including Smartt et al.,^[6] have adopted a conservative approach to manage bilateral squamous synostosis. Only patients with multisuture involvement or unilateral involvement of squamous suture required surgery. Even when squamosal synostosis is present in conjunction with other synostoses, its impact on intracranial volume might be minimal as seen in a study by Leikola et al.^[9] However, in syndromic cases, there might be a significant decrease in middle cranial fossa volume.^[10] Our patient had a very subtle deformity, appreciated only by palpation, and no evidence of raised intracranial pressure. Hence, a conservative management was advocated with close follow-up.

Absence of a clinical photograph of the patient might be viewed as a limitation of our report. The fact that the patient had no visible deformity discouraged us from unnecessarily displaying the photograph of the patient.

Conclusion

Bilateral squamosal suture synostosis is rare. Its presence in isolation or in combination with other sutural synostosis seems to have minimal discernible effect on the morphology or function of the skull.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

References

1.	Eley KA, Thomas GP, Sheerin F, Cilliers D, Wall S, Johnson D. The significance of squamosal suture synostosis. J Craniofac Surg 2016;27:1543-9.
2.	Murphy BD, Ajabshir N, Altman N, Wolfe SA, Perlyn C. Squamosal suture synostosis: Incidence, associations, and implications for treatment. J Craniofac Surg 2017;28:1179-84.
3.	Chieffe D, Naffaa L, Doumit G. Squamous suture synostosis: A review with emphasis on cranial morphology and involvement of other cranial sutures. J Craniofac Surg 2017;28:51-5.
4.	Diab J, Anderson PJ, Moore MH. Late presenting bilateral squamosal synostosis. Arch Craniofac Surg 2020;21:106-8.
5.	Law J, Marucci DD, Gates RJ, Fowler A. Unilateral pterional polycraniosynostosis treated with craniectomy and helmet therapy. Plast Reconstr Surg Glob Open 2017;5:e1245.
6.	Smartt JM Jr., Singh DJ, Reid RR, Hellinger JC, Hsu VM, Bartlett SP. Squamosal suture synostosis: A cause of atypical skull asymmetry. Plast Reconstr Surg 2012;130:165-76.
7.	Chaisrisawadisuk S, Vatanavicharn N, Praphanphoj V, Anderson PJ, Moore MH. Bilateral squamosal synostosis: Unusual presentation of chromosome 1p12–1p13.3 deletion. Illustrative case. J Neurosurg Case Lessons 2021;1:CASE20102.
8.	Ranger A, Chaudhary N, Matic D. Craniosynostosis involving the squamous temporal sutures: A rare and possibly underreported etiology for cranial vault asymmetry. J Craniofac Surg 2010;21:1547-50.
9.	Leikola J, Heliövaara A, Koivikko M, Koljonen V. Additional squamosal suture synostosis and segmented intracranial volume in patients with non-syndromic sagittal synostosis. Childs Nerv Syst 2019;35:205-7.
10.	Lu X, Chen G, Forte AJ, Cabrejo R, Singh A, Kyle G, et al. What is the skull structure influence of squamosal suture synostosis in nonsyndromic and syndromic crouzon craniosynostosis? J Craniofac Surg 2019;30:1671-5.