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New-Onset Craniosynostosis Following Posterior Vault Distraction Osteogenesis
Tahiri Y, Paliga JP, Shubinets V, Bartlett SP, Taylor JA
ABSTRACT
Background: The aim of this study is to document the incidence of new-onset craniosynostosis (NOC) following posterior vault distraction osteogenesis (PVDO), to determine risk factors for the development of NOC, and to deduce the cranial ramifications of NOC.
Methods: An IRB-approved retrospective review of all patients who underwent PVDO at the Children’s Hospital of Philadelphia was performed. Demographics, peri-operative data, and pre-operative and post-operative 3D-CT scans were analyzed. Suture patency pre- and post-operatively were recorded.
Results: 30 patients underwent PVDO for suspected increased intracranial pressure and/or severe turribrachicephaly from 2008 to 2013. 24 patients had syndromic diagnoses. The average age at the time of PVDO was 2.03 years. Distraction distances range from 19 to 40 mm, with an average of 28.7mm. Among the 19 patients who had a patent lambdoid sutures prior to PVDO, new-onset lambdoid fusion was seen in 17 patients following PVDO (89.5%), while the suture remained open in two patients (10.5%). New-onset lambdoid fusion was not significantly associated with age at distraction (p=0.28), gender (p=0.47), length of distraction (p=0.93), or diagnosis (p=0.61). Similarly, new-onset sagittal synostosis was not associated with age at distraction (p=0.06), gender (p=0.64), length of distraction (p=0.83), or diagnosis (p=0.25). None of the patients who developed NOC had characteristic head shape changes such as mastoid bulges or scaphocephaly.
Conclusion: New-onset lambdoid and sagittal synostosis occur frequently following PVDO. While the diagnosis of NOC is obvious radiographically, the clinical importance of the diagnosis morphometrically, neurodevelopmentally, and in cranial growth have yet to be fully investigated.
Table 1: Demographics and diagnoses

		N	%
Total Number of patients		30
	Non-syndromic	6	20
	Apert	6	20
	Crouzon	6	20
	Saethre Chotzen	6	20
	Muenke	3	10
	Pfeiffer	2	6.7
	Others (Vacterl)	1	3.3
Gender
	Female	17	56.6
	Male	13	43.3
Mean age at PVDO		2.03 years
Previous Surgeries
	No	20	66.6
	Yes (FOA)	10	33.3
Indications for Surgery
	Concern for IH	13	43.3
	Turribrachycephaly	12	40
	Concern for IH and Turribrachycephaly	5	16.7
Average distraction distance		28.7mm

Tab le 2: Lambdoid and Sagittal cranial suture patency status prior to and following PVDO

		Lambdoid (N)	Sagittal (N)
Prior to PVDO
	Open	19	17
	Closed	11	13
After PVDO
	Open	2	10
	Closed	28	20

Table 3: Variables tested for correlation with the development of NOC

	P-value
Risk Factors	NOC - Lambdoid	NOC - Sagittal
Age	0.28	0.06
Gender	0.47	0.64
Length of Distraction	0.93	0.83
Diagnosis (syndromic vs. non-syndromic)	0.61	0.25