Reformation of Suture Following Surgery for Isolated Sagittal Craniosynostosis

1. Reformation of Suture Following Surgery for Isolated Sagittal Craniosynostosis Deepak Agrawal, Paul Steinbok, D Cochrane Division of Pediatric Neurosurgery, UBC and BC Children’s Hospital, Vancouver, BC

2. ISOLATED SAGITTAL CRANIOSYNOSTOSIS BASIS FOR MANAGEMENT • Isolated entity in a normal child • Operative Intervention-Improve cosmesis

3. ETIOLOGY Moss’s Hypothesis • Abnormality at cranial base Moss, M. L. (1959). "The pathogenesis of premature cranial synostosis in man." Acta Anat (Basel)37: 351-70. • Proven for syndromic craniosynostosis

4. ETIOLOGY Babler’s Hypothesis • Abnormality is in the affected calvarial sutures Babler, W. J., J. A. Persing, et al. (1982). "Compensatory growth following premature closure of the coronal suture in rabbits." J Neurosurg57(4): 535-42. • Support from animal experiments Mabbutt, L. W. and V. G. Kokich (1979). "Calvarial and sutural re-development following craniectomy in the neonatal rabbit." J Anat129(2): 413-22.

5. Reformation of sagittal suture should similarly be expected in children with isolated sagittal synostosis

6. OBJECTIVE • To determine the incidence of reformation of the sagittal suture following surgical procedures for sagittal synostosis that involved a minimum of sagittal strip craniectomy

7. MATERIALS AND METHODS • Retrospective study 1987-2000 • Children with isolated sagittal craniosynostosis

8. Operative Procedure Minimum of vertex and parietal craniectomies (removal of the sagittal suture + 1.5 - 2.5 cm piece of adjacent parietal bone with the attached pericranium) Children who had the bone flap replaced were excluded from the study

9. Assessment of resynostosis POST-OP SKULL RADIOGRAPHS • Suture morphology • Patency of coronal and lambdoid sutures

10. RESULTS • 114 children operated for isolated sagittal craniosynostosis in the above period. • 42 children composed the study group.

11. RESULTS • Median age at surgery- 3.9 months (1.9 to 7.6 months) • Mean follow up - 32.2 months (6 to 144 months)

12. RESULTS • Only 7/42 (16.7%) reformed the suture • 35/42 (83.3%) had resynostosis of the sagittal suture

16. These findings are contrary to the results from animal experiments WHY THE DISCREPANCY?

17. DISCUSSION • Both dura mater and pericranium have osteogenic properties • Dura-source of central new bone • Pericranium- enhances peripheral new bone formation Gosain AK, Santoro TD, Song LS, et al: Osteogenesis in calvarial defects: contribution of the dura, the pericranium, and the surrounding bone in adult versus infant animals. Plast Reconstr Surg 112:515-527, 2003

18. DISCUSSION • In Sag synostosis surgery-central strip of bone with the attached pericranium removed • Removal of this pericranium could potentially impair bony regeneration as well as suture reformation

19. DISCUSSION • Common practice to coagulate the bleeding points on the dura • This again could impair the osteogenic capacity of the dura

20. DISCUSSION • Primary aim of surgery is cosmetic • Persistence of bony defects and uneven contour of the bony regrowth may result in patient dissatisfaction, rarely culminating in repeat surgery

21. OUR HYPOTHESIS Limiting coagulation on the dura & replacing pericranium could potentially result in consistent bone regeneration with smooth contour and reformation of a normal suture. Further prospective studies would be required to prove this hypothesis

22. OTHER POTENTIAL FACTORS GENETIC BASIS • Inclusion of undiagnosed syndromic patients • Genetic predisposition to synostosis

23. CONCLUSIONS • We found a very high incidence of resynostosis following surgery for sagittal craniosynostosis • The variability in reformation of the suture after surgery suggests a heterogeneous etiology and pathogenesis of isolated sagittal synostosis.

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