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 Neurosurg 57(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 Anat 129(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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