1. Recurrence of Synostosis Following Surgery for Isolated Sagittal Craniosynostosis Deepak Agrawal, P 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 Isolated entity in a normal child Albright, A. L. and R. P. Byrd (1981). "Suture pathology in craniosynostosis." J Neurosurg 54(3): 384-7. Operative Intervention-Improve cosmesis Operative Intervention-Improve cosmesis

3. ETIOLOGY Moss’s Hypothesis Abnormality at cranial base 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 Proven for syndromic craniosynostosis

4. ETIOLOGY Babler’s Hypothesis Abnormality is in the affected calvarial sutures 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 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. OBJECTIVE To determine the incidence of resynostosis of the sagittal suture following surgical procedures for sagittal synostosis that involved a minimum of sagittal strip craniectomy To determine the incidence of resynostosis of the sagittal suture following surgical procedures for sagittal synostosis that involved a minimum of sagittal strip craniectomy

6. MATERIALS AND METHODS Retrospective study 1987-2000 Retrospective study 1987-2000 Inclusion criteria Children with isolated sagittal craniosynostosis Children with isolated sagittal craniosynostosis Postoperative skull radiographs available Postoperative skull radiographs available

7. 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 in whom this bone was replaced were excluded from the study

8. Assessment of resynostosis SKULL RADIOGRAPHS Sagittal suture morphology Sagittal suture morphology Patency of coronal and lambdoid sutures Patency of coronal and lambdoid sutures

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

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

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

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

15. DISCUSSION Both dura mater and pericranium have osteogenic properties Both dura mater and pericranium have osteogenic properties Dura-source of central new bone Dura-source of central new bone Pericranium- enhances peripheral new bone formation 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

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

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

18. DISCUSSION Primary aim of surgery is cosmetic Primary aim of surgery is cosmetic persistence of bony defects and uneven contour of the bony regrowth may result in patient dissatisfaction, occasionally culminating in repeat surgery persistence of bony defects and uneven contour of the bony regrowth may result in patient dissatisfaction, occasionally culminating in repeat surgery

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

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

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

22. THANK YOU