Recurrence of Synostosis Following Surgery for Isolated Sagittal Craniosynostosis

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 Albright, A. L. and R. P. Byrd (1981). "Suture pathology in craniosynostosis." J Neurosurg54(3): 384-7. • 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. 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

6. MATERIALS AND METHODS • Retrospective study 1987-2000 Inclusion criteria • Children with isolated sagittal craniosynostosis • 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 • Patency of coronal and lambdoid sutures

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

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

11. RESULTS • 35/42 (83.3%) had resynostosis of the sagittal 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 • 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

16. 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

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

18. DISCUSSION • 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

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. • Further prospective studies would be required to prove this hypothesis

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

21. 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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