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Skip Navigation LinksHome > December 2013 - Volume 132 - Issue 6 > Foramen Magnum Size and Involvement of Its Intraoccipital Sy...
Plastic & Reconstructive Surgery:
doi: 10.1097/PRS.0b013e3182a8077e
Pediatric/Craniofacial: Original Articles

Foramen Magnum Size and Involvement of Its Intraoccipital Synchondroses in Crouzon Syndrome

Rijken, Bianca F. M. M.D.; Lequin, Maarten H. M.D., Ph.D.; de Rooi, Johan J. Ph.D.; van Veelen, Marie-Lise C. M.D.; Mathijssen, Irene M. J. M.D., Ph.D.

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Abstract

Background: Cranial sutures and synchondroses tend to close prematurely in patients with Crouzon syndrome. This influences their skull vault and skull base development and may involve in common disturbances such as increased intracranial pressure and cerebellar tonsillar herniation. The authors’ hypothesis was that Crouzon patients patients have a smaller foramen magnum than controls because of premature fusion of the intraoccipital synchondroses, putting them at risk for cerebellar tonsillar herniation. Therefore, foramen magnum size and time of intraoccipital synchondroses closure were evaluated and were related to the presence and degree of cerebellar tonsillar herniation.

Methods: The foramen magnum surface area and anteroposterior diameter were measured on three-dimensional computed tomographic scans of 27 Crouzon patients and 27 age-matched controls. Scans had a slice-thickness between 0.75 and 1.25 mm and were aligned in a three-dimensional reformatting platform. The t test was used to study size differences. Synchondroses were graded as described by Madeline and Elster and studied with ordinal logistic regression analysis.

Results: Crouzon patients had a smaller foramen magnum surface area (602 mm2 versus 767 mm2, p < 0.001) and anteroposterior diameter (31 mm versus 35 mm, p < 0.001) compared with controls. Differences stayed constant over time. Intraoccipital synchondroses closed 3 to 9 months earlier in Crouzon patients than in controls (p < 0.05).

Conclusions: Since intraoccipital synchondroses close earlier in Crouzon patients, from early life on their foramen magnum is smaller compared with controls. Within Crouzon patients, the presence of cerebellar tonsillar herniation could not be related to foramen magnum size.

CLINICAL QUESTION/LEVEL OF EVIDENCE: Risk, II.

©2013American Society of Plastic Surgeons

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