Achondroplastic base of skull abnormalities
Citation, DOI, disclosures and article data
At the time the article was created Frank Gaillard had no recorded disclosures.View Frank Gaillard's current disclosures
As the skull base forms by endochondral ossification whereas the skull vault by membranous ossification, there is a marked discrepancy in relative size as the skull vault, brain and cord grow normally whereas the skull base remains small.
As a result of this size discrepancy, there is stenosis of the foramen magnum, often with basilar invagination. Compression of the medulla may result in quadriparesis, sleep apnea, and even sudden death. Interruption to normal cerebrospinal fluid (CSF) flow can lead to hydrocephalus.
small/non-existent cisterna magna
enlarged lateral ventricles
enlarged third ventricle
+/- enlarged fourth ventricle
enlarged CSF space between and over the cerebral hemispheres
occasional transependymal edema
more vertical course of the straight sinus
increased tentorial angle (55-70 degrees)
small jugular foramen which can result in elevated venous pressures and reduced flow in the superior sagittal sinus 4
foramen magnum narrowed
obliteration of the CSF space around the cervicomedullary junction
Treatment and prognosis
Surgical decompression may be required, with resection of the posterior aspect of the foramen magnum, the posterior arch of C1 and duroplasty.
- 1. Kao SC, Waziri MH, Smith WL et-al. MR imaging of the craniovertebral junction, cranium, and brain in children with achondroplasia. AJR Am J Roentgenol. 1989;153 (3): 565-9. AJR Am J Roentgenol (abstract) - Pubmed citation
- 2. Wang H, Rosenbaum AE, Reid CS et-al. Pediatric patients with achondroplasia: CT evaluation of the craniocervical junction. Radiology. 1987;164 (2): 515-9. Radiology (abstract) - Pubmed citation
- 3. Albright AL, Adelson PD, Pollack IF. Principles and practice of pediatric neurosurgery. Thieme Medical Pub. (2007) ISBN:1588903958. Read it at Google Books - Find it at Amazon
- 4. Hirabuki N, Watanabe Y, Mano T et-al. Quantitation of flow in the superior sagittal sinus performed with cine phase-contrast MR imaging of healthy and achondroplastic children. AJNR Am J Neuroradiol. 2000;21 (8): 1497-501. AJNR Am J Neuroradiol (full text) - Pubmed citation