Bone Abstracts

Objectives: In the context of a lack of national consensus, the aim of this study was to identify the clinical impact of skull base imaging in children with osteogenesis imperfecta (OI).

Methods: A retrospective review was conducted of case-notes and radiological images of children with severe, complex and atypical OI at a designated specialist centre, between 01/2012 and 08/2018. Patient demographics, clinical features at time of imaging and radiological parameters (Wormian bones, platybasia, basilar impression (McGregor’s technique) and basilar invagination (McRae’s technique)) were recorded and correlated.

Results: Of the 127 patients, 33 were excluded due to absence of imaging. A total of 321 radiographs and 39 MRI scans of 94 patients (52% males) were analysed. Prevalence of radiographic abnormalities was, Wormian bones 59/94(62.8%), platybasia 58/94(61.7%), basilar impression 10/94(7.1%) and basilar invagination 1/94(1.1%). Platybasia, basilar impression and basilar invagination could not be measured in 71/321(22.3%), 48/321(14.8%), and 33/321(19.6%) radiographs respectively (reasons included poor positioning, anatomical abnormalities and poor image quality). Of the 23 radiographs with basilar impression, 17(85%) also had platybasia while 3(13%) did not (P=0.04). Wormian bones had equal prevalence in patients with and without basilar impression. Prevalence of skull base abnormalities on MRI was basilar impression 23(58.9%), basilar invagination 9 (23.0%) and abnormal spinal cord signal, CSF flow or cerebellum 14(35.9%). There was a lack of concordance between MRI and matched radiographs in 22.2% (4/18), 35.7% (5/14) and 14.3% (2/14) for platybasia, basilar impression and basilar invagination respectively. Fewer than 5% had positive clinical symptoms or signs at the time of their radiographs; (2.1%(7/321) had macrocephaly, 0.6% (2/321) headache, all other neurological features were absent). However, these features were not documented in >85% of cases.

Conclusion: There is 1) a low prevalence of neurological symptoms and skull base abnormalities and 2) poor concordance between MR and radiographic skull base parameters in children with OI. Although it may reflect their absence, neurological symptoms and signs are not routinely documented. A prospective study is required to produce data to inform the development of national guidelines for skull base imaging in OI.

Disclosure: The authors declared no competing interests.