Background Achondroplasia is the most common skeletal dysplasia. A significant complication is foramen magnum stenosis. When severe, compression of the spinal cord may result in sleep apnea, sudden respiratory arrest and death. To avoid complications, surgical decompression of the craniocervical junction is offered in at-risk cases. However, practice varies among centres. To standardize magnetic resonance (MR) reporting, the achondroplasia foramen magnum score was recently developed. The reliability of the score has not been assessed. Objective To assess the interobserver reliability of the achondroplasia foramen magnum score. Materials and methods Base of skull imaging of children with achondroplasia under the care of Sheffield Children’s Hospital was retrospectively and independently reviewed by four observers using the achondroplasia foramen magnum score. Two-way random-effects intraclass coefficient (ICC) was used to assess inter- and intra-observer reliability. Results Forty-nine eligible cases and five controls were included. Of these, 10 were scored normal, 17 had a median score of 1 (mild narrowing), 11 had a median score of 2 (effacement of cerebral spinal fluid), 10 had a score of 3 (compression of cord) and 6 had a median score of 4 (cord myelopathic change). Interobserver ICC was 0.72 (95% confidence interval = 0.62–0.81). Intra-observer ICC ranged from 0.60 to 0.86. Reasons for reader disagreement included flow void artefact, subtle T2 cord signal and myelopathic T2 cord change disproportionate to canal narrowing. Conclusion The achondroplasia foramen magnum score has good interobserver reliability. Imaging features leading to interobserver disagreement have been identified. Further research is required to prospectively validate the score against clinical outcomes.

Objectives: The aim of this paper is to assess the acute haemorrhage rate in patients who had CT head investigation out-of-hours with and without trauma and compare the rates of haemorrhage between warfarin and DOACs, at a busy teritary teaching hospital. Methods: All CT heads performed between January 2008 and December 2019 were identified from the radiology information system (RIS) at Sheffield Teaching Hospitals (STH), with the requesting information being available from January 2015. The clinical information was assessed for the mention of trauma or anticoagulation and the reports were categorised into acute and non-acute findings. Results: Between 2008 and 2019 the number of scans increased by 63%, with scans performed out of hours increasing by 278%. Between 2015 and 2019, the incidence of acute ICH was similar over the 5 year period, averaging at 6.9% and ranging from 6.1 to 7.6%. The rate of detection of acute haemorrhage following trauma was greater in those not anticoagulated (6.8%), compared with patients on anticoagulants such as warfarin (5.2%) or DOACs (2.8%). Conclusions: Over 12 years, there has been a significant increase in the number of CT heads performed at STH. The rate of ICH has remained steady over the last 5 years indicating a justified increase in imaging demand. However the incidence of ICH in patients prescribed DOACs is lower than the general population and those on warfarin. Advances in knowledge: : This finding in a large centre should prompt discussion of the risk of bleeding with DOACs in relation to CT head imaging guidelines.

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