MRCP-0260

A 24-year-old man was hit on the lateral aspect of his head by a high velocity cricket ball and lost consciousness immediately. Paramedics found him to have a Glasgow coma score of 15 but take him to the A&E for further investigation. His Glasgow coma score on examination in the A&E is 13 (M5, V4, E4) and he has anterograde and retrograde amnesia to recent events. The doctors arrange an urgent CT scan. Which clinical sign would be most concerning if present?