CT performed some 5 hours after symptom onset shows reduced contrast in the left vertebral artery compared to the right side, suspicious for at least partial thrombotic occlusion, starting in the V2 segment and almost up to the basilar artery, with frank arterial wall dissection at the level of C2-C4. The non-contrast CCT performed just before the CTA does not show obvious infarction or intracranial haemorrhage.