Some cases of acute antero-lateral cervical pain cannot be accurately classified by medical imaging (ultrasound and/or magnetic resonance imaging and/or CT-scan) : imaging rules out carotid dissection, carotid occlusion or vasculitis as well as musculoskeletal causes and thus the pain is considered "of unknown origin".

The investigators hypothesize that in such cases perivascular inflammation of the carotid may be involved.

This study aims at systematically reviewing medical files (including imaging) of patients suffering from acute cervical pain in which carotid dissection, carotid occlusion or vasculitis as well as musculoskeletal causes have been ruled out by ultrasound and/or magnetic resonance imaging and/or CT-scan

Inclusion Criteria:

• Adult patient with acute cervical pain
• Presence of at least one medical imaging modality of the neck : ultrasound with doppler imaging, magnetic resonance imaging, CT-scan
• Medical imaging of the neck includes dedicated vessel analysis
• Absence of definite diagnosis for the cause of the pain after imaging

Exclusion Criteria:

• Musculoskeletal cause of the pain
• Carotid dissection
• Carotid occlusion
• Carotid vasculitis

All adult patients from 10 centers in France, who presented from January 2009 through April 2016 with acute cervical pain and with at least 1 diagnostic image (MR imaging, CT, or US including a dedicated vessel analysis) in which no clearly identified and classified vascular or musculoskeletal cause of the pain was found.