By analysing the anatomy of upper cervical segment

the atlas - axis relation in plain X - ray film in 3-1 cases revealed that the joint displacement is one of the important causes for vertebral artery type or sympathetic type cervical spondylopathy. The main manifestations for diagnosing atlas - axis displacement included headache

dizziness

unilateral protrusion and tenderness of the affected vertebra

displacement of tooth protrusion up to 1 mm at anterior mouth -open positions. The most effective therapy was accurate and dexterousmanipulation for reduction.