Atlanto-occipital and lateral atlanto-axial joint pain patterns.

STUDY DESIGN: Five asymptomatic subjects underwent provocative injections of the lateral atlanto-axial and atlanto-occipital joints.

OBJECTIVES: This study isolated and stimulated the lateral atlanto-axial and atlanto-occipital joints via fluoroscopically guided intra-articular injections to determine if they are potential pain generators. If they are pain generators, preliminary pain pattern maps will be constructed.

SUMMARY OF BACKGROUND DATA: The cervical zygapophyseal joints (C2-3 to C6-7) are potential pain generators as demonstrated by referred pain induced via isolated intra-articular joint injections in normal subjects. Tentative referral patterns based on direct mechanical stimulation of the lateral atlanto-axial and atlanto-occipital joints have not been reported.

METHODS: Five volunteers without histories of upper cervical pain underwent two joint injections each. In all five subjects, the left atlanto-occipital and right lateral atlanto-axial joints were stimulated via injection of contrast medium causing distension of the joint capsule.

RESULTS: Referred pain was produced with all ten injections. The lateral atlanto-axial injections resulted in consistent referral patterns, whereas the atlanto-occipital referral patterns varied significantly. A tentative composite diagram of the experimentally induced pain was created for each joint.

CONCLUSION: This study confirms the nociceptive ability of these cervical synovial joints. This study may assist the clinician in the differential diagnosis of head and neck pain.