Purpose of Sharp Purser Test: To determine if subluxation of the atlas on the axis vertebra is present and diagnose atlantoaxial instability (1).

Patient position: Sitting.

Examiner position: Standing beside the patient.

Procedure: Ask the patient to perform a slight cervical retraction/nod to correct the poke chin posture. Place the palm of one hand over the patient’s forehead. Place the thumb and the index finger of the other hand over the spinous process of the axis vertebra. Maintain both arms parallel to the ground in order to apply a gentle force along the transverse plane. Apply a gentle posteriorly directed force on the patient’s forehead while stabilizing the spinous process of the axis vertebra.

Outcome: This test is positive if there is a sliding movement of the patient’s head and/or your patient reports a decrease in the following symptoms: weakness, numbness, nausea, abnormal pupil response, twitching eyes, nystagmus, lump in the throat, dizziness, and paraesthesia of the lip, face or limbs (1-3). A positive test indicates atlantoaxial instability and may be accompanied by a clunk/click sensation on the palate. The test is negative if there was no sliding sensation or laxity.

Additional Notes: As the sharp purser test increases the vertebral canal space, it is recommended to perform this test before proceeding with the provocative transverse ligament stress test.

Reference: 

1. Uitvlugt G, Indenbaum S. Clinical assessment of atlantoaxial instability using the sharp‐purser test. Arthritis & Rheumatism: Official Journal of the American College of Rheumatology. 1988;31(7):918-22.
2. Sharp J, Purser D. Spontaneous atlanto-axial dislocation in ankylosing spondylitis and rheumatoid arthritis. Annals of the rheumatic diseases. 1961;20(1):47.
3. Vogelsang H, Zeidler H, Wittenborg A, Weidner A. Rheumatoid cervical luxations with fatal neurological complications. Neuroradiology. 1973;6(2):87-92.