Allen’s Manoeuvre or Allen’s test is used to examine for neurovasular compression (thoracic outlet syndrome, TOS), caused by a cervical rib or anterior scalene muscle syndrome.
- Patient seated, shoulder abducted to 90° and elbow flexed to 90°.
- Examiner palpates radial pulse and asks patient to turn head away from affected side.
Patient may be instructed to take a deep breath and hold it after the head is rotated to help apply further pressure to the brachial plexus nerve roots and subclavian artery.
Positive AC Shear Test
Decrease or loss of pulse: neurovasular compression (TOS) from a cervical rib, anterior scalene muscle syndrome.