Extension Rotation Test | Vertebrobasilar Insufficiency (VBI)
The vertebral artery supplies blood flow to the hindbrain and courses through the transverse foramina of the cervical levels from C6 to C1 and is tethered at foramina C2, C1, and the atlanto-occipital membrane. Abnormal stress (amongst others through cervical rotation) on this artery may lead to a reduction of blood flow to the hindbrain, which we call vertebrobasilar insufficiency or VBI– a condition that can develop into cerebral or brain stem ischemia and lead to severe morbidity or death.
Our most important tool to evaluate our patient’s individual presentation is amongst others our knowledge about the pathophysiology, risk factors of arterial dysfunction, and above all awareness of the classical vascular clinical presentation coupled with a high index of suspicion. Watch our video on those topics first before you carry on!
The goal of pre-manipulative vertebrobasilar testing is to evaluate the adequacy of blood supply to the brain by compressing the vertebral artery and to examine for the onset of signs and symptoms indicative of VBI.
Hutting et al. (2013) have conducted a systematic review of the extension rotation test and have found a low sensitivity ranging from 0-57% and a moderate to good specificity ranging from 67-100%. For this reason, a surplus value for pre-manipulative tests seems unlikely.
To perform this test, have your patient in supine lying position with his head above the edge of the table.
Support your patient’s head, rotate it submaximally to one side, and bring his head into extension.
Hold this position for 30 seconds, talk to the patient or have him count to 20 to look for changes in speech and monitor his eyes to notice a possible nystagmus.
Because we are compromising the blood flow through the artery in the opposite direction of the rotation, we are actually testing the vertebral artery on the side of rotation which has to compensate for the decrease in blood supply to the hindbrain.
All typical signs and symptoms indicative of VBI, which indicate a positive test can be seen in the overview table here:
All of those are absolute contraindications to cervical manipulation making an urgent referral to the GP or specialist necessary.
21 OF THE MOST USEFUL ORTHOPAEDIC TESTS IN CLINICAL PRACTICE
In order to screen for cervical artery dysfunction, it is recommended to assess the cranial nerve function of nerves VIII to XII:
- Cranial Nerve VIII: Vestibulocochlear Nerve
- Cranial Nerve IX & X: Glossopharyngeal & Vagus Nerve
- Cranial Nerve XI: Accessory Nerve
- Cranial Nerve XII: Hypoglossal Nerve
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