Introduction: The authors propose a new terminology called Rotational Ischemic Vertebral Artery Compression (RIVAC) Syndrome to characterize patients with severe cervical facet hypertrophy below C2 that compresses the vertebral artery during rotation of head. The authors describe presentation, diagnosis, and surgical management of three patients with RIVAC syndrome.

Methods: Retrospective analysis of 3 patients who presented with reproducible symptoms of vertebrobasilar ischemia on rotation of head was performed between 2004 and 2012. We reviewed pre-operative and post-operative dynamic cerebral angiograms and CT scans of the cervical spine. We reviewed the method of surgical treatment and clinical and angiographic outcome.

Results: A total of 3 patients (mean age 65 +/- 5 years) presented with symptoms of vertebrobasilar ischemia (reproducible dizziness or near-syncope) when the head is rotated to the left side. Dynamic cerebral angiogram showed occlusion of the left cervical vertebral artery at C5-6 disc level (N=1) or severe compression without occlusion at C4-5 (N=2) only when the head is turned to left beyond 45 degrees. Pre-operative CT scan of cervical spine showed severe facet hypertrophy encroaching the vertebral foramen at the respective levels. All three patients underwent posterior cervical partial or complete facetectomy at the respective levels and lateral mass screw fixation and fusion with complete resolution of symptoms after the surgery. Post-operative CT scan of the cervical spine without contrast and repeat dynamic cerebral angiogram showed no compression of the artery with rotation of the head.

Conclusions: Cervical facet hypertrophy below C2 level can be a potential unique cause of vertebrobasilar ischemia (RIVAC Syndrome) that is manifested with rotation of head. RIVAC Syndrome should be strongly considered in the differential diagnosis of patients with history of cervical spondylosis or prior cervical fusion surgery that present with reproducible ischemic symptoms with rotation of head.

Patient Care: Patients with previously unrecognized vertebrobasilar ischemia resulting from facet hypertrophy causing rotational vertebral artery compression will now be investigated for RIVAC syndrome and may be prevented from having future strokes

Learning Objectives: By the conclusion of this session, participants should be able to: 1) understand the importance of cervical facet hypertrophy as a cause of rotational vertebral artery compression and vertebrobasilar ischemia and 2) review the diagnostic imaging modalities of vertebral artery compression, and 3) discuss the surgical management of vertebral artery compression due to facet hypertrophy

References: 1) Rotational vertebral artery syndrome: oculographic analysis of nystagmus. Choi KD, Shin HY, Kim JS, Kim SH, Kwon OK, Koo JW, Park SH, Yoon BW, Roh JK. Neurology. 2005 Oct 25; 65(8):1287-90. 2) Rotational vertebral artery syndrome due to compression of nondominant vertebral artery terminating in posterior inferior cerebellar artery. Noh Y, Kwon OK, Kim HJ, Kim JS. J Neurol. 2011 Oct; 258(10):1775-80. Epub 2011 Mar 17. 3) Bow hunter's stroke due to instability at the uncovertebral C3/4 joint. Eur Spine J. 2011 Jul ;20 Suppl 2:S266-70. Epub 2011 Jan 30 . 4) Transient rotational compression of the vertebral artery caused by herniated cervical disc. Case report. J Neurosurg. 2003 Jan ;98(1 Suppl):80-3. 5) Bow Hunter's Stroke Caused by a Severe Facet Hypertrophy of C1-2 Chung Kee Chough, M.D.,1 Boyle C. Cheng, Ph.D.,2 William C. Welch, M.D.,3 and Chun Kun Park, M.D. J Korean Neurosurg Soc. 2010 Feb;47(2):134-136.