"Ostrich Sign" Indicates
Bilateral Vertebral Artery Dissection

This section is compiled by Frank M. Painter, D.C.
Send all comments or additions to:    Frankp@chiro.org

FROM:   J Stroke Cerebrovasc Dis. 2012 (Nov); 21 (8): 903. e1-2 ~ FULL TEXT

David Z. Rose, Rizwan Husain

Department of Neurology,
University of Pennsylvania,
Philadelphia, Pennsylvania.

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Vertebral artery dissections (VADs) comprise about 2% of ischemic strokes and can be associated with trauma, chiropractic manipulation, motor vehicle collisions, whiplash, amusement park rides, golfing, and other motion-induced injuries to the neck. We present a case of bilateral extracranial VAD as a complication of conducting an orchestra. To our knowledge, this has not been documented in the literature. Conceivably, vigorous neck twisting in an inexperienced, amateur conductor may place excessive rotational forces upon mobile portions of the verterbral arteries, tear the intima, deposit subintimal blood that extends longitudinally, and cause neck pain and/or posterior fossa ischemic symptoms. Magnetic resonance angiography examinations of axially oriented slices of bilateral VADs resemble the face of an ostrich. This observation is similar to the "puppy sign," in which bilateral internal carotid artery dissections resemble the face of a dog. Craniocervical dissections of either the carotid or vertebral arteries have the potential to form an aneurysm, cause artery-to-artery embolism, or completely occlude the parent artery, resulting in an ischemic stroke. Because bilateral VADs in axial magnetic resonance angiographic sections stand out like the eyes of an ostrich, and because the fast identification of VADs is so critical, we eponymize this image the "ostrich sign."

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From the FULL TEXT Article:

Case Report

Figure 1

A 32-year-old right-handed man who is an amateur orchestra conductor presented to a sports medicine physician with marked pain in the nape of his neck shortly after conducting a local community symphony. The neurologic examination and the patient’s medical history were both unremarkable. Because of the persistent, sharp, intense pain, a magnetic resonance imaging (MRI) scan of his cervical spine was obtained. This revealed normal vertebral bone and disc alignment, but extensive longitudinal dissections of his bilateral extracranial vertebral arteries was also noted. He was sent to a vascular neurologist, and this finding was confirmed on a dedicated, fatsaturated, T1-weighted magnetic resonance angiography (MRA) scan of the neck. After an MRA scan of the brain, the anterior circulation and internal carotid arteries were found to be normal without dissection.

Vertebral artery dissections (VADs) comprise about 2%of ischemic strokes in the general population—with bilateral dissection being amuch rarer phenomenon—and can be associated with trauma, chiropractic manipulation,migraine, the use of oral contraceptive pills, or fibromuscular dysplasia. [1] Motor vehicle collisions, whiplash, amusement park rides, golfing, and other motion-induced injuries to the neck have also been implicated. [1–3] However, arterial dissection as a complication of conducting an orchestra never has been reported in the literature. Conceivably, vigorous neck twisting in an inexperienced conductor may place excessive rotational forces upon mobile portions of the verterbral arteries, tearing the intima, depositing subintimal blood that extends longitudinally, and causing neck pain and/or posterior circulation ischemic stroke–like symptoms. [3]

We postulate that MRA scans of axially oriented slices of bilateral VADs (Fig 1A) resemble the face of an ostrich (Fig 1B). This perception is similar to the “puppy sign,” a concept reported in 2007 in which bilateral internal carotid artery dissections resemble the face of a dog. [4] Just as awareness of the “puppy sign” may ease quick visual diagnosis of bilateral internal carotid artery dissections, cognizance of the “ostrich sign” may help rapid identification of bilateral VADs. Craniocervical dissections of either the carotid or vertebral arteries have the potential to form an aneurysm, cause artery-to-artery embolism or completely occlude the parent artery, resulting in a devastating ischemic stroke. Because bilateral VADs in axial MRA sections stand out like the eyes of an ostrich, and because the fast identification of VADs is so critical, we eponymize this image as the “ostrich sign.”

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References:

1. Schneck M, Simionescu M, Bijari A.
   Bilateral vertebral artery dissection possibly precipitated in delayed fashion as a result of roller coaster rides.
   J Stroke Cerebrovasc Dis 2008;17:39-41.

2. Maroon JC, Gardner P, Abla AA, et al.
   “Golfer’s stroke”: Golf-induced stroke from vertebral artery dissection.
   Surg Neurol 2007;67:163-168.

3. Burneo JG, Shatz R, Papamitsakis NIH.
   Amusement park stroke.
   Neurology 2000;55:564.

4. Feddersen B, Linn J, Klopstock T.
   Neurological picture. “Puppy sign” indicating bilateral dissection of internal carotid artery.
   J Neurol Neurosurg Psychiatry 2007;78:1055.

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