Abstract 159: Computed Tomography Angiography Negative Spinal Artery Dissection

Introduction Vertebral artery dissection (VAD) is a relatively common cause of ischemic stroke, especially after chiropractic neck manipulation. VAD usually can be diagnosed by noninvasive imaging studies such as CT angiography (CTA) of the head and neck with suggestive findings of an arterial string sign, arterial stenosis, a double lumen sign, a pseudoaneurysm, or an occlusion. However, in rare situations, CTA may display normal arterial caliber except for very subtle signs such as abnormal dorsal thickening of the arterial wall against adjacent fat at the V3 segment of the vertebral artery. This is referred to as the "suboccipital rind sign." Here we wish to report such a case as identified at our institution. Methods Electronic charts of a patient with acute spinal shock and strokes were reviewed. Results The patient is a 36‐year‐old female with chronic neck pain, status‐post C5‐T1 spinal fusion who presented emergently with quadriparesis that following chiropractic neck manipulation. She felt a “pop” at the neck during the neck manipulation. She shortly thereafter began experiencing persistent neck pain associated with tingling sensations of both upper extremities on her drive home. She then noted transient right‐hand weakness as she was attempting to open a package. Her symptoms then temporarily resolved with rest, but after some time the paresthesia and neck pain reoccurred, worsened, and quickly progressed to quadriplegia. Brain MRI was negative for acute stroke. However, MRI of the cervical spine demonstrated acute cervical spinal cord ischemia in addition to post‐surgical changes. CTA head and neck reported normal arterial caliber. A diagnostic angiogram was performed that showed no evidence of arterial dissection but did demonstrate absence of the anterior spinal artery. Subsequently, CTA was further reviewed on thin slice revealing a “suboccipital rind sign" of the left V3 segment, suggesting left vertebral artery V3 segment dissection. Hypercoagulable workup was negative, and the patient was treated with anticoagulation. Conclusion Arterial dissection is usually readily diagnosable by CTA with high sensitivity. However, a study with normal caliber vessels in the reconstituted images does not always exclude an arterial dissection. To our knowledge there have been six reported vertebral dissection cases with a normal appearing lumen on CTA or conventional angiography. However, similar to our case, they displayed “suboccipital rind” signs on CTA thin cross‐section due to the thickening of the dissected artery on the V3 segment. The V3 segment has a horizontal course which runs parallel to the axially acquired imaging plane, which makes it difficult to appreciate the classic crescentic wall hematoma associated with arterial dissection. We hope that increased awareness of the typical location and appearance of the “suboccipital rind” sign on CTA may increase the detection rates of subtle arterial dissections in the setting normal‐appearing arterial lumens.