title: Rotational vertebrobasilar insufficiency due to dynamic compression of the dominant vertebral artery by the thyroid cartilage and occlusion of the contralateral vertebral artery at C1-2 level.
abstract: BACKGROUND
  Vertebrobasilar insufficiency caused by head rotation is an uncommon event. The mechanism is obstruction of the vertebral artery resulting in flow limitation or, less frequently, thromboembolism.
  
  
  METHODS
  A 41-year-old male developed dizziness and light-headedness during chiropractic manipulation when his head was turned to the extreme right position. Computed tomography angiography (CTA) of the neck and selective digital subtraction angiography (DSA) of the vertebral arteries revealed that when the patient turned his head to the extreme right position the dominant right vertebral artery was compressed between the posterior aspect of the thyroid cartilage and anterior aspect of the right transverse process of C6 resulting in focal stenosis, while the left vertebral artery is severely compressed with significant flow limitation at the level of C1-2. Because the patient was healthy and asymptomatic, conservative management was adopted. At the 9-month follow-up visit the patient was asymptomatic and able to compensate for his problem avoiding turning his head to the extreme right position.
  
  
  CONCLUSIONS
  We present an uncommon case of rotational vertebrobasilar insufficiency (VBI) where the dominant vertebral artery has an anomalous course compressed by the thyroid cartilage at C6 level, associated with contralateral vertebral artery rotational stenosis at C1-2. The patient was successfully managed conservatively.
authors.affiliation: Massachusetts General Hospital-Harvard Medical School-Division of Interventional Neuroradiology, Boston, Massachusetts 02114, USA. gdabus@partner.org
authors.forename: Guilherme
authors.initials: G
authors.lastname: Dabus
authors.forename: Ronald J
authors.initials: RJ
authors.lastname: Gerstle
authors.forename: Matthew
authors.initials: M
authors.lastname: Parsons
authors.forename: Dewitte T
authors.initials: DT
authors.lastname: Cross
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Moran
authors.forename: Robert
authors.initials: R
authors.lastname: Thompson
authors.forename: Colin P
authors.initials: CP
authors.lastname: Derdeyn
mesh_terms: D000328:Adult; D015901:Angiography, Digital Subtraction; D001157:Arterial Occlusive Diseases / Q000150:complications* / Q000000981:diagnostic imaging; D001241:Aspirin / Q000008:administration & dosage; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging; D019416:Head Movements; D006801:Humans; D008297:Male; D012399:Rotation; D013957:Thyroid Cartilage / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed; D014711:Vertebral Artery / Q000000981:diagnostic imaging; D014715:Vertebrobasilar Insufficiency / Q000000981:diagnostic imaging / Q000209:etiology*
chemical_list: D001241:Aspirin