title: Sonographic visualization and ultrasound-guided block of the third occipital nerve: prospective for a new method to diagnose C2-C3 zygapophysial joint pain.
abstract: BACKGROUND
  Chronic neck pain after whiplash injury is caused by cervical zygapophysial joints in 50% of patients. Diagnostic blocks of nerves supplying the joints are performed using fluoroscopy. The authors' hypothesis was that the third occipital nerve can be visualized and blocked with use of an ultrasound-guided technique.
  
  
  METHODS
  In 14 volunteers, the authors placed a needle ultrasound-guided to the third occipital nerve on both sides of the neck. They punctured caudal and perpendicular to the 14-MHz transducer. In 11 volunteers, 0.9 ml of either local anesthetic or normal saline was applied in a randomized, double-blind, crossover manner. Anesthesia was controlled in the corresponding skin area by pinprick and cold testing. The position of the needle was controlled by fluoroscopy.
  
  
  RESULTS
  The third occipital nerve could be visualized in all subjects and showed a median diameter of 2.0 mm. Anesthesia was missing after local anesthetic in only one case. There was neither anesthesia nor hyposensitivity after any of the saline injections. The C2-C3 joint, in a transversal plane visualized as a convex density, was identified correctly by ultrasound in 27 of 28 cases, and 23 needles were placed correctly into the target zone.
  
  
  CONCLUSIONS
  The third occipital nerve can be visualized and blocked with use of an ultrasound-guided technique. The needles were positioned accurately in 82% of cases as confirmed by fluoroscopy; the nerve was blocked in 90% of cases. Because ultrasound is the only available technique today to visualize this nerve, it seems to be a promising new method for block guidance instead of fluoroscopy.
authors.affiliation: Department of Anesthesiology, Division of Pain Therapy, University of Bern, Inselspital, CH-3010 Bern, Switzerland. urs.eichenberger@insel.ch
authors.forename: Urs
authors.initials: U
authors.lastname: Eichenberger
authors.forename: Manfred
authors.initials: M
authors.lastname: Greher
authors.forename: Stephan
authors.initials: S
authors.lastname: Kapral
authors.forename: Peter
authors.initials: P
authors.lastname: Marhofer
authors.forename: Roland
authors.initials: R
authors.lastname: Wiest
authors.forename: Luca
authors.initials: L
authors.lastname: Remonda
authors.forename: Nikolai
authors.initials: N
authors.lastname: Bogduk
authors.forename: Michele
authors.initials: M
authors.lastname: Curatolo
mesh_terms: D000328:Adult; D000779:Anesthetics, Local; D018771:Arthralgia / Q000175:diagnosis*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005260:Female; D005471:Fluoroscopy; D006801:Humans; D008297:Male; D009407:Nerve Block; D013127:Spinal Nerves / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D014463:Ultrasonography; D021801:Zygapophyseal Joint
chemical_list: D000779:Anesthetics, Local