title: Venipuncture-induced causalgia: anatomic relations of upper extremity superficial veins and nerves, and clinical considerations.
abstract: BACKGROUND
  In 1994, 11 patients with injury to upper extremity cutaneous nerves after routine venipuncture were reported. All developed causalgia (Complex Regional Pain Syndrome, Type 2). Nerve injury appeared secondary to direct trauma via "inappropriate" needle or bolused material entry into the plane of the nerves beneath the veins, or nerves overlying the veins. However, in 3 of 13 additional patients, the venipunctures were properly performed and atraumatic.
  
  
  METHODS
  To explore the anatomic relationships of superficial veins and cutaneous nerves with regard to the role of direct nerve trauma during venipuncture in the development of causalgia, the 14 upper extremities of seven randomly chosen cadavers were dissected at three common venipuncture sites. In addition, the clinical features of all 24 patients are presented.
  
  
  RESULTS
  Major branches of cutaneous nerves were superficial to and overlay veins in six extremities. In multiple instances, nerves and veins were intertwined, requiring detailed dissection to separate them. In the classic situation, nerves were immediately as deep as veins, often with no fascial separation.
  
  
  CONCLUSIONS
  Anatomical relationships between upper extremity superficial veins and cutaneous nerves are so intimate that needle-nerve contact during venipuncture is common. Because venipuncture-induced nerve injuries are rare, factors other than direct nerve contact appear necessary for the chronic pain syndrome to occur.
authors.affiliation: Division of Neurology, Department of Psychiatry and Neurology, University of Missouri-Columbia, Columbia, Missouri 65212, USA. horowitzs@health.missouri.edu
authors.forename: S H
authors.initials: SH
authors.lastname: Horowitz
mesh_terms: D000328:Adult; D000368:Aged; D002102:Cadaver; D002422:Causalgia / Q000209:etiology* / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018962:Phlebotomy / Q000009:adverse effects*; D014680:Veins / Q000033:anatomy & histology*