title: Analysis of failed spinal cord stimulation trials in the treatment of intractable chronic pain.
abstract: OBJECTIVE
  The purpose of this study is to identify the factors affecting the failure of trials (<50% pain reduction in pain for trial period) to improve success rate of spinal cord stimulation (SCS) trial.
  
  
  METHODS
  A retrospective review of the failed trials (44 patients, 36.1%) among the patients (n=122) who underwent SCS trial between January 1990 and December 1998 was conducted. We reviewed the causes of failed trial stimulation, age, sex, etiology of pain, type of electrode, and third party support.
  
  
  RESULTS
  Of the 44 patients, 65.9% showed unacceptable pain relief in spite of sufficient paresthesia on the pain area with trial stimulation. Four of six patients felt insufficient paresthesia with stimulation had the lesions of the spinal cord. Seventy five percent of the patients experienced unpleasant or painful sensation during stimulation had allodynia dominant pain. Third-party involvement, sex, age and electrode type had no influence on the outcome.
  
  
  CONCLUSIONS
  We conclude that SCS trial is less effective for patients with neuropathic pain of cord lesions, postherpetic neuropathy or post-amputation state. Further, patients with allodynia dominant pain can feel unpleasant or painful during trial stimulation.
authors.affiliation: Department of Neurosurgery, College of Medicine, Yeungnam University, Daegu, Korea.
authors.forename: Hyun-Dong
authors.initials: HD
authors.lastname: Jang
authors.forename: Min-Su
authors.initials: MS
authors.lastname: Kim
authors.forename: Chul-Hoon
authors.initials: CH
authors.lastname: Chang
authors.forename: Sang-Woo
authors.initials: SW
authors.lastname: Kim
authors.forename: Oh-Lyong
authors.initials: OL
authors.lastname: Kim
authors.forename: Seong-Ho
authors.initials: SH
authors.lastname: Kim