• Pain severity (rated using a 0-10 Numeric Rating Scale [NRS]) [ Time Frame: Average of daily ratings over 14 days ]
  

• Adverse Events [ Time Frame: Daily ]
  
• Short McGill Pain Questionnaire (modified) (SF-McGill) [ Time Frame: at randomization and at the midpoint of each 7-week drug or placebo period ]
  
• Opioids cognitive effects scale [ Time Frame: at randomization and at the midpoint of each 7-week drug or placebo period ]
  
• Patient Generated Index for activity (PGI) [ Time Frame: at randomization and at the midpoint of each 7-week drug or placebo period) ]
  
• Daily number of attacks of paroxysmal pain [ Time Frame: Daily ]
  
• Allodynia, hyperalgesia, and temporal summation (determined using quantitative sensory testing) [ Time Frame: at randomization and at the midpoint of each 7-week drug or placebo period) ]
  
• Concomitant medication usage [ Time Frame: daily ]
  
• Subject global impression of change [ Time Frame: two times during the 14 week study period (at the midpoint of each 7-week drug or placebo period ]
  
• Short-Form 36 (SF-36) [ Time Frame: at randomization and at the midpoint of each 7-week drug or placebo period ]
  
• Positive And Negative Affect Schedule (PANAS) [ Time Frame: at randomization and at the midpoint of each 7-week drug or placebo period ]
  
• Brief Patient Health Questionnaire (PHQ-9) [ Time Frame: at randomization and at the midpoint of each 7-week drug or placebo period ]
  
• Multidimensional Pain Inventory Life Interference subscale (MPI-LIS) [ Time Frame: at randomization and at the midpoint of each 7-week drug or placebo period ]
  
• Sleep interference assessment [ Time Frame: at randomization and at the midpoint of each 7-week drug or placebo period ]
  
• Medication quantity effective for analgesia or maximally tolerated [Time Frame: [ Time Frame: two times during the 14 week study period (at the midpoint of each 7-week drug or placebo period)] ]
  

Neuropathic pain occurs as a result of damage to neural tissue either in the peripheral or in the central nervous system. Three types of neuropathic pain after SCI are especially difficult to treat: at level central pain (ALCP), at level radicular pain (ALRP), and below level central pain (BLCP). Various analgesic medications with distinct mechanisms and sites of action are currently used in clinical practice for treatment of neuropathic pain after SCI, including antidepressants, anticonvulsants, nonsteroidal anti-inflammatory drugs (NSAIDs), and opioids. These analgesic medications, when evaluated in animal models of SCI pain and in the treatment of other neuropathic pain states, have been shown to have only modest pain reducing effect. This modest effect is seen clinically as the majority of persons with SCI receiving these drugs continue to experience pain, which is severe and disabling in one third of cases.

This study proposes to examine the efficacy of oral modified release morphine in reducing pain in persons with neuropathic pain after SCI who have not adequately responded to other oral pharmacologic, psychologic, or physical interventions. Only subjects who have failed prior pain treatment regimes will be enrolled. Failure of pain regimen is defined as the presence of pain in spite of medication(s) or other pain treatment, such as biofeedback or other psychological or physical therapy interventions prescribed by a physician.

The following hypothesis will be tested: morphine, when added to non-opioid medications, is more effective than placebo in reducing pain and increasing activity and subjective well-being, in persons with ALCP, ALRP and BLCP. In order to test this hypothesis, a randomized, double blind, placebo-controlled, two period cross-over trial is proposed, during which subjects with ALCP, ALRP, and BLCP will receive daily placebo or modified release morphine while being closely monitored and assessed for: (1) adverse effects, (2) quality and intensity of pain, (3) intensity of allodynia and hyperalgesia, and (4) activity levels and well-being.

All subjects whether assigned to the placebo or active drug will be able to continue any previously prescribed or non-prescribed (over-the-counter) non-opioid medication that has been taken on a regular basis, without dose change, for at least three weeks prior to study entry. These medications may include but are not limited to the analgesics: acetaminophen and any non-steroidal anti-inflammatory drugs; local anesthetics- topical patches such as the lidocaine patch or otherwise; and adjuvant pain medications of the anti-depressant or anticonvulsant classes. Subjects will not be allowed to take any opioid medication, including non-opioid-opioid combination analgesics, other than the study drug for the duration of the study.