Attal et al. 2002;
France
PEDro=10
RCT
N=15

Population: SCI: Mean age = 54.9 yrs; Gender: males = 6, females = 9; Mean duration of pain = 5 yrs.
Treatment: Initially, patients received IV morphine titrated up to the maximal tolerated dosage using successive bolus injections of 2 mg morphine every 10 minutes. Double blind phase began 3 weeks after titration phase. IV morphine or saline was administered.
Outcome Measures: Spontaneous pain, Tactile Allodynia, Psychophysical Measurements, Mechanical detection and pain thresholds, Thermal Detection and pain.

1. Spontaneous pain scores decreased immediately after the end of the infusion of morphine and placebo for up to 120 minutes in both groups.
2. The effects of the morphine did not differ significantly from those who were given the placebo post injection.
3. Those who reported pain relief from the treatment was higher (3x) after the morphine than after the placebo was given from 15 to 60 minutes post injection.
4. Burning pain was weakened by the morphine in 7 pts and by placebo in 4 pts.
5. When looking at the effects of morphine on mechanical allodynia it could be seen that the morphine produced a reduction in intensity. The saline treatment did not have an effect.
6. The morphine significantly reduced (p<0.01) dynamic mechanical allodynia but not other pains.

Norrbrink & Lundeberg 2009
Sweden
PEDro=8
RCT
N=35

Population: Mean age=51.3yrs; Gender: males=28, females=7; Level of injury: tetraplegia=16, paraplegia=19; Type of pain=neuropathic.
Treatment: Patients were randomized in a 2:1 ratio (tramadol/placebo) and treatment was administered for 4 weeks. Both patients and staff were blind to the treatments. Each patient was given 50mg tramadol or placebo 3 times daily. The daily dose was increased by 1 tablet every 5 days to a max dose of 8 tablets.
Outcome Measures: Patient Global Impression of Change; Multidimensional Pain Inventory

1. Significant differences were seen in between group pain ratings (p<0.05).
2. Patient Global Impression of Change rating was significantly higher in the tramadol group than the control group.
3. Significant improvements were seen in ratings of anxiety, global life satisfaction and sleep quality (p<0.05).
4. No significant changes were seen in pain pleasantness, depression, or on the MPI scales pain interference, perceived life control, affective distress or social support.

Eide et al. 1995
Norway
PEDro=7
RCT
N=9

Population: Age = 25-72 yrs; Gender: males = 8, females = 1; Level of injury: cervical, thoracic; Severity of injury: AIS: A-D; Onset of pain: <6 mths post injury, Length of pain: 14-94 mths.
Treatment: Ketamine hydrochloride, alfentanil or a placebo was given as combination of bolus and continuous intravenous infusions.  The bolus dose was administered for 60 secs and the continuous intravenous infusion started simultaneously and was delivered by IVAC syringe pump. This lasted 17 to 21 minutes while the testing was performed.
Outcome Measures: Continuous pain was measured by a 100 mm visual analogue scale (no pain to unbearable pain (0 to 100)) before and after each drug treatment.

1. Freidmann's two-way analysis by ranks showed differences between the various treatments (p=0.005).
2. The effect of alfentanil and ketamine was also significant (p<0.01 & p<0.04 respectively).
3. No significant differences were noted between the actions of ketamine and alfentanil (Wilcoxon p=0.19).
4. Significant differences were noted between the treatment groups (p=0.008). It was also noted that allodynia was not more changed by ketamine than by alfentanil (Wilcoxon p=0.93).
5. Alfentanil reduced wind-up-like pain (p=0.014) compared to the placebo group. The effect of ketamine on wind-up-like pain was not significantly reduced (p=0.07).
6. A high correlation between the serum concentration of ketamine and the reduction of continuous pain (r=0.78, p<0.002) and the reduction of wind-up-like pain (r=0.83, p<0.002) was noted.