TABLE 2.
Summary of the findings of the studies included in qualitative analysis.
| Study | Attal et al. (2002) | Bainton et al. (1992) | Budd (1985) | Maier et al. (2002) | Rowbotham et al. (2003) | Yamamoto et al. (1991) | Yamamoto et al. (1997) | Saitoh et al. (2003) |
|---|---|---|---|---|---|---|---|---|
| Primary outcomes | First phase: spontaneous pain = ongoing pain intensity (VAS); evoked pain = intensity of allodynia (VAS); intensity of mechanical pain (VAS); intensity of thermal pain (VAS) Second phase: mean pain intensity (VAS) | Pain intensity (VAS and 5 – word pain score) assessed immediately after the injection | Changes in pain state (direct questioning) | Pain intensity (NRS) Pain tolerability (VRS) Rate and intensity of adverse effects (VRS) | Daily pain intensity (VAS) Pain relief (NRS) | Pain assessed through a visual analog scale | Pain assessed through a visual analog scale | Pain assessed through a visual analog scale and the McGill Pain Questionnaire |
| Secondary outcomes | Global assessment of pain relief (complete, a lot, moderate, slight, none, or worse pain) Reports of side effects (direct questioning) | Long-term pain intensity reduction (VAS) | Pain relief duration | Sleep quality (VRS) Physical fitness and endurance (NRS) Pain disability index (NRS) Mental state and mood (NRS) Depression (DS) Intensity of symptoms (SC-S) | Mood disturbances (PMS) Quality of life (MPI) Cognitive functioning (SDMT) Symptoms related to agonist and antagonist activity (OAES; OWS) Number of capsules/day Blood levorphanol levels | NA | NA | NA |
| Results | a First phase: morphine significantly reduced dynamic mechanical allodynia (in 9 patients reduction of 50% of pain intensity - VAS) respect to placebo; no significant differences on ongoing pain intensity between morphine and placebo a Second phase: 3 patients out of 15 still took oral morphine after one year follow-up, reporting a 50–70% reduction of mean pain intensity measured with VAS | Inconsistent effects of naloxone compared to placebo on pain intensity reduction: mean ±SE of VAS for naloxone (− 9.35 ± 4.86) vs saline (− 10.05 ± 4.99) Pain relief obtained either with naloxone or placebo was not maintained beyond one day after the injection | 7 patients experienced analgesia within 5 min of the completion of naloxone administration lasting from 4 days to 2 and a half years | 2 CPSP patients were classified as partial responders ( a mean pain intensity from 7.8 to 5.6 after morphine; tolerable side effects) a Pain intensity reduction correlated with improvement of physical function a Other secondary outcomes measures did not show significant improvement after morphine treatment compared to placebo |
a
Pain reduction from baseline (high-strength 23 mm vs low-strength 14 mm VAS)
a
66% patients under high-strength treatment reported pain relief a No significant changes in total mood disturbance in either treatment group a No significant changes in quality of life measures in either treatment group a No significant changes in cognitive functioning in either treatment group a Fewer capsules each day for the high-strength group compared to low-strength (11.9 ± 5.5 vs. 18.3 ± 4.3) a Mean blood levorphanol level closely mirrored the ratio of the actual levels of levorphanol intake in either treatment group |
Only 2 patients with thalamic or suprathalamic lesions were responding to morphine | 8 patients with CPSP were sensitive to morphine | 5 patients resulted responding to morphine |
| Drop – out rates | a First phase: None a Second phase: 60% of patients dropped out because of insufficient pain relief and/or side effects | NA | NA | a Only 1 patient dropped the trial | 7 out of 10 patients with CPSP dropped | NA | NA | NA |
| Adverse effects | a Nausea, somnolence, headache (mild, rapidly reversible) mainly for morphine administration (60% patients) a Somnolence after placebo (40% patients) | Slight side effects (i.e., rise in pulse rate, sweating, tremor, salivation, pain, nausea, faintness) either after naloxone | Slight transitory changes in heart rate (increase of 10–40 beats/min) | a Severe side effects (constipation, vomiting, nausea, sedation and micturition disturbances) occurred in 58% of patients under morphine and in 22% of patients under placebo, independently of dose | a Physical or psychological adverse events, treatment failure, lack of adherence | NS | Two patients reported an increase in pain with transient abnormal sensations and anxiety in the ketamine test | NS |
CPSP = Central Post-Stroke Pain; DS = Depression Scale; MPI = Multidimensional Pain Inventory; NA = not applicable; NaCl = sodium chloride; NRS = Numerical Rating Scale; NS = not specified; OAES = Opiate Agonist Effects Scale; OWS = Opiate Withdrawal Scale; PMS = Profile of Mood States; SC-S = Symptom Complaint Score; SDMT = Symbol Digit Modalities Test; VAS = Visual Analogue Scale; VRS = Visual Rating Scale.
a
Considering the whole sample (no separation between patients with CPSP and those with other types of pain).