Predicting outcome of chronic pain treatment via a modified self-efficacy scale.

This study utilized a modified self-efficacy scale and examined the relationship of perceived self-efficacy to treatment outcome in a chronic, intractable, benign pain population (N = 62). In two separate studies a self-efficacy scale was given to inpatients in a combined cognitive-behavioral and medical treatment program. The scale categories consisted of (1) walking distance, (2) lifting ability, (3) pain coping, (4) working ability, and (5) social and recreational engagement. Self-efficacy beliefs were found to be associated with the level of functioning of these patients and their response to treatment. Patients with higher self-efficacy scores following treatment rated themselves as more improved and demonstrated better overall functioning with greater reductions in chronic illness behavior at followup. These observations support the merits of self-efficacy measures as predictors of treatment outcome in chronic pain patients.

Peak B endorphin concentration in cerebrospinal fluid: reduced in chronic pain patients and increased during the placebo response.

The level of an endogenous opioid (peak B endorphin) was measured in chromatographically fractionated cerebrospinal fluid (CSF) sampled from two groups of chronic pain patients before and after intrathecal saline (placebo) injection. As assessed by a verbal rating scale, one group reported no change in their level of pain (non-responders, NR; n = 6) while the other group reported complete or greater than 50% pain relief (placebo responders, PR; n = 14). We find, as has been reported previously, that initial peak B levels were lower (by 50%) in these chronic pain patients' CSF than in CSF from pain-free (PF) normal controls (P less than 0.001, t-test). Peak B levels measured from CSF of the NR group undergoing this procedure did not change (P greater than 0.4, paired t-test). In contrast, a significant 2.3-fold increase was measured in the CSF peak B level of the PR group (P less than 0.05, paired t-test). This is the first direct evidence that a CSF opioid is correlated with placebo pain relief in chronic pain patients. Peak B is a potent analgesic substance when administered by the intracerebroventricular route in mice and its level is related to the patients' pain status in a presumably causal manner.

Morphine tolerance is associated with elevated levels of an uncharacterized endorphin (peak B) in mouse brain with no change in 3H-dihydromorphine binding.

A partially characterized mouse brain endorphin was shown to be elevated (p 0.01 U-Test) in ICR strain mice that had been made tolerant but not dependent upon morphine (5 mg/kg sc., given for 32 days). The animals were tolerant to the antinociceptive effect of morphine as judged by the tail immersion assay (48 degrees C) but showed no detectable dependence or withdrawal syndrome effects following the administration of naloxone (writhing, jumping, diarrhea or hypermotility) on day 33. No significant changes were seen in any other mouse brain endorphins (p 0.05 U-Test). Also there was no apparent change in the number of binding properties of 3H-dihydromorphine (3H-DHM) receptors (mu-receptors) in chronic morphine (CM) treated, as compared with chronic saline (CS) treated animals.

Relief of postlaminectomy syndrome in selected patients by injection of autogenous cerebrospinal fluid.

We have been using the differential spinal block to study patients referred to our Pain Clinic for treatment of their chronic pain syndromes. In a selected group of chronic-pain patients from whom cerebrospinal fluid (CSF) could not be obtained at the L4 or L5 interspace, administration of autogenous CSF obtained at a higher interspace gave immediate and complete but temporary pain relief. Endorphins were present in these autogenous CSF samples. These studies, indicating that CSF even from chronic-pain patients contains analgesic substances (possibly endorphins), may point to new treatment modalities for certain chronic back pain syndromes.

Comparison of butorphanol and pentazocine as postoperative analgesics.

Sixty patients with moderate or severe postsurgical pain were randomly divided into three equal groups for a double-blind comparison of the analgesic effectiveness of intramuscular butorphanol (2 and 4 mg) and pentazocine (60 mg). The groups were demographically similar. Pain intensity and pain relief were scored at 10, 20, 30, 60, 120, 180, and 240 minutes after administration of the drug. All treatments provided significant analgesic activity (P less than .05) within ten minutes. However, both doses of butorphanol reached their peak effect at 30 minutes, in contrast to 60 minutes for pentazocine. The duration of effect appeared somewhat longer for butorphanol, though this did not achieve statistical significance. Butorphanol (4 mg) had a significantly greater (P less than .05) analgesic effect at ten minutes than pentazocine (60 mg), and both butorphanol treatments (2 and 4 mg) were significantly better than pentazocine, according to many parameters at 20 and 30 minutes. Side effects, chiefly sleepiness and dizziness, were seen in 15% of the patients, with no significant difference between the treatment groups.

Renal tubular site of action of fluoride in Fischer 344 rats.

Methoxyflurane is capable of producing high-output renal failure in some patients and animal models, probably through metabolic liberation of free fluoride. The tubular site of action of fluoride was examined in Fischer 344 rats using clearance techniques. Free water reabsorption (TCH2O) and free water excretion (CH2O) were measured during mannitol or water diuresis in control rats and in rats given methoxyflurane or pretreated with sodium fluoride. Pretreatment produced statistically significant increases in urinary flow (from 10.5 +/- 1.4 to 20.1 +/- 1.9 mul/min/100 g b. wt.), in glomerular filtration rate (from 814 +/- 31 to 1,039 +/- 53 mul/min/100 g b. wt.), in per cent sodium excretion (from 0.107 +/- 0.008 to 0.155 +/- 0.015 per cent), and in per cent water excretion (from 1.27 +/- 0.15 to 2.00 +/- 0.20 per cent). Free water excretion remained relatively unaltered in rats pretreated with fluoride, perhaps due to elevated glomerular filtration rate and/or reduced proximal tubular reabsorption combined with inhibition of reabsorption in the ascending loop. Percentage free water reabsorption, on the other hand, was markedly reduced by the pretreatment, from 2.66 +/- 0.21 to 0.66 +/- 0.09 per cent. The observations are consistent with the hypothesis that fluoride inhibits tubular reabsorption primarily in the medullary portion of the ascending limb of Henle's loop, perhaps by inhibition of an active chloride pump located in this nephron segment.

Sickling dynamics of red blood cells and other physiologic studies during anesthesia.

Nineteen patients with electrophoretically proven sickle cell diseases were studied prospectively at intervals, using halothane, methoxyflurane, cyclopropane, and fluroxene. Simultaneous venous and arterial samples were taken from the same arm in heparinized syringes at the sampling intervals and analyzed for blood gases, hematocrit, and percent sickle cells. Measurements of blood pressure, pulse, temperature, tidal volume, minute ventilation, and other significant data were recorded. There were no anesthetic deaths, and the morbidity seen was an extension of pre-existing pathology. Sickling was found to be greatly reduced in both arterial and venous blood during anesthesia, with the greater reduction in venous blood. Following anesthesia, sickling returned toward, but often did not reach, pre-anesthetic levels. Blood-gas measurements reflected the slightly increased ventilation and considerably increased inspired oxygen during anesthesia. Other measurements were not remarkable.