Ronald J. Ignelzi

Measurement of pain: patient preference does not confound pain measurement.

Abstract Chronic pain patients reported pain intensity on each of 3 pain intensity scales, the visual analog, numerical and adjectival scales, and then ranked the scales in order of perceived best communication of pain intensity. All patients were able to complete an adjectival scale but 11% were unable to complete a visual analog scale and 2% failed at a numeric scale. The intensity of the pain ratings on the 3 scales were significantly correlated and there were no reliable differences in reported intensity as a function of preference. Pain intensity was reliably higher on each scale for depressed‐anxious patients as compared to non‐depressed/non‐anxious patients. Patients completing all 3 scales indicated a significant preference for the adjectival scale but the basis for this preference did not appear related to sex, etiology of pain, affective variables nor selected psychological variables. These data indicate that pain scale preference does not influence pain intensity report. Nevertheless, there are some clinical situations in which a numeric scale is likely to yield a better measure of pain intensity.

Pain measurement: The affective dimensional measure of the McGill pain questionnaire with a cancer pain population☆

Abstract Two experiments used the McGill Pain Questionnaire (MPQ) to examine the affective dimension of pain in patients whose pain was secondary to malignancy. In experiment I, segregating groups of cancer patients on the basis of extreme scores (high versus low) on the MPQ failed to produce segregation on independent measures of affect and infirmity. This outcome contrasts with earlier work with chronic benign pain patients. Experiment II compared cancer pain patients matched with benign pain patients on intensity of pain report on the affective dimension of the MPQ. Cancer pain patients reported a reliably higher affective loading to their pain. These data suggest that cancer pain patients employ different criteria than benign pain patients in selecting affective pain descriptors. Possible explanations for this difference are discussed.

Transcutaneous electrical analgesia: A follow-up analysis

&NA; One year follow‐up data are analyzed for the effects of using transcutaneous neurostimulators on patients with chronic benign pain. Those who have successful surgery for pain relief have lower pain and analgesic intake levels than those who supplement their surgery with neurostimulation. Those who do not receive surgery for pain but use neurostimulators have greatly increased activity levels than those who do not use these devices. The neurostimulators lower the clinical pain level component of the tourniquet test score for non‐surgery patients to a degree comparable to that of patients with successful surgical outcomes, but maximum pain tolerance is not significantly altered. This supports the hypothesis that the analgesic effect is primarily a peripheral one.

Repetitive Electrical Stimulation of Peripheral Nerve and Spinal Cord Activity

Spinal cord neuron and dorsal column fiber responses to electrical stimulation of the sciatic nerve in anesthetized cats were recorded before, during, and after periods of repetitive electrical stimulation of the sciatic nerve through an implantable nerve cuff stimulator device of the type and method used in human patients for pain relief. In previous publications from this laboratory using similar experimental conditions, we reported that repetitive electrical stimulation of the peripheral nerve suppressed all components of the compound action potential of nerves. The present study confirms that 5 percent of the spinal cord units studied showed facilitated discharge, 46 percent showed inhibited or depressed discharge, 36 percent underwent no change, and 13 percent showed equivocal responses to repetitive electrical stimulation. Inhibition of dorsal column fiber activity following repetitive electrical stimulation of peripheral nerve is not consistent with the Melzack-Wall gate hypothesis in which suppression of small fiber nociceptive input is mediated by large fiber activity. Our work suggests that the most commonly observed effect of electroanalgesia is to cause a more diffuse depression of nociceptive as well as nonnociceptive spinal cord activity.

Pain and Its ModulationPart 2. Efferent Mechanisms

Recent studies of central nervous system effects on pain and on its efferent modulation have created new theories and have led to direct clinical applications that may in time eclipse more classical interventions. In this review electrical stimulation analgesia is presented as a paradigm of how basic science work has been applied clinically to produce some of the most exciting advances in recent years in the treatment of chronic pain. Opiate receptors and analgesia are presented in relationship to the descending inhibitory systems used in electroanalgesia. Neuromodulators and neurotransmitters important in pain modulation through complex inhibitory and excitatory pathways are discussed, with the roles of B-endorphin, enkephalin, serotonin, and other important biogenic amines being stressed. The neuropharmacology of pain as it is currently understood clinically suggests that psychotropic interventions may be quite useful in treating difficult pain problems.

Observations on fast axoplasmic transport in peripheral nerve following repetitive electrical stimulation

&NA; In a series of 13 cats the effect of electrical stimulation of peripheral nerve on the mechanism of fast axoplasmic transport was studied. Electrical stimulation was used for varying time periods at parameters reported in the range of those used to produce electroanalgesia in man. Our results indicate that at these parameters, electrical stimulation produced no effect on this important aspect of nerve function, and, therefore, our work lends support to the safety of these devices in pain states.

An Analysis of the Nuclear Sodium Content of Human Normal GLIA as Well as Tumors Of Glial and Nonglial Origin

Normal human brain nuclei and nuclei obtained from glioblastoma, as well as other primary brain and metastatic tumors, were analyzed for their sodium content. The greatest concentration of sodium was found in glial tumor nuclei with lesser amounts in normal glial nuclei and least amounts in nuclei from nonglial tumors. This data supports our hypothesis that glial nuclei sequester brain sodium and also suggests that sodium in the nucleus may be important in glial mitogenesis.

Sodium, Potassium, and Metabolic Studies of Glial, Liver, and Kidney Nuclei Under Anoxic-Ischemic Conditions

Glial, liver, and kidney nuclei were studied under anoxic-ischemic conditions. It was found that glial nuclei were significantly depleted of sodium and potassium as early as 15 seconds after the insult, whereas liver and kidney nuclei were not. There was a concomitant significant drop in high-energy substrates (ATP, P-creatine, glucose) in both glial and brain homogenate, whereas these substrates remained relatively constant in kidney and began to drop only at the four-minute time point in liver. These unique observations in glial nuclei may have important implications in the glial swelling that is seen in ischemic states.

Light element abundance in brain nuclei using energy dispersive x-ray analysis and atomic absorption spectrophotometry.

A comparative study of light element (congruent to ion) abundance in isolated brain nuclei, using atomic absorption (AA) spectrophotometry and the scanning electron microscope mode of energy dispersive x-ray analysis (EDXA), demonstrated similar statistical trends in the abundance of Na, Mg, and K at 0 time and at 4 min of total brain ischemia. The obtained correlation strengthens the validity of the comparison of quantitative and semi-quantitative procedures. The EDXA technique represents a new approach to the study of ionic shifts in brain ischemia that may prove useful in other areas of brain research as well.