Evaluation of multi-dimensional pain scales.
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Humans↗
Biomedical subjects
Richard H Gracely
Publications and source records attributed to Richard H Gracely.
Painful neuropathy: altered central processing maintained dynamically by peripheral input.
We performed sensory assessments before and during diagnostic tourniquet-cuff and local anesthetic blocks in 4 patients diagnosed with reflex sympathetic dystrophy (RSD). All patients complained of mechano-allodynia; lightly touching the skin evoked an intense pain sensation. At detection levels, electrical stimuli were perceived as painful, suggesting that the mechano-allodynia was mediated by A beta low-threshold mechanoreceptor afferents. A beta-mediated allodynia was further supported by reaction time latencies to painful electrical stimuli at threshold for A-fiber activation and, in 1 patient, by differential cuff blocks which abolished A beta function and allodynia while thermal sensation (warm and cold) were preserved. Local anesthetic block of painful foci associated with previous trauma abolished mechano-allodynia, cold allodynia, and spontaneous pain in all patients and relieved the motor symptoms in 1 patient with tonic contractures of the toes. Tactile and thermal perception in the previously allodynic area was preserved. When the local anesthetic block waned, spontaneous pain, allodynia, and motor symptoms returned. We propose a model of neuropathic pain in which ongoing nociceptive afferent input from a peripheral focus dynamically maintains altered central processing that accounts for allodynia, spontaneous pain, and other sensory and motor abnormalities. Blocking the peripheral input causes the central processing to revert to normal, abolishing the symptoms for the duration of the block. The model accounts for sympathetically maintained (SMP) and sympathetically independent (SIP) pain. The peripheral input can be independent of sympathetic activity or driven completely or in part by activity in sympathetic efferents or by circulating catecholamines. The shared final common pathway may explain the common features of SMP and SIP.
Adult↗
Efficacy of desipramine in painful diabetic neuropathy: a placebo-controlled trial.
Although amitriptyline relieves pain in many patients with painful diabetic neuropathy, side effects often preclude effective treatment. Desipramine has the least anticholinergic and sedative effects of the first generation tricyclic antidepressants. We compared a 6 week course of desipramine (mean dose, 201 mg/day) to active placebo in 20 patients with painful diabetic neuropathy in a double-blind crossover trial. Pain relief with desipramine was statistically significant in weeks 5 and 6. Eleven patients reported at least moderate relief with desipramine, compared to 2 with placebo. Pain relief tended to be greater in depressed patients, but relief was also observed in patients who did not show an antidepressant effect. We conclude that desipramine relieves pain in many patients with painful diabetic neuropathy, offering an alternative for patients unable to tolerate amitriptyline. Blockade of norepinephrine reuptake, an action shared by desipramine, amitriptyline, and other antidepressants proven effective in neuropathic pain, may mediate this analgesic effect.
Adult↗
The Descriptor Differential Scale: applying psychophysical principles to clinical pain assessment.
The Descriptor Differential Scale (DDS) applies psychophysical principles to clinical pain assessment. It contains 12 descriptor items for each pain dimension assessed. For each item, subjects indicate if their pain either is equal in magnitude to that implied by the anchoring descriptor, or how much greater or lesser on a 10-point graphic scale. The method permits collection of multiple responses, reducing scaling error, and assess both pain magnitude and scaling consistency. Ninety-one patients completed the sensory intensity and unpleasantness forms of the DDS at both 1 and 2 h after surgical extraction of a lower third molar. Results show that the DDS satisfies standard psychometric criteria for reliability, objectivity and item homogeneity. The coefficients found satisfy standard psychometric criteria and improve after elimination of inconsistent profiles.
Adolescent↗
Reliability and validity of verbal descriptor scales of painfulness.
Previous studies have provided information about the reliability and validity of verbal descriptor scales of sensory intensity and unpleasantness and have shown that these two dimensions can be differentially affected by pharmacological manipulations. Since the relation between these dimensions and the general term 'pain' is not known, two experiments developed a verbal descriptor scale of painfulness and compared the sensitivity of this scale to pharmacological manipulations used previously with scales of sensory intensity and unpleasantness. In exp. I, 20 subjects used cross-modality matching to both handgrip force and tone duration to quantify the amount of pain implied by verbal descriptor phrases such as 'slightly painful,' 'somewhat painful' and 'very painful.' Ratio scales of relative magnitude for each individual were highly correlated within subjects (mean r = 0.92) and between a scale from each individual and a combined scale from others in the group (mean r = 0.93). These correlations indicate agreement between individual scales; an individual's scale values were predicted equally well by that individual or by a group of similar persons. In exp. II, 4 groups of 10 subjects rated the magnitude of painful tooth pulp sensations by choosing pain descriptors from randomized lists. Seven electrical stimuli spaced between individually determined pain threshold and tolerance values were delivered in random sequence 6 times before and after double-blind intravenous infusions of placebo, 0.11 mg/kg diazepam, 0.66 microgram/kg fentanyl or a combination of the diazepam and fentanyl doses. Mean responses were reduced significantly after all active drugs but not after placebo. These results suggest that the term pain does not represent a simple combination of sensory intensity and/or unpleasantness and shows that the sensitivity to an inert placebo, an active placebo, and an analgesic can vary with the type of pain assessment procedure.
Adolescent↗
Ratio scales of sensory and affective verbal pain descriptors.
The results of two experiments show that ratio scales of sensory and affective verbal pain descriptors are valid, reliable and objective. In the first experiment, 16 subjects rated 15 sensory and 15 affective verbal pain descriptors by numerical magnitude estimation and by cross-modality matching to handgrip force. Ratio scales of sensory and affective verbal pain descriptors computed for two separate groups were highly correlated between the groups (sensory, r = 0.97; affective, r = 0.98), as well as over session (r = 0.99, 0.98). Scales based on an individual's data correlated equally with either another set of scales from the same individual (r = 0.96, 0.98) or a mean scale from a similar group (r = 0.96, 0.89). Sensory and affective verbal descriptor scales from the first experiment correlated highly (r = 0.99, 0.99) with those from the second experiment in which 40 subjects rated verbal pain descriptors by cross-modality matching to time duration and to handgrip force. The ratio responses to the verbal descriptors in both experiments demonstrated specific functional relationships found for measurable psychophysical stimuli. This result supports the validity of cross-modality matched ratio scales of verbal stimuli. The reliability of these scales is shown by the high between-session, between-group and between-experiment correlations. The objectivity is shown by the similarity of within-subject and between-subject correlations for both group and individual descriptor scales.
Adolescent↗
Validity and sensitivity of ratio scales of sensory and affective verbal pain descriptors: manipulation of affect by diazepam.
The results of two experiments suggest that sensory and affective verbal descriptors provide a valid scaling method which discriminates between the sensory intensity and the affect, or unpleasantness, of electrocutaneous stimuli. Twenty-four subjects judged the sensory intensity and affect of noxious electrocutaneous stimuli by choosing verbal descriptors from randomized lists and by cross-modality matching to time duration and to handgrip force. The psychophysical functions for sensory intensity generated by the descriptor and the cross-modality functions for sensory intensity generated by the descriptor and the cross-modality methods are the same. Psychophysical functions for affect generated by thedescriptor and the cross-modality methods are different. However, only the descriptor method produces psychophysical functions for affect that are significantly different from all the sensory functions. This result suggest that only the descriptor method distinguishes between sensory intensity and affect. The discriminative power of the descriptor method is demonstrated further in an experiment in which 32 subjects rated either the sensory intensity or the affect of the electrocutaneous stimuli immediately before and after an i.v. administration of 5 mg diazepam. This common minor tranquilizer significantly lowered affective descriptor responses (P less than 0.005) without altering sensory descriptor and sensory and affective handgrip responses. These experiments indicate that sensory and affective verbal pain descriptors may be used as a valid and sensitive tool for the evaluation of pain and pain control methods.
Adolescent↗
Peripheral suppression of first pain and central summation of second pain evoked by noxious heat pulses.
Psychophysical experiments were carried out on 6 huma subjects to determine how first and second pain are influenced by peripheral receptor mechanisms and by central nervous system inhibitory and facilitatory mechanisms. For these experiments, brief natural painful stimuli delivered to the hand were a train of 4-8 constant waveform heat pulses generated by a contact thermode (peak temp. = 51-5% C). The magnitude of first and second pain sensations was estimated using cross-modality matching procedures and reaction times were determined. The latter confirmed the relationship between first and second pain and impulse conduction in Adelta and C noxious heat afferents, respectively. The intensity of first pain decreased with each successive heat pulse when the interpulse interval was 80 sec or less. This decrease was most likely the result of heat induced suppression of Adelta heat nociceptors since it did not occur if the probe location changed between successive heat pulses. In contrast, second pain increased in intensity with each successive heat pulse if the interval was 3 sec or less. This summation was most likely due to central nervous system summation mechanisms since it also occurred after blockage of first pain by ulnar nerve compression and when the location of the thermode changed between heat pulses. These observations and their interpretations are supported by our recording of responses of singlt Adelta heat nociceptive afferents, C polymodal nociceptive afferents, and "warm" afferents of rhsus monkeys to similar trains of noxious heat pulses. Their responses to these heat pulses show a progressive suppression. Furthermore, previous studies have shown that wide dynamic range dorsal horn neurons show summated responses to repeated volleys in C fibers (greater than 1/3 sec). These spinal cord summation mechanisms could account for the summation of second pain.
Adult↗