John M. Gregg

Acupuncture and chronic pain mechanisms.

&NA; Forty patients with chronic pain below the waist level not amenable to conventional medical and/or surgical treatment were randomly assigned to one of two different methods of acupuncture, after studying the underlying pain mechanisms using a Multidisciplinary Pain Clinic approach and the differential spinal block (DSB). One group received acupuncture needling in the classical acupuncture points referred to as meridian loci needling (MLN) and the other group received tender area needling (TAN) with needles inserted in the dermatomal distribution of the painful areas. The responses between the two groups showed no significant difference. Results were then related to the predetermined somatopsychological basis of the individuals pain problems as classified by the DSB. A group of patients in whom pain relief occurred upon subarachnoid injection of 0.25% procaine followed by sympathetic blockade or 0.5% procaine injection followed by hypalgesia without motor loss, also reported maximum subjective improvement in their pain level following acupuncture therapy performed at a later time. The other group of patients in whom pain persisted despite sensory and motor blockade (1% procaine) responded very poorly to acupuncture therapy. DSB was found to be complimentary to acupuncture therapy in that it facilitated patient selection for the therapy.

The effects of psychological factors and physical trauma on recovery from oral surgery

This study evaluated the effects of several psychological factors on postsurgical recovery while controlling for and also evaluating the effects of the physical trauma induced by the surgery. Subjects were 38 patients (18 males and 20 females) who were scheduled to have four third molars surgically removed. The psychological factors measured included anxiety and expectations about recovery, trait anxiety, coping behaviors, and health locus of control. Surgical trauma was rated after surgery, and the following aspects of recovery were monitored: postoperative pain, interference with normal function, swelling, and healing. Poorer postoperative recovery was significantly predicted by each of the psychological variables and by higher levels of surgical trauma. In addition, the effects of the psychological variables on recovery were shown to be largely independent of the trauma effects. The data suggest that (a) future studies which give patients more positive expectations and reduce their anxiety about recovery may improve their recovery and (b) the types of patients most in need of preoperative psychological support would be those who have higher trait anxiety, vigilant coping behaviors, or an internal locus of control.

Effects of intravenous tetrahydrocannabinol on experimental and surgical pain; Psychological correlates of the analgesic response

Two intravenous doses of tetrahydrocannabinol (THC) (0.022 mg/kg and 0.044 mg/kg) were compared to intravenous diazepam (0.157 mg/kg) and to placebo (Ringers lactate) as premedication for dental extraction in 10 healthy volunteers. Pain detection and tolerance thresholds were measured and psychiatric interviews were supplemented by Minnesota Multiphasic Personality Inventories (MMPI), the Zung Depression Scale (ZDS), Beck Depression Inventories (BDI), and the State‐Trait Anxiety Inventory (STAI). Pain detection thresholds were altered unpredictably with high THC doses, but analgesia as indicated by pain tolerance was less than that after diazepam and placebo. In three subjects low‐dose THC (0.022 mg/kg) was a better analgesic than placebo but not diazepam. Six subjects preferred placebo to low‐dose THC as an analgesic; this group experienced increases in subjective surgical pain and were submissive, rigid, and less introspective with high State Anxiety and MMPI profiles that differed from subjects whose pain was not increased. STAI following THC presaged a poor analgesic response in this group.

The Effect of Delta-9-Tetrahydrocannabinol on Intraocular Pressure in Humans

As early as 1971, it was noted that smoking marijuana lowered intraocular pressure. In this study one of the active components of marijuana, delta-9-tetrahydrocannabinol, was given intravenously to ten subjects with normal intraocular pressures. Two strengths were used—0.022 mg/kg of body weight and 0.044 mg/kg of body weight. Intraocular pressure was found to decrease as much as 51% of baseline normal with an average decrease of 37%. Heart rate increased in a range of 22% to 65% of the resting pulse. Respiratory rate was not affected. No analgesic properties were demonstrated by either cutaneous or periosteal stimulation. Anxiety levels were increased by delta-9-tetrahydrocannabinol over placebo and diazepam (Valium). The mechanism of action is still uncertain but it is believed by some workers to be similar to that of a beta-adrenergic stimulator.

High versus low intensity acupuncture analgesia for treatment of chronic pain: Effects on platelet serotonin

&NA; The 26 chronic pain patients were tested in a baseline plus cross‐over design. Half of the subjects were first treated with high intensity acupuncture; then they were treated with low intensity acupuncture. For the other 13 subjects the treatment order was reversed. In the first treatment sequence subjects reported lower pain estimates and engaging in more activities of daily living during treatment with high intensity acupuncture — but not with low intensity acupuncture. In addition, under high intensity acupuncture (i.e. with low pain levels), subjects had higher levels of platelet serotonin; this last finding is consistent with recent research which implicates central serotonin in pain control. The results of the second treatment sequence were ambiguous.

Myofascial pain of the temporomandibular joint: A review of the behavioral-relaxation therapies

&NA; This paper reviews the behavioral‐relaxation treatments of myofascial pain‐dysfunction syndrome. The evidence indicates that this pain (located around the oral cavity) is due to muscle hyperactivity, most commonly of the lateral pterygoids. Research concerning relaxation techniques (i.e. progressive muscle relaxation and electromyographic feedback) has indicated the following: (a) in analogue research, normal healthy controls can learn to relax their muscles of mastication profoundly even during stress, and (b) in case reports, relaxation treatments are helpful clinical interventions, especially for pain patients who are not depressed, and who have not had the pain for more than a few years. Well controlled research is the next, essential step.

Acupuncture and chronic pain mechanisms: The moderating effects of affect, personality, and stress on response to treatment

&NA; The present study, part of a larger project investigating neurophysiological and psychosocial factors affecting response to acupuncture for chronic pain, compares responders and non‐responders to acupuncture on a series of variables assessing personality, affect and stress. Subjects were 40 patients with pain beneath the waist level longer than 6 months duration selected from the roles of the Multidisciplinary Pain Clinic. Responders, defined as 50% or more reduction in pain estimate for greater than two weeks, were found to be less depressed, less passive and overly conventional, have shorter duration of pain, endorse less frequent exposure to stressors, and have less serious non pain‐related illnesses. The findings are viewed as linking the intractability of pain states with psychosocial factors which may directly interfere with response to somatic modes of therapy or which may interfere via alterations of tonic neurohumoral factors. The study also is seen as supporting the importance of considering psychological variables in evaluating patients for pain treatment strategies and suggests inclusion of such variables in investigating response to other modalities of treatment for chronic pain.

The pain profile: a computerized system for assessment of chronic pain

&NA; A computer‐based system to assess and quantify three components of the chronic pain experience is described. The system produces a Pain Profile and classification for each patient based on a mathematical comparison of the pathophysiologic, psychological and behavioral aspects of chronic pain. This computer‐based evaluation assists the researcher in analyzing the relative importance of the chronic pain components and helps direct the clinician to the appropriate emphasis of therapy.

Radiofrequency thermoneurolysis of peripheral nerves for control of trigeminal neuralgia

&NA; Radiofrequency thermoneurolysis (RFTN) was performed in the peripheral infraorbital and inferior alveolar nerves of eight patients with paroxysmal trigeminal neuralgias. Pain severity as measured by tourniquet test and global estimate was significantly reduced in seven of eight patients. The sharp, paroxysmal component of neuralgia was controlled in all seven successes although significant pain was recurring in two patients one year post‐operatively. Neurosensory threshold responses to tactile‐discriminative stimuli were not permanently changed from pre‐lesion levels but pain detection and pain tolerance threshold responses to mechanical pin‐pressure and thermal stimuli were significantly raised, suggesting that RFTN is more selective for small myelinated and unmyelinated fibers. This procedure was found to be safe, effective, simple, and predictable on the basis of diagnostic blocks. Results suggest that it is a temporary control measure which nevertheless can be repeated. It may also prove useful as a test to identify those patients who may experience anesthesia dolorosa. It is suggested for patients with toxic responses to medical therapy and as an alternative to more invasive surgeries for the long‐term management of trigeminal neuralgia.

Towards an understanding of chronic pain mechanisms: the use of psychologic tests and a refined differential spinal block.

Forty patients with chronic pain below the waist level were evaluated in a multidisciplinary pain clinic using a refined differential spinal block (DSB) technique. The refinements consisted of verbal instructions to prevent biasing the patients, coupled with a thorough evaluation of verbal and physiologic responses to the block. When demographic and psychologic data were assessed according to pain mechanisms, a pattern of patient groups emerged along a chronic pain continuum. Stress, anxiety, depression, and hysteria, as well as the neurophysiologic and demographic factors, modified the responses to the block. Long-term follow-up of these patients, including repeat DSB procedures and confirmatory anatomic blocks of sympathetic and somatic nerves, validated these impressions. The findings indicate a link between pain mechanisms and psychosocial factors that may directly influence responses to DSB.