(293) Central sensitization, chronic pain syndromes, and pregabalin

(293) Central sensitization, chronic pain syndromes, and pregabalin

Abstracts (292) Treatment effects on changes in pain and changes in sleep: Pregabalin (lyrica) in fibromyalgia patients I Russell, L Pauer, E Whalen, ...

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Abstracts (292) Treatment effects on changes in pain and changes in sleep: Pregabalin (lyrica) in fibromyalgia patients I Russell, L Pauer, E Whalen, J Barrett; University of Texas Health Science Center, San Antonio, TX Chronic pain and related sleep disturbance is prominent in patients with FM. Previous trials found pregabalin to be effective for treating pain and symptoms of disturbed sleep associated with FM. Here we explore the relationship between changes in pain and changes in sleep quality as measured on an 11 point numeric rating scale (NRS) and recorded in a daily sleep diary. These trials evaluated the relationship between pain and sleep quality in patients with chronic pain from FM. Patients meeting ACR criteria for FM for ⱖ3 months and who had pain VAS score ⱖ40 mm were followed for 8-14 weeks in 3 randomized, double-blind, placebo-controlled trials. A total of 2022 patients received either 150, 300, 450 or 600 mg/d pregabalin, or placebo after a 1-week baseline phase. The primary efficacy parameter was Endpoint Mean Pain Score (MPS) compared to baseline. Pearson correlations were used to explore relationships between changes in pain and changes in sleep. Pregabalin treatment at 300, 450 and 600 mg/d showed significant improvement in Endpoint MPS. Likewise, significant improvement was demonstrated for endpoint mean sleep quality across the pregabalin treatment groups. Correlations by treatment between changes in pain and sleep were as follows: 0.71 (placebo), 0.65 (150 mg/d), 0.73 (300 mg/d), 0.66 (450 mg/d) and 0.67 (600 mg/d). Adverse events were consistent with known side effects of pregabalin; dizziness and somnolence were the most frequently reported AEs for patients who received pregabalin and tended to resolve with treatment. Changes in pain correlated with changes in sleep quality across all treatments (including placebo) for patients with FM. Study funded by Pfizer, Inc.

P49 (294) Treatment for pain management and addiction J Rand, D Bergman; Bay Recovery Centers, San Diego, CA Society for Neuroscience abstract

(293) Central sensitization, chronic pain syndromes, and pregabalin

(295) Iliopsoas bursa injection for groin pain induced by weight loss therapy program

M Tuchman, E Durso-DeCruz, T Murphy, J Barrett; Pfizer Global Pharmaceuticals, New York, NY Central sensitization, as first described by Woolf in 1983,1 has been advanced as a contributing mechanism to physiologic and pathologic pain. Subsequent studies with intradermally or topically applied capsaicin have shown long-lasting secondary allodynia (ie, away from the sites of capsaicin application) resulting from changes in the CNS. This form of central sensitization has been hypothesized to be a product of sustained activation of unmyelinated C-fibers at their synaptic endings within the dorsal horn of the spinal cord. The release, by dense-core synaptic vesicles in C-fiber terminals within the dorsal horn, of glutamate and substance P appears to be required for central sensitization. The alpha 2-delta ligands, gabapentin (neurontin) and pregabalin (lyrica), both reduce release of glutamate from hyperexcited neurons, and Fehrenbacher demonstrated that gabapentin and pregabalin decrease the release of substance P after sensitization of the spinal cord. Studies with healthy volunteers suggest that gabapentin and pregabalin can reduce central sensitization following application of pain-inducing stimuli. Pregabalin has demonstrated robust efficacy as treatment of pain and sleep interference in 9 of 11 peripheral neuropathic pain trials (painful diabetic peripheral neuropathy or postherpetic neuralgia), 1 of 1 central neuropathic pain trial (spinal cord injury), and 4 of 4 fibromyalgia trials. We present pain-relief data from these studies of pregabalin that, taken together, are suggestive of 1) shared processes of central sensitization among these chronic pain syndromes and 2) the likelihood that pregabalin can be efficacious in other chronic pain syndromes that involve central sensitization. Supported by Pfizer Global Pharmaceuticals. (1. Woolf, Nature, 1983; 2. Fehrenbacher et al, Pain, 2003.)

M Johnson, P Nance; Long Beach Veteran’s Hospital, Long Beach, CA We present a case of iliopsoas bursitis/tendonitis originating from a course of physical therapy for weight loss and subsequently treated with psoas bursa injection with excellent relief. Patient X presented to the musculoskeletal pain clinic at Long Beach Veteran’s hospital complaining of severe left groin pain and moderate hip pain of several weeks duration which originated during a course of kinesiotherapy for weight loss. The patient’s pain was significant enough to limit his gait, mobility and ability to work. The patient related a history of using the stationary cycle during the course of KT and felt this modality had initiated his pain. His initial presentation was suspicious for hip fracture but this was ruled out on plain films. Physical examination was consistent with iliopsoas tendinitis/bursitis. An ilipsoas bursa injection was performed with 100% resolution of the patient’s groin pain which was maintained at one month post-injection. Groin pain is a common musculoskeletal complaint with a multitude of etiologies most frequently seen in younger active athletes. We present a case of groin pain in an older gentleman from iliopsoas bursitis/tendonitis originating from a prescribed course of KT for weight loss. Groin pain is most often attributed to the adductor muscles of the thigh or in older populations, bony hip pathology. In this case the patient acquired the bursitis/tendonitis from repetitive hip flexion on a stationary cycle. Iliopsoas bursa injection in this case was an extremely effective acute treatment modality utilized in light of the patient’s extremely pain-limited mobility and activity.