The Genesis of Pain Medicine as a Subspecialty in Anesthesiology.

Certification in pain medicine as a subspecialty in Anesthesiology was conceived in 1989 and first discussed by the American Board of Anesthesiology in 1990. Shortly thereafter, the ABA submitted an application to the American Board of Medical Specialties for recognition to certify in pain management. That was approved in 1991.

Pain tests provoke modality-specific cardiovascular responses in awake, unrestrained rats.

Nociception modulates heart rate (HR) and mean arterial pressure (MAP), suggesting their use of HR and MAP as indicators of pain in animals. We explored this with telemetric recording in unrestrained control and neuropathic (spinal nerve ligation) rats. Plantar stimulation was performed emulating techniques commonly used to measure pain, specifically brush stroke, von Frey fiber application, noxious pin stimulation, acetone for cooling, and radiant heating, while recording MAP, HR, and specific evoked somatomotor behaviors (none; simple withdrawal; or sustained lifting, shaking, and grooming representing hyperalgesia).

Depletion of calcium stores in injured sensory neurons: anatomic and functional correlates.

Background: Painful nerve injury leads to disrupted Ca signaling in primary sensory neurons, including decreased endoplasmic reticulum (ER) Ca storage. This study examines potential causes and functional consequences of Ca store limitation after injury.

Methods: Neurons were dissociated from axotomized fifth lumbar (L5) and the adjacent L4 dorsal root ganglia after L5 spinal nerve ligation that produced hyperalgesia, and they were compared to neurons from control animals.

Species and strain differences in rodent sciatic nerve anatomy: implications for studies of neuropathic pain.

Hindlimb pain models developed in rats have been transposed to mice, but assumed sciatic nerve neuroanatomic similarities have not been examined. We compared sciatic nerve structural organization in mouse strains (C57BL/6J, DBA/2J, and B6129PF2/J) and rat strains (Wistar, Brown Norway, and Sprague-Dawley). Dissection and retrograde labeling showed mouse sciatic nerve origins predominantly from the third lumbar (L3) and L4 spinal nerves, unlike the L4 and L5 in rats.

Permeability of injured and intact peripheral nerves and dorsal root ganglia.

Background: Nerve injury that produces behavioral changes of allodynia and hyperalgesia in animals is associated with electrophysiologic changes in dorsal root ganglion (DRG) cells. The introduction of drugs into the DRG or the peripheral nerve that alter calcium, sodium, or potassium channel activity may be of therapeutic benefit after nerve injury. For this reason, the authors sought to determine whether drugs that do not ordinarily cross the blood-nerve barrier will enter the DRG after intravenous or regional injection and to determine whether nerve injury alters drug access to DRGs or peripheral nerves.

Painful nerve injury decreases resting cytosolic calcium concentrations in sensory neurons of rats.

Background: Neuropathic pain is difficult to treat and poorly understood at the cellular level. Although cytoplasmic calcium ([Ca]c) critically regulates neuronal function, the effects of peripheral nerve injury on resting sensory neuronal [Ca]c are unknown.

Methods: Resting [Ca]c was determined by microfluorometry in Fura-2 AM-loaded neurons dissociated from dorsal root ganglia of animals with hyperalgesia to mechanical stimulation after spinal nerve ligation and section (SNL) at the fifth and sixth lumbar (L5 and L6) levels and from animals after skin incision alone (control group).

Intrathecal baclofen in pain management.

Baclofen is a GABA(B) agonist that is administered spinally via an implanted drug delivery device to treat spasticity. It has been shown to have powerful antinociceptive effects in experimental animal models at doses that produce little or no motor-blocking effects but has rarely been used as a spinal analgesic agent in patients without spasticity. Several studies have indicated that intrathecal baclofen provides relief of central pain in patients with spasticity.

Synovial cysts and the lithotomy position causing cauda equina syndrome.

We describe a case of cauda equina syndrome caused by synovial cysts and the lithotomy position. A transurethral resection of the prostate was performed under spinal anesthesia in the lithotomy position. We believe that this is the first case report of facet joint synovial cysts and the lithotomy position causing ischemic neurologic injury to the cauda equina.

Intrathecal baclofen: a useful agent in the treatment of well-established complex regional pain syndrome.

Background And Objectives: We present 2 case reports that illustrate that chronic intrathecal (IT) baclofen administration may be efficacious in treating patients with long-standing complex regional pain syndrome, type I (CRPS I) who have failed treatment with multiple drugs and procedures.

Case Reports: Both cases presented were women who developed CRPS I following multiple lower extremity surgeries. One patient had had symptoms for 5 years and had continued symptoms despite multiple sympathetic blocks, sympathectomy, spinal cord stimulation, and various medication trials.

Factors predicting short-term outcome of nerve blocks in the management of chronic pain.

In order to identify those chronic pain patients unlikely to improve from nerve blocks, preadmission questionnaires of 337 patients were studied and various pre-existing factors were analyzed against short term treatment results. Factors associated with significant reductions in treatment success (P less than 0.05) included: being injured at work, being out of work because of pain, receiving financial compensation, involvement in legal action, previous surgery for pain, long duration of pain, high pain severity ratings, frequent analgesic use and use of tranquilizers.