Locoregional Anesthesia of the Thoracic Limbs and Thorax in Small Animals.

The incorporation of nerve stimulation and ultrasound guidance to veterinary regional anesthesia allows accurate performance of techniques to block the thoracic limb and the thorax. When performed correctly, regional anesthesia can either constitute an alternative to the use of opioids and other systemic analgesics, or have a significant opioid-sparing effect. This article provides an overview of some techniques described using objective methods of nerve location, which can be used to provide perioperative locoregional anesthesia and analgesia to the thoracic limb and thorax. The approaches described may be used to decrease the perioperative use of opioids in small animals.

Regional anesthetic techniques for the thoracic limb and thorax in small animals: A review of the literature and technique description.

Veterinary regional anesthesia (RA) has been rapidly increasing in popularity over the last 10 years, as evidenced by the increasing amount of literature available and the continuous development of new techniques in small animals. The introduction of new technologies such as nerve stimulation and ultrasound (which increased the objectivity and precision of the procedure) and the promising beneficial perioperative effects conferred by RA are encouraging clinicians to incorporate these techniques in their daily perioperative anesthetic and analgesic animal care. However, there is a lack of consensus regarding outcomes when RA is used, as well as outcome comparisons between regional anesthetic techniques. Further large-scale clinical studies are still necessary. This article is the first part of a two-part review of RA in small animals, and its aim is to discuss the most relevant studies in the veterinary literature, where objective methods of nerve location have been used, and to illustrate in pictures the currently used techniques for providing RA to the thoracic limb and the thorax in small animals.

The effects of combined trunk and gluteal neuromuscular electrical stimulation on posture and tissue health in spinal cord injury.

OBJECTIVE: To investigate whether combined trunk and gluteal neuromuscular electrical stimulation (NMES) alters seated posture and improves pelvic tissue health in persons with a spinal cord injury. DESIGN: Intervention study; case series. SETTING: Research laboratory, medical center. PARTICIPANTS: Seven persons with spinal cord injury recruited from a group of experienced implanted lower extremity NMES system users. INTERVENTION: Combined trunk and gluteal NMES in the sitting position. Five minutes of preintervention sitting was assessed, followed by 5 minutes of NMES application, and then 5 minutes of postintervention. MAIN OUTCOME MEASURES: Pelvic tissue health was evaluated by concurrently measuring transcutaneous oxygen tension (TcPO2) bilaterally over the ischia and the seating interface pressure (IP). TcPO2 data were binned into low (<10 mm Hg), medium (10-30 mm Hg), and high (>30 mm Hg) ranges, and the percentage time that TcPO2 was in each range was calculated. Ischial and sacral regions of interest were defined and the maximum region of interest and mean IP were determined, together with the maximum IP gradient for the entire contact area. Initial seating postures varied; 4 persons were initially sacral sitters. Tissue health responses to NMES were reviewed for sacral and nonsacral sitters. RESULTS: For sacral sitters, the sacral region IP and the maximum IP gradient tended to decrease during NMES and increased again after the intervention. Mean ischial TcPO2 increased during NMES and remained elevated after the intervention, increasing high TcPO2 percentage time for 50% of the sacral sitters both during and after the intervention. Nonsacral sitters showed few changes in tissue health as the result of the application of NMES. CONCLUSIONS: Trunk and gluteal stimulation acutely corrects anterior/posterior IP distribution, improving regional tissue health for sacral sitters. This correction requires constant application of NMES. The potential for positive changes in tissue health would be maximized by regular NMES use incorporating weight shifting.

TRPV1 properties in thoracic dorsal root ganglia neurons are modulated by intraperitoneal capsaicin administration in the late phase of type-1 autoimmune diabetes.

Pharmacological therapies in type 1 diabetes for efficient control of glycemia and changes in pain alterations due to diabetic neuropathy are a continuous challenge. Transient receptor potential vanilloid type 1 (TRPV1) from dorsal root ganglia (DRG) neurons is one of the main pharmacological targets in diabetes, and its ligand capsaicin can be a promising compound for blood-glucose control. Our goal is to elucidate the effect of intraperitoneal (i.p.) capsaicin administration in type 1 diabetic mice against TRPV1 receptors from pancreatic DRG primary afferent neurons. A TCR(+/-)/Ins-HA(+/-) diabetic mice (dTg) was used, and patch-clamp and immunofluorescence microscopy measurements have been performed on thoracic T(9)-T(12) DRG neurons. Capsaicin (800 µg/kg, i.p. three successive days) administration in the late-phase diabetes reduces blood-glucose levels, partly reverses the TRPV1 current density and recovery time constant, without any effect on TRPV1 expression general pattern, in dTg mice. A TRPV1 hypoalgesia profile was observed in late-phase diabetes, which was partly reversed to normoalgesic profile upon capsaicin i.p. administration. According to the soma dimensions of the thoracic DRG neurons, a detailed analysis of the TRPV1 expression upon capsaicin i.p. treatment was done, and the proportion of large A-fiber neurons expressing TRPV1 increased in dTg capsaicin-treated mice. In conclusion, the benefits of low-dose capsaicin intraperitoneal treatment in late-phase type-1 diabetes should be further exploited.

Peripheral subcutaneous stimulation for the treatment of intractable postherpetic neuralgia: two case reports and literature review.

Postherpetic neuralgia (PHN) is a common cause of chronic pain in the elderly. Antidepressants, anticonvulsants, and opioids may reduce discomfort in many patients, while others have pain intractable to all forms of therapy. We present a novel treatment approach for intractable PHN utilizing percutaneous peripheral nerve stimulation. Two cases are described in which an 80-year-old man and a 67-year-old woman with intractable PHN, lasting 2 and 10 years, respectively, were effectively treated with implantation of two octapolar leads in the lateral thoracic region. These cases suggest that peripheral nerve stimulation may offer an alternative treatment option for intractable pain associated with PHN especially in the elderly where treatment options are limited because of existing comorbidities.

Can classical acupuncture points and trigger points be compared in the treatment of pain disorders? Birch's analysis revisited.

BACKGROUND: A 1977 study by Melzack et al. reported 100% anatomic and 71% clinical pain correspondences of myofascial trigger points and classical acupuncture points in the treatment of pain disorders. A reanalysis of this study's data using different acupuncture resources by Birch a quarter century later concluded that correlating trigger points to classical acupuncture points was not conceptually possible and that the only class of acupuncture points that could were the a shi points. Moreover, Birch concluded that no more than 40% of the acupuncture points examined by Melzack et al. correlated clinically for the treatment of pain (correlation was more like 18%-19%). OBJECTIVE: To examine Birch's claims that myofascial trigger points cannot conceptually be compared to classical acupuncture points and that most (at least 60%) of the classical acupuncture points examined by the study of Melzack et al. are not recommended for treating pain conditions, negating their findings of a 71% clinical pain correspondence of trigger points and acupuncture points. METHODS: Acupuncture references and literature were reviewed to examine the validity of the Birch study findings. RESULTS: Acupuncture references support the conceptual comparison of trigger points to classical acupuncture points in the treatment of pain disorders, and their clinical correspondence in this regard is likely 95% or higher. CONCLUSIONS: Although separated by 2000 years temporally, the acupuncture and myofascial pain traditions have fundamental clinical similarities in the treatment of pain disorders. Myofascial pain data and research may help elucidate the mechanisms of acupuncture's effects.

Sectional neuroanatomy of the lower thoracic spine and chest.

This is the fourth in a series of articles on the spine. The first reviewed the anatomy of the neck; the second reviewed the upper thoracic spine and chest (T1-T4); and the third reviewed the middle thoracic spine and chest (T5-T8). The procedures performed in the lower thoracic spine include percutaneous biopsies of the liver and kidneys, percutaneous nephrolithotomy, spinal injections, radiofrequency ablations, electromyography of the diaphragm, trigger point injections, chemodenervation with botulinum toxin, acupuncture, aneurysm repair, and, occasionally, chest tube placement in the lower lung fields. Complications include subcapsular hematomas, infections, pneumothorax, hemothorax, spinal cord ischemia and resultant paraplegia, and, rarely, nephropleural fistulas. This article provides anatomically accurate schematics of innervations of the lower thoracic chest and spine (T9-T12) that can be used to interpret the magnetic resonance images of the muscles and the nerves. Cross-sectional schematics of the lower thoracic chest and spine were drawn as they appear on imaging projections. The relevant nerves were color coded. The muscles and skin surfaces were labeled and assigned the color of the appropriate nerves. An organized comprehensive map of the motor innervation of the lower thoracic chest and spine allows the physician to increase the accuracy and the efficacy of interventional procedures. This could also assist the electromyographer in correlating the clinical and electrophysiological findings with magnetic resonance images.

Trigger point--acupuncture point correlations revisited.

UNLABELLED: In 1977, Melzack and colleagues examined the possible correspondence of acupuncture points and trigger points for the treatment of pain. They claimed a 71% correspondence between these two classes of points. Their findings have influenced many researchers and practitioners but have not been examined since 1977. The current study explores the claim of a 71% correspondence between these two classes of points through a more extensive examination of the acupuncture literature. OBJECTIVES: To investigate the claim of a 71% correspondence of acupuncture points and trigger points for the treatment of pain. METHODS: The study involved a review of acupuncture texts published since 1977, focusing on five textbooks for the in-depth analyses and a broader range of texts for the more general analyses. RESULTS: If trigger points correspond to any class of acupuncture points it would have to be to the a shi points rather than the "channel" or "extra" points with which the 1977 study attempted to find correlation. Approximately 35% of recommended acupuncture points in the treatment of pain are distant from the site of the pain, making assumptions about the infrequency of use of distant acupuncture points for pain suspect. Sixty-one percent (61%) of the acupuncture points that the 1977 study examined for the treatment of pain are not recommended at all for the treatment of pain, and 44% are not recommended in the treatment of any problem, while only 19% of the acupuncture points are frequently recommended for pain and 20% for all conditions. For the acupuncture points that corresponded in the 1977 study, the equivalent numbers are: 60% not recommended at all for pain, 47% not recommended for anything, 18% commonly recommended for pain, and 16% commonly recommended for anything. CONCLUSION: The claimed 71% correspondence of trigger points to acupuncture points is conceptually not possible. Furthermore, even putting this conceptual problem aside, no more than 40% of the acupuncture points that the 1977 study examined could correlate for the treatment of pain, and more likely, only approximately 18%-19% correlate rather than the 71% that was claimed. However, this study found a probable correspondence of trigger points to a different class of acupuncture points, the a shi points, which appears to be an important finding. Researchers and clinicians who have assumed the conclusions of the 1977 study to be correct will need to reexamine the impact of the current findings on any claims that are dependent on the conclusions of that study.

Crustacean hyperglycemic hormone in the lobster nervous system: localization and release from cells in the subesophageal ganglion and thoracic second roots.

Crustacean hyperglycemic hormones (CHHs) are neuropeptides involved in the regulation of hemolymph glucose. The primary source of CHHs has been identified as the neurosecretory neurons of the eyestalk X-organ and its associated neurohemal organ, the sinus gland. We have identified another source of CHH-like peptides in the nervous system. With the use of immunocytochemistry, cells in the second roots of the thoracic ganglia have been observed to stain positively for CHH-reactive material. We also identified a pair of cells in the subesophageal ganglion that contain large amounts of CHH-reactive material. Depolarization of these cells with elevated potassium mediates a calcium-dependent release of CHH-like material from the ganglion as quantified with an enzyme-linked immunosorbent assay (ELISA).

Tracing of a neuronal network in the locust by pressure injection of markers into a synaptic neuropil.

Central neuronal circuits of vertebrates have often been investigated using injection of markers into synaptic neuropils, whereas similar techniques have rarely been applied in invertebrates. In this study we tested several neuroanatomical tracers for their ability to mark central neuronal circuits in insects, using the well described auditory network of the locust, Locusta migratoria. After physiological localization of an auditory neuropil various tracers were pressure injected. Horseradish peroxidase, dextrans (3 and 10 kDa) and especially biocytin and neurobiotin were effectively incorporated by auditory interneurons, which resulted in their extensive labeling. Postsynaptic regions turned out to be the major, if not exclusive sites of uptake of injected markers, which is deduced from two lines of evidence: (i) for labeling of identified auditory neurons it was necessary to apply the tracer to postsynaptic sites of the neuron; (ii) only a few non-auditory neurons were labeled (probably by lesioning axons during electrode impalement). No evidence could be found for an activity dependent uptake. We conclude that pressure injection of certain tracers into synaptic areas can be used to identify central nervous circuits in insects.

Neurons with histaminelike immunoreactivity in the segmental and stomatogastric nervous systems of the crayfish Pacifastacus leniusculus and the lobster Homarus americanus.

We used a polyclonal antiserum against histamine to map histaminelike immunoreactivity (HLI) in whole mounts of the segmental ganglia and stomatogastric ganglion of crayfish and lobster. Carbodiimide fixation permitted both HRP-conjugated and FITC-conjugated secondary antibodies to be used effectively to visualize HLI in these whole mounts. Two interneurons that send axons through the inferior ventricular nerve (ivn) and the stomatogastric nerve to the stomatogastric ganglion had strong HLI, both in crayfish and in lobster. These ivn interneurons were known from other evidence to be histaminergic. The neuropil of the stomatogastric ganglion in both crayfish and lobster contained brightly labeled terminals of axons that entered the ganglion from the stomatogastric nerve. No neuronal cell bodies in this ganglion had HLI. Each segmental ganglion contained at least one pair of neurons with HLI. Some neurons in the subesophageal ganglion and in each thoracic ganglion labeled very brightly. Axons of projection interneurons with strong HLI occurred in the dorsal lateral tracts of each segmental ganglion, and sent branches to the lateral neurophils and tract neurophils of each ganglion. All the labeled neurons were interneurons; no HLI was observed in peripheral nerves.

Convergence of phrenic and cardiopulmonary spinal afferent information on cervical and thoracic spinothalamic tract neurons in the monkey: implications for referred pain from the diaphragm and heart.

1. Spinothalamic tract (STT) neurons in the C3-T6 spinal segments were studied for their responses to stimulation of phrenic and cardiopulmonary spinal afferent fibers. A total of 142 STT neurons were studied in 44 anesthetized, paralyzed monkeys (Macaca fascicularis). All neurons were antidromically activated from the ventroposterolateral nucleus and/or medial thalamus. 2. Electrical stimulation of phrenic afferent fibers (PHR) excited 43/58 (74%), inhibited 2/58 (3%), and did not affect 13/58 (13%) of cervical STT neurons. Neurons with excitatory somatic fields confined to the proximal limb or encompassing the whole limb were excited to a significantly greater extent by electrical stimulation of PHR than were neurons with somatic fields confined to the distal limb. Mechanical stimulation of PHR by probing the exposed diaphragm excited 11/22 (50%), inhibited 3/22 (14%), and did not affect 8/22 (36%) cervical STT neurons. 3. The technique of minimum afferent conduction velocity (MACV) was used to obtain information about the identity of the PHR that excited 35 cervical STT neurons. Evidence was obtained for excitation of these neurons by group II and III PHR. The mean +/- SE MACV for all neurons was 14 +/- 2 m/s. 4. Electrical stimulation of cardiopulmonary spinal afferent fibers excited 41/57 (72%), inhibited 8/57 (14%), and did not affect 8/57 (14%) of cervical STT neurons. Neurons with excitatory somatic fields confined to the proximal limb or encompassing the whole limb were excited to a significantly greater extent by electrical stimulation of cardiopulmonary spinal afferents than were neurons with somatic fields confined to the distal limb. 5. Excitatory convergence of PHR and cardiopulmonary spinal afferent input was observed for 36/57 (63%) cervical STT neurons. 6. Electrical stimulation of PHR excited 36/84 (43%), inhibited 25/84 (30%), and did not affect 23/84 (27%) of thoracic STT neurons. All of these neurons received excitatory cardiopulmonary spinal afferent input. 7. Neurons were more likely to be excited by electrical stimulation of PHR if they were located in C3-C6 spinal segments. Furthermore, the net excitatory effect of PHR input decreased in more caudal segments, such that thoracic STT neurons were weakly excited relative to cervical STT neurons. 8. We conclude that cervical STT neurons with excitatory somatic fields that include or are restricted to proximal sites are excited by electrical or mechanical stimulation of PHR. Those effects demonstrate a physiological substrate for pain referred from the diaphragm to the shoulder in patients with pleural effusions or subphrenic abscesses.(ABSTRACT TRUNCATED AT 400 WORDS)

Trigger points and acupuncture points for pain: correlations and implications.

Trigger points associated with myofascial and visceral pains often lie within the areas of referred pain but many are located at a distance from them. Furthermore, brief, intense stimulation of trigger points frequently produces prolonged relief of pain. These properties of trigger points--their widespread distribution and the pain relief produced by stimulating them--resemble those of acupuncture points for the relief of pain. The purpose of this study was to determine the correlation between trigger points and acupuncture points for pain on the basis of two criteria: spatial distribution and the associated pain pattern. A remarkably high degree (71%) of correspondence was found. This close correlation suggests that trigger points and acupuncture points for pain, though discovered independently and labeled differently, represent the same phenomenon and can be explained in terms of the same underlying neural mechanisms. The mechanisms that play a role in the genesis of trigger points and possible underlying neural processes are discussed.