We performed a randomized, double-blinded study to compare levobupivacaine with racemic bupivacaine for labor analgesia. Eighty term parturients received either levobupivacaine 0.125% or racemic bupivacaine 0.125%, to which was added sufentanil 0.75 μg/mL and epinephrine 1.25 μg/mL. As part of a combined spinal-epidural procedure, 2 mL of this mixture was initially injected intrathecally, and the same solutions were subsequently administered epidurally. For both combinations, onset until the first painless contraction was 4 to 5 min. Most patients were pain free during the second contraction. The duration of initial spinal analgesia was 93.5 ± 20 min and 94.7 ± 31 min for levobupivacaine and racemic bupivacaine, respectively. The duration of analgesia for the first epidural top-up dose was also similar in the two groups. Total local anesthetic requirements during labor were not different. The only major difference observed was the absence of motor impairment in levobupivacaine-treated parturients as compared with the Racemic Bupivacaine group, in which the incidence of a Bromage-1 motor block was 34%. Other side effects and obstetric or neonatal outcomes were not different between groups. Intrathecal levobupivacaine has a similar clinical profile as racemic bupivacaine, but at equal doses it produced less motor block.
Animal models are important tools to study the pathophysiology and pharmacology of neuropathic pain. This manuscript describes the surgical and behavioral procedures to study trigeminal neuropathic pain in rats. To meet the specificity of trigeminal neuropathic pain syndromes, the infraorbital nerve (IoN) is subjected to a chronic constriction injury (CCI) by loosely ligating the nerve. An intra-orbital approach is presented here to expose and ligate the IoN in the orbital cavity. After IoN ligation, rats exhibit changes in spontaneous behavior and in response to von Frey hair stimulation that are indicative of persistent pain and mechanical allodynia. Two phases can be defined in the development of the behavioral changes. During the first week following IoN-CCI (phase 1), rats show an increased and asymmetric face grooming activity, i.e., with face wash strokes primarily directed to the nerve-injured IoN territory. A distinction is made between face grooming behavior that is part of a more general body grooming behavior, which remains largely unaffected by IoN-CCI, and face grooming that is neither preceded nor followed by body grooming, which is significantly increased after IoN-CCI. During this period, responsiveness to mechanical stimulation of the IoN territory is reduced. This hyporesponsiveness is abruptly replaced by an extreme hyperresponsiveness whereby even very weak stimulus intensities provoke nocifensive behavior (phase 2). The phenomenological similarities between these behavioral alterations and reported signs of facial pain (i.e., responses to noxious stimulation of the face) suggest the presence of dysesthesia/paresthesia and mechanical allodynia in the ligated IoN territory.
Breakthrough cancer pain can be treated effectively by rapid-onset opioids, such as sublingual fentanyl. However, it remained unclear how the optimal dose of sublingual fentanyl should be determined. Dosing proportional to basic opioid regimen is now proposed as an alternative to dose titration.
Endothelin-1 (ET-1) is an endogenously expressed potent peptide vasoconstrictor. There is growing evidence that ET-1 plays a role in the pain signaling system and triggers overt nociception in humans. The underlying neuronal pathways are still a matter of great debate. In the present study, we applied an intradermal ET-1 sensitization model to induce mechanical hyperalgesia in healthy subjects. Functional magnetic resonance imaging (fMRI) was used to tease out the cortical regions associated with the processing of ET-1-induced punctate hyperalgesia, as compared to a nonnoxious mechanical stimulation of the contralateral arm. Von Frey hair testing revealed the presence of increased responsiveness to punctate stimulation in all subjects. Activational patterns between nonpainful control stimulation and hyperalgesic stimulation were compared. Two major observations were made: (1) all cortical areas that showed activation during the control stimulation were also present during hyperalgesic stimulation, but in addition, some areas showed bilateral activation only during hyperalgesic stimulation, and (2) some brain areas showed significantly higher signal changes during hyperalgesic stimulation. Our findings suggest that injection of ET-1 leads to a state of punctate hyperalgesia, which in turn causes the activation of multiple brain regions. This indicates that ET-1 activates an extended neuronal pathway.
To use quantitative sensory testing (QST) to assess whether a stellate ganglion block (SGB) modulates the analgesia induced by cervical paravertebral block (CPVB).A prospective double-blind randomized controlled trial.Department of Anesthesia, Antwerp University Hospital, October 2011 to December 2015.Twenty-eight adults scheduled for arthroscopy of a nonfractured shoulder were enrolled.Participants were randomly assigned to receive either single CPVB (5 mL of levobupivacaine 0.5%) or combined CPVB + SGB (5 mL and 3 mL of levobubivacaine 0.5%, respectively). The detection thresholds for cold/warm sensations and cold/heat pain were established using thermal QST on the C4-C7 dermatomes before local anesthetic infiltration and at 0.5, 6, 10, and 24 hours thereafter. Our primary outcome was the time course of QST thresholds for the different neurosensitive/nociceptive modalities. As secondary and tertiary outcomes, we evaluated the degree of motor block and the time to first administration of rescue analgesics.We randomized 20 patients. There were no significant differences in the detection thresholds for the neurosensitive/nociceptive modalities, motor block, or timing for rescue analgesics between the groups (P = 0.15-0.94). All patients with CPVB + SGB exhibited Horner's signs, whereas patients in the CPVB group did not exhibit these signs; however, this does not exclude sympathetic block.We were unable to demonstrate any analgesic benefit of CPVB + SGB in arthroscopic shoulder surgery. It is therefore not unreasonable to suppose that pain from soft tissue injuries without bony lesions is transmitted mainly by somatic nerves with no or only minimal involvement of the sympathetic nervous system.
Background: The large surgical incision and extensive tissue trauma in posterior spinal fusion for adolescent idiopathic scoliosis causes severe acute postoperative pain. Furthermore, posterior spinal fusion is associated with a risk of persistent postsurgical pain. Six months after posterior spinal fusion, the incidence of persistent postsurgical pain is as high as 22% of the patients. Optimizing pain management therefore remains crucial, but challenging. Objective: The study objective is to design and implement an enhanced recovery pathway for patients with adolescent idiopathic scoliosis undergoing posterior spinal fusion integrating all aspects of biopsychosocial care. Its outcomes are assessed, including its effect on postoperative pain and early mobilization. Design and settings: A prospective cohort study was performed at the Antwerp University Hospital. Methods: In December 2019, a prospective cohort study was set up in which an enhanced recovery pathway substitutes more than the patient controlled intravenous analgesia containing morphine postoperatively. This pathway consists of m/eHealth based psychological screening questionnaires, patient education, early mobilization, and a multimodal analgesia protocol consisting of preemptive gabapentin, an intraoperatively given single dose of methadone (0.2 mg kg-1), non-steroidal anti-inflammatory drugs, and acetaminophen. Results: We treated 25 adolescents (10 males and 15 females) with the developed enhanced recovery pathway with a mean age of 16.5 years (range 12-22). The mean number of spinal levels fused was 10 (range 6-13). Mean numerical rating scale scores were 4.17 at postoperative day 1, 4.46 at postoperative day 2, and 3.74 at postoperative day 3 in enhanced recovery pathway treated patients. Mean bladder catheterization duration was 3.04 days and enhanced recovery pathway patients stayed in the hospital for an average of 7.4 days. Conclusions: Using an enhanced recovery pathway for patients undergoing posterior spinal fusion could not only reduce the acute and chronic opioid consumption and its side effects, but could also result in less postoperative pain, shorter hospital stay and higher patient satisfaction. Further reevaluation and improvement focused on these variables will likely further improve the effectiveness of enhanced recovery pathways. Trial registration: ClinicalTrials.gov NCT04038229.
