Case report: limbic system activation by intravenous lidocaine in a patient with a complex regional pain syndrome and major depression

Utilization of Intravenous Lidocaine Infusion for the Treatment of Refractory Chronic Pain

Context

Chronic pain accounts for one of the most common reasons patients seek medical care. The financial burden of chronic pain on health care is seen by direct financial cost and resource utilization. Many risk factors may contribute to chronic pain, but there is no definite risk. Managing chronic pain is a balance between maximally alleviating symptoms by utilizing a therapeutic regimen that is safe for long-term use. Currently, non-opioid analgesics, NSAIDs, and opioids are some of the medical treatment options, but these have numerous adverse effects and may not be the best option for long-term use. However, Lidocaine can achieve both central and peripheral analgesic effects with relatively few side effects, which may be an ideal compound for managing chronic pain.

Evidence Acquisition

This is a Narrative Review.

Results

Infusion of lidocaine (2-(diethylamino)-N-(2,6-dimethylphenyl)acetamide), an amino-amide compound, is emerging as a promising option to fill the therapeutic void for treatment of chronic pain. Numerous studies have outlined dosing protocols for lidocaine infusion for the management of perioperative pain, outlined below. While there are slight variations in these different protocols, they all center around a similar dosing regimen to administer a bolus to reach a rapid steady state, followed by infusion for up to 72 hours to maintain the therapeutic analgesic effects.

Conclusions

Lidocaine may be a promising pharmacologic solution with a low side effect profile that provides central and peripheral analgesia. Even though the multifaceted mechanism is not entirely understood yet, lidocaine may be a promising novel remedy in treating chronic pain in various conditions.

Cerebral 18F-FDG metabolism alteration in a neuropathic pain model following brachial plexus avulsion: A PET/CT study in rats

The present study aimed to investigate cerebral metabolic changes in a neuropathic pain model following deafferentation. A total of 24 Sprague-Dawley rats were included for modeling of right brachial plexus avulsion (BPA) through the posterior approach. As nerve injury would cause central sensitization and facilitate pain sensitivity in other parts of the body, thermal withdrawal latency (TWL) of the intact forepaw was assessed to investigate the level of pain perception following BPA-induced neuropathic pain. [Fluorine-18]-fluoro-2-deoxy-d-glucose (¹⁸F-FDG) positron emission tomography (PET) was applied to the brain before and after brachial plexus avulsion to explore metabolic changes in neuropathic pain following deafferentation. The TWL of the left (intact) forepaw was significantly lower after BPA than that of baseline (p < 0.001). Using TWL as a covariate, standardized uptake values (SUVs) of ¹⁸F-FDG significantly increased in the ipsilateral dorsolateral thalamus and contralateral anterodorsal hippocampus after BPA. Conversely, SUVs in multiple brain regions decreased, including the contralateral somatosensory cortex, ipsilateral cingulate cortex, and ipsilateral temporal association cortex. The Pearson correlation analysis showed that the SUVs of the contralateral anterodorsal hippocampus and ipsilateral dorsolateral thalamus were negatively related to the TWL of the intact forepaw, whereas the SUVs in the contralateral somatosensory cortex and ipsilateral cingulate cortex were positively related to it (p < 0.05). These findings indicate that upregulation of metabolism in the anterodorsal hippocampus and dorsolateral thalamus and downregulation metabolism in the contralateral somatosensory cortex and ipsilateral cingulate cortex could be a unique pattern of metabolic changes for neuropathic pain following brachial plexus avulsion.

The cumulative analgesic effect of repeated electroacupuncture involves synaptic remodeling in the hippocampal CA3 region

In the present study, we examined the analgesic effect of repeated electroacupuncture at bilateral Zusanli (ST36) and Yanglingquan (GB34) once a day for 14 consecutive days in a rat model of chronic sciatic nerve constriction injury-induced neuropathic pain. In addition, concomitant changes in calcium/calmodulin-dependent protein kinase II expression and synaptic ultrastructure of neurons in the hippocampal CA3 region were examined. The thermal pain threshold (paw withdrawal latency) was increased significantly in both groups at 2 weeks after electroacupuncture intervention compared with 2 days of electroacupuncture. In ovariectomized rats with chronic constriction injury, the analgesic effect was significantly reduced. Electroacupuncture for 2 weeks significantly diminished the injury-induced increase in synaptic cleft width and thinning of the postsynaptic density, and it significantly suppressed the down-regulation of intracellular calcium/calmodulin-dependent protein kinase II expression in the hippocampal CA3 region. Repeated electroacupuncture intervention had a cumulative analgesic effect on injury-induced neuropathic pain reactions, and it led to synaptic remodeling of hippocampal neurons and upregulated calcium/calmodulin-dependent protein kinase II expression in the hippocampal CA3 region.

Differential proteomics analysis of the analgesic effect of electroacupuncture intervention in the hippocampus following neuropathic pain in rats

Background

Evidence is building steadily on the effectiveness of acupuncture therapy in pain relief and repeated acupuncture-induced pain relief is accompanied by improvement of hippocampal neural synaptic plasticity. To further test the cellular and molecular changes underlying analgesic effect of acupuncture, the global change of acupuncture associated protein profiles in the hippocampus under neuropathic pain condition was profiled.

Methods

The chronic constrictive injury (CCI) model was established by ligature of the unilateral sciatic nerve in adult Wistar rats. Rats were randomized into normal control (NC) group, CCI group, and CCI with electroacupuncture (EA) stimulation group. EA was applied to bilateral Zusanli (ST36) and Yanglingquan (GB34) in the EA group. Differentially expressed proteins in the hippocampus in the three groups were identified by two-dimensional gel electrophoresis and matrix-assisted laser desorption/ionization time of flight mass spectrometry. The functional clustering of the identified proteins was analyzed by Mascot software.

Results

After CCI, the thermal pain threshold of the affected hind footpad was decreased and was reversed gradually by 12 sessions of acupuncture treatment. Following EA, there were 19 hippocampal proteins identified with significant changes in expression (>2-fold), which are involved in metabolic, physiological, and cellular processes. The top three canonical pathways identified were “cysteine metabolism”, “valine, leucine, and isoleucine degradation” and “mitogen-activated protein kinase (MAPK) signaling”.

Conclusions

These data suggest that the analgesic effect of EA is mediated by regulation of hippocampal proteins related to amino acid metabolism and activation of the MAPK signaling pathway.

Intravenous lidocaine for neuropathic pain: Diagnostic utility and therapeutic efficacy

Lidocaine is a use-dependent sodium channel blocker that produces analgesia when administered intravenously to patients with neuropathic pain. This article reviews the role and limitations of intravenous lidocaine infusions for neuropathic pain. Lidocaine infusions rarely provide relief that persists significantly beyond the duration of the infusion. Diagnostically, systemic lidocaine may help establish the presence of neuropathic pain and the responsivity to oral sodium channel blockade. However, the data supporting diagnostic infusions remain sparse. Therapeutically, infusions should generally be restricted to patients with neuropathic pain who are unable to take oral medication.