Long-term epidural ketamine, morphine and bupivacaine attenuate reflex sympathetic dystrophy neuralgia

Spinal epidural abscess associated with an epidural catheter in a woman with complex regional pain syndrome and selective IgG3 deficiency: A case report

RATIONALE

Continuous epidural infusion of local anesthetic may be an alternative to sympathetic blocks in refractory cases of complex regional pain syndrome (CRPS). Spinal epidural abscess (SEA) is a well-known complication associated with this technique, especially in patients with immune deficiencies. We herewith report a cervical SEA associated with an epidural catheter in a woman with CRPS and selective IgG3 subclass deficiency.

PATIENT CONCERNS

Severe pain interfering with activities of daily living.

DIAGNOSIS

Complex regional pain syndrome type-1 with involvement of upper extremity.

INTERVENTIONS

The patient underwent inpatient epidural infusion for management of left upper extremity CRPS. Her history was notable for previous left shoulder injury requiring numerous surgical revisions complicated by recurrent shoulder infections, and selective IgG3 deficiency. She received antibiotic prophylaxis and underwent placement of a C6-C7 epidural catheter. On day 5, she became febrile. Neurological examination remained unchanged and an MRI demonstrated acute fluid collection from C3-T1. The following day she developed left arm weakness and was taken for emergent cervical decompression. Intraoperative abscess cultures were positive for Pseudomonas aeruginosa.

OUTCOMES

Postoperatively, the patient's neurological symptoms and signs improved.

LESSONS

Patients with selective IgG3 deficiency who are being considered for epidural catheterization may benefit from expert consultation with infectious diseases specialist. A history of recurrent device- or tissue-related infections should alert the clinician to the possible presence of a biofilm or dormant bacterial colonization. Close monitoring in an ICU setting during therapy is recommended. In case of early signs of infection, clinicians should have a high suspicion to rule out a SEA in immunocompromised patients.

Validation of proposed diagnostic criteria (the "Budapest Criteria") for Complex Regional Pain Syndrome

Current IASP diagnostic criteria for CRPS have low specificity, potentially leading to overdiagnosis. This validation study compared current IASP diagnostic criteria for CRPS to proposed new diagnostic criteria (the "Budapest Criteria") regarding diagnostic accuracy. Structured evaluations of CRPS-related signs and symptoms were conducted in 113 CRPS-I and 47 non-CRPS neuropathic pain patients. Discriminating between diagnostic groups based on presence of signs or symptoms meeting IASP criteria showed high diagnostic sensitivity (1.00), but poor specificity (0.41), replicating prior work. In comparison, the Budapest clinical criteria retained the exceptional sensitivity of the IASP criteria (0.99), but greatly improved upon the specificity (0.68). As designed, the Budapest research criteria resulted in the highest specificity (0.79), again replicating prior work. Analyses indicated that inclusion of four distinct CRPS components in the Budapest Criteria contributed to enhanced specificity. Overall, results corroborate the validity of the Budapest Criteria and suggest they improve upon existing IASP diagnostic criteria for CRPS.

A pilot open-label study of the efficacy of subanesthetic isomeric S(+)-ketamine in refractory CRPS patients

OBJECTIVE

Complex regional pain syndrome (CRPS) is a severe neuropathic pain state that is often disproportionate to the initial trauma. Associated features are autonomic dysregulation, swelling, motor dysfunction, and trophic changes to varying degrees. Despite a multitude of treatment modalities, a subgroup of CRPS patients remain refractory to all standard therapies. In these patients, the disease may spread extraterritorially, which results in severe disability. A critical involvement of N-methyl-D-aspartate receptors (NMDARs) has been demonstrated both clinically and by animal experimentation. NMDA antagonists may be effective in many neuropathic pain states. In long-standing, generalized CRPS, we investigated the effects of S(+)-ketamine on pain relief and somatosensory features, assessed by quantitative sensory testing (QST).

METHODS

Four refractory CRPS patients received continous S(+)-ketamine-infusions, gradually titrated (50 mg/day-500 mg/day) over a 10-day period. Pain intensities (average, peak, and least pain) and side effects were rated on visual analogue scales, during a 4-day baseline, over 10 treatment days, and 2 days following treatment. QST (thermo-, mechanical detection, and pain thresholds) was analyzed at baseline and following treatment.

RESULTS

Subanesthetic S(+)-ketamine showed no reduction of pain and effected no change in thermo- and mechanical detection or pain thresholds. This procedure caused no relevant side effects. The lack of therapeutic response in the first four patients led to termination of this pilot study.

CONCLUSION

S(+)-ketamine can be gradually titrated to large doses (500 mg/day) without clinically relevant side effects. There was no pain relief or change in QST measurements in this series of long-standing severe CRPS patients.

New drugs for neuraxial blockade

Recent years have seen a dramatic increase in the number of agents used for neuraxial blockade. Together with the developments in local anaesthetics and opioids, completely new categories of agents have been investigated for intrathecal and epidural use. A review of the recent literature reveals the potential for improvement in achieving balanced anaesthesia and analgesia, in particular combining agents to reduce adverse effects.

Correlation between changes in regional cerebral blood flow and pain relief in complex regional pain syndrome type 1

OBJECTIVE

Analyzing changes in regional cerebral blood flow (rCBF) with SPECT in complex regional pain syndrome type 1 (CRPS 1), formerly known as reflex sympathetic dystrophy, is an optimal method for evaluating effective pain relief. We attempted to investigate the correlation of changes in rCBF with pain relief during treatments of sympathetic blockade and multimodal epidural pain control.

CASE REPORT

We describe a patient with severe CRPS 1 in whom conventional treatment failed to relieve the pain. Combined repeated lumbar sympathetic blocks and long-term epidural morphine, bupivacaine, and ketamine administration provided satisfactory pain relief and functional activity recovery. Six normal control subjects having one Tc-99m HMPAO scan each and the patient with CRPS having 3 Tc-99m HMPAO scans (once before treatment and twice at 4 months and 6 months after treatment, respectively). The patient with CRPS showed lower rCBF than normal controls in the left thalamus and higher rCBF than normal controls in the right parietal lobe and left frontal lobe. After subsequent treatment, the subtraction images showed increased rCBF in the left thalamus and decreased rCBF in the right parietal and left frontal lobes.

CONCLUSIONS

Tc-99m HMPAO SPECT showed a relationship of rCBF in the thalamus, parietal lobe, and frontal lobe with pain relief. rCBF alterations may provide an indicator for the quality of pain management for neuropathic pains. Subtraction analysis between pre- and posttreatment, by using statistical parametric mapping (version 2), can be used as an objective indicator for the effectiveness of therapy.

Treatment of complex regional pain syndrome type I of the hand with a series of intravenous regional sympathetic blocks with guanethidine and lidocaine

The aim of this study was to evaluate the efficacy of guanethidine and lidocaine in the treatment of complex regional pain syndrome (CRPS) type I of the hand. Seventeen patients, aged between 33 and 72 years, suffering from CRPS type I of the hand received two series of intravenous regional sympathetic block (Bier's block) sessions with guanethidine and lidocaine according to the following therapeutic protocol: (1) 5 sessions (once every second day) composed of intravenous regional administration of 15 mg guanethidine and 1 mg lidocaine/kg body weight each and (2) 20 sessions (twice a week) composed of intravenous regional administration of 10 mg guanethidine and 1 mg lidocaine/kg body weight each. Complete disappearance of pain and return of the normal function and movement of the extremity were achieved. No side effects were observed. The above-described therapeutic protocol method resulted in excellent pain relief and full restoration of both function and range of movement of the affected extremity in 17 patients suffering from CRPS type I of the hand.

Interventional modalities in the treatment of complex regional pain syndrome

Complex regional pain syndrome (CRPS) applies to a variety of conditions in which symptoms such as allodynia and hyperalgesia predominate along with hyperpathia and vasomotor/sudomotor disturbances. The incidence of CRPS in the chronic pain population varies and is difficult to determine, though it appears to affect women more than men. Treatment is multidisciplinary, and recovery of function and the reduction of pain are the main goals of treatment;this article addresses some of the interventional modalities that are used.

Ketamine in chronic pain management: an evidence-based review

Ketamine has diverse effects that may be of relevance to chronic pain including: N-methyl-D-aspartic acid, alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid, kainate, gamma-aminobutyric acid(A) receptors; inhibition of voltage gated Na(+) and K(+) channels and serotonin, dopamine re-uptake. Ketamine has been in clinical practice for over 30 yr; however, there has been little formal research on the effectiveness of ketamine for chronic pain management. In this review we evaluate the available clinical data as a basis for defining the potential use of ketamine for chronic pain. Literature referenced in this review was obtained from a computer search of EMBASE and MEDLINE from 1966 through August, 2002. Search terms included ketamine, ketalar, pain, painful, analgesic, and analgesia. Abstracts were screened for relevance and publications relating to chronic pain use were obtained. Levels of evidence were stratified according to accepted guidelines (level I-IV). For central pain, there is level II and level IV evidence of efficacy for parenteral and oral ketamine. For complex regional pain syndromes, there is only level IV evidence of efficacy of epidural ketamine. For fibromyalgia, there is level II evidence of pain relief, reduced tenderness at trigger points, and increased endurance. For ischemic pain, a level II study reported a potent dose-dependent analgesic effect, but with a narrow therapeutic window. For nonspecific neuropathic pain, level II and level IV studies reported divergent results with questionable long-term effects on pain. For phantom limb pain and postherpetic neuralgia, level II and level II studies provided objective evidence of reduced hyperpathia and pain relief was usually substantial either after parenteral or oral ketamine. Acute on chronic episodes of severe neuropathic pain represented the most frequent use of ketamine as a "third line analgesic," often by IV or subcutaneous infusion (level IV). In conclusion, the evidence for efficacy of ketamine for treatment of chronic pain is moderate to weak. However, in situations where standard analgesic options have failed ketamine is a reasonable "third line" option. Further controlled studies are needed.

Complex regional pain syndrome

As suggested by this article, considerable advances in clinical management and research have taken place during the past 20 years. Although mechanisms underlying the pain syndrome CRPS I and CRPS II remain far from one's understanding, glimpses of the pathophysiology are beginning to take shape. There is now strong evidence that these syndromes exemplify a complex neurologic disease involving the brain at several integrated levels. The changes that occur in CRPS I patients involve somatosensory, sympathetic, and somatomotor systems. The diagnostic criteria have helped to focus on aspects of these foregoing systems and whereas there is no specific laboratory test for CRPS, enough is now known about the pathophysiology to use the following tests: quantitative sensory testing (QST), autonomic testing that include quantitative sudomotor axon reflex test (QSART) for sweating abnormalities, the cold pressor test in conjunction with thermographic imaging to observe the vasoconstrictor response, and laser Doppler flowmetry to monitor background vasomotor control. Recognition of a motor disorder requires accurate documentation and may be a component of the diagnostic criteria in the future. Until a better understanding of mechanistic overtones that would help to put in place mechanism-based therapeutic strategies, current management is built around a rehabilitation model. For this to be successful, as described in the foregoing pages, different non-interventional and interventional modalities are applied in a time-restricted manner to facilitate those modalities that favor progress in the treatment algorithm. As has been described, it is important when using physiotherapeutic maneuvers to minimize joint movement in the affected region to reduce the mechanorecpetor barrage and its increase in perceived pain to encourage and maintain a patient's compliance with their rehabilitation. Finally, of greater significance is the understanding that sympatholysis per se is not a "diagnostic" test for CRPS, but rather a useful procedure that may facilitate treatment for pain that is sympathetically maintained.

Complex regional pain syndrome

Complex regional pain syndrome (CRPS) is a heterogeneous disorder that falls in the spectrum of neuropathic pain disorders. It is maintained by abnormalities throughout the neuraxis (the peripheral, autonomic, and central nervous systems). The pathophysiology of CRPS is not fully known. There are no scientifically well-established treatments. The diagnostic criteria for CRPS at this time are purely clinical, and the use of diagnostic tests has not been demonstrated. The most appropriate management of CRPS uses a multidisciplinary approach, with the inclusion of medical and psychologic intervention, and physical and occupational therapy. The key is gradual, persistent, functional improvement. The rational use of pain therapies must be grounded in a thorough knowledge of the neurobiology of pain, its endogenous modulation, and the clinical presentation. Potential peripheral pathophysiologic targets (and possible treatments) include increased spontaneous firing and responsiveness of peripheral afferent fibers mediated by inflammatory and other algogenic substances (somatosensory blocks, corticosteroids), altered levels of expression and functioning of multiple ion channels (local anesthetics, calcium channel blockers, anticonvulsants), abnormal interneuronal communication, and increased peripheral expression of adrenergic receptors and sympathetic excitation (sympathetic blocks, alpha-adrenergic antagonists, alpha-2 agonists). CRPS is also perpetuated by central mechanisms, with pathophysiologic targets (and possible treatments) including reorientation of dorsal horn terminals (desensitization techniques), functional reduction in inhibitory interneuron activity (tricyclic antidepressants, gabapentin, opioids), central sensitization and increased central excitability (gabapentin, topiramate, spinal cord stimulation, somatosensory blocks), impaired descending nociceptive inhibition (tricyclic antidepressants, opioids), and adaptive changes in the cortical centers underlying the sensory-discriminative and affective-motivational dimensions of pain (psychologic, physical, and occupational therapies). The treatment choices should be aimed at remodulating, normalizing, disrupting, or preventing the progression of abnormalities in pain processing. Sympathetic nerve blocks should be performed at least once to assess if sympathetically maintained pain is present. To the extent that peripheral somatosensory nerve blocks can diminish nociceptive input to the central nervous system, these techniques may help reduce the nociceptive sensitization of spinal neurons. Pain relief, however it is achieved and however temporary it is, is intended to facilitate participation in functional therapies to normalize use and to improve motion, strength, and dexterity. Psychologic therapies, such as biofeedback and cognitive-behavioral techniques targeting pain, stress, and mood disorders, are valuable adjunctive treatments for pain control and can facilitate functional improvement.

Complex regional pain syndrome: a review of evidence-supported treatment options

Complex regional pain syndrome consists of pain and other symptoms that are unexpectedly severe or protracted after an injury. In type II complex regional pain syndrome, major nerve injury, often with motor involvement, is the cause; in complex regional pain syndrome I, the culprit is a more occult lesion, often a lesser injury that predominantly affects unmyelinated axons. In florid form, disturbances of vasoregulation (eg, edema) and abnormalities of other innervated tissues (skin, muscle, bone) can appear. Because of these various symptoms and the difficulty in identifying causative lesions, complex regional pain syndrome is difficult to treat or cure. Complex regional pain syndrome has not been systematically investigated; there are few controlled treatment trials for established complex regional pain syndrome. This article reviews the existing studies (even if preliminary) to direct clinicians toward the best options. Treatments for other neuropathic pain syndromes that may be efficacious for complex regional pain syndrome also are discussed. Some common treatments (eg, local anesthetic blockade of sympathetic ganglia) are not supported by the aggregate of published studies and should be used less frequently. Other treatments with encouraging published results (eg, neural stimulators) are not used often enough. We hope to encourage clinicians to rely more on evidence-supported treatments for complex regional pain syndrome.

Epidural Infusion of Opiates and Local Anesthetics for Complex Regional Pain Syndrome

Complex Regional Pain Syndrome Type-I (CRPS-I) is a neuropathic pain syndrome resulting from complex pain mechanisms that involve several levels and components of the nervous system. CRPS-I consists of multiple signs, including autonomic dysfunction, in the form of edema, vasomotor changes, motor dysfunctions, muscle spasms, tremors and dystonia, as well as burning pain, hypersensitivity and allodynia that could present in any combination. The treatment is progressive physical therapy rehabilitation program. Multiple analgesic modalities have been used to facilitate the rehabilitation program with varying rates of success. The most successful treatment is a multi-disciplinary comprehensive approach, where initial pain control allows for physical and psychological interventions that are believed to be the basis for successful treatment.(1) The pain in CRPS-I may be mediated through the sympathetic nervous system, sympathetic maintained pain (SMP) or sympathetic independent pain (SIP)(2).

Differential antinociceptive effect of transcutaneous electrical stimulation on pain behavior sensitive or insensitive to phentolamine in neuropathic rats

The effects of transcutaneous electrical stimulation and systemic injection of phentolamine, a non-specific alpha-adrenergic antagonist, on the behavioral signs of mechanical allodynia and cold hyperalgesia in rats with nerve injury were investigated. Mechanical allodynia and cold hyperalgesia were evaluated by measuring the paw withdrawal frequency (PWF) resulting from repetitive application of a von Frey hair and the paw lift duration (PLD) at a cold temperature, respectively. After a unilateral nerve injury, both PWF and PLD increased in the injured hind paw. Application of low-frequency, high-intensity transcutaneous electrical stimulation (LFHI-TES) to the injured hind paw depressed the injury-induced increased PWF, whereas it had no effect on the injury-induced increased PLD. Naloxone reversed the LFHI-TES produced depression of PWF. Intraperitoneal administration of phentolamine depressed the injury-induced increased PLD without affecting the injury-induced increased PWF. Our results suggest that LFHI-TES, which activates the endogenous opioid systems, produces an antinociceptive effect that appears to be related to whether or not the pain is mediated by sympathetic activity.

The Epidural and Intrathecal Administration of Ketamine

An overview of the spinal administration of ketamine is presented. Ketamine acts as a noncompetitive antagonist of the NMDA receptor Ca(++ channel pore. This effect provides interesting possibilities in pain therapy. However, there are still contrasting results that seem to be due to a lack of comparative controlled studies. The presence of systemic and neurotoxic effects presently limits clinical use).

Premedication with dextromethorphan provides posthemorrhoidectomy pain relief

PURPOSE

Previous studies have shown that N-methyl-D-aspartate receptor antagonists provide a preemptive analgesic effect in humans. This study was designed to examine whether premedication with dextromethorphan, an N-methyl-D-aspartate antagonist, also provided a preemptive analgesic effect that improved postoperative pain management.

METHODS

Sixty patients who were American Society of Anesthesiologists status I and II scheduled for hemorrhoidectomy (modified Whitehead procedure) were included in the study. Patients were randomly assigned to the control and study groups. For the control group patients received chlorpheniramine maleate (20 mg), a component of the injection form of dextromethorphan, intramuscular injection 30 minutes before skin incision. In the study group dextromethorphan 40 mg containing 20 mg chlorpheniramine maleate (intramuscular) was given as premedication 30 minutes before skin incision. Pethidine (1 mg/kg, intramuscular) was given for pain relief as required postoperatively. The time to first pethidine injection, total pethidine consumption, worst pain score, and pethidine-related side effects were recorded for 48 hours postoperatively.

RESULTS

The times to first pethidine injection (mean +/- standard error of the mean) were 5.2 +/- 3 and 19.6 +/- 6 hours in the control and study groups, respectively. Total pethidine consumption was 140 +/- 11.3 and 63.5 +/- 11.8 mg in the control and study groups. The worst visual analog scale pain scores were 7.4 +/- 0.2 and 5.6 +/- 0.3 in the control and study groups during the two-day observation. The numbers of patients who required pethidine injection were 29 and 20 in the control and study groups, respectively. Two patients suffered pethidine-related side effects, such as nausea, vomiting, dizziness, and headache, in the control group, and no patient complained of any side effect in the study group.

CONCLUSION

We found that dextromethorphan premedication provided a preemptive analgesic effect, thus producing reduced postoperative pain and pethidine requirement and improved recovery from hemorrhoidectomy.

Simultaneous analysis of ketamine and bupivacaine in plasma by high-performance liquid chromatography

A reversed-phase HPLC technique for the simultaneous measurement of both bupivacaine and ketamine in plasma is described. Plasma samples (0.5 ml) were prepared using a rapid and simple back-extraction technique. Resolution of both analytes and the internal standard, desipramine, from medicines coadministered to surgical paediatric patients was obtained using a 5 microm cyano (CN) (250x4.6 mm) column and a mobile phase comprising methanol-acetonitrile-orthophosphoric acid-0.01 M sodium dihydrogenphosphate (200:80:2:718). Good sensitivity for both analytes was observed using UV detection at a wavelength of 215 nm. The method has been validated according to the criteria established by the Journal of Chromatography B.