Lumbar sympathetic block for pain relief in two patients with interstitial cystitis. (Shimane Medical University, Izumo, Japan) Reg Anesth Pain Med 2001;26:271–273.

This case report discussed the effective treatment of interstitial cystitis (IC) with regard to a 63-year-old woman and a 78-year-old woman. Medical therapy with nonsteroidal anti-inflammatory drugs, anticholinergics, and hydrodistention of the bladder failed to improve their symptoms. Subsequently, a continuous lumbar epidural block using 1% mepivacaine was used in these patients. A transient reduction of the symptoms in both patients was achieved. A lumbar sympathetic block with a neurolytic agent produced almost complete and long-lasting relief of their symptoms. Conclude that lumbar sympathetic block using a neurolytic agent produced long-lasting pain relief in 2 patients with IC.
Comment by Pedro F. Bejarano, M.D. Chronic visceral pain association to the neurovegetative system and to sympathetically-maintained mechanisms has been well documented nowadays. The multiple neural connections among different abdominal nerve plexus has also been described, and this anastomoses may account for the observed analgesic effects in this case obtained without specific blockade of the superior hypogastric plexus. Despite the reported good results, the use of the lumbar approach may be controversial in this cases, as the uncomfortable peripheral effects of a permanent lumbar sympathetic neurolytic block (i.e.: lower limb vasodilation) favors a more anatomically restricted (visceral) area like that obtained with a superior hypogastric approach.
We must remark that the existence of Sympathetically mediated and/or maintained pain is not enough phenomenae to fit the diagnostic criteria of a RCPS, as suggested by the authors, but it is less so in the case of an evidently persistent, organic source of visceral nociception like in the Intersticial Cystitis disease.     

Postoperative epidural analgesia and possible transient anterior spinal artery syndrome. (HaEmek Medical Center, Afula, Israel) Reg Anesth Pain Med 2001;26:274–277.

An unusual complication of epidural analgesia used to facilitate postoperative pain relief while mobilizing a patient is presented in this case report. A 65‐year‐old woman with a history of chronic obstructive pulmonary disease, atherosclerotic cardiovascular disease, chronic renal failure, and degenerative vertebral anatomy underwent resection of the left ureter due to an obstructing tumor. The day following the surgery, mobilization to an armchair was started, followed by a decrease in blood pressure. Soon after, flaccid paralysis was sparing of sensory functions, consistent with anterior spinal artery syndrome, was diagnosed. This complication should be taken into account, especially in patients at risk, when considering epidural analgesia techniques in the postoperative period. Comment by Pedro F. Bejarano, M.D. Fortunately infrequent, the Anterior Spinal Artery Syndrome (ASAS) has been described in the early postoperative period in association with surgery involving the retroperitoneum (specially on the left side), as well as unexpectedly with regional anesthesia procedures (Spinal, Epidural and Celiac Plexus Blocks) in the vicinity of the T6 to L2 “critical zone” of medulary arterial blood flow.^1,2 This case highlights the importance of a proper evaluation and prevention when feasible, of combining risk factors (besides type of surgery and anesthetic technique) that may potentiate otherwise subclinical—but certainly prevalent—vascular, circulatory or spinal anatomy aging derangements leading to ASAS. As the authors state in the discussion of this case, it is remarkable the aethiological association with an apparently uncomplicated and retrospectively “preventable” hypotensive episode, whether it be a consequence of a relative hypovolemia, a pharmacological (postanesthetic or not) impairment of baropressor responses, or to an excessive local anesthetic sympathetic blockade. Learning from unexpected negative outcomes in anesthesia makes us more sensible to risk factors that are not specially highlighted in daily practice. In this sense, a case with so multiple patient's risk factors including the diagnosis of spinal stenosis, may had lead to other postop analgesia choices, namely systemic or even sole epidural opioid analgesia (that maybe was not considered here due to the COPD) as has been suggested before.³ Moreover, in the scope of an obstructive coronary disease high‐risk patient, a more aggressive treatment to the hypotensive episode including quick return to the recumbent or trendelemburg position limiting the isquemia could have favored this neurological adverse outcome. 1. Hong DK, Lawrence HM: Anterior Spinal Artery Syndrome following total Hip Artroplasty. Anesth Intensive Care. 2001;29:62–66. 2. Hachisuka K, Ogata H, Kohshi K: Postoperative Paraplegia with spinal myoclonus possibly caused by epidural anaesthesia: case report. Paraplegia. 1991 Feb;29(2):131–136. 3. Linz SM, Charbonnet C, Mikhail MS, et al.: Spinal artery syndrome masked by postoperative epidural analgesia. Can J Anaesth. 1997;44(11):1178–1181.     

Axillary brachial plexus block with patient controlled analgesia for complex regional pain syndrome type I: a case report. (National Cheng Kung University, Tainan, Taiwan) Reg Anesth Pain Med 2001;26:68–71.

A 32-year-old man who suffered from complex regional pain syndrome type I (CRPS I) of the right upper limb after surgical release of carpal tunnel syndrome of the right hand is the subject of this case report. Symptoms and signs over the right hand were alleviated under rehabilitation and conventional pharmacological management, but severe painful swelling of the right wrist persisted. Axillary brachial plexus block (BPB) with patient controlled analgesia (PCA) was performed on the 32^nd postoperative day, which soon resulted in significant reduction of pain with gradual improvement of function of the right wrist. Conclude that axillary BPB with PCA may provide patients with CRPS I of the upper limb a feasible and effective treatment.     

Herpes zoster in older adults. (Duke University Medical Center, Durham, NC) Clinical Infectious Diseases. 2001;32:1481–1486.

Herpes zoster (HZ) strikes millions of older adults annually worldwide and disables a substantial number of them via postherpetic neuralgia (PHN). Key aged‐related clinical, epidemiological, and treatment features of zoster and PHN are reviewed in this article. HZ is caused by renewed replication and spread of the varicella‐zoster virus (VZV) in sensory ganglia and afferent peripheral nerves in the setting of age‐related, disease‐related, and drug‐related decline in cellular immunity to VZV. VZV‐induced neuronal destruction and inflammation causes the principal problems of pain, interference with activities in daily living, and reduced quality of life in elderly patients. Recently, attempts to reduce or eliminate HZ pain have been bolstered by the findings of clinical trials that antiviral agents and corticosteroids are effective treatment for HZ and that tricyclic antidepressants, topical lidocaine, gabapentin, and opiates are effective treatment for PHN. Although these advances have helped, PHN remains a difficult condition to prevent and treat in many elderly patients. Comment by Miles Day, M.D. This article reviews the epidemiology clinical features diagnosis and treatment of acute herpes zoster. It also describes the treatment of postherpetic neuralgia. While this is a good review for the primary care physician, the discussion for the treatment for both acute herpes zoster and postherpetic neuralgia do not mention invasive therapy. It is well documented in pain literature that sympathetic blocks with local anesthetic and steroid as well as subcutaneous infiltration of active zoster lesions not only facilitate the healing of acute herpes zoster but also prevents or helps decrease the incidence of postherpetic neuralgia. All patients who present to the primary care physician with acute herpes zoster should have an immediate referral to a pain management physician for invasive therapy. The treatment of postherpetic neuralgia is a challenging experience both for the patient and the physician. While the treatments that have been discussed in this article are important, other treatments are also available. Regional nerve blocks including intercostal nerve blocks, root sleeve injections, and sympathetic blocks have been used in the past to treat postherpetic neuralgia. If these blocks are helpful, one can proceed with doing crynourlysis of the affected nerves or also radio‐frequency lesioning. Spinal cord stimulation has also been used for those patients who are refractory to noninvasive and invasive therapy. While intrathecal methylprednisolone was shown to be effective in the study quoted in this article one must be cautious not to do multiple intrathecal steroid injections in these patients. Multilple intrathecal steroid injections can lead to archnoiditis secondary to the accumulation of the steroid on the nerve roots and in turn causing worsening pain.     

Fentanyl improves analgesia but prolongs the onset of axillary brachial plexus block by peripheral mechanism. (Sapporo Medical University, School of Medicine, Sapporo, Japan) Anesth Analg 2000;91:384–387.

This double‐blinded study evaluated the effects of fentanyl added to lidocaine for axillary brachial plexus block in 66 adult patients scheduled for elective hand and forearm surgery. All patients received 40 mL of 1.5% lidocaine with 1:200,000 epinephrine, injected into the brachial plexus sheath using the axillary perivascular technique, and they were randomized into 3 groups. Group 1 was given lidocaine containing 2 mL of normal saline plus 2 mL of normal saline IV. Patients in Group 2 received lidocaine containing 100 μg fentanyl plus 2 mL of normal saline IV. Group 3 patients received lidocaine containing 2 mL of normal saline plus 100 μg fentanyl IV. Sensory and motor blockade were evaluated by using a pinprick technique and by measuring the gripping force, respectively. The success rate of sensory blockade for radial and musculocutaneous nerves and the duration of the sensory blockade significantly increased in Group 2 (323 ± 96 min) as compared with Group 1 (250 ± 79 min). However, the onset time of analgesia was prolonged in every nerve distribution by adding fentanyl to the brachial plexus block. IV fentanyl had no effect on the success rate, onset, or duration of the blockade. Conclude that the addition of fentanyl to lidocaine causes an improved success rate of the sensory blockade, but a delayed onset of analgesia, although this may be accounted for by the decreased pH caused by the fentanyl. Comment by Alan Kaye, M.D. The addition of opioids to regional blocks is controversial. This is due in part to the potential uptake and distribution centrally of the opioid agent. In 66 patients undergoing axillary block, all had 40 mL of 1.5% lidocaine with epinephrine. One group had normal saline, another group has fentanyl plus saline, and a third had just fentanyl. The authors found that the addition of fentanyl caused an improved success rate with regard to sensory blockade. However, onset of the blockade was delayed with fentanyl and this was theorized by a decreased pH caused by the fentanyl. More studies are needed to better elucidate mechanistic effects of opioids and other agents in enhancing or modulating local anesthetics in regional blockade.     

Memantine (a N-methyl-d-aspartate receptor antagonist) in the treatment of neuropathic pain after amputation or surgery: a randomized, double-blinded, cross-over study. (Danish Pain Research Center, University of Aarhus, Aarhus, Denmark) Anesth Analg 2000;91:960–966.

Evidence has accumulated that the N‐methyl‐d ‐aspartate receptor system plays a role in continuous and stimulus‐evoked pain after nerve injury. The analgesic effect of memantine on a group of patients with chronic pain after surgery was examined in this randomized, double‐blinded, study. Nineteen patients randomly received either memantine or placebo in the first 5‐week treatment period. A washout period of 4 weeks was followed by another 5‐week treatment period of the opposite drug. The dosage of drug was increased from 5 to 20 mg/d. Pain was recorded daily, with the use of a 0‐10 numeric rating scale. Before and at the end of each treatment, pain and sensitivity were also assessed by using the McGill Pain Questionnaire, allodynia to touch, brush, and cold, wind‐up‐like pain, and thresholds to mechanical stimuli (pressure and von Frey hair). A total of 15 patients completed the study. There was no difference between memantine and placebo on any of the outcome measures. Conclude that memantine at a dosage of 20 mg/d does not reduce spontaneous or evoked pain in patients with nerve injury pain. Comment by Tat‐Leang Lee, M.D. The treatment of patients suffering from chronic neuropathic pain remains a clinical challenge, particularly in cases where opioid therapy fails to provide sufficient pain relief. Experimental data concerning the role of NMDA‐mediated processes in central sensitization and the effects of NMDA receptor antagonists in different models of neuropathic pain have been well established. Currently, clinically available NMDA antagonists have narrow therapeutic windows and are limited by psychomimetic and other side effects. There exists a need to improve on this therapeutic ratio. Potential methods include the use of more selective NMDA antagonists that modulate binding sites within the NMDA complex, using novel routes including central axis delivery, or in combination with drugs. Combinations of opioids and NMDA antagonists may hold the most promise. Recently, a 1:1 mixture of morphine with dexmethorphan hydrobromide allowed satisfactory pain relief in chronic pain patients at a significantly lower morphine dose.¹ In this study, there were 3 patients who had morphine as part of their conventional treatment. Although specific data is not available, it would be interesting to know if memantine proved to be more effective in these patients.     

Periradicular infiltration for sciatica: a randomized controlled trial. (University Hospital of Oulu, Helsinki, Finland). Spine. 2001;26:1059–1067.

In this study, 160 consecutive, eligible patients with sciatica who had unilateral symptoms of 1 to 6 months duration, and who never underwent surgery were randomized for a double-blinded injection with methylprednisolone bupivacaine combination or saline. Objective and self-reported outcome parameters and costs were recorded at baseline, at 2 and 4 weeks, at 3 and 6 months, and at 1 year. Recovery was better in the steroid group at 2 weeks for leg pain, straight leg raising, lumbar flexion, and patient satisfaction. Back pain was significantly lower in the saline group at 3 and 6 months. Sick leave and medical costs were similar for both treatments, except for cost of therapy visits and drugs at 4 weeks, which were in favor of the steroid injection. By 1 year, 18 patients in the steroid group and 15 in the saline group underwent surgery. Conclude improvement during the follow-up was found in both the methylprednisolone and saline groups. The combination of methylprednisolone and bupivacaine seems to have a short-term effect, but at 3 and 6 months, the steroid group seems to experience a "re-bound" phenomenon.     

TNF-alpha expression in painful and nonpainful neuropathies. (University Hospital, Basel, Switzerland) Neurology. 2001;56:1371–1377.

The objective of this study was to determine whether the cytokine tumor necrosis factor α (TNF-α) acts as a pain mediator in neuropathic pain in humans. Patients with painful neuropathies showed a stronger TNF-α immunoreactivity in myelinating Schwann cells relative to the epineurial background staining compared with patients with nonpainful neuropathy. Although there was no difference in sTNF-RI levels between painful and nonpainful neuropathies, patients with a mechanical allodynia had elevated serums sTNF-RI as compared to patients without allodynia. Conclude that TNF-α expression of human Schwann cells may be up-regulated in painful neuropathies. The elevation of sTNF-RI in patients with centrally mediated mechanical allodynia suggests that systemic sTNF-RI levels may influence central pain processing mechanisms.     

Obtaining informed consent for clinical pain research: patients'' concerns and informational needs. (University of Pennsylvania Center for Bioethics, Philadelphia, PA) Pain. 2001;92:71–79.

The object of this study was to clarify the existence of dorsal root ganglion (DRG) neurons with dichotomizing axons projecting to the lumbar facet joint and to the sciatic nerve in rats. Two kinds of neurotracers (Dil and FG) were used in the study. Dil crystals were placed in the left F5-F6 facet joint, and FG was applied to the ipsilateral sciatic nerve or along the midline of the F% dermatome. Bilateral DRGs T13-S1 were observed by fluorescence microscope. DRG neurons double labeled with Dil and FG were recognized only in the ipsilateral DRGs from L3-L6 levels. Approximately 3% of DRG neurons innervating the L5-L6 facet joint had other axons to the sciatic nerve. By contrast, no double-labeled neurons were observed after FG was applied to the L5 dermatome. Conclude that in rats approximately 3% of DRG neurons innervating the lumbar facet joints have dichotomized axons projecting to the sciatic nerve.     

A comparison of superficial versus combined (superficial and deep) cervical plexus block for carotid endarterectomy: a prospective, randomized study. (University of Michigan Medical Center, Ann Arbor, MI) Anesth Analg 2000;91:781–786.

Carotid endarterectomy may be preformed by using cervical plexus blockade with local anesthetic supplementation by the surgeon during surgery. Most practitioners use either a superficial cervical plexus block or a combined (superficial and deep) block, but it is unclear which offers the best operative conditions or greatest patient satisfaction. This study compared the 2 techniques in 40 patients undergoing carotid endarterectomy. The patient randomly received either a superficial or a combined cervical plexus block. Bupivacaine 0.375% to a total dose of 1.4 mg/kg was used. The main outcome measure was the amount of supplemental lidocaine 1% used by the surgeon. Subsidiary outcome measures were postoperative pain score, sedative and analgesic requirements before and during surgery, and postoperative analgesic requirements. Median supplemental lidocaine requirements were 100 mg in the superficial block group and 115 mg in the combined block group. These differences were not statistically significant. There was no significant difference in the number of patients needing postoperative analgesia between the groups in the 24 h after surgery. The median time to first analgesia in the superficial block group was 150 min. more than in the combined block group, but this difference, although large, was not statistically significant. No significant differences were found between the anesthetic techniques studied. Comment by Alan Kaye, M.D. Carotid endarterectomy surgery can be performed with regional or general anesthesia. It is probable that a substantial majority of CEAs performed in North America are performed under general anesthesia. Debate over choice of regional versus general anesthesia persists because of various studies of risks and benefits. Each type of anesthesia has its own advantages and disadvantages, which must be considered when choosing the optimal anesthetic for patients. Regional anesthetic techniques available include local infiltration, superficial and deep cervical plexus block, a combination of these with or without contralateral superficial plexus, and cervical epidural anesthesia. This prospective, randomized, double‐blinded study compared superficial versus combined (superficial and deep) cervical plexus block in 40 patients. Outcomes were measured by supplemental local anesthetic used by the surgeon, postoperative pain scores, and sedative and analgesic requirements before, during, and postoperatively. The results showed no significant difference in either study group. Therefore, this small study suggests that superficial block should be preferred in as much that it is relatively easy to do and the potential side‐effects are far less than deep cervical block. Larger studies are warranted in this difficult population of patients.     

Subdural hematoma after dural puncture headache treated by epidural blood patch. (St. Thomas Hospital, London, United Kingdom) British J Anesth. 2001;86:720–723.

This case study discussed an accidental dural puncture in a 39-year-old patient during the siting of an epidural catheter for pain relief in labor. Twenty hours after the puncture, the mother developed a typical postdural headache, which increased in severity over the subsequent 24-hour period. An epidural blood patch was performed at 48 hours, and this initially relieved the headache. After discharge from the hospital, and 14 days after the dural puncture, the headache recurred, together with expressive dysphasia, poor coordination, and sensory loss in the right arm. A magnetic resonance imaging scan demonstrated a left-sided subdural hematoma, which drained successfully with complete recovery.     

Complex regional pain syndrome type I treated with topical capsaicin: a case report. (Erasmus University Medical Center, Rotterdam, The Netherlands) Arch Phys Med Rehabil. 2001;82:851–852.

This report described the case of a multitrauma patient who underwent an amputation of the left arm and had a complicated left crural fracture with a delayed union. He was treated in an inpatient setting for preprosthetic training for a myoelectric prosthesis and to regain walking abilities. After consolidation of the crural fracture, complex regional pain syndrome type I (CRPS I) developed in the left foreleg, which hindered mobilization. Topical capsaicin 0.075% was prescribed and a stress-loading mobilization schema was instituted. No other treatment modalities directed at CRPS I were added. After 6 weeks, no signs or symptoms of CRPS I were present and capsaicin was discontinued. Capsaicin is a well-accepted and documented treatment modality in neuropathic pain states such as postherpetic neuralgia. However, it has rarely been described in CRPS I. Capsaicin is discussed within the framework of recent insights in the neurobiology of nociception, and it is concluded that it may provide a theory-driven treatment for CRPS I, especially in the acute stage, which facilitates physical therapy and prevents peripheral and spinal sensitization.     

Orexin-A, an hypothalamic peptide with analgesic properties. (SmithKline Beecham Pharmaceuticals, Harlow, Essex, United Kingdom) Pain. 2001;92:81–90.

This study investigated the effects of acute and chronic tramadol treatment on T lymphocyte function and natural killer (NK) cell activity in rats receiving chronic constriction injury (CCI) of the sciatic nerve. T lymphocyte function was evaluated based on concanavalin-A (ConA)-induced and phytohemagglutinin (PHA)-induced splenocyte proliferation. NK cell activity was measured by lactic acid dehydrogenase release assay. The effects of tramadol on thermal hyperalgesia were also assessed by measuring paw withdrawal latency (PWL) in the rats. PWL was dose-dependently reversed by tramadol after acute treatment (single subcutaneous injection) with 10, 20, and 30 mg/kg, respectively. There was no significant change among acute treatments groups in NK cell activity, whereas splenocyte proliferation induced by ConA and PHA was significantly suppressed starting from a dose of 20 mg/kg. The reversal of the thermal hyperalgesia persisted throughout a period of chronic tramadol treatment of 40 and 80 mg/kg per day, respectively, with continuous subcutaneous infusion for 7 days at a uniform rate via osmotic minipumps. No modulation of NK cell activity was found in either dose group. However, the activity of splenocyte proliferation was decreased in the 80 mg/kg per day group when compared with the saline and 40 mg/kg per day groups. Suggest that tramadol treatment has an immunological profile different from pure μ-opioid agonists like morphine, which is known to suppress both NK cell activity and T lymphocyte proliferation at a subanalgesic dose in CCI rats. Conclude that tramadol treatment may be a better choice than morphine for treatment of chronic neuropathic pain, particularly in patients with compromised immunity.     

Activation of brainstem N-methyl-D-aspartate receptors is required for the analgesic actions of morphine given systemically. (Oregon Health Sciences University, Portland, OR) Pain. 2001;92:129–138.

This study was designed to characterize the contribution of N-methyl-D-aspartate (NMDA) and non-NMDA-mediated excitatory transmission within the rostral ventromedial medulla (RVM) to activation of brainstem inhibitory output neurons and analgesia produced by systemic morphine administration. The results highlight 2 important aspects of RVM pain modulatory circuits. First, morphine given systemically produces it analgesic effect at least in part by recruiting an NMDA-mediated excitatory process to activate off-cells within the RVM. This excitatory process plays a role in the analgesic synergy produced by simultaneous μ-opioid activation at different levels of the neuraxis. Second, reflex-related activation of on-cells is medicated by a non-NMDA receptor, and this activation does not appear to play a significant role in regulating reflex responses to acute noxious stimuli. Excitatory amino acid-mediated excitation, thus, has 2 distinct roles within the RVM, activating off-cells and on-cells under different conditions.