Causalgia is caused by nervous system lesions. Here, we present recently accumulating data about the contribution of the dorsal root ganglion neurons spared from direct injury to the pathomechanisms of causalgia. The phenotypic changes in the spared neurons are similar with those in the neurons in peripheral inflammation models, as opposed to those in the directly injured neurons. Electrophysiological changes also favor the contribution of the spared neurons. On the other hand, the injured A-fiber neurons also can cause sensitization of the secondary neurons in dorsal column nucleus, and modulate nociceptive input to the thalamus. These attractive targets of study will give us new approaches for understanding the abnormal pain.

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Neuropathic pain results from injury to neural structures within the peripheral or central nervous systems. Such injury promotes spontaneous and ectopic firing of nerves as well as reorganization of the nervous system. Neuropathic pain persists chronically. Patients who suffer from neuropathic pain exhibit persistent or paroxysmal pain without apparent immediate cause or pain hypersensitivity after tissue damage. This hypersensitivity is manifest as hyperalgesia and allodynia. Complex regional pain syndrome, CRPS is a category of neuropathic pain and is further divided into type I (reflex sympathetic dystrophy, RSD) and type II (causalgia). CRPS is characterized by localized autonomic dysregulation in the affected area with vasomotor and/or sudomotor changes, edema, colour difference, sweating abnormality, and atrophy.

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Osteoarthropathy is often seen in patients with complex regional pain syndrome (CRPS). The bone pathology is usually accompanied by inflammatory tissue changes that include edema, tenderness, pain, increased temperature and decreased range of motion in the affected joints. The bone pathology seems to share the same underlying mechanisms that occur in Sudeck's bone atrophy and Charcot joints. Recent development of molecular biology in bone metabolism may help understanding the underlying mechanisms of the bony changes. We discussed possible mechanisms to elucidate the bone pathology seen in CRPS. Neuropeptides released from sensory and sympathetic nerves are possible candidates to induce the osteoarthropathy. Cytokines released after tissue injury are other possible candidate to induce the osteoarthropathy. In addition, immobilization itself is also a possible cause to activate osteoclasts and subsequent osteoporosis. Further studies to elucidate the bone pathology associated with CRPS are extremely important for understanding the pathophysiology of CRPS and for its proper treatments.

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Objective: The purpose of this study was to investigate the effects of polarized light irradiation around the stellate ganglion (SG) area on temperature and blood flow in the hand and head.
Methods: Twenty healthy adult volunteers (10 males, 10 females) were enrolled in a double- blind, crossover and placebo-controlled study after institutional approval and informed consent were obtained. Each volunteer received irradiation for 7 minutes at 80% and 0% (placebo) power on separate days in a randomized fashion. Room temperature, deep temperature of the hands, surface temperature of their middle fingers, blood flow in the thumbs, temperature of tympanums, blood flow in the middle brain artery, and oxygen saturation of the forehead were measured continuously from 15 minutes before to 30 minutes after irradiation. The values of parameters were collected for statistical analysis before, immediately after (7 minutes) and 30 minutes after the irradiation.
Results: No significant changes of measured parameter were observed by the irradiation.
Conclusion: Polarized light irradiation around the SG area had no effect on temperature or blood flow in the hand or head in healthy adults.

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We retrospectively ivestigated the effect of neural block with local anesthetics on post-herpetic neuralgia (PHN) in 6 patients. The regions of herpes zoster were the ophthalmic nerve area in 3 patients, cervical nerve area in 1 patient and thoracic nerve area in 2 patients. The interval between the onset of herpetic pain and the begining of neural block was longer than 1 year. The mean interval was 31.5 months. The mean follow-up period was 19 months. These patients received stellate ganglion block or epidural block once or twice a week in the first 1-2 months. After that the frequency of neural block was gradually decreased in each case. They were simultaneously administered amitriptyline 10-20mg/day from the beginning of the treatment. Remarkable pain relief was obtained in five of the six cases in four weeks. It has been reported that neural block has little effect on established post-herpetic neuralgia. However, appreciable pain relief is possible by neural block with local anesthetics accompanied by oral amitriptyline, even in patients suffering from herpetic pain for over 1 year.

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We examined the effect of supplementary administration of morphine hydrochloride to spinal anesthesia on the tenesmus after transurethral resection of the prostate. Forty-four patients were divided into a control group (n=20) and a morphine group (n=24). In the control group, 2.5 or 3ml of dibucaine hydrochloride was administered to the spinal subarachnoidal space through a Quincke Badcock type spinal needle inserted between L3/L4 or L4//L5. In the morphine group, 0.1mg morphine hydrochloride injected into the 2.5 or 3ml dibucaine hydrochloride was given to cerebrospinal fluid with the spinal needle. The tenesmus was significantly relieved for 24 hours following operation in the morphine group compared to the control group (P=0.039), and the required amount of NSAIDs suppository per patient body weight was significantly decreased in the morphine group (P=0.034). No adverse effects except skin itchiness and constipation were observed. Compared with other anesthetic means such as epidural anesthesia, supplementary administration of morphine hydrochloride to spinal anesthesia was easy to achieve and very effective on the tenesmus after transurethral resection of the prostate.

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It has been suggested that bleeding time is predictor of abnormal bleeding in patients receiving antiplatelet therapy, but Duke bleeding time does not show actual platelet function. To assess platelet function in patients receiving aspirin, we analysed the Sonoclot signature in 12 patients taking aspirin. The peak signature was unclear in 5 of 12 patients with aspirin, and time to peak was prolonged in 1 patient There is a possibility of platelet dysfunction in patients receiving aspirin with normal Duke bleeding time, and Sonoclot is a useful monitor to detect platelet dysfunction.

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Anterior uveitis and keratitis frequently occur in patients with herpes zoster opthalmicus. Three cases of herpes zoster opthalmicus with eye complications are reported. A 77-year-old man with chronic renal failure was treated with vidarabine and stellate ganglion block from the 2nd day after the occurrence of skin eruption. On the eighth day after the onset, corneal ulceration and uveitis developed. A 55-year-old woman without underlying disease was treated with acyclovir and stellate ganglion block from the 2nd day after the start of local pain and skin eruption. On the eighth day after the onset, corneal edema and uveitis were noted. A 68-year-old man without concurrent disease received acyclovir and stellate ganglion block since the 10th day after the start of local pain and skin eruption. On the 15th day after the onset, superficial corneal inflammation and uveitis with precipitation developed and worsened during the following five days. The eye complications in the first and the second cases improved after anti-viral and anti-bacterial treatments. In the third case, ocular symptoms did not worsen. Careful observation of the eye is important in patients with herpes zoster involving the first branch of the trigeminal nerve.

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A 55-year-old man underwent mitral valve replacement. After recovery from anesthesia, he developed cardiac arrest and was successfully resuscitated by the use of a percutaneous cardiopulmonary system (PCPS) via the right femoral arterial and venous cannulations. Following recovery of consciousness, he complained of paralysis and severe pain in the left leg. A computed tomographic scan of the abdomen demonstrated a hematoma in the left psoas muscle. Surgical evacuation of the hematoma was not indicated because of unstable hemodynamics and necessity of anticoagulant therapy for the artificial valve. He was treated conservatively including analgesics and neurolytic lumber sympathetic block. However, the effects of these therapies on the pain were minimal and severe pain was persistent. The hematoma had disappeared two month later but severe pain and paralysis of the left leg remained. At present, one and a half years later, he is taking oral morphine sulfate (MS contain^TM) 450mg/day for control of the pain.
Nerve blocks for pain control of iliopsoas hematomas are difficult because hematomas commonly result from coagulopathy or anticoagulant therapy. This case suggests that surgical evacuation of iliopsoas hematomas should be considered when severe pain is persistent.

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There are few reports concerning epidural abscess following a single epidural block without catheter. In the case reported here, a single epidural block was considered to be involved in the etiology of lumbar epidural abscess and discitis. A 74-year-old man was diagnosed with lumbar spinal canal stenosis combined with radiculopathy and received a single epidural block once a week. After the 5th epidural block, he had progressive back pain and fever without neurologic deficits. MRI examination showed a subcutaneous and epidural mass behind the L₄ vertebral body and L_4/5 discitis. Antibiotic therapy was initiated immediately and emergency surgical decompression (laminectomy) was performed. Intraoperative findings showed discitis and liquid pus in the ventral epidural space. Culture of the pus and blood revealed staphylococcus epidermidis. He could walk independently without complication in 1 month after surgery. A single epidural block repeated through same route may cause epidural abscess.

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Epidural hematoma, abcess and catheter migration are well known complications of epidural catheterization.
We report a 23-year-old female patient who underwent surgical intervention to remove a knotted epidural catheter.

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The patient was a 39-year-old man. His chief complaint was pain in the lumbar region and in both legs. At the age of 36, he had an operation for lumbar disk hernia (L_3-4-5) to treat lumbago and numbness of both legs. Eight months after total spinal anesthesia, he suffered from sharp lumbar pain again, so he consulted an orthopedic surgeon. At that time, CT and MRI in the lumbar region and blood laboratory examination showed no remarkable findings to explain the causes of the pain. He was referred to a psychiatrist and finally to our pain clinic. Epidural nerve block and other conventional conservative therapy failed to achieve satisfactory pain relief. Psychological examination revealed that there were some evidence for pain disorder. Three consecutive m-ECT (modified electroconvulsive therapy), once a week for three weeks, was planned for him. After the first m-ECT, dramatic improvement was obtained for 3 days. Although the second m-ECT showed little effect, sharp pain disappeared almost completely after the third m-ECT. He has been enjoying daily life for more than 12 months since the third treatment without medication. We conclude that ECT may be an alternative treatment for patients with pain disorder.

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