Neurogenic pain is defined as pain initiated or caused by a primary lesion, dysfunction, or transitory perturbation in the peripheral or central nervous system. Pain initiated or caused by a primary lesion or dysfunction in the nervous system is also called neuropathic pain. Postischemic pain is an example of neurogenic pain due to a transitory perturbation in the peripheral nerve. This is associated with abnormal burst discharges in primary afferent fibers, which may be due to two-stable states of axon membrane in high K⁺ environment. Carpal tunnel syndrome is an entrapment neuropathy. In the advanced stage of this syndrome, neuropathological changes responsible for pain are demyelinization, degeneration and regeneration of nerve fibers in the median nerve. Both demyelinated axons and sprouts of regenerating axons show spontaneous discharges and mechanosensitivity. Spontaneous discharges are due to accumulation of Na⁺ channels, and can be suppressed by Na⁺ channel blockers. Phantom limb pain is referred to a surgically removed limb or portion thereof. After amputation nearly all patients describe a persistent sensation of the missing limb (phantom limb). It is almost always associated with distorted image of lost part. Some patients additionally suffer from phantom limb pain. The neural networks for perceiving the body and its parts are built into the brain. Epidural anesthesia has been used for identifying whether the trigger for painful phantom is peripheral or central. If epidural anesthesia does not relieve chronic phantom limb pain, tigger mechanism is central; deafferentation of central neurons and their spontaneous and evoked hyperexcitability. Denervation hypersensitivity, damage to inhibitory mechanisms (disinhibition), glial neuronal interactions, and synaptic reorganization following collateral sprouting have been considered as possible mechanisms underlying hyperexcitability. Lesions anywhere along the course of the lateral ascending pain pathway (the spinothalamocortical pathway) can cause deafferentation pain. Neurons upstream in the spinothalamocortical pathway develop a state of hyperexcitability, when their major afferent input has been interrupted by a lesion. Hyperexcitable neurons discharge spontaneously in burst. The thalamic relay of this system is nucleus ventralis posterolateralis, and the somatosensory cortex receives painful impulses relayed through this thalamic nucleus. Local anesthesia or surgical removal of the somatosensoy cortex can only temporarily relieve phantom limb and deafferentation pains.

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Pathophysiological study of neck and shoulder pain was carried out using thermography, deep body thermometer and laser Doppler blood flowmeter. The examination with thermography revealed three different types of thermographs: cold group, intermediate group and hot group. The cold group indicated lower skin temperature of painful portion than that of the opposite painless portion. The hot group showed vice versa. In the intermediate group, it was almost the same (±0.3°C) as that of painless portion.
Most of the patients in the cold group had chronic history of pain, whereas most of the hot group had acute pain history. Subsequently, clinical pilot study on magnetotherapy was carried out under the double blind test. A static magnetic field was applied externally for this pain using the samalium-cobalt (Sm-Co) magnets (180m Tesla, 4.5mmφ×2.2mm). Dummy magenets (0m Tesla) were also applied at random as placebo. In the cold group, three measurable parameters (skin temperature, deep body temperature and skin blood flow) were monitored for 96 hours to investigate the response to magnetotherapy.
Significant pain relief was observed at 24 hours after the application of the active magnets. Skin temperature and deep body temperature increased significantly after 48 hours in the exposure to the active magnets. The highly significant increases of all of three parameters were observed after 72 hours. Until 24 hours after removal of the active and dummy magnets, these parameters showed no significant difference, between double blind test, whereas the pain relief was continued in the active magnets.
Therefore, the mechanism of healing of chronic ischemic pain to magnetic field exposure was suggested to be due to the increase of blood flow in microcirculation.

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Epidural spinal cord stimulation (SCS) was performed for pain control in twenty two patients, 14 males and 8 females with chronic intractable pain. These patients were followed for a period ranging from 3 months to 6.5 years postoperatively. At the time of their monthly visit, magnitudes of pain before and after stimulation were evaluated by using a visual analogue scale (VAS). As demonstrated by VAS, pain continued to decrease by more than 50 % in 12 of 22 SCS patients. In the 10 remainig patients the VAS indicated that pain decreased by 50% or less. In 6 of these 10 patients VAS decreased again by more than 50% after the positions of electrodes were re-adjusted, or replaced with new receiver or connective lead. However, in 4 of 10 patients SCS became ineffective. We demonstrated that SCS was reliable and safe for long-term use in the treatment of patients with chronic intractable pain without serious complications.

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Purpose: To determine the usefulness of Brachial Plexus Block (BPB) performed under fluoloscopy to alleviate cervical, shoulder and arm pain.
Materials and Methods: The brachial plexus was blocked following the subclavian approach in 100 patients who were treated at the Kanto Teishin Hospital Pain Clinic. BPB was performed with the patients in the supine position on the fluoroscopic table. One-direction radiographs of P-A views were taken after placing needles in the first rib and administering the contrast solution.
Results: Among the 59 patients with radiculopathy, an excellent effect was obtained in six and a good effect in 33 patients. As for the 41 patients without radiculopathies, an excellent effect was attained in 13 and a good effect in 23 patients. There was a significant difference between excellent groups and good+unchanged groups, and also between excellent+good groups and unchanged groups regarding the efficacy of BPB. Patients with radiculopathy were painless for 4.5±1.9 days after BPB, while those without radiculopathy were painless for 6.9±3.1 days after the treatment. The overall effectiveness ratio of BPB was 77%, and the ratio of BPB combined with Stellate Ganglion Block (SGB) was 81%.
Conclusion: BPB effectively alleviated pain in almost 75% of the radiculopathy cases; and patients were painless after BPB for various days. BPB was frequently combined with SGB, and it was possible that the effect of BPB was increased by SGB. BPB was significantly more effective in patients without radiculopathies than in those with radiculopathies, suggesting that the effectiveness of BPB will depend on the severity of clinical symptoms.

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Background: In the present study we examined an effect of superior cervical ganglionectomy on gastric ulcer formation in rats.
Material and Methods: Rats were classified into 4 groups: right ganglionectomy (RG) group, left ganglionectomy (LG) group, bilateral ganglionectomy (BG) group and control (C) group. Using indomethacin, alcohol or stress, gastric ulcers were induced in all rats; the ulcers were measured according to the ulcer index, and gastric secretion in all groups were measured. We also used immunohistochemical techniques to determine the numbers of sympathetic nerve in gastric mucosa.
Results: The ulcer index formed by indomethacin in the LG group was significantly less than that in the RS group, while in BG group it was significantly less than in RS and C groups. The ulcer index value formed by stress in LG group was significantly less than that in RG and C groups, while in the BG group it was significantly less than in C group. Gastric secretions were not different between all groups. Gastric mucosal neurofibers were reduced in LG and BG groups.
Conclusion: Superior cervical ganglionectomy results in a decrease in gastric ulcer formation induced by indomethacin and stress. This action may be caused by maintaining microcirculation in gastric mucosa.

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We have investigated the range and direction of the spread of the contrast medium in the epidural space, and the relation to age, height and weight analyzing from the epidurography. This study involved 197 patients who were subjected to the epidural anesthesia. Subjects were classified in four groups according to the position of the epidural catheter as follows; cervical, upper thoracic, lower thoracic, lumbar. After catheterization, 3ml of Iotrolan was injected into the epidural space through the catheter on 3 seconds, and radiographies were taken in supine and lateral position.
Following results were obtained. Radiopaque area in cervical region was most extensive, and decreased in the order of upper, lower thoracic, and lumbar region. Injected Iotrolan tended to spread to cranialis in cervical and upper thoracic regions, and in lower thoracic region, to caudalis in lumbar region symmetrically. There was only significant relationship (p<0.05) between age and radiopaque area in lower thoracic region.
We conclude that there are interesting characters of range and direction of the spread of contrast medium in each of the epidural space, and the radiopaque area increased with advancing age in only lower thoracic region.

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We investigated the effects of epidural analgesia and general anesthesia on the postoperative pain after laparoscopic cholecystectomy. Eleven patients (group E) received epidural anesthesia with mepivacaine during surgery followed by bolus epidural buprenorphine (3μug/kg) only. Another twenty-four patients were randomly allocated into two groups: Group EB (n=12) received epidural anesthesia with mepivacaine during surgery followed by continuous epidural buprenorphine (12μg/h) for 24 hours postoperatively; Group GB (n=12) received general anesthesia with isoflurane and received continuous epidural buprenorphine (12μg/h) for 24 hours postoperatively. At the end of the operation, all patients received epidural bolus administration of buprenorphine (3μg/kg). Postoperative pain score (VAS: Visual Analogue Scale) and supplemental analgesics (indomethacin suppository and pentazocine i. m.) use were compared.
The VAS values (mm: median [range]) at rest 24, 48, and 72 hours after operation were 8 (0-51), 7 (0-31), and 5 (0-25), respectively, for Group E, and 6 (0-21), 0 (0-21), and 0 (0-0), respectively, for Group GB. Those were all zero for Group EB. The VAS values at rest 24 and 48 hours after operation for group EB were significantly lower (p<0.01) than those for Group GB. The VAS values on movement, there was no significant different between Groups GB and EB at 24, 48 and 72 hours after operation. Ten of 11 patients (91%) for Group E and nine of the 12 patients (75%) for Group GB needed supplemental analgesics. On the other hand, only one of the 12 patients (8%) for group EB consumed supplemental analgesics (p<0.001).
We conclude that, although intraoperative epidural analgesia can reduce postoperative pain after laparoscopic cholecystectomy, pain relieving strategy should be taken at least during the first 24 hours after laparoscopic cholecystectomy even under intraoperative epidural analgesia.

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Two cases of patients with difficult pain relief in oral cavity, especially in tongue and palate were treated. Both case 1 and 2 had shown primarily organized disease in oral cavity and each disease considered to have the trigger of these pain disorders. There was, however, no obvious clinical changes in their oral cavities at our first examination. We performed the treatments of stellate ganglion block at the pain-dependent side and administration of psychoactive agents such as fluphenazine, amitriptyline and lorazepam. This combination therapy was successfully effective for these pain, although the pain was recured when this therapy was interrupted. Since when the treatments were restarted the prominent pain relief was obtained, this pain clinic has been continuing up to now for 20 months in case 1 and 9 months in case 2, respectively. Pain disorder in oral cavity called glossodynia involved several parts of psychosomatic diseases, and stellate ganglion block therapy accompanied with psychoactive agents might be effective for this type of pain disorders.

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Background: In some patients numbness in the leg is persistent and occasionally resists block therapy. In such cases we tried acupuncture therapy to relieve the numbness.
Patients and methods: Thirteen patients who complained of numbed leg or paresthesia and did not improve by nerve block therapy were performed acupuncture therapy. In the outcome, ‘excellent’ describes a decrease of the numbed area and improvement of consciousness, while ‘effective’ describes only improvement of consciousness.
Results: Acupuncture resulted in one excellent case and four effective cases.
Conclusion: Acupuncture may be an appropriate therapy for patients with severe numbness for whom block therapy is ineffective.

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While palliative radiation therapy is well-known to be one of the most useful therapy for cancer pain due to spinal-epidural metastasis, the radiation therapy is sometimes difficult to fulfill because of the intractable cancer pain per se. We experienced two cases with intractable cancer pain due to bone metastasis. When these cases were hard to start palliative radiation therapy because of the intractable pain, we treated with continuous intrathecal administration of lidocaine and morphine during the palliative radiation therapy. Excellent pain relief was obtained in all patients during and after the radiation therapy. Palliative radiation therapy combined with continuous subarachnoid analgesia is thought to be a useful therapy for the intractable cancer pain due to spinal-epidural metastasis.

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We reported a case of a 46-year-old female who had topographical change of the neck following bilateral neck dissection. She experienced the pain from the neck to the upper arm. We diagnosed the pain as reflex sympathetic dystrophy and we tried to perform stellate ganglion block (SGB) therapy.
We ascertained no neoplasm nor abnormal structure through the pathway of block-needle by ultrasonogram. Then we performed C6-SGB with local anesthetic and contrast medium. We got images by X-ray and CT scanning, and ascertained the effectiveness and safety of SGB therapy. The pain decreased to the pain, the patient could endure at the third treatment of SGB.

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We report our results on the management of indwelling epidural catheters in our out-patients over a three year period (from April 1992). Thirty-five out-patients (17 males and 18 females) were included in our study. Patients were able to visit our pain clinic daily, except on Sundays. The average age was 58 years old (range 18-82 years old). Their diagnoses were herpes zoster (n=29), lumbago or pain in the lower extremities (n=4), causalgia (n=1), and brachial plexus damage (n=1). Catheter was inserted into the cervical (n=8), the thoracic (n=19), or the lumbar (n=8) vertebral space. The average duration of the indwelling epidural catheterization was 41 days (range 2-351 days). Among those, three catheters had been indwelt for more than 100 days. The indwelling of the epidural catheters was discontinued because of the remission of the disease (n=20), the hospitalization (n=8), or the suspicion of a catheter-related infection (n=2). For the diagnosis of catheter-related infection, pains triggered by the local anesthetic injections into the epidural space were monitored on a six-days a week basis. The results may indicate that the long term out-patient management of the epidural catheterization is possible when early diagnosis of the infections is intensively monitored.

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