Opioid analgesics are usually prescribed for patients being treated in the pain clinic. However, opioids have undesirable effects such as physical and psychological dependence. To avoid causing drug dependence, we should understand the strategies for use and the risks of these drugs. Although the mechanism of psychological dependence on drugs of abuse is very complex, it is well established that the mesolimbic dopaminergic system, projecting from the ventral tegmental area of the midbrain to the nucleus accumbens, is the critical substrate for psychological dependence on drugs of abuse. However, various studies provide evidence that noradrenergic transmission originating from the locus coeruleus is most likely to play the primary causal role in the expression of physical dependence on morphine. In addition, there is considerable evidence suggesting that GABAergic and glutamatergic systems may also contribute to the development of physical dependence on drugs of abuse. This review attempts to summarize some of the mechanisms underlying the development of dependence on drugs of abuse in the pain clinic and the prevention of psychological dependence on opioids under the condition of chronic pain.

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The postoperative pain of vaginal total hysterectomy (VTH) is thought to be comparatively less because the transvaginal approach does not involve abdominal skin wound. However, we often find it difficult to control postoperative pain following VTH. We conducted a case-control study to elucidate the efficacy and safety of continuous epidural analgesia after VTH. A total of 128 patients who underwent VTH at two institutions between January 2002 and August 2004 were recruited. Patients were classified into the two groups: one that had received combined continuous epidural analgesia and spinal analgesia (E group) and one that received spinal analgesia only (S group). We compared the numbers of analgesic agent given, the time until the first time administration of analgesic agent, visual analogue scale (VAS), Prince Henry pain scale (PHPS), the region of the pain and side effects in these two groups. The E group required a significantly lower amount of analgesic agents compared to that of the S group (1.8 vs. 3.7, p<0.05). The postoperative continuous epidural analgesia is significantly advantageous with regard to other factors such as VAS and PHPS. The postoperative pain of VTH can be unexpectedly serious, therefore the postoperative continuous epidural analgesia is useful to provide stable postoperative analgesic effects.

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Purpose: This study was performed to determine whether we could predict treatment effect and analyze disease period from their relation with Hospital Anxiety and Depression Scale (HAD).
Methods: The Hospital Anxiety and Depression Scale (HAD) was evaluated at pain patient's first visit to the Pain Center at Aichi Medical University Hospital. The score was compared with the length of the delay between the onset of symptoms and patient's first visit to the Pain Center.
Results: Fifty patients (men=25, women=25, mean age=57.1±18.8 years)were studied, 14 herpes zoster pain, 11 lumbago and lower limb pain, 9 shoulder and neck pain, 7 neuralgia, and 9 others. The results of treatment were as follows: 10 showed excellent improvement, 15 mild improvement, 16 no change, 0 worse, and 9 unknown. There was neither a relationship between HAD and treatment results, nor a relationship between HAD and the length of delay in attending the Pain Clinic.
Conclusions: The results of this study may not indicate intractable pain and longer delayed visits to health care in pain patients with higher HAD.

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Introduction: An arthroscopic rotator cuff repair is frequently accompanied with severe postoperative pain. In this study, we evaluated postoperative analgesic effects of combined intra-articular treatment with ropivacaine and morphine in patients who had arthroscopic rotator cuff repair under general anesthesia.
Methods: Thirty-nine patients who underwent an elective arthroscopic rotator cuff repair were randomly divided into 3 groups according to intra-articular administration of drug after the end of surgery. Group A (n=12) received 10ml of 0.5% bupivacaine and 0.1ml of normal saline. Group B (n=14) received 10ml of 0.75% ropivacaine and 0.1ml of normal saline. Group C (n=13) received 10ml of 0.75% ropivacaine and 1mg of morphine. The effectiveness of each drug was measured by a visual analogue scale (VAS) and the amount of buprenorphine consumption at 0.5, 1, 2, 4, 6, 12, and 24hrs after surgery.
Results: The [median(range)] values of VAS in groups B [25mm (0-80mm)] and C [20mm (0-60mm)] were significantly (p<0.05) lower than those in group A [45mm (10-100mm)] at 24hrs. The amounts of buprenorphine consumption in group B [0mg (0-0.2mg)] and group C [0mg (0-0.2mg)] were also significantly (p<0.01) less than that in group A [0.2mg (0-0.3mg)] at 6-24hrs. There were no significant differences in VAS and buprenorphine consumption between groups B and C.
Conclusions: An intra-articular administration of ropivacaine is useful for postoperative analgesia in arthroscopic rotator cuff repair, while the combination of ropivacaine and morphine does not show any enhancement of the effect.

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Isolated facial nerve paralysis is rarely the result of metastasis. We report a case of facial nerve palsy secondary to metastatic lung cancer to the temporal bone. A 62-year-old woman presented with acute-onset facial nerve weakness with facial pain on the right side. She also complained of right temporal pain and left shoulder pain. At the time of presentation with facial weakness, hearing and lacrimation were grossly intact. Taste was slightly impaired. She had low-grade fever and laboratory findings demonstrated leukocytosis (12, 500/μl) and elevated CRP (13.7mg/dl). Chest X-ray demonstrated lung tumor. After further examination, the patient was diagnosed as having squamous cell carcinoma of the lung with bone metastasis to the temporal bone. Isolated facial nerve palsy as a consequence of metastatic disease involving the temporal bone is rare. Although progressive, unilateral, peripheral facial nerve paresis over weeks is strongly suggestive of neoplasm, the sudden onset of peripheral nerve paralysis, as in our patient, does not exclude the diagnosis of tumor. It is therefore, imperative to consider the possibility of a malignant neoplasm in patients with atypical symptoms.

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We encountered a case of compression neuropathy of the superficial peroneal nerve caused by elastic stocking used during the perioperative period. A 45-year-old woman with ovarian tumor underwent a transabdominal hystrectomy under combined general and epidural anesthesia. The entire anesthetic course as well as surgery was uneventful. On the 55th postoperative day, she was referred to our pain clinic due to numbness of the left ankle. Pressure marks and pigmentation was noted surrounding the left ankle. There after, it was found out that the morning after the operation, a tight hole at the toe of the elastic stocking had slipped and risen, creating strong pressure on the left ankle.
Since pain observed along the pressure mark region paralleled the course of the superficial peroneal nerve, compression neuropathy caused by elastic stocking was suspected. With oral administration of vitamin B₁₂ for one month, her symptoms improved.

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Central post-stroke pain (CPSP) is often difficult to treat. We report a case of intractable pain of the extremity and orbit due to the vascular lesion of the thalamus which was successfully treated by cervical epidural spinal cord stimulation (SCS).
A woman in her sixties had been surgically treated for right intracerebral hemorrhage 4 years previously. Three month thereafter, she developed left hemiparesis. Three weeks afterthat, she developed right hemiparesis, which was followed by intractable burning pain and allodynia of the right arm, right leg, and right orbit. Computed tomography in December 1998 demonstrated a low density area at the right temporal lobe and putamen. Regional cerebral blood flow using single photon emission computed tomography on November 1998 demonstrated a low blood flow area in the bilateral thalamus.
On September, 2002, she was referred to our clinic for severe pain with a visual analog scale (VAS) of 100/100. Result of drug challenge tests with lidocaine, thiamylal, morphin and ketamine, showed that only ketamine could alleviate her pain. Because of nausea, she refused intravenous ketamine treatment. SCS at the level of the cervical epidural space was tried, which successfully decreased her pain to a VAS range of 20/100-30/100.

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Pamidronate, which strongly suppresses osteoclast-induced bone resorption, was effective for an intractable CRPS type I case. The patient was a 30-year-old woman who had injured her left ankle in a traffic accident, and developed CRPS type I 8 years ago. Her symptoms were refractory to conventional therapies, including nerve blockades, lumbar sympathetic blockade, spinal cord stimulation, and physical therapy. She was treated by an intravenous administration of pamidronate, and the VAS decreased and ROM improved.

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We report three cases which demonstrated the efficacy of oral paroxetine, a selective serotonin reuptake inhibitor (SSRI), in relieving chronic lumbago and lower limb pain.
The first case was a 64-year-old man who fell from a tree, sustaining a comminuted fracture of the first lumbar vertebra (LI) with paresis of both lower extremities. He was treated with anterior spinal fusion using bone grafts obtained from the ilium, and suffered postoperative chronic pain in his right leg and both feet. His chronic pain was alleviated after several caudal blocks were performed and oral paroxetine 10mg day was administered. His pain was further alleviated when paroxetine was increased to 20mg day.
The second case was a 65-year-old man with chronic lumbago and pain of both lower extremities due to L4-L5 and L5-S1 disk herniation and degenerative spondylolisthesis of L5. His chronic pain was not alleviated after epiduroscopy and caudal blocks were performed. Oral paroxetine 10mg/day was administered. His pain was further alleviated when paroxetine was increased to 30mg/day. Erectile impotence occurred as a side effect of paroxetine.
The third case was a 74-year-old man with right lumbar pain and lower limb pain due to lumbar canal stenosis at the level of L4-L5. His chronic pain was alleviated by oral paroxetine 20mg/day. As hypomnesia and amnesia sometimes occurred as a side effect of paroxetine, oral paroxetine was discontinued. However, his severe pain recurred, and oral paroxetine 20mg/day was restarted.
As all cases were old men, we administered paroxetine and did not administer tricyclic antidepressants with side effects of anuresis. These cases suggested the efficacy of paroxetine in relieving chronic lumbago and lower limb pain that are associated with depression dosedependently. Erectile impotence, hypomnesia and amnesia might occur as side effects of paroxetine.

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Epiduroscopy, which was reported by Saberski and Kitahata in 1995, has been performed in cases with chronic low back pain and lower limb pain resistant to various drug therapies and various kinds of nerve blockades. We experienced more than 100 cases of epiduroscopy and first revised an information and consent sheet on epiduroscopy at The University of Tokyo in June 2004. In describing some accidental complications, we included boring pain, high intracranial pressure, dural puncture, nerve injury, infection, hemorrhage, allergy, and heart, lung, brain, liver, and kidney failures in the information sheet. Concerning the outcome of epiduroscopy, we wrote that the rate of aggravated cases was 4%. However, the rate of each accidental complication was not given in detail and accidental complications were not classified into during and after epiduroscopy. We experienced some cases of boring pain, low back pain, lower limb pain, headache, posterior neck pain, hypertension, and tachycardia during epiduroscopy, and two cases of headache, and posterior neck pain, and one case of intrathecal block through dural puncture, consciousness disturbance, and rhabdomyolysis after epiduroscopy. We could refer to the accidental complications in the epidural block. Further, we should inform the patients that accidental complications not previously-experienced might occur, because epiduroscopy is a new medical therapy. Then, we secondly revised an information and consent on epiduroscopy in May 2005. We should investigate the outcome and complications on epiduroscopy in multiple facilities and provide patients with useful information.

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