Since pain is a subjective experience comprising unpleasant sensation and affection, the objective assessment of pain has been difficult. Recent brain imaging methods, such as functional magnetic resonance imaging (fMRI), positron emission tomography (PET), magnetic resonance spectroscopy (MRS), and voxel-based morphometry (VBM) have identified the brain regions involved in the pain-related neural network. Many noninvasive brain imaging studies have revealed that chronic pain patients have functional, chemical, and structural changes in different areas of the brain related to emotional and cognitive dimension of pain. We review the literature of brain imaging and latest knowledge regarding the central mechanism of pain.

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Neuropathic pain presents significant clinical problems. It has recently been reported that minocycline inhibited the activation of microglia, which plays an important role in neuropathic pain. We studied the effects of intraperitoneal (i.p.) administration of minocycline which has inhibitory effect on microglia to develop allodynia. Mechanical allodynia was induced by partial sciatic nerve ligation (PSNL) in mice and evaluated using a von Frey filament. Minocycline was administered daily before and after PSNL (pre-emptive and repeated administration), or only after PSNL. Expressions of microglia and astrocytes in the spinal cord were examined by immunohistological and western blotting analyses. Pre-emptive and repeated administration of minocycline prevented PSNL-induced development of allodynia. In addition, treatment with minocycline after PSNL partially attenuated allodynia. Immunohistological and western blotting analyses showed that microglial proliferation in the ipsilateral side was inhibited by pre-emptive and repeated administration of minocycline. The behavioral and histochemical results suggest that minocycline is a potentially effective therapeutic strategy for management of neuropathic pain.

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The author reports a patient who complained of persistent pain, dysesthesia, and swelling of the lower limb after traffic accident and was treated with lumbar sympathetic ganglion block. A 64-year-old man was suspected of being malingering. However, detailed history taking and precise physical examination suggested that the patient was suffering from complex regional pain syndrome. Repeated nerve blocks and active mobilization of the limb by the patient improved the pain. Lumbar sympathetic ganglion block performed 9 months after the accident markedly improved the pain and dysfunction.

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We report a patient with infrapatellar fat pad syndrome causing pain in the lower limb who could not walk due to the pain. An 81-year-old man had pain in the extensor aspect of the thigh and the knee on the right. Magnetic resonance imaging (MRI) performed at another hospital showed the presence of a herniated lumbar disc at L3/4. L3 nerve root block and repeated caudal blocks did not alleviate the pain. MRI of the knee suggested a degenerated lateral meniscus. He received repeated intra-articular injections of a local anesthetic, which did not lessen the pain. He was referred to us because the pain did not improve and he could not walk due to the pain. The pain was 83 mm on a visual analog scale of pain. The right quadriceps femoris was atrophied. There was marked tenderness along the edges of the muscles and around the knee joint. There was no sensory impairment over the right thigh. Since the pain began in the knee and there was marked tenderness around the knee, in?ammation of the infrapatellar fat pad was suspected. Injection of 1% mepivacaine 3.5 ml with betamethasone 2.5 mg into the infrapatellar fat pad promptly relieved the pain and he became to be able to walk. Thereafter, injections of a local anesthetic with a steroid were repeated three times. The pain almost disappeared. The atrophied right quadriceps femoris gained muscle bulk after daily exercise of the thighs.

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Glossodynia is a disorder characterized by burning sensation on the tongue in the absence of any other clinical signs or mucosal lesions. Although psychological factors may play a significant role, the etiology is still unclear. We report a patient with glossodynia whose pain was improved by Yokukansankachinpihange. An 82-year-old man developed brain infarction 4 years before. Pain in the tongue occurred 1 year after the brain infarction. There were no apparent lesions in the oral cavity. He was referred to us for treatment of the pain. The initial examination revealed he had gait disturbance due to brain infarction, and complained of epigastric distress and irritation. He was also anxious about pathology of the tongue. Yokukansankachinpihange was administered at a dose of 7.5 g/day according to his "Sho." The pain improved and the painful area became almost half 7 days after starting Yokukansankachinpihange. Correct selection of medicine based on "Sho" is essential for the treatment of long-standing intractable glossodynia.

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We report a patient who developed syndrome of inappropriate secretion of antidiuretic hormone (SIADH), which may have been caused by carbamazepine. A 75-year old woman with idiopathic trigeminal neuralgia had been treated with carbamazepine and repeated right mandibular nerve blocks. Since the pain could not be controlled with carbamazepine 600 mg/day, she was admitted for mandibular nerve block. The pain worsened on the day of admission. Carbamazepine 100 mg was taken. She became anxious and complained of general malaise, nausea, and headache. Laboratory examination revealed that the concentration of serum sodium was 119 mEq/L. There were low urine output, low serum osmolarity, and high urine osmolarity, suggesting carbamazepine-induced SIADH. Carbamazepine was withdrawn, and water intake was restricted. The serum sodium concentration increased to 135 mEq/L on day 8. Thermocoagulation of the right mandibular nerve relieved the pain. Carbamazepine-induced SIADH is rare but needs attention. When carbamazepine cannot be taken for the treatment of trigeminal neuralgia because of its side effects, treatment with thermocoagulation may be beneficial to control trigeminal neuralgia.

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We report a child with abdominal migraine who presented with odontalgia. A 14-year-old boy developed pain in the right mandibular molar tooth and received pulpectomy. However, the pain did not improve. Computed tomography scan of the brain did not reveal abnormality. He was referred to our department. He complained that the pain was in the right maxillary and mandibular molar teeth. The pain occurred one to two times in the morning and night, lasting 2-3 hours. Precise history taking revealed there were scintillating scotomas before the onset of tooth pain accompanied by nausea, photophobia, and lacrimation. The pain and lacrimation disappeared after oral medication with zolmitriptan 2.5 mg in 10 minutes. He was referred to a headache specialist who noted that the child had had repeated bouts of upper abdominal pain and nausea and vomiting. He was diagnosed as having abdominal migraine.

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We report a patient with intractable ulcer in the left fingers whose pain was relieved by repeated stellate ganglion blocks (SGB). A 77-year-old woman had developed paresthesia and pain of the hands for 1 month. She received thermal therapy, medication with Gosya-jinkigan, vitamin E, and intravenous vasodilator. However, the symptoms did not improve. The left fingers II and III became necrotic. She was referred to our hospital. Laboratory examination did not show any positive results for collagen diseases, thrombosis, or angiitis. Stellate ganglion block on the left and contralateral laser radiation to the lower neck aiming at stellate ganglion were performed. The pain lessened after the first stellate ganglion block and the color of the fingers improved in 1-week treatment. The finger ulcers gradually changed to granulation tissue, and the pain improved markedly in 1-month treatment. The pain in the fingers disappeared in 3-month treatment. The granulation tissue epithelized after 4 months. Repeated stellate ganglion blocks are effective in some selected patients with ischemic ulcers of the fingers.

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The committee on Safety in Japan Society of Pain Clinicians sent a questionnaire on patient safety to all Board Certificated Training Facilities in Japan (307 facilities) in February 2009. One hundred ninety-seven facilities (64%) responded. The results were as follows. Incidents were experienced by 103 of 191 respondents (54%) in the previous year. Troubles with patients despite no adverse events were experienced by 65 of 192 respondents (34%) in the last 10 years, and half the respondents experienced violent or unreasonable behaviors of the patients. Although measures for patient safety were fully or almost taken in 61% of the facilities, adverse events, such as infection, pneumothorax, nerve injury, and respiratory arrest, occurred in 101 facilities (52%). Twenty percent of the respondents were faced with legal actions for the adverse events. Precise informed consent was the most predominant view for the prevention of troubles with patients and poor relationship with patients was the most probable factor for disputes. Previous surveys of safety in pain treatment revealed accidents and troubles associated mainly with nerve blocks. The present survey indicated frequent occurrences of adverse events in pain clinic practices. It is essential to create good relationships between medical staff and patients so as to facilitate effective treatwents.

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