Inflammation is a defense response generated against invasion in order to maintain homeostasis, while pain is the sensation to avoid further damage and promote wound healing. Inflammatory pain often accompanies the chronic inflammatory state arising due to surgery, cancer, aging, and autoimmune diseases. Therefore, the approach towards inflammatory pain is to control pain without inhibiting inflammatory responses that are essential for defense. Since analgesics including nonsteroidal antiinflammatory drugs, opioids, and local anesthetics have immune-suppressive effects, their use may inhibit inflammation and delay the wound-healing process, further resulting in the development of chronic pain. Analgesics influence wound repair and can consequently lead to infections and progression towards cancer.

Transient receptor potential (TRP) channels are expressed in many different tissues and play pivotal roles in many physiological functions. TRPA1, which is predominantly expressed in peripheral nociceptive neurons, is one of the most studied nociceptor targets. TRPA1 is activated by a wide variety of exogenous irritants that cause acute pain and a range of inflammation-related endogenous mediators. Under inflammatory conditions, TRPA1 expression increases and its trafficking to the cell membrane is enhanced; thus, TRPA1 is suggested to be involved in inflammatory pain. Some anesthetics may worsen inflammatory pain by activating TRPA1, which should be considered in the clinical setting. TRPA1 expression in the spinal cord has been recently reported; unexpectedly, activation of spinal TRPA1 channels was found to relieve pain. Considering these findings, the development of a new generation of pain therapeutics targeting TRPA1 is warranted.

The treatment modality for failed back surgery syndrome (FBSS) is currently being researched. We evaluated whether a posterior sacroiliac ligament block could successfully alleviate sacroiliac joint (SIJ) pain in 64 patients with FBSS. The sequential changes in the numerical rating scale (NRS) were evaluated in out-patients, following the administration of a posterior sacroiliac ligament block. The duration of symptoms of FBSS, the sites of pain, and the type of surgery required were analyzed. Out of 64 patients with FBSS, 55 patients were diagnosed with SIJ pain. In 47 of these 55 cases (85.5％), the pain was relieved using a posterior sacroiliac ligament block alone. The average duration of the FBSS was 18 months. It was noted that 68.1％ of the patients complained of not only low back pain, but also leg pain. Greater than 50％ improvement in the NRS from the first block was observed in 53.2％ of patients. This study showed that a posterior sacroiliac ligament block may be effective in relieving FBSS pain, both as a diagnostic method and as treatment.

We present the clinical features of 58 cases in which an epidural blood patch (EBP) was performed after a diagnosis of cerebrospinal fluid leakage (CSFL) was confirmed by CT myelography (CTM). From December 2004 to February 2016, we retrospectively evaluated 58 cases of CSFL in terms of epidemiology, presence of orthostatic headache, subarachnoid hematoma, diffuse pachymeningeal gadolinium enhancement, number of EBPs required, amount of autologous blood injected into the epidural space, and whether patients were treated with fluoroscopy-guided EBP. CSFL occurs predominantly in women and is most common in patients in their late thirties. In this study, 79.3％ (46/58) of CSFL patients developed orthostatic headache. Subdural hematoma was found in 34.5％ (20/58) of patients and 13.8％ (8/58) needed a burr hole. At most, patients required 6 EBPs until their symptoms diminished (the median was two EBPs). In fact, 74.1％ (43/58) of patients completely recovered after two EBPs. The results of this report suggest that orthostatic headache and diffuse pachymeningeal gadolinium enhancement are common in CSFL patients, and fluoroscopy-guided EBP is an effective treatment method for CSFL.

A 35-year-old man presented with severe pain, numbness, and a cold sensation on the ulnar side of his fifth finger. Although cervical radiculopathy and cubital tunnel syndrome were initially suspected, thoracic outlet syndrome was diagnosed based on a provocation test and the observation of subclavian artery disruption by magnetic resonance angiography. As his activity was impaired due to oral administration of several analgesics, we reconsidered therapeutic treatment. His pain was alleviated with a stellate ganglion block; therefore, we diagnosed his pain as sympathetically maintained pain and performed a left thoracic sympathetic nerve block (TSB). After TSB, his pain was relieved almost completely, and oral analgesics became unnecessary. The patient's pain increased every 6–12 months, and the TSB has been repeated each time, for a total of 6 times, with good clinical results. We conclude that for sympathetically maintained pain caused by thoracic outlet syndrome, careful repetition of TSB may be useful for pain management.

A 76-year-old man presented at our institution, with a 6-year history of left trigeminal neuralgia, originally treated with carbamazepine. Although the drug had to be discontinued due to hypersensitive reaction, the patient's neuralgia resolved following administration of prednisolone. Recurrence of the trigeminal neuralgia occurred 2 years ago, and this was relieved by pregabalin. The patient presented this year with pain during conversation, swallowing, and chewing. However, pregabalin no longer relieved the patient's pain. On the basis of his symptomology, the patient was diagnosed with glossopharyngeal neuralgia. A brain magnetic resonance imaging scan showed that there was no contact of the blood vessels with either the trigeminal or the glossopharyngeal nerves. The patient was found to be suffering from a severe eating disorder, and carbamazepine was prescribed to be taken as needed. A few days later, there was improvement in the patient's pain, but systemic drug eruption had recurred. Despite the discontinuation of the carbamazepine, the patient's neuralgia disappeared following prednisolone pulse therapy, and it did not recur after the prednisolone therapy was terminated. We conclude that prednisolone pulse therapy represents a possible treatment modality in cases of refractory trigeminal or glossopharyngeal neuralgia.

Drug therapies for mucositis, such as stomatitis caused by radiotherapy for cancer, include anti-inflammatory drugs, gargling with local anesthetics, and pain medication such as nonsteroidal anti-inflammatory analgesics or narcotics. However, the effects of these treatments are not adequate. Radiotherapy is often interrupted due to the pain induced by mucositis, infections, or the deterioration of nutritional status which might directly affect patients' prognosis, thus creating a demand for new therapeutic drugs. In this study, we observed that patients diagnosed with symptoms of endoesophagitis and stomatitis caused by radiation therapy improved after treatment with the traditional oriental medicine Kikyo-to. The drug was administered to two patients, one with pulmonary adenocarcinoma and another with buccal mucosa cancer, and they were able to complete their radiation therapy. Kikyo-to is a herbal medicine composed of Platycodon root and licorice root, and it is reported that both Platycodon root and licorice root have anti-inflammatory and anti-ulcer effects. Kikyo-to is expected to provide a similar effect; therefore, it could be used as an effective supportive therapy for radiation-induced mucositis.

The present case study describes an 11-year-old boy, who presented with a 3-month history of right ankle pain and allodynia that developed after falling down while running at school. Following the investigation, a clinical diagnosis of complex regional pain syndrome (CRPS) was made. A pharmacotherapeutic agent, pregabalin, was administered at a low dose initially, which was subsequently increased. Additional treatment with mirror therapy and clonazepam was performed for complete recovery from allodynia. Over the period of three months, his condition gradually improved and no severe complications were observed. Moreover, during the follow-up period, symptoms recovered and there was no relapse. It is suggested that early diagnosis and management are the major factors for treating pediatric CRPS, and multidisciplinary treatment is recommended in such cases.

Many patients with autosomal dominant polycystic kidney disease (ADPKD) have some sort of pain, and a stepwise approach has been proposed as a management method for it. We managed the pain of an ADPKD patient who had combined multiple hepatic cysts. Since tramadol was effective for the pain, which was also relieved by an epidural block using a low concentration of a local anesthetic, we diagnosed that the pain was mainly derived from internal organs. We prescribed opioids and the pain was relieved. We need to pay attention to the possibility of an increase in renal cysts due to enhanced vasopressin action by opioids, but opioids may be effective for the visceral pain of ADPKD.

The clinical symptoms of complex regional pain syndrome (CRPS) sometimes extend to other limbs. We report on two patients who showed spreading of the pain from CRPS, which was treated by spinal cord stimulation (SCS). Case 1 was that of a man in his 50s. An SCS implant was placed in X−10 for pain in the left upper thigh that developed after trauma. In X−1, pain on the ipsilateral side was recognized and was thought to have been caused by spreading of the CRPS symptoms. Case 2 was that of a man in his 40s. After thoracic surgery in X−6, allodynia developed in the wound and the pain gradually expanded towards the back of the chest. Pain from the left buttock to the left foot appeared in X−1, which was thought to be an expansion of the symptoms of CRPS. SCS implantations in both cases resulted in pain improvement. In conclusion, SCS may be useful for alleviating pain due to spreading of CRPS.