Chronic postsurgical pain (CPSP) is a serious surgical complication that can impair patient quality of life. Understanding the pathology of CPSP is challenging because CPSP is induced by a complex mechanism that involves surgical, individual, psychological, and social–environmental risk factors. Although previous studies have reported the effects of various interventions (preventive analgesia, nerve blockade, and surgical approach), further studies are needed for the development of an optimal CPSP treatment. A simple evaluation and multiple pain evaluations that involve psychological factors and quality of life assessments are necessary. We recently conducted a study that objectively evaluated the risks and pathological conditions associated with CPSP using advanced methods, which included genetic technologies and magnetic resonance imaging.

Tramadol is currently widely administered to patients with chronic pain. We investigated dose, visual analogue scale (VAS), and side effects in cases where tramadol was administered for 3 years or more at our pain clinic center. Tramadol was prescribed in 2,656 cases, and in 50 cases, it was continuously administered for above 3 years (average patient age: 61 years; back pain: 24 cases; upper limb pain: 14 cases; lower extremity pain: 7 cases; post herpetic neuralgia: 4 cases; other: 1 case). Initial VAS score was 70.7 mm; it decreased to an average of 40 mm or less after 3 months. Major side effects included dizziness, somnolence, malaise, nausea, vomiting, and constipation; the incidence of these within the first 3 months was high. There were no serious adverse effects due to the continuous administration of tramadol for above 3 years. Tramadol can be administered in the long term if used carefully while observing the patient.

Patients with chronic pain often complain of daytime sleepiness (DS) due to night pain, sleep disturbance, and the adverse effects of analgesics. DS is associated with cognitive decline and creates a daily burden on the patient. We investigated DS in 100 outpatients with chronic pain via a questionnaire. The visual analogue scale (VAS) for DS was utilized, and patients were divided into two groups based on the score: group A, VAS＜50 and group B, VAS≧50. We compared the two groups and verified the risk factors for DS using logistic regression analysis. VAS score in group B (n＝62) tended to be greater than that in group A (n＝38). Patients with chronic pain had DS and insomnia. The risk factors of DS were postherpetic neuralgia, prescription of three or more medicines, and complication of mental illness. These patients should be paid close attention in clinical practice.

Little is known about the factors that influence opioid dose in the treatment of cancer pain. Therefore, the objective of this study was to identify predictors for opioid dosage in patients with cancer. Data were obtained from the electronic medical records of patients with cancer at Niigata University Medical and Dental Hospital from January 1, 2009, to December 31, 2014. Patients were included if they were cared for by a palliative care team and prescribed opioids from the beginning of care until their death. A total of 109 patients were classified into three groups. Patients in group A (n＝51; 46.8％) were prescribed ＜120 mg of oral morphine equivalent (OME), those in group B (n＝33; 30.3％) were prescribed 120–300 mg of OME, while those in group C (n＝25; 22.9％) were prescribed ≧300 mg of OME. Young age, long-term opioid use, rapidly increased opioid dose, and malignant invasion of the nerve independently predicted high opioid dose. Further studies are needed to improve understanding of the factors associated with high-dose opioid use in cancer pain.

We evaluated the effects of a topical menthol cream, containing a TRPM8 channel agonist, on sensitivity to mechanical and electrical stimuli. An over-the-counter menthol cream was applied to the ulnar nerve area of the forearms of 80 healthy volunteers. Participants were stimulated with a pinprick and received an electrical non-noxious or noxious stimulus with a PainVision^® (Nipro Co., Tokyo, Japan). We evaluated visual analogue scale (VAS) scores for responses to both stimuli, the perception threshold, and the pain threshold current that was induced by PainVision^® electrical stimulation before and three minutes after menthol cream application. The topical menthol caused no VAS score changes for pinprick and perception threshold currents. However, the pain threshold current significantly decreased, by a mean of 19.2％ (95％ CI: 18.6–19.8, P＜0.001), and its rate of change and the pre-application pain threshold were negatively correlated (r＝−0.39, P＜0.001). Subjects with higher pain thresholds tended to experience greater hyperalgesic effects. We conclude that menthol causes hyperalgesia upon electrical stimulation, especially in subjects who are less sensitive to pain.

At our pain clinic, malignancies were discovered during initial examinations in 13 patients over a period of six years. We retrospectively investigated the chief complaints, malignant disease types, and processes that led to the diagnoses. Ten of the 13 patients had been referred by other departments or facilities. The chief complaint was pain caused by herpes zoster in four patients and malignant tumors or metastases in nine. The median period from the appearance of symptoms to initial presentation to our pain clinic was 35 days, and the median period from the first visit to diagnosis was one day. Diagnostic imaging detected malignancies in 10 of the 13 patients, and seven of the 13 patients underwent imaging assessments on the examination day. Our results suggest that if malignant disease is suspected owing to physical and laboratory findings, it is important to take the initiative to plan careful examinations for ensuring accurate diagnosis in pain clinics.

The authors encountered a case in which administration of venlafaxine alleviated depressive symptoms and neuropathic pain in a patient with low back pain. This case involved an 83-year-old woman with low back pain who was transferred to our Department. Upon transfer, pain and depression were noted. The patient was administered pregabalin and tramadol, but depression and neuropathic pain remained. Venlafaxine was then administered, and depression and neuropathic pain were alleviated. The current case suggests that venlafaxine is efficacious in treating depressive symptoms and neuropathic pain in patients with chronic pain.

Pulsed radiofrequency (PRF) stimulation is a therapeutic modality with many potential applications in pain management. Here, this was demonstrated in a patient with costal cartilage trauma. The patient was a professional athlete in his 20s who had damaged his costal cartilage during training. He could not perform his routine activities because of pain associated with movement, particularly during the initial motion. Five days after the injury, PRF was applied to the intercostal nerves using the ultrasound-guided, electrical-stimulation method and an in-plane needling technique with a microconvex probe. The patient's pain was reduced, and he could perform his normal activities. In many cases of costal cartilage trauma, treatment is conservative. Consequently, patients endure pain associated with movement until they fully recover. Since PRF has a low risk of causing nervous tissue denaturation, it is an effective treatment for the nociceptive pain associated with costal cartilage trauma, and is also likely to be safe and advantageous in length of the effect time.

We report on two patients with single dermatomal herpes zoster ophthalmicus (HZO) who developed electrolyte abnormalities. Case 1 involved a 75-year-old woman admitted for the treatment of HZO pain that she had been experiencing for 1 month. Blood tests revealed hyponatremia (119 mEq/ℓ) and hypokalemia (2.6 mEq/ℓ). Case 2 involved a 74-year-old man who had developed HZO with pain lasting for 2 weeks; his blood examination revealed hyponatremia (127 mEq/ℓ). Further investigation in both cases suggested that hyponatremia was caused by the syndrome of inappropriate antidiuretic hormone of the HZO, but the cause of hypokalemia was unclear. Water restriction and/or replenishment of electrolytes was required in each case. Although electrolyte abnormalities in HZO might be rare, blood examinations are necessary, as required in HZO patients.

We report three cases of patients with severe pain in which music therapy (MT) was applied and resulted in improved hospital discharge motivation and a further reduction in pain. Case 1 was that of a 78-year-old woman with recurrent low back and leg pain, and cases 2 and 3 involved 84- and 85-year-old women with acute herpetic pain. All patients reported their pain as 10 on the numerical rating scale (NRS), and exhibited comorbidities, such as sleep disorder and depression. Nerve block and pharmacotherapy significantly reduced reported pain scores; however, patients remained depressive and did not show willingness for hospital discharge. In case 1, MT was used to improve the quality of hospital stay, which unexpectedly improved the motivation for discharge and further reduced the NRS score. This experience was applied in cases 2 and 3 with similar effects. MT has been reported to have analgesic and anxiolytic effects in patients with chronic pain; however, our experience suggests its potential usefulness in cases of acute pain with comorbidities, such as depression.