In January 2016 and 2017, the Committee on Safety of the Japan Society of Pain Clinicians distributed questionnaires on pain management-related adverse events (AEs) in 2015 and 2016 to all board-certified training facilities in Japan. Responses were received from 162 facilities (response rate, 46％) in 2016 and 197 facilities (response rate, 57％) in 2017. Most AEs were reported to result from analgesics, analgesic adjuvants, and nerve blocks. The most frequent drugs to cause AEs were pregabalin, tricyclic antidepressants, and tramadol/acetaminophen. Complications of nerve blocks included infections induced by epidural nerve blocks, loss of consciousness or central nervous system excitation induced by intravascular injections of local anesthetics for stellate ganglion blocks, and development of pneumothorax after intercostal nerve blocks or trigger point injections. Information on these AEs should be shared to ensure safety during pain treatment.

Tricyclic antidepressants (TCAs) have side effects but are frequently effective for neuropathic pain. Analgesic effects of amitriptyline (AT) and nortriptyline (NT) are equivalent, however, NT offers higher tolerability than AT. The aim of this study was to investigate the number of outpatients who discontinued with TCAs because of intolerable side effects. We performed a single-center, retrospective study of 87 patients prescribed with AT (AT group) or NT (NT group) from July 2015 to January 2018. Primary outcomes were the ratio of the number of patients who discontinued to that of patients who continued and the type of side effects. TCAs were discontinued by 14/87 patients (7/37 [18％] in the AT group and 7/50 [14％] in the NT group). The side effects were drowsiness (6/37 in the AT group and 2/50 in the NT group), urinary retention (2/50 in the NT group), exacerbation of constipation (1/37 in the AT group and 1/50 in the NT group), and abnormal blood sampling test results (2/50 in the NT group). In conclusion, when prescribing TCAs, clinicians should consider the possibility of side effects that may lead to discontinuation.

Background: We compared the efficacy of intramuscular and interfascial routes of local anesthetic administration for trigger point injections (TPI). Methods: We investigated 50 patients with myofascial pain syndrome (MPS) of the trapezius muscle who were assigned to an intramuscular injection group (Group M, n＝25) and an interfascial injection group (those who received the TPI between the trapezius and the supraspinatus muscle) (Group F, n＝25). The primary outcome was the efficacy after the first injection, and the secondary outcome was efficacy of injections after four subsequent TPI. Results: The mean numerical rating scale (NRS) was significantly reduced in both groups (p＜0.001) after the first TPI, although this intergroup difference was statistically insignificant (p＝0.766). The mean NRS was significantly lower in Group F than in Group M (p＝0.016) with each subsequent TPI. Conclusion: Both intramuscular and interfascial injections are effective routes of administration for TPI. Repeat TPI showed greater efficacy with interfascial than with intramuscular injections.

A 60-year-old man developed right-sided cephalalgia and facial pain, caused by right-sided ethmoid sinus carcinoma, which had invaded the cranium and brain. Although the patient had received continuous intravenous 50 mg/day morphine infusion, the symptoms had not improved; subsequently, he was referred to our hospital. We changed the treatment regimen from morphine to continuous subcutaneous oxycodone and ketamine infusion; however, the therapeutic effect did not improve. Therefore, we performed a right Gasserian ganglion block (GGB) using absolute ethanol. After GGB, the opioid subcutaneous administration could be decreased and finally substituted with 1 mg/day transdermal fentanyl. Although for a short period of time, the patient could be discharged from the hospital. GGB was effective not only against facial pain, but also against cephalalgia caused by cancer-invaded dura mater.

Herein, we report a case of perineal pain in which saddle block with a hyperbaric tetracaine solution was effective. The patient developed interstitial cystitis and dysuria from a neurogenic bladder and experienced severe perineal pain during self-urination. Treatment with analgesics, sympathetic block, and nerve root block were ineffective. Therefore, the subarachnoid saddle block was performed using tetracaine dissolved in 20％ glucose solution. Although a sustained analgesic effect was not obtained with the 0.5％ solution, good analgesia on a monthly basis was obtained when 1.0％ solution was used. Since tetracaine is a powder formulation, it is possible to adjust the concentration such that there is no bladder or rectal disturbance. Moreover, because the analgesic effect of tetracaine is reversible, it can be a useful tool for analgesia in the perineal region when nerve destruction of phenol glycerin is a contraindication.

A 59-year-old Japanese woman suffered from necrotizing fasciitis in her right lower limb and underwent amputation of the limb at the hip joint. Immediately after the surgery, she experienced phantom sensations in the right lower limb, dysesthesia, and stump pain. We started pregabalin treatment (oral 150 mg/day) on postoperative day 3, but the phantom limb sensation and dysesthesia did not improve. When amantadine (oral 200 mg/day) was started on postoperative day 8, her symptoms gradually improved. Mexiletine (oral 200 mg/day) was started on postoperative day 31, and symptoms further alleviated. In the combination therapy with pregabalin (oral 450 mg/day), amantadine (oral 450 mg/day), and mexiletine (oral 300 mg/day) to treat phantom limb pain, amantadine was particularly effective. The patient's positive outcome suggests that amantadine is an effective treatment option for phantom limb pain and phantom limb sensations after limb amputation.

A 47-year-old man presented with severe phantom limb pain (PLP) seven days after amputation of the left brachium following an industrial accident. The initial pain was managed at the pain clinic using a continuous brachial plexus block and drug therapy. Consequently, his numerical rating scale (NRS) score for pain temporarily decreased from 5/10 to 2/10 during the nerve block treatment; however, pain intensified after the treatment ended. Subsequently, 15 mg of mirtazapine was administered once a day and increased to twice a day. Mirtazapine reduced the patient's NRS score to 3/10 for 8 h, which was not accomplished with other medicines. These observations indicate that mirtazapine has a unique pharmacological profile, unlike other antidepressants, and may be effective in improving PLP.

A 60-year-old man became febrile and delirious following treatment with a fentanyl transdermal therapeutic system, but he showed marked improvement after intravenous naloxone hydrochloride (0.2 mg) administration. He had a 34-year history of hemodialysis and general pain due to dialysis amyloidosis. When he became delirious (Japan coma scale: JCS, 10–20), he had decreased blood pressure (systolic blood pressure: 60–70 mmHg) and fewer breaths (10/minute), but his condition showed immediate and marked improvement after intervention. Fentanyl blood levels were lower than those that caused the respiratory depression (2 ng/ml).

Purpose: We retrospectively evaluated the post-operative analgesic effect of intravenous fentanyl infusion on patients who underwent intervertebral lumbar decompression. Methods: We selected thirty-three patients who had received intravenous fentanyl infusion (fentanyl group), and fourteen who were placed on a conventional postoperative analgesic protocol (control group), after posterior 1 or 2 intervertebral lumbar decompression. Flurbiprofen 50 mg and acetaminophen 1,000 mg were administered at induction and the end of surgery respectively. Fentanyl 20 µg/h and droperidol 0.2 mg/h were infused for 24 hours after surgery for the fentanyl group. As a rescue analgesia, when visual analogue score (VAS) became 5 or more, analgesic protocol was active. Results: The VAS scores for the fentanyl group were significantly lower, only within the first 30 post-operative minutes. Conclusion: Intravenous infusion of fentanyl 20 µg/h plus droperidol 0.2 mg/h exhibits better analgesic effect, only within the first 30 minutes after posterior 1 or 2 intervertebral lumbar decompression.

Patients with paranasal sinus cancer occasionally present with severe headache secondary to cranial invasion. Headache and facial pain are usually treated with systemic opioids and adjuvant analgesics; however, high doses of these drugs need to be administered. We describe a patient who remained refractory to high-dose opioid therapy but was successfully treated with cervical epidural analgesia. No guidelines are available for the administration of spinal analgesia for head and neck cancer pain. However, in this case report, we have highlighted that spinally administered morphine can effectively treat headache, as well as facial and neck pain in patients refractory to conservative treatments.

Intractable pain in elderly patients may occasionally be a symptom of dementia and requires prompt attention because dementia may significantly affect the treatment plan. We describe an elderly woman with back pain concomitant with mild parkinsonism, hallucinations, and severe depression in whom this clinical presentation led to the diagnosis of dementia with Lewy bodies (DLB). We initiated medical therapy for DLB, reduced analgesic agent administration to avoid worsening of cognitive impairment and established a social support system for her declining life functions. Despite its multiple symptoms, diagnosis of DLB is challenging and more difficult than the diagnosis of other types of dementia, such as Alzheimer's disease because patients with DLB often show lesser and occasionally no memory deficits. Clinicians should have sufficient knowledge of dementia and perform the necessary tests for cognitive function evaluation.