Jun Hozumi

Minocycline Does Not Decrease Intensity of Neuropathic Pain Intensity, But Does Improve Its Affective Dimension

ABSTRACT Recent understanding of the neuron–glia communication shed light on an important role of microglia to develop neuropathic pain The analgesic effect of minocycline on neuropathic pain is promising but it remains unclear in clinical settings. This study included 20 patients with neuropathic pain of varied etiologies. We administered 100 mg/day of minocycline for 1 week and then 200 mg/day for 3 weeks, as an open-label adjunct to conventional analgesics. An 11-point numerical rating scale. (NRS) and the short-form McGill Pain Questionnaire (SF-MPQ) were used to evaluate pain severity. The data were collected at baseline and after 4 weeks of therapy and analyzed using the Wilcoxon signed-rank test. All except two of the patients tolerated the full dose of minocycline. There was no significant improvement in the scoring of NRS (5.6 ± 1.2 at baseline vs. 5.3 ± 1.9 at 4 weeks; P =.60). The total score of the SF-MPQ decreased significantly (17.2 ± 7.4 vs. 13.9 ± 9.6; P =.02), particularly in the affective subscale (4.4 ± 2.7 vs. 3.3 ± 3.6; P =.007) but not so in the sensory subscale (12.8 ± 5.2 vs. 10.6 ± 6.2; P =.06). We conclude that minocycline failed to decrease pain intensity but succeeded in reducing the affective dimension associated with neuropathic pain.

Development of the Japanese Version of the Leeds Assessment of the Neuropathic Symptoms and Signs Pain Scale: Diagnostic Utility in a Clinical Setting.

We aimed to assess the diagnostic utility of the linguistically validated Japanese version of the Leeds Assessment of Neuropathic Symptoms and Signs Pain Scale (LANSS‐J) as a screening tool for neuropathic pain in the clinical setting.

Relationship between Neuropathic Pain and Obesity

Objectives. Overweight negatively affects musculoskeletal health; hence obesity is considered a risk factor for osteoarthritis and chronic low back pain. This was conducted to determine if obesity affects neuropathic pain, usually considered unrelated to the weight-load on the musculoskeletal system. Methods. Using a cut-off body mass index value of 25, 44 patients with neuropathic pain were grouped into a “high-BMI” group and a “normal-BMI” group. Results. The numeric rating scale of the high-BMI group was significantly higher than that of the normal-weight group (P < 0.05). The total NPSI scores were significantly higher (P < 0.01), and the paroxysmal pain and the negative symptoms were more serious in the high-BMI group than in the normal-BMI group. The high-BMI subjects also had significantly higher SF-MPQ scores (P < 0.05). However, both physical and mental health status on the SF-36 were comparable between the groups. Discussion. Neuropathic pain that did not arise from musculoskeletal damage was higher in the high-BMI patients. Paroxysmal pain was more severe, suggesting that neural damage might be aggravated by obesity-associated inflammation. These findings should have needed to be confirmed in future studies.

Donepezil, an Acetylcholinesterase Inhibitor, Can Attenuate Gabapentinoid-Induced Somnolence in Patients with Neuropathic Pain: A Retrospective Chart Review

ABSTRACT Donepezil, an oral acetylcholinesterase inhibitor, is used to treat Alzheimers disease and reportedly attenuates opioid-induced sedation in patients with cancer pain. Neuropathic pain is often treated with gabapentinoids (pregabalin, gabapentin), but gabapentinoid-induced somnolence sometimes prevents patients from using these agents. We conducted a retrospective chart review of patients with neuropathic pain to examine whether donepezil is useful for gabapentinoid-induced somnolence. We investigated pain severity in 13 patients before and after taking gabapentinoids and donepezil, the degree of gabapentinoid-induced somnolence before and after starting donepezil, and gabapentinoid dose escalation after taking donepezil. Donepezil was started at 3–5 mg/day upon experiencing gabapentinoid-induced somnolence. Likert-scale scores for somnolence (0 = no somnolence; 4 = severe somnolence with stumbling) improved significantly after starting donepezil (before: 2.3 ± 0.9, after: 0.5 ± 0.7; Wilcoxons signed-rank test, P < .05), resulting in gabapentinoid dose escalation (before: 796.2 ± 564.3 mg, after: 1409.6 ± 526.9 mg; P < .05), which significantly decreased pain intensity (before: 7.4 ± 1.2, after: 5.0 ± 1.3; P < .05). Donepezil could be an alternative to psychostimulants for gabapentinoid-induced somnolence. The analgesic effect of gabapentinoids remained uncompromised by donepezil, which could enhance the dose-dependent analgesic effect of gabapentinoids.

Oral Local Anesthesia Successfully Ameliorated Neuropathic Pain in an Upper Limb Suggesting Pain Alleviation through Neural Plasticity within the Central Nervous System: A Case Report.

Neural blockades are considered an alternative to pharmacotherapy for neuropathic pain although these blockades elicit limited effects. We encountered a patient with postbrachial plexus avulsion injury pain, which was refractory to conventional treatments but disappeared temporarily with the administration of the local anesthetic lidocaine around the left mandibular molar tooth during dental treatments. This analgesic effect on neuropathic pain by oral local anesthesia was reproducible. Under conditions of neuropathic pain, cerebral somatotopic reorganization in the sensorimotor cortices of the brain has been observed. Either expansion or shrinkage of the somatotopic representation of a deafferentated body part correlates with the degree of neuropathic pain. In our case, administration of an oral local anesthetic shrank the somatotopic representation of the mouth, which is next to the upper limb representation and thereby expanded the upper limb representation in a normal manner. Consequently, oral local anesthesia improved the pain in the upper limb. This case suggests that pain alleviation through neural plasticity within the brain is related to neural blockade.

Gamma-aminobutyric acid transaminase genetic polymorphism is a candidate locus for responsiveness to opioid analgesics in patients with cancer pain: An exploratory study

Cancer pain impairs not only physical functions but also social functions and roles. Consequently, the overall health‐related quality of life of patients with cancer pain deteriorates. Opioid analgesics are recommended for treating moderate to strong cancer pain. Advances in human genome research have fueled a growing interest to understand individual differences in responsiveness to opioid analgesics. This study aimed to explore and identify novel loci for genes predisposing an individual to opioid analgesic responsiveness.