Botulinum toxin (BoNT) has been used as a treatment for excessive muscle stiffness, spasticity, and dystonia. BoNT for approximately 40 years, and has recently been used to treat various types of neuropathic pain. The mechanism by which BoNT acts on neuropathic pain involves inhibiting the release of inflammatory mediators and peripheral neurotransmitters from sensory nerves. Recent journals have demonstrated that BoNT is effective for neuropathic pain, such as postherpetic neuralgia, trigeminal neuralgia, and peripheral neuralgia. The purpose of this review is to summarize the experimental and clinical evidence of the mechanism by which BoNT acts on various types of neuropathic pain and describe why BoNT can be applied as treatment. The PubMed database was searched from 1988 to May 2017. Recent studies have demonstrated that BoNT injections are effective treatments for post-herpetic neuralgia, diabetic neuropathy, trigeminal neuralgia, and intractable neuropathic pain, such as poststroke pain and spinal cord injury.

Osteoarthritis (OA) is a degenerative disease that is spreading worldwide due to an aging population. This is not simply a disease caused by worn out joints, but a complex disease accompanied by various mechanisms such as inflammatory reactions. Among various joints, knee joints show degenerative changes earlier than other joints because they carry most of the weight load, causing social-economic problems. In the case of OA of the knee that does not respond to relatively simple conservative treatments such as physical therapy or medication, intra-articular injection is preferred. However, intra-articular injection drugs have limited effectiveness and uncertainties. There are several intra-articular viscous supplement drugs such as hyaluronic acid. Tissue regeneration active materials such as polydeoxyribonucleotide and polynucleotide are also newly used. The objective of this paper was to compare effects of intra-articular supplementation drugs used for degenerative arthritis of the knee.

Purpose: Endocrinological complications of an epidural steroid injection (ESI) are rare but dangerous. Nevertheless, despite the associated risks, repeated long-term ESIs are indispensable in some clinical situations. However, only a few reports to date have assessed the safety of this procedure. In this study, we evaluate the incidence of adrenal insufficiency (AI) and Cushing’s syndrome after long-term ESIs. Methods: This clinical observational study enrolled herniated nucleus pulposus or spinal stenosis patients who had received ESIs over a period of six months or longer. The adrenocorticotropic hormone (ACTH) stimulation test was performed to confirm AI and the late-night salivary cortisol (LNSC) test was performed to diagnose Cushing’s syndrome. To evaluate the hypothalamus pituitary adrenal axis suppression, salivary cortisol (SC) levels were measured on days 0, 1, 7, 21, 28, 35, and 42. Results: This study included 17 patients. Among these, two patients (11.8%) developed AI, but no cases of Cushing’s syndrome were reported. There was no predictor for the development of AI. The SC levels tended to increase with time after an ESI (β = 0.003). The slope of the mixed effect model between the AI and non-AI groups showed a significant difference (p value = 0.015). However, the differences in mean SC levels at each time point between the two groups were not significant (adjusted p value = 0.053). Conclusion: Long-term ESI use may be associated with AI development. An unexpected adrenal crisis due to AI could be life threatening. Therefore, regular monitoring of adrenal function in patients who have received long-term ESIs may be prudent.

Jung Hyun Park, Seung Hee Cho, Rip Kim, Sang Hoon Na, Eun-sun Kang, Mi-young Yeom, and Yeon Jang. Korean J Pain 2021;34:185-92. https://doi.org/10.3344/kjp.2021.34.2.185

Despite the high frequency of nerve blocks in the acute phase of herpes zoster, factors associated with intervention, such as response to epidural block, have not been analyzed as predictive factors of postherpetic neuralgia (PHN). To determine the predictive factors of progression to PHN in the presence of interventions, we analyzed the medical records of 145 patients who underwent transforaminal epidural injection (TFEI) in the acute phase of herpes zoster. A total volume of 5 mL (a mixture of 0.5% lidocaine and 5 mg dexamethasone) was injected during TFEI. Corticosteroid was used only for the first TFEI. Clinical data of age, sex, involved dermatome, presence of comorbidity, time from zoster onset to first TFEI, numerical rating scale (NRS) before TFEI, NRS at 1 week and 1, 3, and 6 months after the first TFEI, and number of TFEI were collected and analyzed. Through multivariate logistic regression analysis, pain improvement less than 50% at 1 week after the first TFEI was a strong predictive factor of progression of PHN at all time points. Response to TFEI appears to be a stronger predictive factor of progression to PHN than patient factors of sex, age, degree of initial pain, and presence of co-morbidity.