2022 Expert Review of Neurotherapeutics

A 6-week course of acupuncture proves as effective as 6-month drug prophylaxis for migraines, with specific Chinese point selection and stimulation appearing less important.

The study began by revisiting previous research on acupuncture as a treatment for headache, finding shortcomings in many of these studies. It explored the influence of acupuncture on migraine and how it potentially functions. The methodology involved running several large, randomized trials comparing the use of acupuncture to conventional prophylactic drug treatments, spanning a time frame of six weeks to six months, respectively.

In the discussion of the results, it was found that the 6-week acupuncture treatment was just as effective in treating migraines as the 6-month drug treatment. Specific attributes of the acupuncture treatment, such as the selection and stimulation of Chinese points and the depth of the needles, were found to have lower significance than traditionally believed. The paper therefore suggested the integration of acupuncture into existing migraine therapy protocols.

Role of acupuncture in the treatment of migraine Endres HG, Diener HC, Molsberger A

2022 Neurology

True acupuncture over an eight-week period is effective for reducing the frequency of chronic tension-type headache.

In a randomized controlled trial, 218 participants diagnosed with chronic tension-type headache were divided into an intervention group and a control group, with the study conducted from June 2017 to September 2020. The intervention group received 20 true acupuncture sessions over 8 weeks, where each acupuncture point was needled to achieve a sensation, each session lasting 30 minutes. The control group received the same number of superficial acupuncture sessions, serving as a make-believe treatment, where the needling avoided inducing sensations at the acupuncture points.

The results showed a trend towards greater effectiveness of true acupuncture. By week 16, the 'responder rate' (participants reporting at least a 50% reduction in monthly headache days) was higher in the true acupuncture group compared to the superficial acupuncture group, with similar results by week 32. These findings suggest that true acupuncture, involving the creation of a sensation at each acupuncture site, can noticeably reduce chronic tension-type headaches. This was observed without noting significant adverse events, hinting towards the safety of the procedure.

Acupuncture for Patients With Chronic Tension-Type Headache Zheng H, Gao T, Zheng QH, Lu LY, Hou TH, Zhang SS, Zhou SY, Hao XY, Wang L, Zhao L, Liang FR, Li Y

2022 Annals of Medicine

The Gui Zhi-Shao Yao herb pair in traditional Chinese medicine potentially treats chronic pain, anxiety, and depression through interactions with nine key targets.

The methodology in this research utilised network pharmacology to explore the active components of the "Gui Zhi-Shao Yao" herb pair and their possible targets. Initially, 15 active compounds were identified through a series of analysis which revealed about 130 potential targets. By considering the intersections between the targets of the "Gui Zhi-Shao Yao" herb pair and chronic pain, anxiety disorder, and mental depression, nine vital targets were identified and listed in order of importance.

The results discussion revealed that the "Gui Zhi-Shao Yao" herb pairing acted on the nine identified key targets to alleviate chronic pain, anxiety, and depression. Gene ontology and pathway analysis demonstrated that there were 11 primary pathways, including AGE-RAGE signalling pathway, IL-17 signalling pathway, and TNF signalling pathway. These pathways appear to be actively involved in the pathological processes, providing a holistic understanding of how the "Gui Zhi-Shao Yao" herb pair functions therapeutically.

A network pharmacology approach to predict potential targets and mechanisms of “Ramulus Cinnamomi (cassiae) – Paeonia lactiflora” herb pair in the treatment of chronic pain with comorbid anxiety and depression Pan HT, Xi ZQ, Wei XQ, Wang K

2021 Journal of Clinical Pharmacy and Therapeutics

Acupuncture appears to have an effect on diabetic peripheral neuropathy, effectively improving nerve conduction and clinical symptoms.

Acupuncture appears to have an effect on DPN, effectively improving nerve conduction and clinical symptoms. Although the methodological quality of the included studies was generally very low and defects were frequent, our study highlights areas where improvement in methodology is required. There is a need for further study of the pathogenesis of DPN, and for developing a unified standard for methods of acupuncture treatment, acupoint selection, and adverse reactions reporting. Traditional Chinese medical practices such as acupuncture should adopt an evidence-based approach to provide greater confidence in their use.

Acupuncture treatment of diabetic peripheral neuropathy: An overview of systematic reviews Yu B, Li M, Huang H, Ma S, Huang K, Zhong Z, Yu S, Zhang L.

2020 Neurology and Therapy

In many studies, acupuncture has been shown to be a safe, efficacious and readily available alternative therapy which may be beneficial to certain migraine patients.

Migraines are difficult to treat, and current treatment options have many unwanted side effects, such as exacerbating headache pain in those with chronic migraine. Therefore, while the primary treatment for migraines is drug therapy, acupuncture is gaining increasing attention as a viable addition to the treatment management of migraine patients due to its measurable effects on both the duration and frequency of migraine attacks. Many studies suggest that acupuncture is a safe, helpful and available alternative therapy that may be beneficial to certain migraine patients. Nevertheless, further large-scale RCTs are warranted to further consolidate these findings and provide further support for the clinical value of acupuncture.

Acupuncture and Its Role in the Treatment of Migraine Headaches Urits I, Patel M, Putz ME, Monteferrante NR, Nguyen D, An D, Cornett EM, Hasoon J, Kaye AD, Viswanath O.

2020 Pain Research & Management

Acupuncture reduced more headache days and the times of using painkiller and was more effective in reducing the frequency and degree of headache than western medicine and sham acupuncture.

Based on high quality of evidence, we conclude that acupuncture is more effective and safer than medication or sham acupuncture in the treatment of migraine. However, the methodological quality, risk of bias, and reporting quality of SRs in acupuncture for migraine still needs improvement in future.

Effectiveness and Safety of Acupuncture for Migraine: An Overview of Systematic Reviews Li YX, Xiao XL, Zhong DL, Luo LJ, Yang H, Zhou J, He MX, Shi LH, Li J, Zheng H, Jin RJ

2020 Evidence-Based Complementary and Alternative Medicine

In the treatment of chronic pain with depression, acupuncture could not only achieve better clinical efficacy, but also have higher safety compared with conventional mediation therapy.

Acupuncture has a promising application prospect due to its unique advantages for the treatment of chronic pain with depression comorbidity, which can be used in patients suffering from some certain chronic pain with depression comorbidity with poorer response to the conventional medication or suffering from serious side effects.

Effect of Acupuncture on Chronic Pain with Depression: A Systematic Review Yan B, Zhu S, Wang Y, Da G, Tian G

2019 Neuropediatrics

Currently, acupuncture is considered to be a safe, helpful, and available alternative option for patients who have not responded to or complied with conventional pharmacotherapy.

The authors conducted an exhaustive review of existing literature exploring the use of acupuncture to address migraine headaches in children. This review encompassed understanding the neurobiological mechanisms of acupuncture, studies on adult headaches, pediatric headache studies, consideration of acupuncture's safety, and its application in other health conditions present in children.

The findings of this review suggested that acupuncture emerges as a safe and effective treatment option for migraine in children. Evidence proposes that it can be effectively integrated into the primary treatment regime to reduce the child's discomfort and pain. The effectiveness of acupuncture comes with the added advantage of being safe, with negligible risks, especially important when dealing with young patients. These insights support acupuncture to be seriously considered as an auxiliary treatment strategy for migraines in children.

Acupuncture in Adult and Pediatric Headache: A Narrative Review Doll, E., Threlkeld, B., Graff, D., Clemons, R., Mittel, O., Sowell, M. K.

2019 Headache

There is growing evidence that acupuncture is just as effective and has fewer side effects than many of the standard pharmaceutical agents that are currently used.

Out of the 706 search results, 7 clinical trials, with a total of 1430 participants, met inclusion criteria for trials comparing the effectiveness of acupuncture to standard pharmacologic treatment. Several of the studies showed acupuncture to be more effective than standard pharmacological treatments for migraine prevention; however, methodological heterogeneity precluded aggregation of these data.

Systematic Review: Acupuncture vs Standard Pharmacological Therapy for Migraine Prevention Niushen Zhang, Tim Houle, Nada Hindiyeh, & Sheena K. Aurora

2019 Acupuncture in Medicine

Acupuncture, regardless of the trial design, showed a positive effect on pain-related outcome measures for participants with diabetic peripheral neuropathy.

Acupuncture, regardless of the trial design, showed a positive effect on pain-related outcome measures for participants with DPN. However, a meta-analysis could not be performed owing to the highly heterogeneous outcome measures and limited number of high-quality RCTs available. Findings from this review showed that acupuncture improves symptoms despite the variations in acupuncture dosage, and provides beneficial effects in comparison with vitamin B therapies and no treatment. However, owing to problems with control group suitability and blinding, strong non-specific effects cannot be ruled out.

Acupuncture for the treatment of lower limb diabetic peripheral neuropathy: a systematic review Nash J, Armour M, Penkala S

2019 Acupuncture in Medicine

Acupuncture, regardless of the trial design, showed a positive effect on pain-related outcome measures for participants with diabetic peripheral neuropathy.

Acupuncture, regardless of the trial design, showed a positive effect on pain-related outcome measures for participants with DPN. However, a meta-analysis could not be performed owing to the highly heterogeneous outcome measures and limited number of high-quality RCTs available. Findings from this review showed that acupuncture improves symptoms despite the variations in acupuncture dosage, and provides beneficial effects in comparison with vitamin B therapies and no treatment. However, owing to problems with control group suitability and blinding, strong non-specific effects cannot be ruled out.

Acupuncture for the treatment of lower limb diabetic peripheral neuropathy: a systematic review Nash J, Armour M, Penkala S

2019 World Journal of Acupuncture-Moxibustion

The results of this meta-analysis showed that acupuncture is more effective and safer than medication for migraine.

A total of 13 trails including 1218 participants met the selection criteria. The meta-analysis of 3 articles showed that acupuncture was more effective in reducing the frequency of migraine attacks than medication. The meta-analysis of three articles showed that acupuncture was more effective in reducing the number of migraine days than medication after treatment. The meta-analysis of six articles showed that acupuncture was more effective in reducing VAS after treatment. The meta-analysis of two articles showed that acupuncture was more effective in reducing VAS during follow-up. The meta-analysis of seven articles showed that the total effective rate of acupuncture was higher than that of medication. In addition, fewer adverse effects in acupuncture groups were reported than in medication groups. Overall the quality of the evidence was low.

The results of this meta-analysis showed that acupuncture is more effective and safer than medication for migraine. Acupuncture can be considered a treatment option for patients willing to undergo this treatment. But more high-quality studies, based on standardized, comprehensive and objective evaluation, are required to enhance the reliability of the conclusion.

Acupuncture for migraine: A systematic review and meta-analysis SHEN, Feng-jiao AU - XU, Jia AU - ZHAN, Yi-jun AU - FU, Qin-hui AU - PEI, Jian PY

2019 Arthritis Research & Therapy

Strong electroacupuncture for at least two weeks improves chronic pain management in knee osteoarthritis patients better than weak or sham electroacupuncture.

In this investigation, a multicenter, three-arm parallel, single-blind randomized controlled trial was conducted in which 301 patients suffering from knee osteoarthritis were randomly divided into three groups based on the electroacupuncture current intensity: strong, weak, and sham. Treatments were carried out in five sessions per week over a two-week period. The impact of these treatments was primarily measured by assessing the Visual Analog Scale, conditioned pain modulation function, and the Western Ontario and McMaster Universities Osteoarthritis Index.

After a week of electroacupuncture, a clinically significant improvement was observed in Visual Analog Scale scores and Western Ontario and McMaster Universities Osteoarthritis Index scores, but not in conditioned pain modulation function. However, after two weeks of treatment, improvements were seen in all three primary outcomes when compared to baseline. In terms of enhancing conditioned pain modulation function specifically, both weak and strong electroacupuncture outperformed the sham option, with strong electroacupuncture showing superiority to weak, and resulted in better pain management.

Effects of intensity of electroacupuncture on chronic pain in patients with knee osteoarthritis: a randomized controlled trial Lv, Z., Shen, L., Zhu, B. et al.

2019 The Oncologist

Acupuncture treatment significantly improves neuropathic symptoms in women suffering from chemotherapy-induced peripheral neuropathy after breast cancer therapy.

In this randomized pilot trial, women with stage I-III breast cancer with grade 1 or higher chemotherapy-induced peripheral neuropathy post adjuvant chemotherapy were tested. Patients were split evenly into two groups: an immediate acupuncture group and a control group. Those in the immediate acupuncture arm underwent 18 acupuncture sessions over 8 weeks before the treatment was halted. Conversely, the control group received the usual care over eight weeks before beginning nine acupuncture sessions across the same time span. Different parameters such as sensory scores, neurotoxicity, and pain severity were evaluated at the start, then at 4, 8, and 16 weeks post enrollment.

The results, which excluded any statistical references, showed a notable improvement in the immediate acupuncture group in terms of neuropathic symptoms, including sensory scores, neurotoxicity summary score, and pain severity score when observed at the end of eight weeks. No negative side effects were observed during the entire period. This indicates acupuncture as a potential therapeutic option for breast cancer patients suffering from chemotherapy-induced peripheral neuropathy.

Acupuncture for Chemotherapy-Induced Peripheral Neuropathy in Breast Cancer Survivors: A Randomized Controlled Pilot Trial Lu W, Giobbie-Hurder A, Freedman RA, Shin IH, Lin NU, Partridge AH, Rosenthal DS, Ligibel JA

2018 Evidence-Based Complementary and Alternative Medicine

There is potential of acupuncture combined with conventional treatment for treating female chronic pelvic pain.

This review suggests the potential of acupuncture combined with conventional treatment compared to conventional treatment alone for treating female chronic pelvic pain. However, there is insufficient evidence to conclude that acupuncture can be recommended as a complementary and alternative (CAM) treatment for women with CPP. To draw a firm conclusion, future studies should require not only lager, more rigorously designed RCTs but also research on different acupuncture treatment types.

Acupuncture Treatment for Chronic Pelvic Pain in Women: A Systematic Review and Meta-Analysis of Randomized Controlled Trials Sung SH, Sung ADM, Sung HK, An TEB, Kim KH, Park JK

2018 Acupuncture in Medicine

Acupuncture for cluster headache may be more effective if treated in the same way as has been shown effective for trigeminal neuralgia.

Acupuncture has not generally been successful for cluster headache. This may be due to acupuncturists approaching the problem as one of severe migraine. In fact, cluster headache is classed as a trigeminal autonomic cephalgia.

In this case report, episodic cluster headache is treated in the same way as has been shown effective for trigeminal neuralgia. Acupuncture is applied to the contralateral side at points appropriate for stimulating branches of the trigeminal nerve. Thus, ST2 is used for the infraorbital nerve, BL2 and Yuyao for the supratrochlear and supraorbital nerves, and Taiyang for the temporal branch of the zygomatic nerve.

Acupuncture for Episodic Cluster Headache: A Trigeminal Approach Simon Hayhoe

2017 The Journal of Pain

Acupuncture has a clinically relevant effect on chronic pain that persists over time. Referral for acupuncture treatment is a reasonable option for chronic pain patients.

We included randomized trials of acupuncture needling versus either sham acupuncture or no acupuncture control for nonspecific musculoskeletal pain, osteoarthritis, chronic headache, or shoulder pain. Trials were only included if allocation concealment was unambiguously determined to be adequate. Raw data were obtained from study authors and entered into an individual patient data meta-analysis. The main outcome measures were pain and function. An additional 13 trials were identified, with data received for a total of 20,827 patients from 39 trials. Acupuncture was superior to sham as well as no acupuncture control for each pain condition (all P < .001) with differences between groups close to .5 SDs compared with no acupuncture control and close to .2 SDs compared with sham. We also found clear evidence that the effects of acupuncture persist over time with only a small decrease, approximately 15%, in treatment effect at 1 year.

Acupuncture is effective for the treatment of chronic musculoskeletal, headache, and osteoarthritis pain. Treatment effects of acupuncture persist over time and cannot be explained solely in terms of placebo effects. Referral for a course of acupuncture treatment is a reasonable option for a patient with chronic pain.

Acupuncture for Chronic Pain: Update of an Individual Patient Data Meta-Analysis Vickers, Andrew J. et al.

2017 The Journal of Pain

Acupuncture has a clinically relevant effect on chronic pain that persists over time. Referral for acupuncture treatment is a reasonable option for chronic pain patients.

We included randomized trials of acupuncture needling versus either sham acupuncture or no acupuncture control for nonspecific musculoskeletal pain, osteoarthritis, chronic headache, or shoulder pain. Trials were only included if allocation concealment was unambiguously determined to be adequate. Raw data were obtained from study authors and entered into an individual patient data meta-analysis. The main outcome measures were pain and function. An additional 13 trials were identified, with data received for a total of 20,827 patients from 39 trials. Acupuncture was superior to sham as well as no acupuncture control for each pain condition (all P < .001) with differences between groups close to .5 SDs compared with no acupuncture control and close to .2 SDs compared with sham. We also found clear evidence that the effects of acupuncture persist over time with only a small decrease, approximately 15%, in treatment effect at 1 year.

Acupuncture is effective for the treatment of chronic musculoskeletal, headache, and osteoarthritis pain. Treatment effects of acupuncture persist over time and cannot be explained solely in terms of placebo effects. Referral for a course of acupuncture treatment is a reasonable option for a patient with chronic pain.

Acupuncture for Chronic Pain: Update of an Individual Patient Data Meta-Analysis Vickers, Andrew J. et al.

2017 Pain Physician

The existing evidence suggests that most acupuncture therapies, including acupuncture combined with other therapies, are effective in decreasing pain and in improving physical function.

Thirty-three trials with 1,692 patients were included. Patients were allocated to 22 kinds of interventions, of which dry needling and manual acupuncture was the most frequently investigated intervention. Compared with placebo-sham acupuncture, scraping combined with warming acupuncture and moxibustion was found to be more effective for decreasing pain intensity; miniscalpel-needle was more effective for increasing the PPT; trigger points injection with bupivacaine was associated with the highest risk of adverse event; and only EA showed a significant difference in the ROM.

Acupuncture for Myofascial Pain Syndrome: A Network Meta-Analysis of 33 Randomized Controlled Trials Li X, Wang R, Xing X, Shi X, Tian J, Zhang J, Ge L, Zhang J, Li L, Yang K.

2016 Cochrane Database of Systematic Reviews

The available evidence suggests that adding acupuncture to symptomatic treatment of attacks reduces the frequency of headaches.

Contrary to the previous findings, the updated evidence also suggests that there is an effect over sham, but this effect is small. The available trials also suggest that acupuncture may be at least similarly effective as treatment with prophylactic drugs. Acupuncture can be considered a treatment option for patients willing to undergo this treatment.

Acupuncture for the prevention of episodic migraine Linde K, Allais G, Brinkhaus B, et al.

2016 Cochrane Database of Systematic Reviews

The available evidence suggests that a course of acupuncture consisting of at least six treatment sessions can be a valuable option for people with frequent tension-type headache.

Acupuncture added to usual care or treatment of headaches only on onset (usually with pain-killers) in two large trials resulted in 48 in 100 participants having headache frequency at least halved, compared to 17 of 100 participants given usual care only.

Acupuncture was compared with ‘fake’ acupuncture, where needles are inserted at incorrect points or do not penetrate the skin, in six trials. Headache frequency halved in 52 of 100 participants receiving true acupuncture compared with 43 of 100 participants receiving ‘fake’ acupuncture. The results were dominated by one large, good quality trial (with about 400 participants), which showed that the effect of true acupuncture was still present after six months. There were no differences in the number of side effects of real and ‘fake’ acupuncture, or the numbers dropping out because of side effects.

Acupuncture for the prevention of tension‐type headache Klaus Linde,Gianni Allais,Benno Brinkhaus, Yutong Fei,Michael Mehring,Byung‐Cheul Shin,Andrew Vickers,Adrian R White

2016 Neural Regeneration Research

A 14-session course of needling at Fengchi is relatively safe for treating posterior circulation ischemia with vertigo.

Acupuncture at Fengchi (GB20) in the posterior neck improves vertigo. However, subarachnoid hemorrhage and spinal epidural hematoma have been reported to occur after acupuncture in the posterior neck. Therefore, in the present study, we assessed the safety of acupuncture at Fengchi.

Of the 136 patients, 120 completed the study. There were no significant differences between pretreatment and posttreatment test results in any of the groups. Only five patients suffered from minor adverse events (needling pain, slight hematoma and transient chest tightness). No serious adverse events were found. Our results indicate that a 14-session course of needling at Fengchi is relatively safe for treating posterior circulation ischemia with vertigo.

Safety of different acupuncture manipulations for posterior circulation ischemia with vertigo Wen Y, Zhang C, Zhao Xf, Deng Sz, He S, Huang Lh, Tian G, Meng Zh

2015 Neurology

The majority of trials demonstrate a positive effect of acupuncture over control condition in the treatment of neuropathy.

The majority of RCTs reviewed showed clear benefit for acupuncture over control in the treatment of diabetic neuropathy, Bell’s palsy and carpal tunnel syndrome. Acupuncture is probably effective in the treatment of HIV-related neuropathy and there is insufficient evidence for its benefits in idiopathic neuropathy. Meta-analyses of all diabetic neuropathy and bell’s palsy data using a summary estimate random effects model showed combined Odds Ratio (OR) of 4.23, p<0.001 favoring acupuncture over control for pain outcomes. The majority of trials demonstrate a positive effect of acupuncture over control condition in the treatment of neuropathy. Further more rigorously designed studies are needed to better characterize this effect.

Effects of Acupuncture on Neuropathic Pain: A Systematic Review and Meta-analysis Alexandra Dimitrova, Charles Murchison, Barry Oken

2015 Neurology

The majority of trials demonstrate a positive effect of acupuncture over control condition in the treatment of neuropathy.

The majority of RCTs reviewed showed clear benefit for acupuncture over control in the treatment of diabetic neuropathy, Bell’s palsy and carpal tunnel syndrome. Acupuncture is probably effective in the treatment of HIV-related neuropathy and there is insufficient evidence for its benefits in idiopathic neuropathy. Meta-analyses of all diabetic neuropathy and bell’s palsy data using a summary estimate random effects model showed combined Odds Ratio (OR) of 4.23, p<0.001 favoring acupuncture over control for pain outcomes. The majority of trials demonstrate a positive effect of acupuncture over control condition in the treatment of neuropathy. Further more rigorously designed studies are needed to better characterize this effect.

Effects of Acupuncture on Neuropathic Pain: A Systematic Review and Meta-analysis Alexandra Dimitrova, Charles Murchison, Barry Oken

2015 BMC Complementary Medicine and Therapies

Acupuncture demonstrates a significant immediate effect in reducing discomforts and VAS of both dizziness and vertigo.

Acupuncture demonstrates a significant immediate effect in reducing discomforts and VAS of both dizziness and vertigo. This study provides clinical evidence on the efficacy and safety of acupuncture to treat dizziness and vertigo in the emergency department.

Efficacy and safety of acupuncture for dizziness and vertigo in emergency department: a pilot cohort study Chiu, CW., Lee, TC., Hsu, PC. et al.

2013 Cochrane Database of Systematic Reviews

Compared with no treatment and standard therapy, acupuncture improves pain and stiffness in people with fibromyalgia.

There is low to moderate-level evidence that compared with no treatment and standard therapy, acupuncture improves pain and stiffness in people with fibromyalgia. There is moderate-level evidence that the effect of acupuncture does not differ from sham acupuncture in reducing pain or fatigue, or improving sleep or global well-being. EA is probably better than MA for pain and stiffness reduction and improvement of global well-being, sleep and fatigue. The effect lasts up to one month, but is not maintained at six months follow-up. MA probably does not improve pain or physical functioning. Acupuncture appears safe. People with fibromyalgia may consider using EA alone or with exercise and medication. The small sample size, scarcity of studies for each comparison, lack of an ideal sham acupuncture weaken the level of evidence and its clinical implications. Larger studies are warranted.

Acupuncture for treating fibromyalgia Deare JC, Zheng Z, Xue CC, Liu JP, Shang J, Scott SW, Littlejohn G.

2001 Cochrane Database of Systematic Reviews

The existing evidence supports the value of acupuncture for the treatment of idiopathic headaches.

Due to the clinical heterogeneity and the poor methodological quality of the included studies, straightforward recommendations for clinical practice cannot be made. Overall, some forms of acupuncture seem to be beneficial, but it is unclear which treatment strategies (points, type of stimulation, frequency, etc.) and which providers may be most promising for particular groups of patients.

Though not risk‐free, acupuncture seems to be relatively safe in the hands of qualified providers. Therefore, we conclude that headache patients who want to try acupuncture should not be discouraged. Existing provision of acupuncture to headache patients also seems justified. Whether acupuncture should be more widely recommended and, if so, which particular type of acupuncture should be offered, are questions that cannot be answered at present.

Acupuncture for idiopathic headache Melchart D, Linde K, Berman B, White A, Vickers A, Allais G, Brinkhaus B