Pathophysiology and Management of Abdominal Myofascial Pain Syndrome (AMPS): A Three-Year Prospective Audit of a Management Pathway in 120 Patients

Myofascial pain - A major player in musculoskeletal pain

Myofascial pain is a soft tissue pain syndrome with local and referred musculoskeletal pain arising from trigger points. Myofascial pain and myofascial pain syndromes are among some of the most common acute and chronic pain conditions. Myofascial pain can exist independently of other pain generators or can coexist with or is secondary to other acute and chronic painful musculoskeletal conditions. Myofascial pain is most effectively treated with a multimodal treatment plan including injection therapy (known as trigger point injections, physical therapy, postural or ergonomic correction, and treatment of underlying musculoskeletal pain generators. The objectives of this review are to outline the prevalence of myofascial pain, describe the known pathophysiology of myofascial pain and trigger points, discuss the clinical presentation of myofascial pain, and present evidence-based best practices for pharmacologic, non-pharmacologic, and interventional treatments for myofascial pain.

Intermediate Cervical Plexus Block in the Management of Refractory Somatosensory Tinnitus Following Whiplash: Prospective Series in 30 Patients

OBJECTIVE

Whiplash-associated disorder comprises of a constellation of persistent symptoms after neck trauma. Tinnitus that develops postwhiplash is termed somatosensory tinnitus. The objective is to assess the role of intermediate cervical plexus block (iCPB) in patients with somatosensory tinnitus secondary to whiplash.

METHODS

Prospective service evaluation in adults with whiplash-associated disorder and concomitant somatosensory tinnitus. Patients underwent specialist otorhinolaryngology review before pain clinic referral. Patients were offered ultrasound-guided iCPB with steroids. Intensity of tinnitus was recorded on a numerical rating scale at baseline, 3 and 6 months posttreatment. Brief Pain Inventory Short Form and Hospital Anxiety Depression Scale questionnaires were also completed.

RESULTS

Over a 36-month period, 32 patients with refractory somatosensory tinnitus following whiplash were offered iCPB(s). Two patients refused because of needle phobia. iCPB(s) was performed in 30 patients as an outpatient procedure. One patient (1/30, 3.3%) was lost to follow-up. Twenty-three patients (23/30, 77%) reported clinically significant reduction in intensity of tinnitus at 3 months postprocedure. Nineteen patients (19/30, 63%) reported ongoing benefit at 6-month follow-up. Six patients failed to report any benefit (6/30, 20%).

CONCLUSION

The cervical plexus could play a significant role in the development of somatosensory tinnitus after whiplash. iCPB may have a role in the management of somatosensory tinnitus in this cohort.

The incidence of post cholecystectomy pain (PCP) syndrome at 12 months following laparoscopic cholecystectomy: a prospective evaluation in 200 patients

OBJECTIVES

Post cholecystectomy pain syndrome can cause significant distress, impairs quality of life and exacerbations often result in emergency visits. Poorly controlled postoperative pain is a recognized cause of persistent postsurgical pain. Abdominal myofascial pain syndrome is an underdiagnosed cause of persistent pain in this cohort. The objective was to estimate the incidence of poorly controlled postoperative pain in the first 48 h after surgery and the likelihood of developing persistent pain at 12 months.

METHODS

The patients undergoing laparoscopic cholecystectomy at a tertiary unit were consented for participation in a prospective service evaluation. A telephone review was performed at three, six and twelve months after surgery. Incidence of poorly controlled pain in the first 48 h after surgery was assessed. Patients with persistent pain were referred to the pain clinic.

RESULTS

Over a six-month period, 200 patients were assessed. Eleven patients were excluded (5.5 %). Twelve patients were lost to follow-up (6.6 %, 12/189). Patient satisfaction with acute postoperative pain management was low in 40 % (76/189). Poorly controlled postoperative pain was reported by 36 % (68/189) of patients. Incidence of persistent pain was 29 % (54/189) at 12 months post-surgery. Over half of patients with persistent pain (63 %, 34/54) reported poorly controlled postoperative pain. A somatic source was diagnosed in 54 % (29/54) with post cholecystectomy pain syndrome.

CONCLUSIONS

Poorly controlled postoperative pain was reported by a third of patients. Persistent pain was present in 29 % at twelve months post-surgery. Abdominal myofascial pain syndrome should be considered as a differential diagnosis in post cholecystectomy pain syndrome.

Interventional pathway in the management of refractory post cholecystectomy pain (PCP) syndrome: a 6-year prospective audit in 60 patients

OBJECTIVES

Post cholecystectomy pain syndrome can affect over a third of patients undergoing laparoscopic cholecystectomy. Acute exacerbations can result in recurrent emergency admission with excessive healthcare utilization. Standard surgical management appears to focus on visceral aetiology. Abdominal myofascial pain syndrome is a poorly recognised somatic pathology that can cause refractory pain in this cohort. It develops as a result of trigger points in the abdominal musculature. The report describes the pathophysiology and a novel interventional pathway in the management of post cholecystectomy pain secondary to abdominal myofascial pain syndrome.

METHODS

The prospective longitudinal audit was performed at a tertiary pain medicine clinic in a university teaching hospital. Over a six-year period, adult patients with refractory abdominal pain following laparoscopic cholecystectomy were included in a structured interventional management pathway. The pathway included two interventions. Intervention I was a combination of abdominal plane blocks and epigastric port site trigger injection with steroids. Patients who failed to report durable relief (>50% pain relief at 12 weeks) were offered pulsed radiofrequency treatment to the abdominal planes (Intervention II). Outcomes included patient satisfaction, change in opioid consumption and impact on emergency visits.

RESULTS

Sixty patients who failed to respond to standard management were offered the pathway. Four patients refused due to needle phobia. Fifty-six patients received Intervention I. Failure rate was 14% (8/56). Forty-eight patients (48/56, 86%) reported significant benefit at 12 weeks while 38 patients reported durable relief at 24 weeks (38/56, 68%). Nine patients received Intervention II and all (100%) reported durable relief. Emergency admissions and opioid consumption were reduced.

CONCLUSIONS

Abdominal myofascial pain syndrome is a poorly recognised cause of post cholecystectomy pain. The novel interventional management pathway could be an effective solution in patients who fail to benefit from standard management.

Abdominal Pain in Inflammatory Bowel Disease: An Evidence-Based, Multidisciplinary Review

Abdominal pain is one of the most common and impactful symptoms associated with inflammatory bowel disease (IBD), including both Crohn's disease and ulcerative colitis. A great deal of research has been undertaken over the past several years to improve our understanding and to optimize management of this issue. Unfortunately, there is still significant confusion about the underlying pathophysiology of abdominal pain in these conditions and the evidence underlying treatment options in this context. There is also a relative paucity of comprehensive reviews on this topic, including those that simultaneously evaluate pharmacological and nonpharmacological therapeutic options. In this review, our multidisciplinary team examines evidence for various currently available medical, surgical, and other analgesic options to manage abdominal pain in IBD.

Interventional pathway in the management of refractory chronic flank pain: Prospective series in 45 patients

BACKGROUND

Chronic flank pain can pose a therapeutic challenge. Current management centres on visceral pathology affecting the renal system. Acute exacerbations can be severe, requiring emergency admission. Patients usually have well-established visceral pathology including polycystic kidney disease, Fowler's syndrome, and renal calculi disease that often cause recurrent urinary tract infections. However, in many cases, despite negative investigations including imaging, biochemistry and urine analysis, flank pain persists. Abdominal myofascial pain syndrome is a poorly recognized pathology in this cohort. The report describes the underlying pathophysiology and a novel interventional management pathway for patients presenting with refractory flank pain secondary to abdominal myofascial pain syndrome.

METHODS

Adult patients with refractory chronic flank pain at a tertiary renal unit were included as a part of an on-going prospective longitudinal audit. Patients refractory to standard management were offered the interventional pathway. The pathway included two interventions: quadratus lumborum block with steroid and pulsed radio frequency treatment. Patients completed brief pain inventory and hospital anxiety and depression scale questionnaires at baseline, 3 and 6 months postprocedure. Outcomes collected included ability to maintain employment, change in opioid consumption at 6 months and impact on emergency hospital admissions at 12 months after initiation of the pathway.

RESULTS

Forty-five patients were referred to the pain medicine clinic over a seven-year period between 2014 and 2021. All patients were offered the interventions. Four patients refused due to needle phobia. Forty-one patients received transmuscular quadratus lumborum plane block with steroids. Twenty-seven patients (27/41, 66%) reported durable benefit at 6 months and six patients (6/41, 15%) had clinically significant relief at 3 months. Fifteen patients received pulsed radiofrequency to quadratus lumborum plane and 11 patients (73%) reported > 50% analgesia at 6 months. Treatment failure rate was 10% (4/41). Opioid consumption at 6 months and emergency admission at 12 months were reduced post intervention.

CONCLUSION

Abdominal myofascial pain syndrome is a poorly recognized cause of chronic flank pain syndrome. The interventional management pathway could be an effective solution in this cohort.

Abdominal Wall Pain and Primary Dysmenorrhea: The Importance of Myofascial Trigger Points

Myofascial trigger points are among the often-overlooked causes of anterior abdominal wall pain and primer dysmenorrhea. It is crucial to evaluate patients with a myofascial perspective in addition to a good history and a detailed physical examination. Myofascial trigger points of the abdominal oblique muscles and rectus abdominis muscle should be considered for patients with abdominal wall pain and primer dysmenorrhea. It should also be kept in mind that myofascial pain syndrome may be the primary pathology responsible for the pain, or it may be an entity accompanying another underlying pathology.

Buccal acupuncture combined with ultrasound-guided dry needle-evoked inactivation of trigger points to treat cervical and shoulder girdle myofascial pain syndrome

BACKGROUND

Myofascial pain syndrome (MPS) is a common disease with easy persistence and recurrence. In clinical practice, although many methods have been adopted to prevent and treat MPS, the control of MPS is still not satisfactory.

OBJECTIVE

To compare the safety and effectiveness of buccal acupuncture, inactivation of trigger points (MTrPs), and their combination in the treatment of MPS.

METHODS

Two hundred MPS patients in the pain clinic were randomly divided into four groups (n= 50) to receive oral drugs (Group A), oral drugs + buccal needle (Group B), oral drugs + MTrP inactivation (Group C), or oral drugs + buccal needle + MTrP inactivation (Group D).

RESULTS

The visual analogue scale (VAS) and cervical range of motion (ROM) of Group D were significantly lower than those of the other three groups, and the pressure pain threshold (PPT) value of labelled MTrPs was significantly higher than those of the other three groups (P< 0.05). The excellent rate and total effective rate of Group D were significantly higher than those of the other three groups. Group C had the highest pain score and the lowest acceptance score. The results showed that buccal acupuncture combined with ultrasound-guided dry needle-evoked inactivation of MTrPs can significantly reduce the VAS score of MPS patients, improve the range of motion of the cervical spine, and improve patient satisfaction.

CONCLUSIONS

This study provides a highly accepted and satisfactory treatment for MPS, which is worthy of clinical promotion.

Medial and dorsal lateral septum involving social disruption stress-primed escalation in acid-induced writhes

Introduction

Stress may cause prospective escalations in abdominal pain magnitude and accumbal TRPV1 expression, while central neural circuits mediating these stress effects remain unclear.

Methods

Using retrograde tracing methods, we first demonstrated the existence of a medial septal-dorsal lateral septal -accumbal circuit very likely involving social disruption stress-primed escalations in acid-induced writhes and accumbal TRPV1 level. An intersectional viral strategy and virus-carrying hM3Dq and hM4Di DREADDs were, then, employed to selectively modulate GABAergic and cholinergic neuronal activity in medial and dorsal lateral septum.

Results

Exciting medial septal GABAergic neuron was found to prevent social disruption stress-primed escalations in acid-induced writhes and accumbal TRPV1 and PKCε expressions. Likewise, inactivating dorsal lateral septal cholinergic neurons was also effective in abolishing these stress-primed escalations. Inactivating GABAergic neuron in non-stressed animals' medial septum was found to reproduce the stress-primed effects in causing heightened acid-induced writhes and accumbal TRPV1 and PKCε levels.

Discussion

These results, taken together, prompt us to conclude that social disruption stress may produce plastic changes in a newly-identified medial septal-dorsal lateral septal-accumbal circuit. Moreover, medial septal GABAergic hypoactivity and dorsal lateral septal cholinergic hyperactivity are, at least, two likely causes reflecting such stress-produced escalations in abdominal pain magnitude and pain transduction-related protein over-expression in nucleus accumbens.

Radiofrequency Ablation for Thoracic and Abdominal Chronic Pain Syndromes

Chronic thoracic pain and chronic abdominal pain are common conditions that can significantly affect quality of life. Pain syndromes encompassing a variety of causes, including cancer pain, neuritis, and postsurgical pain, are traditionally managed by the use of pharmacologic therapy; however, many cases are refractory to these conservative methods. Radiofrequency ablation (RFA) has been increasingly used as a tool to treat resistant, chronic pain of both thoracic and abdominal origin. Multiple cases and trials have been reported that show the efficacy of RFA in the treatment of these chronic pain conditions.

Social disruption-induced stress pre-exposure aggravates, while the presence of conspecifics diminishes, acetic acid-induced writhing

RATIONALE AND OBJECTIVE

This study was undertaken to assess the modulating effects of (1) pre-exposure to repeated social disruption and (2) group testing on writhing associated with visceral pain induced by intraperitoneal administration of acetic acid.

MATERIALS AND METHODS

Six consecutive days of social disruption were used to prime for stress, while group testing referred to 3 mouse cage-mates receiving the acetic acid-induced writhing test as a group.

RESULTS

Social disruption-induced stress-pre-exposed mice displayed a greater number acid-induced writhes compared to mice not receiving the pre-exposure. However, mice displayed fewer acid-induced writhes in a triad group vs. individually, suggesting group-mediated writhing-reducing effects. Likewise, group testing prevented the stress pre-exposure escalation in acid-induced writhes. Additional studies revealed that the stress-pre-exposed mice had increased expression in accumbal TRPV1 receptors. Systemic (0.25 mg/kg) and bilateral intra-accumbal (0.2 ng/0.2 µl/side) administration of SB366791, a TRPV1 receptor antagonist, reliably prevented the stress pre-exposure escalation in acid-induced writhing; SB366791 treatment alone did not affect acid-induced writhing, stress pre-exposure anxiety-like behavior, or the group testing effects. Furthermore, lower neuronal activation was found in the medial septal nucleus in group vs. individual tested mice. Intra-medial septum (0.2 µg/0.5 µl) infusion with bicuculline, a GABAA receptor antagonist, effectively prevented group-mediated writhing-reducing effects, but not individual acid-induced writhing effects.

CONCLUSIONS

These findings suggest that social disruption-induced stress pre-exposure may upregulate accumbal TRPV1 receptor expression and consequently aggravate acid-induced writhing. Group testing prevents such stress pre-exposure escalation of acid-induced writhing most likely by strengthening the GABAergic inhibition on local neural activity in the medial septum.

Re-Examining Myofascial Pain Syndrome: Toward Biomarker Development and Mechanism-Based Diagnostic Criteria

PURPOSE OF REVIEW

We discuss the need for a mechanism-based diagnostic framework with a focus on the development of objective measures (e.g., biomarkers) that can potentially be added to the diagnostic criteria of the syndrome. Potential biomarkers are discussed in relation to current knowledge on the pathophysiology of myofascial pain syndrome (MPS), including alterations in redox status, inflammation, and the myofascial trigger point (MTrP) biochemical milieu, as well as imaging and neurophysiological outcomes. Finally, we discuss the long-term goal of conducting a Delphi survey, to assess the influence of putative MPS biomarkers on clinician opinion, in order to ultimately develop new criteria for the diagnosis of MPS.

RECENT FINDINGS

Myofascial pain syndrome (MPS) is a prevalent healthcare condition associated with muscle weakness, impaired mood, and reduced quality of life. MPS is characterized by the presence of myofascial trigger points (MTrPs): stiff and discrete nodules located within taut bands of skeletal muscle that are painful upon palpation. However, physical examination of MTrPs often yields inconsistent results, and there is no gold standard by which to diagnose MPS. The current MPS diagnostic paradigm has an inherent subjectivity and the absence of correlation with the underlying pathophysiology. Recent advancements in ultrasound imaging, systemic biomarkers, MTrP-specific biomarkers, and the assessment of dysfunction in the somatosensorial system may all contribute to improved diagnostic effectiveness of MPS.

Risk of infection within 4 weeks of corticosteroid injection (CSI) in the management of chronic pain during a pandemic: a cohort study in 216 patients

OBJECTIVES

Targeted corticosteroid injections (CSI) are one of the treatments that can provide pain relief and thereby, enhance quality of life in patients with chronic pain. Corticosteroids (CS) are known to impair immune response. The objective was to evaluate the risk of developing post-procedural infection within 4 weeks of receiving depot CSI for chronic pain as part of on going quality improvement project. We hypothesised that interventional treatment with depot steroids will not cause a significant increase in clinical infection in the first 4 weeks.

METHODS

Telephone follow-up was performed as a part of prospective longitudinal audit in a cohort of patients who received interventional treatment for chronic pain at a multidisciplinary pain medicine centre based at a university teaching hospital. Patients who received interventional treatment in the management of chronic pain under a single physician between October 2019 and December 2020 were followed up over telephone as part of on going longitudinal audits. Data was collected on any infection within 4 and 12 weeks of receiving the intervention. Outcomes collected included type of intervention, dose of depot steroids and pain relief obtained at 12 weeks following intervention.

RESULTS

Over a 15 month period, 261 patients received pain interventions with depot CS. There was no loss to follow-up. Nine patients reported an infection within 4 weeks of receiving depot steroids (9/261, 3.4%). None of the patients tested positive for Covid-19. Eight patients (8/261, 3%) reported an infection between 5 and 12 weeks following the corticosteroid intervention. Although none of the patients tested positive for Covid-19, two patients presented with clinical and radiological features suggestive of Covid-19. Durable analgesia was reported by 51% (133/261) and clinically significant analgesia by 30% (78/261) at 12 weeks following the intervention. Failure rate was 19% (50/261).

CONCLUSIONS

Pain medicine interventions with depot steroids do not appear to overtly increase the risk for Covid-19 infection in the midst of a pandemic.

Expert consensus on the diagnosis and treatment of myofascial pain syndrome

Myofascial pain syndrome (MPS) is characterized by myofascial trigger points and fascial constrictions. At present, domestic and foreign scholars have not reached a consensus on the etiology and pathogenesis of MPS. Due to the lack of specific laboratory indicators and imaging evidence, there is no unified diagnostic criteria for MPS, making it easy to confuse with other diseases. The Chinese Association for the Study of Pain organized domestic experts to formulate this Chinese Pain Specialist Consensus on the diagnosis and treatment of MPS. This article reviews relevant domestic and foreign literature on the definition, epidemiology, pathogenesis, clinical manifestation, diagnostic criteria and treatments of MPS. The consensus is intended to normalize the diagnosis and treatment of MPS and be used by first-line doctors, including pain physicians to manage patients with MPS.

Leiomyosarcoma of the small intestine presenting as abdominal myofascial pain syndrome (AMPS): case report

OBJECTIVE

To highlight an extremely unusual presentation of an aggressive, rare small bowel malignancy presenting as abdominal myofascial pain syndrome.

CASE PRESENTATION

The report is presented from a tertiary pain medicine unit at a university teaching hospital. A female patient presenting with chronic abdominal pain was initially diagnosed as abdominal myofascial pain syndrome. The report details the possible facilitation of the diagnosis of a rare, highly aggressive small bowel tumour by interventional treatment for abdominal myofascial pain syndrome.

CONCLUSION

This case highlights a rare and aggressive malignancy of the small intestine presenting clinically as abdominal myofascial pain syndrome.

Ultrasound-Guided Subcostal TAP Block with Depot Steroids in the Management of Chronic Abdominal Pain Secondary to Chronic Pancreatitis: A Three-Year Prospective Audit in 54 Patients

BACKGROUND

Chronic pancreatitis is a common cause of recurrent chronic abdominal pain that utilizes significant health care resources. Pain in chronic pancreatitis can be of two types. Visceral pain occurs during ongoing pancreatic inflammation. Once pancreatic inflammation subsides, the pain generator can move to the abdominal wall as a result of viscerosomatic convergence and present as abdominal myofascial pain syndrome. Subcostal transversus abdominis plane block is an abdominal plane block that has been proven effective in upper abdominal pain of somatic origin.

DESIGN

The authors discuss the two distinct types of chronic abdominal pain as a result of pancreatitis and present a prospective audit of a management pathway.

METHODS

Over a three-year period, 54 patients with chronic abdominal pain as a result of pancreatitis were prospectively audited at a tertiary care university hospital. Patients were offered bilateral subcostal transversus abdominis plane block with depot steroids as the primary interventional treatment in the pathway.

RESULTS

In patients with myofascial pain secondary to chronic pancreatitis, the block was effective in producing clinically significant pain relief at three months (95%, 20/21) and durable pain relief lasting six months (62%, 13/21). In patients with visceral pain, the block produced a transient benefit lasting two to three weeks in one-third (six of 17).

CONCLUSIONS

Subcostal transversus abdominis plane block may be an option in the management of abdominal myofascial pain syndrome secondary to chronic pancreatitis. The block is ineffective in producing clinically significant pain relief in the presence of ongoing pancreatic inflammation.

Sonography-guided trigger point injections in abdominal myofascial pain syndrome

Even though chronic abdominal pain is 1 of the most common reasons for hospital visits, diagnostic testing is often time-consuming and treatment is inadequate. Abdominal myofascial pain syndrome (AMPS) is usually not included as a differential diagnosis, but it should be considered in cases of chronic abdominal pain. The purpose of this study was to investigate the clinical characteristics of AMPS and to assess the effect of sonography-guided trigger point injections (TPI).A total of 100 patients with AMPS from 2012 to 2018 were retrospectively evaluated for clinical characteristics and TPI effects. AMPS was diagnosed using Srinivasan and Greenbaum's criteria, and the TPIs were performed at intervals of 2 to 4 weeks. The Visual Analog Scale (VAS) ratio was calculated by subtracting the final VAS from the initial VAS score and dividing it by the initial VAS score after injections, and the patients were divided into 4 groups: non-responders, mild, moderate, and good responders.The median duration of pain was 12 months, and the median number of hospital visits before TPI was 2. Of the 100 patients, 66 (66%) were categorized as good responders, 11 (11%) as moderate responders, 7 (6.9%) as mild responders, and 16 (15.7%) as non-responders. When the initial and final VAS scores were compared, the sonography-guided injections were found to be effective in alleviating pain (P < .001). Moreover, patients who received the injections 2 or more times tended to have more significant pain reduction than those who received a single injection (P < .001).Patients with AMPS suffer from long-term pain and undergo many hospital visits and diagnostic tests. TPI with lidocaine can be an effective and safe treatment for patients with chronic AMPS.

The Case for Comorbid Myofascial Pain-A Qualitative Review

Myofascial pain syndrome is widely considered to be among the most prevalent pain conditions, both in the community and in specialized pain clinics. While myofascial pain often arises in otherwise healthy individuals, evidence is mounting that its prevalence may be even higher in individuals with various comorbidities. Comorbid myofascial pain has been observed in a wide variety of medical conditions, including malignant tumors, osteoarthritis, neurological conditions, and mental health conditions. Here, we review the evidence of comorbid myofascial pain and discuss the diagnostic and therapeutic implications of its recognition.

Ultrasound-Guided Inactivation of Trigger Points Combined with Muscle Fascia Stripping by Liquid Knife in Treatment of Postherpetic Neuralgia Complicated with Abdominal Myofascial Pain Syndrome: A Prospective and Controlled Clinical Study

Objective

To evaluate ultrasound-guided inactivation of myofascial trigger points (MTrPs) combined with abdominal muscle fascia stripping by liquid knife in the treatment of postherpetic neuralgia (PHN) complicated with abdominal myofascial pain syndrome (AMPS).

Methods

From January 2015 to July 2018, non-head-and-neck PHN patients in the Pain Department, The First Affiliated Hospital of Soochow University, were treated with routine oral drugs and weekly paraspinal nerve block for two weeks. Patients with 2 < VAS (visual analogue scale) score < 6 were subjects of the study. They were assigned into control group 1 (C1, n = 33) including those with PHN and without myofascial pain syndrome (MPS) and control group 2 (C2, n = 33) including those with PHN complicated with MPS and observation group 1 (PL, n = 33) including those with PHN complicated with limb myofascial pain syndrome (LMPS) and observation group 2 (PA, n = 33) including those with PHN complicated with AMPS. All groups received zero-grade treatment: routine oral drugs and weekly paraspinal nerve block. PL and PA groups were also treated step by step once a week: primary ultrasound-guided inactivation of MTrPs with dry needling, secondary ultrasound-guided inactivation of MTrPs with dry and wet needling, and tertiary ultrasound-guided dry and wet needling combined with muscle fascia stripping by liquid knife. At one week after primary treatment, patients with a VAS score > 2 proceeded to secondary treatment. If the VAS score was <2, the treatment was maintained, and so on, until the end of the four treatment cycles. Pain assessment was performed by specialized nurses at one week after each treatment, including VAS score, McGill pain questionnaire (MPQ) score, pressure pain sensory threshold (PPST), and pressure pain tolerance threshold (PPTT). VAS score was used as the main index and VAS <2 indicated effective treatment. At 3 months after treatment, outpatient and/or telephone follow-up was performed. The recurrence rate was observed and VAS > 2 was regarded as recurrence.

Results

At one week after primary treatment, the effective rate was 66.7% in PL group, significantly higher than that in PA group (15.2%, P < 0.05). At one week after secondary treatment, the effective rate was 100% and 37.5% in PL and PA groups, respectively, with significant difference between the groups (P < 0.05). The effective rate increased to 90.6% in PA group at one week after tertiary treatment. At one week after the end of treatment cycles, the scores of VAS and MPQ were significantly lower in C1, PL, and PA groups than in C2 group (P < 0.05), while PPST and PPTT were significantly higher than in C2 group (P < 0.05). There was no significant difference between C1 group and PL group (P > 0.05). At follow-up at 3 months after treatment, the recurrence rate was low in each group, with no significant difference between the groups (P > 0.05).

Conclusion

About 57% of PHN patients with mild to moderate pain are complicated with MPS, and ultrasound-guided inactivation of MTrPs with dry and wet needling can effectively treat PHN patients complicated with LMPS. However, patients with PHN complicated with AMPS need to be treated with ultrasound-guided MTrPs inactivation combined with muscle fascia stripping by liquid knife as soon as possible.

Sympathetic hyperinnervation in myofascial trigger points

OBJECTIVE

To evaluate the local distribution and activity of sympathetic nerves in myofascial trigger points (MTrPs) and explore the pathological mechanism of myofascial pain syndrome (MPS) using a rat model of disease.

METHODS

MPS was modeled in the model group (MG) by a combination of blunt trauma and eccentric exercise in Sprague-Dawley rats (n = 8). Eight rats were randomly assigned to the control group (CG). Histopathology was applied to detect the local conditions of the MTrPs. Tyrosine hydroxylase (TH), nerve growth factor (NGF), and norepinephrine (NE) were detected in the MTrPs to evaluate sympathetic remodeling.

RESULTS

Muscle fiber rupture, atrophy and shape irregularity were universally observed in the MTrPs. TH expression was significantly increased in the MG, as detected by immunofluorescence, and NGF and TH expression was also higher in MTrPs in the MG than in MTrPs in the CG, as determined by immunohistochemistry. Furthermore, the expression of NE was significantly increased in MTrPs, as determined by ELISA.

CONCLUSION

There was sympathetic hyperinnervation in MTrPs, which could partially explain the symptoms of MTrPs and is an interesting and useful new perspective regarding the diagnosis and treatment of MPS.

PERSPECTIVE

The sympathetic nerves in MTrPs are remodeled, leading to sympathetic hyperinnervation. Sympathetic hyperinnervation can partially explain the symptoms of MPS. The pathological mechanism of sympathetic hyperinnervation may be a new perspective for the diagnosis and treatment of MPS.