Evidence of neuroaxonal degeneration in myofascial pain syndrome: A study of neuromuscular jitter by axonal microstimulation

The treatment effect of intramuscular stimulation on carpal tunnel syndrome: A blinded randomized trial on 75 patients

BACKGROUND

Carpal tunnel syndrome (CTS) is a disorder with a prevalence of about 5.8% for females and 0.6% for males. This study aims to determine whether intramuscular stimulation (IMS) to the pronator teres muscle subsequently reduces the severity of clinical parameters and the diameter of the median nerve.

METHODS

Seventy-five individuals with a cross-sectional diameter of the median nerve of more than 2 mm were included in this randomized clinical trial. Thirty-seven individuals received IMS to the pronator teres muscle with a depth of up to 45-50 mm. The 38 individuals in the control group received an acupuncture needle at Li11 with a depth of 4-5 mm. Both groups had 7 treatments within 7 weeks. The primary outcome was the cross-section of the median nerve in the carpal tunnel. Additionally, Phalen's test, Tinel's sign, VAS for pain intensity, and pincer grip strength were measured.

RESULTS

Both IMS subjects and controls showed significant reductions in the cross-section of the median nerve from baseline to follow-up (p < 0.001 and p = 0.002 respectively). The IMS group had the largest change, but the difference in change between the groups was not significant (p = 0.39). On all clinical tests, IMS subjects showed significant improvement from baseline compared with the control group (largest p = 0.002).

CONCLUSION

In this study we found that IMS to the pronator teres muscle significantly improved all clinical variables measured, compared with the group receiving acupuncture. Furthermore, the cross-section of the median nerve reduced over time for both groups. IMS may be a low-risk alternative while patients are waiting for surgery.

TRIAL REGISTRATION

Clinicaltrials. gov Identifier: NCT01102868. Retrospectively registered: March 29th^, 2010.

Acupotomy Alleviates Energy Crisis at Rat Myofascial Trigger Points

The aim of this study was to determine the effects of acupotomy on energy crises in rat trigger points (TrPs) by measuring mechanical pain thresholds (MPTs) and levels of acetylcholinesterase (AChE), free sarcoplasmic calcium (Ca²⁺), adenosine 5'-triphosphate (ATP), adenosine 5'-monophosphate (AMP), substance P (SP), and calcitonin gene-related peptide (CGRP) in rat muscle TrP tissue. Male Sprague Dawley rats (n = 32) were randomly divided into four groups: control, TrP, acupotomy, and lidocaine injection. Enzyme-linked immunosorbent assays were used to measure AChE, and free sarcoplasmic Ca²⁺ concentrations were determined by fluorescent staining with Fura-2 AM; high-performance liquid chromatography was used to measure ATP and AMP, and SP and CGRP were evaluated by immunohistochemistry. Compared with the control group, free sarcoplasmic Ca²⁺, AMP, SP, and CGRP were higher in the model group, while MPT, AChE, and ATP were lower. Treatment with acupotomy or lidocaine injection reduced free sarcoplasmic Ca²⁺, SP, and CGRP and increased MPTs and AChE levels compared with the model group. However, only acupotomy also led to decreased AMP and increased ATP levels relative to the model group. We conclude that acupotomy can alleviate energy crises at TrPs.

Dry needling - peripheral and central considerations

Dry needling is a common treatment technique in orthopedic manual physical therapy. Although various dry needling approaches exist, the more common and best supported approach targets myofascial trigger points. This article aims to place trigger point dry needling within the context of pain sciences. From a pain science perspective, trigger points are constant sources of peripheral nociceptive input leading to peripheral and central sensitization. Dry needling cannot only reverse some aspects of central sensitization, it reduces local and referred pain, improves range of motion and muscle activation pattern, and alters the chemical environment of trigger points. Trigger point dry needling should be based on a thorough understanding of the scientific background of trigger points, the differences and similarities between active and latent trigger points, motor adaptation, and central sensitize application. Several outcome studies are included, as well as comments on dry needling and acupuncture.

Electrophysiologic evidence of spinal accessory neuropathy in patients with cervical myofascial pain syndrome

OBJECTIVE

To evaluate whether or not spinal accessory neuropathy exists in patients with cervical myofascial pain syndrome (MFPS).

DESIGN

Prospective study.

SETTING

A neurophysiologic laboratory in a university hospital.

PARTICIPANTS

Patients with cervical MFPS (n=25) and healthy controls (n=20).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

We performed nerve conduction studies (NCSs) in bilateral spinal accessory nerves, and electromyography and stimulated single-fiber electromyography in the trapezius muscles of all patients and controls. Parameters including nerve conduction velocities (NCVs), amplitudes and areas of compound muscle action potentials (CMAPs), and mean consecutive differences (MCDs) in single-fiber electromyography were measured, analyzed, and compared with the disease durations of the patients.

RESULTS

Spinal accessory NCSs showed normative NCVs but with prominently reduced CMAP amplitude in the patients with cervical MFPS, which is recognized as an axonal neuropathy of the spinal accessory nerves. Electromyography showed prominent evidence of denervation and reinnervation patterns in 48% of the MFPS patients. The abnormal MCDs in single-fiber electromyography indicated a synaptic delay of motor endplates in the motor units, and may signify evolving instability of neuromuscular transmission in the spinal accessory nerves innervating trapezius muscles of the patients.

CONCLUSIONS

This study demonstrates electrophysiologic evidence of neuroaxonal degeneration and neuromuscular transmission disorder in a significant proportion of patients with cervical MFPS. We suggest that spinal accessory neuropathy may be associated with cervical MFPS.

Sliding pressure algometer, a development in eliciting pressure pain thresholds at the boundaries of surface markings of abnormally tender regions

The pressure algometer probe tip is usually held stationary and pressure is steadily increased from zero until a pressure pain threshold (PPT) is elicited. In order to explore the extent of surface markings of abnormally tender regions in more detail an improved method is proposed whereby the pressure algometer is not kept still. It is slid over the tissues at a predetermined downward pressure and velocity to produce compressive, tensile and shear stress within underlying tissues. It is moved over surrounding non-tender regions until it reaches the surface overlying an abnormally tender region where a PPT is evoked. The probe is removed immediately and the skin marked. When this is repeated from different directions, the boundary of the surface markings of a tender region will appear in corresponding detail. Provided that this 'sliding pressure algometer' produces sufficiently similar amounts of stress when applied on separate occasions, it can be used to monitor the progress of a condition or the effects of treatment. To reduce cost and increase availability, this pressure algometer may be made of a plastic syringe converted into a gas-tight chamber.

Treatment of myofascial trigger points in patients with chronic shoulder pain: a randomized, controlled trial

BACKGROUND

Shoulder pain is a common musculoskeletal problem that is often chronic or recurrent. Myofascial trigger points (MTrPs) cause shoulder pain and are prevalent in patients with shoulder pain. However, few studies have focused on MTrP therapy. The aim of this study was to assess the effectiveness of multimodal treatment of MTrPs in patients with chronic shoulder pain.

METHODS

A single-assessor, blinded, randomized, controlled trial was conducted. The intervention group received comprehensive treatment once weekly consisting of manual compression of the MTrPs, manual stretching of the muscles and intermittent cold application with stretching. Patients were instructed to perform muscle-stretching and relaxation exercises at home and received ergonomic recommendations and advice to assume and maintain good posture. The control group remained on the waiting list for 3 months. The Disabilities of Arm, Shoulder and Hand (DASH) questionnaire score (primary outcome), Visual Analogue Scale for Pain (VAS-P), Global Perceived Effect (GPE) scale and the number of muscles with MTrPs were assessed at 6 and 12 weeks in the intervention group and compared with those of a control group.

RESULTS

Compared with the control group, the intervention group showed significant improvement (P < 0.05) on the DASH after 12 weeks (mean difference, 7.7; 95% confidence interval (95% CI), 1.2 to 14.2), on the VAS-P1 for current pain (mean difference, 13.8; 95% CI, 2.6 to 25.0), on the VAS-P2 for pain in the past 7 days (mean difference, 10.2; 95% CI, 0.7 to 19.7) and VAS-P3 most severe pain in the past 7 days (mean difference, 13.8; 95% CI, 0.8 to 28.4). After 12 weeks, 55% of the patients in the intervention group reported improvement (from slightly improved to completely recovered) versus 14% in the control group. The mean number of muscles with active MTrPs decreased in the intervention group compared with the control group (mean difference, 2.7; 95% CI, 1.2 to 4.2).

CONCLUSIONS

The results of this study show that 12-week comprehensive treatment of MTrPs in shoulder muscles reduces the number of muscles with active MTrPs and is effective in reducing symptoms and improving shoulder function in patients with chronic shoulder pain.

TRIAL REGISTRATION NUMBER

ISRCTN: ISRCTN75722066.

Relationships between pathology and pain severities: a review

The relationships between pathology severity and pain severity are reviewed using the literature available for humans. The aim is to help veterinary radiologists, physicians and pathologists recognise the disorders in which severity of a lesion is likely to be related to the severity of pain or to incipient pain. Specific features or lesions within the following conditions showed a relationship with pain score, which was usually assessed with a visual analogue scale: inflammation; pancreatitis; ileitis; mucositis; fasciitis; synovitis; arthritis; lower back pain; disc herniation; sciatica; scoliosis; myalgia; cancer; arteriosclerosis; skin ulcers; mastalgia; skin and oral neuropathies; endometriosis; hepatopathy and chronic pulp diseases of the teeth. As experience with magnetic resonance imaging grows, there will be further opportunities to look for quantitative relationships in humans between pathology and pain severities. This information will be useful to veterinarians and other people working with animals in evaluating pain in animals in their care.

A randomized, controlled study comparing a lidocaine patch, a placebo patch, and anesthetic injection for treatment of trigger points in patients with myofascial pain syndrome: evaluation of pain and somatic pain thresholds

BACKGROUND

Myofascial pain syndrome (MPS), a regional pain condition caused by trigger points in muscle or muscle fascia, produces muscle pain, tenderness, and disability. The gold standard of treatment for MPS-infiltration of trigger points with anesthetic-may provoke discomfort to the patients and require medical intervention.

OBJECTIVES

This study was designed to compare the effects of a topical lidocaine patch, a placebo patch, and injection of anesthetic (infiltration) for the symptoms of MPS in terms of pain, disability, and local tissue hypersensitivity, and to determine the acceptability of the lidocaine patch to the patients.

METHODS

Patients were randomly allocated to receive 1 of 3 treatments: a lidocaine patch applied to the trigger point for 4 days (replacement every 12 hours; total daily dose, 350 mg), a placebo patch applied to the trigger point for 4 days (replacement every 12 hours), or infiltration of the trigger point with two 1-mL injections of 0.5% bupivacaine hydrochloride given 2 days apart. Treatment with the patches was double-blinded, whereas treatment with infiltration was single-blinded. The number of pain attacks, pain intensity at rest and on movement, and pain-related interference with daily activity, work activity, mood, and quality of life were recorded before, during, and after treatment using a visual analog scale (VAS). Pressure and electrical pain thresholds of the skin, subcutis, and muscle in the trigger point, target area, and a pain-free area were evaluated before starting therapy (day 1) and on days 5 and 9. A VAS was used to measure discomfort from therapy, and a diary was given to each patient to record requests for additional treatment (if needed) and adverse effects.

RESULTS

Sixty white patients (46 women and 14 men) 19 to 76 years of age were studied. Mean (SD) age was 46.88 (15.37) years, and mean (SD) weight was 69.58 (13.94) kg. Twenty patients were assigned to each treatment group. Subjective symptoms did not change with placebo, but decreased significantly with the lidocaine patch and infiltration (both, P < 0.001) relative to baseline. Pain thresholds did not vary with the placebo patch, but increased significantly with the lidocaine patch and infiltration (all, P < 0.001); effects at muscle trigger points and target areas were greater with infiltration. Discomfort from therapy was greater with infiltration than with the lidocaine patch. Only patients in the placebo group requested additional treatment (P < 0.001). No adverse events occurred in any group.

CONCLUSION

Lidocaine patches were effective in, and highly acceptable to, these patients with MPS and high tissue hypersensitivity.