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Perpetuating Factors of MPS

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Many conditions may act as perpetuating factors of chronic MPS including nutritional deficiency states, such as iron insufficiency and vitamin B12 deficiency, hormonal disorders such as hypothyroidism, and trauma such as cervical strain injury. For example, vitamin D deficiency is associated with musculoskeletal pain, loss of type 2 muscle fibers, and proximal muscle atrophy.52 53 One study found that 89% of subjects with chronic musculoskeletal pain were deficient in vitamin D. The deficient state can be treated, but up to 6 months may be required for vitamin D levels to return to normal levels. Iron deficiency in the muscle may also play a role in the development or maintenance of MTrPs. Hypothyroidism also produces a hypometabolic state, which may augment MTrP formation.52

Perpetuating factors may be structural, postural, or ergonomic if co-morbid conditions such as scoliosis, leg length discrepancy, pelvic torsion, or hypomobility or hypermobility of joints, among others, are present. Co-morbid conditions, whether of a medical or mechanical nature, may initiate or interfere with the treatment or recovery process. Thus, in cases of chronic MPS, a thorough history and physical examination as well as a targeted laboratory exam can be beneficial.52

Conclusion

Chronic musculoskeletal pain, specifically MPS, is associated with MTrPs and sensitization. Therefore, it is essential that pain management practitioners perform a comprehensive evaluation to assess these factors and incorporate them into the management of MPS. While the etiology of MPS is uncertain, advances in the characterization of the MTrP and the surrounding environment have increased the knowledge regarding the mechanism and provided some translational insights into the potential role of MTrP in MPS. There remains a lack of consensus on the definition and diagnostic criteria for MPS, hindering a standardized approach to the clinical examination of this common disorder. Additionally, while a variety of pharmacological and non-pharmacological treatments have shown efficacy and improvement in pain associated with MPS, these findings are typically limited to self-reported pain levels pre- and post-treatment. Although such measures are valid, the outcomes are subjective and thus difficult to quantify in the context of the variable presentations of MPS. Moreover, to date, few randomized, placebo-controlled trials have been undertaken, and most have limited sample size. Thus, in addition to the development of standardized diagnostic criteria, studies of sufficient size and power with quantitative outcome measures are sorely needed in order to improve the treatment of chronic musculoskeletal pain and MTrPs.

A Case Scenario

Bethany is a 30-year-old woman who has been living for 15 years with chronic pelvic pain that is primarily focused in her left lower quadrant. She is frustrated and discouraged because her pelvic pain is still present, despite having undergone four laparoscopic procedures for endometriosis over the last few years. She is puzzled by having been told that the endometriosis lesions were in locations different from her most intense areas of pain. This observation along with her continued exhaustion from pain even during recovery after each surgery and the lack of long-lasting pain relief prompted Bethany to seek other medical specialists’ opinions, including that of a physiatrist. To develop an effective approach to treatment for Bethany, the physiatrist reviews her medical and pain history, including eliciting any emotional aspects, and performs a pain-focused physical examination. This strategy enables Bethany’s physiatrist to organize and synthesize her complex 15-year pain history into a pattern of interconnected pain conditions.

During her first visit, the physiatrist focuses on the history and pattern of her painful symptoms. She reports having severe, doubling over midline pelvic cramping during her menstrual cycles that is often accompanied by low back pain. Initially she thought that these symptoms were normal with menstruation and endometriosis as her mother and sisters each had similar pain symptoms. A few years ago, she was diagnosed with irritable bowel syndrome and experiences both constipation and bloating.

For many years before she was diagnosed with endometriosis and irritable bowel syndrome, Bethany had gone from doctor to doctor looking for a diagnosis and a strategy to manage her symptoms. Some clinicians did not acknowledge the severity of her chronic pelvic pain and did not consider the diagnosis of endometriosis, especially since her symptoms occurred primarily during menses. They conveyed a belief that these painful symptoms were normal with menstruation. In fact, Bethany was told by at least four doctors that her symptoms were “in her head” and imaginary. This minimizing of the severity of her symptoms delayed referral to a gynecologist specializing in chronic pelvic pain. Because of this lack of understanding, Bethany alternated between believing her physicians and feeling frustrated and depressed. Over time, her chronic pain worsened and occurred at other times of the menstrual cycle. She found she frequently had negative thoughts and reported a sense of diminished self-worth. She was unable to function well at work and found her feeling began to impact her family and intimate relationships.

After almost ten years of pain, Bethany was first surgically diagnosed with endometriosis at age

25. After her first laparoscopy, the gynecologist told her that he had burned off some endometriosis lesions in her region of pain but left some others that he did not think were related to her pain. Within a year, she switched gynecologists and underwent another laparoscopy, this time with an endometriosis specialist surgeon who resected all the endometriosis lesions she could find. Just before the second surgery, the gynecologist surgeon placed Bethany on 6 months of hormonal therapy with GnRH agonists to suppress endometriosis growth. While Bethany got relief for about 6 months, the pain returned when the hormonal therapy was stopped. The combination of surgery with hormonal management only provided temporary relief of her chronic pain. She tried other hormones including cyclic birth control pills and now uses a progestin-releasing IUD that suppresses her menstrual flow. Over time, she underwent two more similar surgical procedures. Now, at age 35 she still feels the same pain even after a recent endometriosis surgery 6 weeks ago at which all endometriosis lesions were resected. Coulcl Bethany’s continued pain be explained and/or maintained by other factors beyond the pelvic floor? Could potential stressors in her life exacerbate her pain symptoms?

After listening to Bethany’s medical history, the physiatrist explains that active MTrPs in the pelvic floor and abdomen may refer pain to other pelvic regions as well as her lower back and abdomen. Widespread pain might be generated from the active MTrPs and could be a result of central sensitization. This sort of pain would not be addressed by surgical or hormonal therapies that only target the ectopic endometrial lesions.

To determine the additional factors that could maintain Bethany’s pain, the physiatrist conducts a thorough neura-musculoskeletal pain examination to assess for signs of widespread pain, central sensitization, and myofascial dysfunction. He begins by assessing the dermatomes for allodynia and hyperalgesia bilaterally. He brushes the skin with a thin microfilament, approximately 2.5 cm lateral to each spinal process, in order to assess for allodynia. He then uses a Wartenberg pinwheel to scratch the skin and assess for hyperalgesia. As suspected, Bethany exhibits allodynia and hyperalgesia in more than half of the spinal segments, suggesting widespread sensitization.

Next, the physiatrist assesses the myotome for the presence of MTrPs, measuring the PPT over each MTrP. Digital pressure on the active MTrP reproduces her pain. Bethany has active MTrPs in over half of the assessed regions, and a low PPT (<4 kg/cm2) suggests a lowered pressure-pain threshold. This neuro-musculoskeletal exam allows the physiatrist to evaluate the distribution of Bethany’s myofascial dysfunction and the extent of her sensitization. At times, active MTrPs might be a somatic manifestation of an underlying visceral problem like endometriosis. To assess whether Bethany also has MTrPs throughout her pelvic floor muscles, the physiatrist refers her to a gynecologist who understands the complex interaction between myofascial dysfunction, sensitization, and chronic pelvic pain.

The physiatrist conveys the findings of Bethany’s neuro-musculoskeletal exam and her medical and pain history to the gynecologist who then also performs a history and evoked-pain gynecologic examination. The gynecologist examines the abdominopelvic region for allodynia, tenderness, number of MTrPs, and severity of pain elicited upon palpation of the active abdominal wall MTrPs. Bethany did not have abdominal wall allodynia but did experience tenderness in her lower left quadrant and suprapubic region.

Next, the superficial perineal muscles are palpated externally for muscle spasm and tenderness using a single digit. The gynecologist then performed an intravaginal assessment of the pelvic floor muscles to identify the presence of active MTrPs, taut bands, or tenderness. Bethany was found to have active MTrPs in the pubococcygeus, iliococcygeus, and obturator internus on the left side that reproduced her pain, and an active MTrPs in the right iliococcygeus. Bethany also had bladder, urethral, and uterosacral tenderness on gentle single-digit palpation but no forniceal tenderness or uterosacral nodularity. On bimanual exam, she has central uterine tenderness. Bethany reported her pattern of pelvic tenderness to be diffuse with the worst pain in the pelvic floor.

The gynecologist and Bethany also discussed potential topics of emotional and physical stress. Bethany indicated that she had recently been involved in a car accident and now had panic attacks when she had to drive on the highway. She explained that she always strives to do her best and has recently transitioned to a fast-paced, high-stress job.

The gynecologist agrees with the physiatrist that Bethany’s continuing pain after complete surgical resection of ectopic endometrial lesion may be maintained by the presence of MTrPs. This thorough assessment for tenderness throughout the pelvis provides insight on the pattern of the pain as well as potential triggers.

Considering all of Bethany’s symptoms and dysfunction, what is the best course of treatment? The comprehensive neuro-musculoskeletal exam and the gynecological evoked pain assessment together provide a thorough assessment of the patient with chronic pelvic pain. After obtaining the gynecologist’s clinical assessment and impression of Bethany’s condition and results of her pelvic exam, the physiatrist offers Bethany a dry needling treatment in order to deactivate active and latent

MTrPs in the periphery and paraspinous dry needling to desensitize the spinal segments along her areas of pain as a potentially beneficial form of treatment. In addition, the physiatrist recommends trigger point injections with lidocaine on the active MTrPs in Bethany’s abdominal wall.

He also recommends that Bethany supplement the dry needling treatments with myofascial release techniques, biofeedback therapy, cognitive behavioral therapy, or mindfulness-based stress reduction techniques to address both the physiological and psychological components of chronic myofascial pain. This combined approach may also alleviate the pain associated with active MTrPs, improve her strength and flexibility, and provide Bethany with useful coping strategies during a painful episode.

After the paraspinous dry needling sessions in the L3-L4 and T6 segments, Bethany’s low back pain decreased, and her clinical findings of allodynia and hyperalgesia also decreased. Moreover, the lidocaine injections in her abdominal wall provided pelvic pain relief. When an algometer is once again used to measure tenderness along the affected myotomes, there is an increase in PPT, suggesting that the area is no longer sensitized.

In the months following her treatment, Bethany reports that her mood and quality of life have improved significantly. For the first time in years, she is achieving a full night’s rest without waking up in the middle of the night in pain. Even years after her treatment, Bethany’s improvements are sustained, reinforcing the importance of identifying and treating symptoms and signs of peripheral and central sensitization commonly found in chronic pain syndromes such as chronic pelvic pain.

 
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