Trigger points and chronic pelvic pain

The association between CPP and myofascial pain syndrome was identified several years ago (Slocumb 1984, 1990, Schmidt 1991). Myofascial pain is also related to urogenital pain (Doggweiler-Wiygul 2004). Jarrell (2004) found that abdominal trigger points (TrPs) predicted evidence of visceral disease in 90% of a sample of 55 patients with CPP. Montenegro et al. (2009) recently proposed that abdominal myofascial syndrome should be considered in the differential diagnosis of CPP. In 2009 the European Association of Urology published guidelines suggesting that TrPs should be considered in the diagnosis of CPP (Fall et al. 2010). In fact, Anderson et al. (2009) found that TrPs in the abdominal muscles were the most prevalent in male with CPP.

Myofascial pain syndrome can be associated with both TrPs and restrictions of the fascial tissue. The most commonly accepted definition for TrP is: ‘a hyperirritable spot in a taut band of a skeletal muscle that is painful on compression, stretch, overload or contraction which responds with a referred pain that is perceived distant from the spot’ (Simons et al. 1999). From a clinical viewpoint, we distinguish active and latent TrPs. Active TrPs are those in which local and referred pain reproduce symptoms reported by the patient, with the pain being recognized by the patient as a ‘familiar’ pain (Simons et al. 1999). For instance, in patients with CPP, active TrPs will reproduce perineal or pelvic pain. Latent TrPs are those where local and referred pain do not reproduce pain symptoms, or where elicited pain is not familiar to the patient (Simons et al. 1999). For instance, in a patient with neuropathic pelvic pain, referred pain can be elicited but does not reproduce the patient’s symptoms. Furthermore, a relevant feature of both active and latent TrPs is that each can induce muscle imbalances or altered motor recruitment (Lucas et al. 2004).

There are several studies demonstrating a relationship between CPP and muscle TrPs. Weiss (2001) reported the successful amelioration of symptoms in patients with interstitial cystitis using myofascial TrP release. Doggweiler-Wiygul & Wiygul (2002) found that inactivation of TrPs in PFM, gluteus and piriformis muscles improved or resolved the pain in four patients with severe CPP, interstitial cystitis and irritative voiding symptoms. Anderson et al. (2005) showed that incorporation of TrP inactivation into a multimodal approach for CPP in men resulted in an effective therapeutic approach, by providing a reduction in pain and urinary symptoms superior to that of traditional therapy. This study included voluntary isometric contractions and relaxation, to induce post-isometric relaxation and reciprocal inhibition, together with deep soft tissue mobilization (stripping, strumming, skin rolling and effleurage) as interventions directed at TrPs (Anderson et al. 2005). Anderson et al. (2006, 2009) also found that TrP inactivation was associated with significant improvement in urinary symptoms, libido, ejaculatory and erectile pain, and ejaculatory dysfunction in men with CPP. See Chapter 12 for more detail of Anderson’s studies. Langford et al. (2007) demonstrated the effectiveness of TrPs inactivation of the levator ani muscle for the management of some patients with CPP. In this study 13 of 18 women improved with the first TrP injection resulting in a success rate of 72%, whereas 6 of 18 (33%) were completely pain-free. FitzGerald et al. (2009) demonstrated a better response rate (57%) in CPP patients treated with TrP therapy as compared to the response rate (21%) in those patients receiving global therapeutic massage. In a review of prostatitis and CPP, Anderson (2002) described palpation and treatment protocols for locating muscle TrPs associated with prostatitis symptoms. In a subsequent later study, Anderson et al. (2009) confirmed a relationship between muscle TrPs and CPP in men, identifying the most common location of TrPs: pubococcygeus or puborectalis (90%), external oblique (80%), rectus abdominis (75%), adductors (19%) and gluteus medius (18%) muscles. Other relevant muscles in which TrPs also contribute to CPP are levator ani, iliopsoas, quadratus lumborum, gluteus maximus and the thoracolumbar extensor muscles (Simons et al. 1999, Carter 2000, Liebenson 2000, FitzGerald & Kotarinos 2003a, Chaitow 2007a, Montenegro et al. 2008, Anderson et al. 2009).

Why is inactivation of trigger points in chronic pelvic pain important?

The role of neurogenic inflammation has been emphasized as contributing to the pathophysiology of CPP (Wesselmann 2001). It is well accepted that noxious (nociceptive) stimuli can increase the production of pain-promoting substances at the nerve-free endings of the primary afferent nociceptors. When a sensitive nerve fibre is stimulated the impulse runs towards the spinal cord (orthodromic flow) and towards the periphery (antidromic). When the antidromic stimulus reaches the periphery, there is a release of several neuropeptides (e.g. nitric oxide, substance P, calcitonin gene-related protein) promoting neurogenic inflammation, characterized by vasodilatation, oedema and hyperalgesia (Wesselmann 2001). Clinicians should be aware of the neurophysiological theories for inactivating muscle TrPs in CPP.

Best evidence of soft tissue interventions for muscle trigger points

In this section we review the evidence for soft tissue interventions targeted at inactivating muscle TrPs. However, clinicians should consider that current evidence is based on the application of single treatments applied to TrPs, when multimodal approaches are usually practised by clinicians. Further, it is clear that management of myofascial dysfunction in patients with CPP requires a multidisciplinary approach (Srinivasan et al. 2007; see also Chapters 8.1 and 8.2). The inclusion of these techniques into a multimodal approach for patients with CPP has been found to be effective (Weiss 2001, Doggweiler-Wiygul & Wiygul 2002, Anderson et al. 2005, 2006).

Among the different interventions directed at inactivating TrPs, manual therapy is the first treatment option (Dommerholt et al. 2006). Different soft tissue interventions have been suggested, including: static compression (Hong et al. 1993, Simons et al. 1999, Fryer & Hodgson 2005, Fernández-de-las-Peñas et al. 2006, Gemmell et al. 2008, Dommerholt & McEvoy 2010), massage (Simons et al. 1999), stretching (Hong et al. 1993, Simons et al. 1999, Hanten et al. 2000), muscle energy techniques (Lewit 1999, Chaitow 2006, Rodríguez-Blanco et al. 2006), strain–counterstrain (Ibáñez-Garcia et al. 2009, Lewit 1999), neuromuscular techniques (Chaitow & Delany 2008, Ibáñez-García et al. 2009, Palomeque-del-Cerro & Fernández-de-las- Peñas 2009), positional release techniques (Chaitow 2007b) and manipulative interventions (Ruiz-Sáez et al. 2007, Fernández-de-las-Peñas 2009).

Systematic reviews have investigated the effectiveness of soft tissue manual intervention for inactivating TrPs (Fernández-de-las-Peñas et al. 2005, Rickards 2006, Vernon & Schneider 2009). These reviews found moderate to strong evidence supporting the use of static compression for immediate pain relief of muscle TrPs but limited evidence for long-term pain relief. Additionally, there is preliminary evidence demonstrating changes in muscle sensitivity after spinal manipulations (Ruíz-Sáez et al. 2006, Fernández-de-las-Peñas 2009), although further studies are required.

Compression interventions

Different compression techniques, depending on the amount of pressure applied, presence/absence of pain (Lewit 1999, Simons et al. 1999), duration of application (Hou et al. 2002), or position of the tissue (shortened or lengthened), have been described. In our clinical practice, the pressure level, duration of application, and position of the muscle, depend on sensitization mechanisms of the patient, and degree of irritability of the TrP. Table 11.1.1 summarizes clinical application of four different forms of compression: ischaemic compression (Travell & Simons 1983), TrP pressure release (Lewit 1999, Simons et al. 1999), strain/counter-strain (Jones 1981) or positional release therapies (Chaitow 2007b), and intermittent compression (Chaitow 1994).

Simons (2002) proposed that compressing the sarcomeres by direct pressure in a vertical and perpendicular manner may equalize the length of the muscle sarcomeres in the involved TrP and decrease pain. Hou et al. (2002) suggested that pain relief may result from reactive hyperaemia within the TrP or a spinal reflex mechanism for the relief of muscle tension.

Under the next heading, we describe different forms of compression interventions applied to pelvic muscle TrPs. Clinicians can apply ischaemic compression (Travell & Simons 1983), pressure release (Lewit 1999, Simons et al. 1999) or positional release therapy (Chaitow 2007b) principles depending on the patient’s characteristics.

Static compression of piriformis/external obturator muscle trigger points

Typical piriformis TrP referred pain is shown in Figure 11.1.1 (Simons et al. 1999). TrPs in this muscle may contribute to pain in the lower back, buttock, hip, posterior thigh and leg, but also to pain into the groin, perineum and sometimes in the rectum during defecation. For this technique, the patient is prone with the therapist standing to the side. The therapist localizes the TrP (it can be located just lateral to the sacrum or the muscle belly), and applies a static compression directly over it. Clinicians are encouraged to use both hands during the technique (Figure 11.1.2). A similar technique may be applied over the external obturator muscle belly which has a similar pattern of referral to that of the piriformis (Cox & Bakkum 2005).

Figure 11.1.1 • Referred pain elicited by piriformis muscle TrPs

Figure 11.1.2 • Static compression of piriformis muscle TrPs

Static compression of pectineus muscle trigger points

The pectineus muscle is an important adductor muscle in relation to CPP since TrP referred pain is commonly perceived as a deep dull pain in the lateral groin area (Figure 11.1.3A). For the technique, the patient lies supine with the therapist standing to the side. The therapist localizes the TrP which is usually located in the muscle belly (just lateral to the tendon of the adductor longus muscle at the pubic bone), and applies a static compression directly over it. Clinicians are encouraged to use both hands during the compression, although the thumb is also frequently employed (Figure 11.1.4).

Figure 11.1.3 • Referred pain elicited by pectineus (A), adductor longus (B) and adductor magnus (C) muscle TrPs

Figure 11.1.4 • Static compression of pectineus muscle TrPs

Intermittent compression of pelvic floor muscle trigger points

PFM TrPs can mimic symptoms of painful coccydynia or levator ani syndrome (Simons et al. 1999, Chaitow 2007a). In general, pelvic floor muscle TrPs refer pain toward the perineum, vagina, penile base, and give a sensation of fullness into the rectum and an urgency to urinate (Figure 11.1.5A–C). Nevertheless, it seems that TrPs in some PFM are more prevalent in CPP (Anderson et al. 2009). For instance, referred pain from pubococcygeus and puborectalis muscles spreads to the perineum and adjacent urogenital structures. Lewit & Horacek (2004) demonstrated that inactivation of pubococcygeus muscle TrPs induced secondary inactivation of erector spine TrPs. Levator ani and coccygeus TrPs refer pain to the sacrococcygeal region and also to the vagina or penis. TrPs in the internal obturator refer pain to the anococcygeal region and to the vagina. It has also been observed clinically that in some patients with CPP, pelvic floor muscle TrPs can refer pain to the sacrum.

Figure 11.1.5 • (A) Scheme of pelvic floor muscles: 1. Coccygeus. 2. Iliococcygeus. 3. Pubococcygeus. 4. Levator ani. (B) Referred pain from coccygeus or iliococcygeus muscle TrPs. (C) Referred pain from pubococcygeus or levator ani muscle TrPs

In our clinical experience, PFM respond very well to TrP pressure release. For this technique the patient lies supine or side-lying. The therapist localizes the TrP which is usually located in a specific PFM (particularly located in the ischiorectal fossa) and applies an intermittent digital (finger or thumb) compression to it (Figure 11.1.6). Further details regarding PFM trigger point techniques can be found in Chapter 13.

Figure 11.1.6 • Intermittent compression of pelvic floor muscle TrPs

Compression and contraction of gluteus maximus muscle trigger points

TrP-referred pain from gluteus maximus muscle is perceived as deep and burning pain located in the sacroiliac, coccyx and buttock areas (Figure 11.1.7). This technique consists of applying a TrP compression combined with an isometric contraction of the compressed muscle (Gröbli & Dejung 2003). For that purpose, the patient is side-lying with the therapist behind. TrPs within the gluteus maximus muscle are best palpated and compressed by pincer palpation. Once the therapist locates a TrP (it can placed in any part of the muscle belly) a pincer compression is applied using one or both hands (as illustrated in Figure 11.1.8). When the therapist perceives a slight relaxation of the TrP, the patient is asked to contract the muscle by squeezing both buttocks for 5 seconds. The therapist should maintain the compression during the contraction. If two hands are employed, stretching of the tissues housing the trigger point should follow the contraction, as illustrated. In the authors’ clinical experience, a total of ten repetitions is usually sufficient to achieve inactivation of gluteal muscle TrPs.

Figure 11.1.7 • TrP referred pain from gluteus maximus muscle

Figure 11.1.8 • Compression and contraction of gluteus maximus muscle TrPs (with accompanying stretch following contraction)

Stretching compression of iliopsoas muscle trigger points

TrPs in the iliopsoas muscle refer pain to the groin area, superior part of the thigh and to the back (Figure 11.1.9). This is an important muscle since it is anatomically related to several urogenital structures and the lumbar plexus (Stepnik et al. 2006).

Figure 11.1.9 • Referred pain from TrPs in the iliopsoas muscle

A stretching compression technique combines a compression intervention with passive or active stretching of the TrP taut band. For this purpose the patient is supine with the knee and hip flexed, and the foot on the table. The therapist compresses the TrP (usually located within the muscle belly reached through overlying abdominal muscles) with the tips of the fingers of one or both hands. At the time that the therapist perceives a slightly relaxation of the TrP taut band, the patient is asked to straighten the knee and the hip, either passively or actively, to increase the tension in the taut band (Figure 11.1.10). The aim of this technique is for the patient to achieve pain-free extension of the hip and knee, at the same time that the therapist maintains the compression.

Figure 11.1.10 • Stretching compression of iliopsoas muscle TrPs

Massage

Massage has multiple clinical applications with positive effects, but often lacks scientific evidence. This may be related to the fact that there are so many different forms of massage that still remain under-researched. The application of massage for inactivating muscle TrPs was discussed by Simons (2002) and Hong et al. (1993), who proposed that massage may exert a lengthening effect, similar to compression interventions. Massage can be performed along the TrP taut band (stretching longitudinal massage) or across the taut band (transverse massage). Hence, transverse massage offers transverse mobilization to the TrP taut band, whereas a longitudinal massage offers longitudinal mobilization to the taut band. In those muscles where clinicians can use pincer palpation, fingers can grasp the taut band from both sides of the TrP. Strokes centrifugally away from the TrP can lengthen the tissues (Simons 2002).

Transverse massage of quadratus lumborum muscle trigger points

Referred pain from quadratus lumborum TrPs spreads along the crest of the iliac bone, to the outer upper aspect of the groin, the greater trochanter, the sacroiliac joint and the lower buttock (Figure 11.1.11). In some patients, additional referred pain to the anterior thigh, testicle and scrotum has been described (Simons et al. 1999).

Figure 11.1.11 • TrP referred pain from quadratus lumborum muscle

For this technique the patient is side-lying with the therapist standing in front of the patient. The ulnar aspect of the therapist’s forearm should be placed over the muscle belly of the quadratus lumborum (where TrPs are usually located). The technique consists of applying a smooth and slow transverse massage over the TrP taut band (Figure 11.1.12). It is important to note that there is no established guideline (number of repetitions, time of application, or amount of pressure) for this technique. In the authors’ experience, the transverse massage should be painless, and applied until the therapist feels the tissues relax.

Figure 11.1.12 • Transverse massage of quadratus lumborum muscle TrPs

Stretching longitudinal massage of adductor muscle trigger points

TrPs within the adductor (brevis, longus and magnus) muscles refer pain to the medial aspect of the thigh and to the groin area (Figure 11.1.3B,C). In some patients, the adductor magnus TrPs also elicit an intrapelvic referred pain (Simons et al, 1999). For this technique the patient is supine or side-lying. Once the therapist locates a TrP (it can located in any of the adductor muscles), a pincer palpation of the TrP taut band is applied. The fingers of the therapist grasp the taut band from both sides, and stroke centrifugally away from the TrP (Figure 11.1.13).

Figure 11.1.13 • Stretching longitudinal massage of adductor muscle TrPs

Muscle energy interventions

There are several stretching applications targeted at inactivating TrPs: passive stretching (where the therapist passively stretches the muscle without participation of the patient), active stretching (where the patient actively stretches the muscle without participation of the therapist), spray and stretch involving a vapo-coolant spray applied during stretch (Hong et al. 1993, Simons et al. 1999), or muscle energy techniques (Fryer & Fossum 2009).

Muscle energy techniques comprise a system of manual procedures that utilize isometric and isotonic muscle contraction efforts from the patient, usually against a controlled matching counterforce from the therapist. Although there are different approaches for application of muscle energy techniques, the ‘contract–relax–release’, is the most commonly utilized technique. This involves the accurate localization of an isometric contraction (3–7 seconds) at a barrier defined as ‘the first sign of resistance’. An unyielding counterforce is supplied by the therapist. After the patient releases the contraction effort a new barrier is engaged, or stretching is introduced, past the previous barrier, actively or passively. The force and duration of isometric contraction can be varied, depending on the objective of the technique and the tissues involved. In fact, different durations of contraction have been proposed: 2–3 seconds (Mitchell & Mitchell 1995), 3–5 seconds (Greenman 2003), or 5–7 seconds (Chaitow 2006).

Several studies have demonstrated that muscle energy techniques increase muscle extensibility (Feland et al. 2001, Ferber et al. 2002, Ballantyne et al. 2003) and range of motion (Fryer & Ruszkowski 2004, Burns & Wells 2006) in healthy subjects. For a review of scientific evidence of muscle energy techniques, readers are referred to another text (Fryer 2006). The physiological therapeutic mechanisms by which muscle energy techniques exert their effect are speculative and controversial. Of the three most studied mechanisms that have been proposed, i.e. reflex relaxation, viscoelastic or muscle property changes (Fryer 2000), and increased tolerance to stretch, it is the latter that is most supported by the scientific literature (Fryer 2006).

Increased stretch tolerance may result from a decrease in pain perception (hypoalgesia) through the activation of muscle and joint mechanoreceptors, peripheral and central (activation of descending inhibitory pain systems) mechanisms (Fryer & Fossum 2009), and/or reduced concentrations of pro-inflammatory cytokines, and reduced sensitivity of peripheral nociceptors. Enhanced release of endocannabinoids may be one of the mechanisms of osteopathic manipulative treatment (McPartland et al. 2005), parallel to the effects of manipulative treatment upon serum endorphin levels (Vernon et al. 1986).

Muscle energy technique of quadratus lumborum muscle trigger points