Prior to the landmark article by Mixter and Barr (1934), who described the characteristics of sciatica following disk herniation with subsequent surgical correction, legion papers were published attempting to explain the different musculoskeletal pain syndromes, often on the basis of empirical descriptions and hypothetical postulates. Particular interest in the source of pain originating from soft-tissue structures such as muscles, ligaments, tendons, and the various articulations, in particular the sacroiliac joint, is evident in the literature up to the 1930s and 1940s. Probably all of the anatomic structures known have at one time or another been considered as the source of pain. Mixter and Barr (1934), however, rather than presenting a single case study or a listing of empirical observations, introduced a well thought-out series from the “base of the skull down, covering the ‘waterfront.’ Cervical, dorsal and lumbar lesions were all included in this first article” (Barr, 1977).

Attention and effort thereafter, so it seems, were primarily directed toward the subject of the herniated intervertebral disk and its role in the radicular pain syndromes. This ultimately steered attention away from muscle and other soft tissues and toward nerve root compression as a cause of pain (Gerwin, 2000).

In the most recent two or three decades, however, there has been a noticeable trend in which both the “old” or orthodox branches of medicine and the “new” or alternative health-care counterparts alike have shown particular interest in investigating many of the nonradicular pain syndromes. The exact reasons for this rising interest are not entirely clear.

Many published reports have attempted to organize and categorize the seemingly countless descriptions of the apparently diverse painful soft-tissue disorders and nonradicular pain syndromes. The terminology seemed to get in the way, as many previous accounts had been categorically lumped under such nonspecific terms as inflammatory soft-tissue rheumatism. Although seemingly similar somatic phenomena appear to have been described by the various authors over the years, the language and terminology used often seemed to reflect more the individual author’s opinion or that of a particular school of thought than a common scientific language. The sheer number of the many neurophysiologic hypothetical postulates, coupled with the often confusing, nonstandard language, which also varied from country to country may, at least in part, explain why even clinically relevant observations might have been lost or hitherto ignored. From a historical perspective, this is understandable (Dvořák, 1982b, 1983; Gibson, 1980; Wardwell, 1980). The scholarly work and scientific language used by such pioneering investigators as Korr (1975) and Wyke and his colleagues (1967, 1979b) have fundamentally contributed to a better understanding of some of the neurophysiologic principles underlying musculoskeletal pain phenomena.

Other articles have addressed the various clinical presentations in an effort to come up with a consistent correlation of the various functional disturbances that affect the spinal column or the peripheral joints (Brügger 1962, 1977; Feinstein et al., 1954; Hohermuth, 1981; Jones, 1981; Mitchell et al., 1979; Sutter, 1975; Sutter and Fröhlich, 1981; Waller, 1975; Dejung, 1985; Dvořák et al., 1987c; Southwick and White, 1983; Herron and Turner, 1985; Mattle, 1986). Simons (1976a, 1988) has presented an exhaustive summary of the many reports in the literature that relate the muscles and fascia to the various pain syndromes, while at the same time posing the question “Why should so common and serious a problem be so neglected by modern medicine?” (Simons, 1988).

The ideal is to identify those clinically meaningful parameters and diagnostic criteria that would unequivocally assist in distinguishing from true radiculopathies the painful nonradicular musculoskeletal syndromes that mimic or are similar to the explicit radicular syndromes. This should, at least in theory, facilitate the proper choice of therapy for a particular disorder, clinical presentation, or syndrome. For the field of manual medicine this means that one goal is to determine which approach or technique (s) are best suited for a particular patient, ranging from such varied maneuvers as the high-velocity, low amplitude manipulations (thrusting techniques) to the “gentle” approaches of soft-tissue techniques, including the various trigger point and tender point approaches, myofascial release techniques, muscle energy or facilitatory techniques, among many others. There already exist a number of good, rational rehabilitation approaches that ultimately should allow the patient to undertake the transition to an independent home exercise program as soon as the clinical situation allows.

1. Referred pain.

2. Myofascial pain syndromes.

3. Postural pseudoradicular syndromes.

4. Somatic dysfunction and tender points.

5. Spondylogenic reflex syndromes.

Despite the diversity in terminology, the attentive reader will readily recognize the overlap of, and the similarities among, the different descriptions of the various clinically observed phenomena and the postulates of the proposed neurophysiologic mechanisms.

Referred pain, in the simplest terms, may defined as pain that is perceived by the patient at a location distant from or different from the structure that is presumed to be the pain generator. This broad definition includes pain referred from visceral structures and somatic structures either directly or via reflex pathways. Here we describe observations on referred pain originating from somatic skeletal (nonvisceral) structures.

Fig. 6.1 Pain pattern upon injection of hypertonic sodium chloride solution into (a) the superficial and (b, c) the deep structures (vertebral arches, infraspinous fossa of the scapula). (After Kellgren, 1939.)

Fig. 6.2 Diagram of the patchwork distribution of referred pain after stimulation of deep structures of the thoracic spine (vertebral arches, joints). (After Kellgren, 1939.)

“The superficial fascia of the back, the spinous processes, and the supraspinous ligaments induce local pain upon stimulation, while stimulation of the superficial portions of the interspinous ligaments and the superficial muscles result in a diffuse type of pain. The deep muscles, ligaments, and periosteum of the apophyseal joints, as well as the joints themselves, can cause referred pain according to the segmental innervation when sufficiently stimulated.”

Feinstein et al. (1954) also injected a hypertonic sodium solution into the paravertebral structures associated with the vertebral segments between C1 and S3, such as the deep muscles and ligaments. The manifestation of referred pain and the localization of zones with decreased sensitivity to pain did not always correspond to known radicular innervation patterns such as the zones described by Head, for instance. In Feinstein’s studies, the pain was felt mostly in the reflexly hypertonic muscles upon injection of the sodium salt solution. This was accompanied by autonomic symptoms, such as paleness, excess perspiration, decreased blood pressure, fainting, and nausea, among others.

Fig. 6.3 Schematic representation of referred pain after injection of hypertonic sodium chloride solution into the deep somatic soft tissues. (After Feinstein et al., 1954.)

The myofascial pain syndrome is a muscle pain disorder in one or more muscles or groups of muscles accompanied by local and referred pain, and is associated with decreased range of motion, weakness, and often autonomic phenomena. Patients are readily recognized by their history of characteristic muscle pain and the presence of myofascial trigger points, which are specific areas of hyperirritability in a muscle that cause local and referred pain on palpation (Meyer, 2002).

Research during the past 20 to 30 years has provided valuable information for clinical practice about the painful syndromes associated with the myofascial trigger points (Melzack, 1978; Reynolds, 1981; Rubin, 1981; Simons 1975, 1976b; Travell and Rinzler, 1952; Travell 1976; Travell and Simons, 1992).

Myofascial Trigger Points

Fig. 6.4 Examples of trigger points and referred pain in the reference sites (pain reference pattern; after Travell and Simons, 1983a).

Referred pain, in the presence of either an active or a latent MTrP, is usually very well-localized by the patient. Using palpation, the painful muscle or part of the muscle (“myotenone”, for definition see below) can be demarcated. The MTrP is described as a “palpable band” (Simons, 1975, 1976b), which should be palpated perpendicular to the direction of the incriminated muscle fibers (similar to the “myotendinoses” also defined below). Palpation often causes a local, painful twitch response in the muscle involved (Simons, 1976a; Travell, 1952).