Thoracic Pain Syndromes

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CHAPTER 74 Thoracic Pain Syndromes

Thoracic pain accounts for approximately 5% of all referrals to the authors’ pain clinic in a University Hospital in the Netherlands,¹ which is consistent with that of other clinics.² Thoracic pain has a varied spectrum of possible etiologies including visceral pain from cardiac and lung pathology to pain from intra-abdominal organs (upper abdominal organs such as gall bladder and pancreas may be referred to the chest). In the lower thoracic regions pain must be differentiated from renal pathology.³ Pain from C5 may be referred over the anterior chest, while pain from C6, C7, and C8 may be referred to the scapular region.

Thoracic pain may have an underlying pathology such as disc herniations, aneurysms, tumors,⁵ postoperative sternal wound infection,⁶ trauma,⁷ old fractures, or herpetic infections,⁸ and stress fractures in athletes.^9,¹⁰ Chronic postsurgical pain has been described following many different operations, most notably thoracotomy, mastectomy, and coronary artery bypass grafting (CABG) postsurgical pain syndromes.¹¹^–¹⁵

However, in most cases of thoracic pain there is no specific pathology identified as the cause of the pain and by default the pain is judged to be of spinal origin, emanating from nociceptive nerve endings in the periosteum, ligaments, discs, or joints.¹⁶

Diagnostically and clinically, thoracic pain can be divided into thoracic mechanical joint pain and thoracic segmental pain. An appreciation of the intricate anatomy of the thoracic spine is required to understand the various pain syndromes of the thoracic spine. It is somewhat surprising that there is any mechanical pain in the thoracic spines since it is a relatively immobile section of the spine. The range of motion for both flexion and extension is of the order of 10°, and lateral flexion is minimal. Rotation of the thoracic spine provides the only meaningful movement of the thoracic spine. Pain in the thoracic region may come from the articulations with ribs, costovertebral joints between the rib and the vertebral body, and the costotransverse joints between the transverse process and tubercle of the rib. The costotransverse joints are absent at T1, T11, and T12.

THORACIC MECHANICAL PAIN FEATURES

Clinical syndrome

Thoracic mechanical pain includes pain from both thoracic facet joints and thoracic discs.

Pain emanating from thoracic facet joints is usually related to degenerative processes, vertebral collapse, and continuous mechanical straining.¹⁶^–¹⁸ The initial problem can be in the facet joint but may be elsewhere in the spine.¹⁹ As with lumbar and cervical facet syndromes there are no specific criteria which have been established whereby facet joint pain could be diagnosed based on patient’s history and/or physical examination. A diagnosis of thoracic facet joint syndrome can be made based on similarity of symptoms to lumbar and cervical facet syndromes.

Extensive examination should be performed to exclude any other pathology as a primary cause for the patient’s signs and symptoms.

In 1993, Stolker et al. defined ‘major’ and ‘minor’ criteria for the diagnosis of thoracic facet joint pain.¹⁸

Major criteria include:

1 Continuous or nearly continuous unilateral or bilateral paravertebral pain in a distinct thoracic area of the back, in the absence of objective neurological signs.

2 Tenderness over paravertebral muscles in the same region by palpating the facet joints.

Minor additional diagnostic criteria include:

1 Exacerbation of all complaints following back movements, most notably hyperextension and rotation.

2 Pain aggravated more in sitting position than in other positions.

3 Localization of radiation (if present) in more than one segment but not extending through a complete segment.

4 Decreased or absent mobility in the painful region of the back

5 Radiological signs (although uncommon) may illustrate slight rotation and curvature of the vertebral column.

When thoracic spinal pain becomes chronic and resistant to conservative modalities of treatment such as physical therapy, pharmacological therapy, and transcutaneous electric nerve stimulation (TENS), more aggressive treatment of thoracic pain including radiofrequency ablation of the facet joints can be considered.

Indications for radiofrequency procedures

These criteria were the basis for a study by Stolker et al. when they evaluated 40 patients who had a diagnosis of thoracic facet syndrome based on the above-mentioned criteria. These patients underwent percutaneous facet joint denervation (PFD). Included were 24 left sided, 21 right sided and 6 bilateral cases. Seven study patients underwent two sessions and two patients had three PFD sessions. Eighty-two percent of patients had 50–75% pain relief at 2 months. Four patients were lost to long-term follow-up (18–54 months; mean 31 months). Forty-four percent of study patients were pain free while 39% had a 50% or greater reduction in their pain.¹⁸ Interestingly, considering that these criteria were non-specific for thoracic facet syndrome, all patients in this study had positive diagnostic blocks performed prior to radiofrequency ablation. Stolker et al. attributed the results to the consistent course that the medial branch of the dorsal rami of the thoracic spinal nerves travel as they leave the intertransverse space; however, the anatomical target point (junction between the superior articular process and the transverse process) utilized in their study is at variance with the anatomical course of thoracic medial branch described by Chua and Bogduk.²⁰

Chua and Bogduk reported that the medial branch crosses the superolateral corner of the transverse processes and then passes medially and inferiorly along the posterior surfaces of the transverse processes, before entering the multifidus muscle which it supplies.²⁰ Chua and Bogduk have called for the need for a double-blind, controlled clinical trials of Stolker et al.’s approach to thoracic facet nerve denervation or modification of their procedure so as to be consistent with the surgical anatomy of the thoracic medial branches.²⁰

In another study by Tzaan and Tasker in 2000 which evaluated 17 patients with thoracic facet syndrome, 15 patients had satisfactory pain relief at follow-up with 2 patients having their procedure repeated.²¹

Pevsner et al. evaluated radio frequency ablation in 122 patients with mechanical spinal pain at cervical (20%) and thoracolumbar (80%) levels. At 1-year follow-up 63% had good results (at least 50% decrease in pain levels) and 37% had no effect (<30 % reduction in their pain levels).²²

Side effects and complications

Spinal thermocoagulation procedures are generally free from side effects other than local contusion and edema at the needle sites. The most common side effect was sensory loss and neuropathic pain in the distribution of the cutaneous branches of the posterior rami.²¹ Minor complications occurred in 27 patients (22%) who had transient discomfort and burning pain.²²

Serious complications of radiofrequency are fortunately rare when optimum target point needle positioning is utilized, i.e. in the lateral facet line on the anteroposterior (AP) projection and posteriorly in the foramen on the transverse projection.

Outcomes

While the evidence base is low in the management of thoracic facet pain there is evidence to support the use of percutaneous radiofrequency procedures as therapy.^18,^21,²²

THORACIC DISC LESIONS

Clinical syndrome

Thoracic disc lesions account for 0.5–2% of all disc lesions.^23,²⁴

Symptomatic disc disease is thought to be an uncommon problem with a prevalence of asymptomatic cases of 14.3%.²⁵ Degenerative disc disease is more commonly found in the lower thoracic spine with the upper third (T1–2 to T4–5) being the least affected area.^26,²⁷ However, T1–2 is the most common level affected when the upper thoracic spine is involved.²⁸

Recently, Arana et al., in a study of 156 patients with cervical disc pain, reported that 13.4% of these patients had degenerative changes in the upper thoracic spine, most notably at T2–3, with correlation between degenerative disc contour at the C7–T1 level and T1–2, T2–3, T3–4.²⁹

Girard, in another study, evaluated temporal changes in thoracic disc in 40 patients with pain.^29a Baseline presence of disc herniation was 10%, degenerative disease 14%, endplate marrow signal alteration 2.3%, Schmorl’s nodes 9.6%; follow-up was 4–149 weeks. Repeat scan revealed a new incidence of disc herniation of 1.5%, degenerative disc disease 2%, all findings predominated in the lower thoracic vertebrae T6–10. Herniations showed the most ability to modify over time with just over one-quarter (27%) showing change. Schmorl nodes showed the least change over time.²⁹

While the majority of prediction indicator studies have been done on lumbar spine, one can infer that a similar clinical picture holds for the thoracic spine. A tissue can only generate pain if it is innervated. In a normal human lumbar disc, nerve endings can only be found in the periphery of the outer anulus at a depth of a few millimeters.³⁰ In highly degenerated discs nerves may even penetrate into the nucleus pulposus.³¹

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