Approximately 5% of the patients who are referred to a pain clinic suffer from thoracic pain. Patients with thoracic pain should be carefully examined for identifying or excluding various severe diseases that might be the cause of pain.
The chronic thoracic pain considered to be of unknown aetiology may be due to various health conditions, such as angina pectoris, herpes zoster infection, lumbar intervertebral disc herniation, malignant lung or/and pleural tumor and aortic aneurysm. Chronic thoracic pain quite often occurs following thoracic surgery, mastectomy and aortocoronary surgery (bypass). Diffuse thoracic pain may be of radiating origin due to other diseases , such as pulmonary embolism, oesophageal carcinoma, oesophageal achalasia and pancreatic diseases.
Chronic thoracic pain may also be provoked by diseases of the thoracic muscles and ligaments (simple thoracic pain), facet joint disorders, defect or dysfunction of intercostal nerves and vertebral body fractures.
The analysis that follows deals with simple thoracic pain, thoracic facet joint syndrome and intercostal neuralgia. These three entities are the most common causes of chronic thoracic pain confronted in pain clinics. The pain due to thoracic vertebral body fracture falls in the category of vertebral compression fractures.
A. SIMPLE THORACIC PAIN
Simple thoracic pain may extend in the region from T1 to T12 thoracic vertebrae. It is pain due to a benign cause, like injury, contusion or overloading of some of the superficial thoracic tissues (muscles and ligaments). In the case of simple thoracic pain, intervertebral nerves are not implicated in the aetiology (intervertebral disc herniation, nerve entrapment etc).
In many cases, the pain may be also due to poor body posture while working or sleeping or due to a bad cold. Radiological examinations with plain X-rays and MRI reveal nothing more than some probable age-related degenerative changes of the spine. In most cases, the simple thoracic pain improves with conservative treatment within two weeks.
The overloading or injury of superficial thoracic tissues (muscles and ligaments) causes inflammation and transmission of pain signals to the spinal cord. Should the afferent pain signals be strong and durable enough, then centres of the spinal cord (dorsal horns) get stimulated and send efferent signals to the inflamed muscles that get contracted. This is how a muscle spasm is induced. Initially, this process acts as a protective mechanism of the body, preventing further aggravation of the tissue inflammation. When this muscle spasm is strong enough, the muscle tension receptors get activated and send strong signals to the spinal cord which are decodified as pain. So, the price for the protective mechanism is pain eminating from the muscle spasm.
After some period of time -varying in each case- the initial cause (injury, contusion, overloading) is eliminated, the signals to the spinal cord are minimized and, as a result, spinal cord sensitization is decreased. Signals from the spinal cord to the muscles are also reduced, allowing muscles to relax normally and consequently the pain subsides.
|Contusion||Inflammation||Pain||Sensitization of Spinal Cord|
|Stimulation of Muscle Tension Receptors||Muscle Spasm|
A small percentage of patients have more complex thoracic pain due to inflammation of one or more of the small spinal joints, the so-called “facet joints” (zygoapophyseal joints or z-joints).
The patients usually complain about paravertebral pain which is aggravated with prolonged standing, overextension or rotation of the thoracic spine. The pain may be unilateral or bilateral, extending to a small or large thoracic area. The pain does not extend to the anterior thoracic spine, as opposed to the radicular neuropathic pain that follows the nerve course.
During physical examination, there is usually tenderness to pressure in the paravertebral affected area with no objective neurological signs. None of the findings of physical examination can offer a diagnosis.
CLINICAL SIGNS AND SYMPTOMS IN THORACIC FACET JOINT SYNDROME
• Almost continuous unilateral or bilateral paravertebral pain in a specific posterior thoracic region with no neurological signs
• Paravertebral tenderness to pressure of the same thoracic region
• No significant radiological findings
• Postitive diagnostic block of medial nerve branches with local anesthetic (joint innervation)
CT scan or MRI should always be conducted for excluding other causes of more severe thoracic pain aetiology, such as:.
• Intrathoracic pathology (cancer, aortic aneurism etc)
• Intra-abdominal pathology (pain radiating to the thoracic area)
• Herniated intervertebral discs
Even if these imaging techniques reveal morphological facet joint abnormality, the final diagnosis is established only with diagnostic block of the medial nerve branches, applied at two levels per each joint in the painful region. Once the block is done, if the patient reports signifant pain relief for as long as the local anaesthetic lasts, then the diagnosis is made with certainty for facet joint syndrome.
1. CONSERVATIVE TREATMENT
The conservative treatment includes combination of analgesics, anti-inflammatory drugs, physiotherapy, kinesiotherapy and TENS (Transcutaneous Electrical Nerve Stimulation).
Should the conservative treatment fail to relieve the patient, the next therapeutic step is Radiofrequency Facet Joint Denervation in the nerve branches that innervate the painful joints (two branches per joint). Success rates are not as high as in the corresponding treatment of the cervical and lumbar spine, and this is due to the difficulty of predicting with accuracy the course of nerves innervating the thoracic spine facet joints.
C. THORACIC RADICULAR NEUROPATHIC PAIN
Thoracic radicular pain arises from a defect or dysfunction of a thoracic spinal nerve root and is located in the innervation area of the affected intercostal nerve which is the continuation of the nerve root to the posterior thoracic area along the ribs. The pain is not so typical as in lumbar spine radiculitis. It may be continuous or intermittent, nociceptive or neuropathic or even of mixed type.
AETIOLOGY OF THORACIC RADICULAR PAIN
• Intercostal neuralgia
• Neuralgia of the abdominal wall
PAIN RADIATING FROM SPINAL CORD
• Vertebral compression fracture
• Vertebral metastases
• After thoracotomy
• After mastectomy
• After thoracoscopy
• Intercostobrachial neuralgia
• After lobectomy
• Fracture/ Non-union (pseudarthrosis)
• Costectomy (excision/resection of a rib)
Thoracic radicular pain may be due to intercostal neuralgia of unknown aetiology, or nerve root compression (at the point where the nerve root exits through the intervertebral foramen), or some rib pathology. There is also a rare syndrome usually occurring in middle-aged individuals, the so-called ”Twelfth Rib Syndrome”. This disorder occurs due to irritation of the subcostal nerve which is compressed upon the iliac crest bone in the pelvis. The pain is usually located in the region between the 11th and 12th rib.
General symptoms, such as loss of weight and chronic cough, should not be overlooked and have to be investigated.
In case of intercostal neuralgia, the pain is acute and stabbing along the nerve pathway under the rib. The pain is not affected either by the patient’s position or by hand palpation.
Pain induced by rib pathology or intercostal nerve entrapment/ compression is usually dependent on the patient’s position. It is aggravated in the standing and sitting position, and reduced in the supine position.
Symptoms such as hyper/hypo-algesia, allodynia and sensory loss indicate that the pain might be neuropathic.
Thoracic spine MRI and Abdominal Digital Tomography are useful in excluding or determining the probability of another severe cause that could induce thoracic pain.
Diagnostic intercostal nerve block from the 10th thoracic nerve and transforaminal selective blocks of the 11th and 12th thoracic spinal nerves can identify with accuracy the location of the affected region.
1. CONSERVATIVE TREATMENT
• Mild opioids
• TENS (Transcutaneous Electrical Nerve Stimulation)
2. INVASIVE THERAPY
• Intercostal Nerve Block
• Radiofrequency application ( RF, PRF) to the dorsal spinal root ganglion
• Radiofrequency application to the intercostal nerve
There are no recent publications assessing efficacy of intercostal nerve blocks in the treatment of thoracic radicular pain.
Two published papers report good results for the treatment of thoracic radicular pain with conventional radiofrequency. Stolker et al evaluated 45 patients with thoracic radicular pain and significant pain improvement was observed in 70% of the patients 13-46 months after the therapy. In a similar study by Van Kleef and Spaans, 52% of patients reported significant pain reduction for 9-39 months. The efficacy of the treatment was lower when more thoracic levels were involved in the pain syndrome.
There are no studies comparing efficacy between compatible Radiofrequency and Pulsed Radiofrequency.
A small study showed that Pulsed Radiofrequency had higher success rate and longer duration of efficacy when applied on the dorsal root ganglion than when applied straight to the intercostal nerve (5 months and 3 months respectively).
The result of the therapy with Conventional Radiofrequency is better and lasts longer, but this technique destroys the dorsal root nerve ganglion (van Kleef et al).
|Exclusion of other severe causes|
|Identifying painful region with diagnostic blocks|
|(P)RF to dorsal spinal root ganglion|
MEDICAL INFORMATION SOURCES
1. PAIN PRACTICE JOURNAL
2. BONICA”S MANAGEMENT OF PAIN
3. PAIN PHYSICIAN JOURNAL
4. INTERVENTIONAL PAIN MANAGEMENT BOOK