Definition

Intercostal neuralgia is pain in the thoracic region emanating from an intercostal nerve. The pain is typically a sharp, shooting, or burning pain radiating around the chest wall. It can be accompanied by altered sensitivity to touch, such as allodynia or an area of hyperalgesia. Intercostal neuralgia occurs commonly after thoracotomy [1–4]. It can also be seen in elderly debilitated patients without a known precipitating event [5]. Other causes include rib trauma, very rarely benign periosteal lipoma [6], and pregnancy [7].

Intercostal nerves are peripheral nerves that run along with the vascular bundle on the inferior surface of each rib (Fig. 103.1). Intercostal nerves are derived from the ventral rami of the first through twelfth thoracic nerves (Fig. 103.2), with the first, second, third, and twelfth being atypical on the basis of anatomic differences. Only 17% of intercostal nerves were found in the classic subcostal position in one study [8]. In Hardy’s study, a midcostal location was the most prevalent at 73%; an additional 10% were supracostal. The intercostal nerve gives off four main branches as it travels anteriorly: gray rami communicantes, posterior cutaneous branch, lateral cutaneous division, and anterior cutaneous division.

Symptoms

Chest pain is the cardinal symptom. Because intercostal neuralgia involves a peripheral nerve, the pain is neuropathic rather than nociceptive. Neuropathic pain is often unrelenting, shooting, burning, and deep. The International Association for the Study of Pain defines neuropathic pain as “pain initiated or caused by a primary lesion or dysfunction in the nervous system.” [9] Neuropathic pain is characterized by three symptoms: dysesthesia, paroxysmal pain, and allodynia [10]. Dysesthetic pain is an abnormal sensation described as unpleasant. Patients commonly use terms such as aching, cramping, pressure, and heat to describe a dysesthetic pain [11]. Paroxysmal pain is pain that comes in waves and is often described as lancinating or electric. Allodynia is the abnormal perception of pain after a normally nonpainful mechanical or thermal stimulus [11]. Patients with allodynia may respond to light touch with an exaggerated pain response or report a sensation of heat when a cold stimulus is applied. Intercostal neuralgia pain is unilateral. It is common (up to 81% of patients) after thoracotomy for coronary artery bypass grafting to the internal thoracic artery and after thoracotomy for tumor excision [3,4]. During thoracotomy (either open or video-assisted thoracoscopic surgery), the intercostal nerve may be directly injured during rib resection, compressed by a retractor, or later entrapped by a healing rib fracture. Intercostal neuralgia may follow other forms of chest trauma. It may mimic the pain of shingles (herpes zoster) but without the rash and can occur without significant trauma in the elderly.

The mechanism of neuropathic pain may be due to ectopic signals from neural “sprouts” after axonal injury. This new nerve growth may become a pain generator, especially if it becomes entrapped in scar tissue, forming a neuroma. Another mechanism may be compression or disruption of the nervi nervorum afferents in the connective tissue covering, producing a peripheral neuropathic pain.

Physical Examination

Much of the physical examination in intercostal neuralgia is done to exclude other sources of pain. First, it is important to exclude cardiac and other visceral sources of chest pain (Table 103.1). Although point tenderness is uncommon during myocardial infarction, the presence of point tenderness does not exclude significant cardiac disease. In intercostal neuralgia, there are no constitutional signs, such as fever, dyspnea, diaphoresis, or shortness of breath. Cardiopulmonary examination findings should be normal or stable if prior cardiovascular or pulmonary disease exists.

Intercostal neuralgia is common after thoracotomy [1–3]. However, chest pain that recurs after a pain-free period following a thoracotomy for tumor resection is likely (90%) to be due to tumor recurrence. On the other hand, pain that persists for months or years after thoracotomy is most likely (70%) intercostal neuralgia [12].

Once the chest pain has been determined to be neuromusculoskeletal and nonvisceral, the task becomes one of differentiation of intercostal neuralgia from thoracic radiculopathy, herpes zoster, rib fracture, costochondritis, and local contusion. History of trauma, ecchymosis, crepitus, and point tenderness over a rib suggests rib fracture. If the trauma was minor, a contusion or intercostal neuralgia may be the source of discomfort. Contusions typically improve quickly during a period of weeks and are responsive to simple analgesics, such as acetaminophen and nonsteroidal anti-inflammatory medications. In contrast, pain from intercostal neuralgia persists and can be refractory to acetaminophen, nonsteroidal anti-inflammatory drugs, and even low-dose narcotics.

Careful palpation along the thoracotomy scar or rib may reveal a neuroma with the presence of a Tinel sign. Larger neuromas can often be visualized on magnetic resonance imaging. Sensory examination often reveals a small (1 to 2 cm) band of dermatomal sensory loss.

Examination of the thoracic spine in patients with intercostal neuralgia reveals full active range of motion without tenderness. In contrast, thoracic radiculopathy may be accompanied by pain with range of motion and at times thoracic spinal tenderness. Still, pain from thoracic radiculopathy is similar in quality and distribution to intercostal neuralgia.

Intercostal neuralgia is distinct from postherpetic neuralgia (shingles), and no herpes zoster virus can be identified in cases of intercostal neuralgia. Furthermore, in most cases of shingles, the chest pain is followed within a matter of days to weeks by a vesicular, linear eruption. The more debilitating pain of postherpetic neuralgia follows the skin lesions of shingles.

Functional Limitations

The pain of intercostal neuralgia is commonly mild to moderate but can be debilitating because it may interfere with one’s ability to comfortably wear clothes. In one study, nearly 10% of post-thoracotomy patients observed for a mean of 19.5 months had moderate to severe pain that required daily analgesics, nerve blocks, relaxation therapy, acupuncture, or referral to a pain clinic [4