THE CLINICAL SYNDROME
Essentially all patients who undergo thoracotomy will suffer from acute postoperative pain. This acute pain syndrome will invariably respond to the rational use of systemic and spinal opioids as well as intercostal nerve block. Unfortunately, a small percentage of patients who undergo thoracotomy will suffer persistent pain beyond the usual course of postoperative pain. This pain syndrome is called post-thoracotomy pain syndrome and can be difficult to treat. The causes of post-thoracotomy pain is listed in the table below and include direct surgical trauma to the intercostal nerves, fractured ribs due to the rib spreader, compressive neuroma formation, and stretch injuries to the intercostal nerves at the costovertebral junction. With the exception of fractured ribs, which produce characteristic local pain that is worse with deep inspiration, coughing, or movement of the affected ribs, the other causes of post-thoracotomy pain result in moderate to severe pain that is constant in nature and follows the distribution of the affected intercostal nerves. The pain may be characterized at neuritic and may occasionally have a dysesthetic quality.
Causes of Post-thoracotomy Pain Syndrome
- Direct surgical trauma to the intercostal nerves
- Fractured ribs due to the rib speader
- Compressive neuropathy of the intercostal nerves due to direct compression of the intercostal nerves by retractors
- Cutaneousneuroma formation
- Stretch injuries to the intercostal nerves at the costoverlebral junction
SIGNS AND SYMPTOMS
Physical examination of the patient suffering from post-thoracotomy syndrome will generally reveal tenderness along the healed thoracotomy incision. Occasionally, palpation of the scar will elicit paresthesias suggestive of neuroma formation. The patient suffering from post-thoracotomy syndrome may attempt to splint or protect the affected area. Careful sensory examination of the affected dermatomes may reveal decreased sensation or allodynia. With significant motor involvement of the subcostal nerve, the patient may complain that his or her abdomen bulges out. Occasionally, patients suffering from post-thoracotomy syndrome will develop a reflex sympathetic dystrophy of the ipsilateral upper extremity. If the reflex sympathetic dystrophy is left untreated, a frozen shoulder may develop.
The patient with post-thoracotomy syndrome will exhibit tenderness to palpation of the scar.
Initial treatment of post-thoracotomy syndrome should include a combination of simple analgesics and the nonsteroidal anti-inflammatory drugs or the cyclooxygenase-2 inhibitors. If these medications do not adequately control the patient’s symptomatology, a tricyclic antidepressant or gabapentin should be added.
Traditionally, the tricyclic antidepressants have been a mainstay in the palliation of pain secondary to post-thoracotomy syndrome. Controlled studies have demonstrated the efficacy of amitriptyline for this indication. If the antidepressant compounds are ineffective or contraindicated, gabapentin represents a reasonable alternative.
The local application of heat and cold may also be beneficial to provide symptomatic relief of the pain of post-thoracotomy syndrome. The use of an elastic rib belt may also help provide symptomatic relief. For patients who do not respond to these treatment modalities, the following injection technique using local anesthetic and steroid may be a reasonable next step. The patient is placed in the prone position with the patient’s arms hanging loosely off the side of the cart.
The use of the aforementioned pharmacologic agents, including gabapentin, will allow the clinician to adequately control the pain of post-thoracotomy syndrome. Intercostal nerve block is a simple technique that can produce dramatic relief for patients suffering from post-thoracotomy syndrome.