Postesternotomy pain is the pain in the sterum which usually occurs after surgery. Not all patients develop the post sternotomy chronic pain syndrome, but a large group of patients express their inability to perceive normal sensation following surgery.
Sternum is also called breast bone and resembles a Romon sword.
The upper portion resembling handle is called as manubrium, the middle part resembling blade is called body and lower part is called as xiphoid process. It is flat bone, very rich in red bone marrow. The bone articulates on either side with clavicle and upper seven cartilages. It gives attachment to various major muscles like pectoralis major and sternocleidomastoid and minor like sternohyoid, syernothyroid and others.
Cause of Poststernotomy Pain
This pain appears to be a kind of deafferentation pain. Many people get adapted over course of time to pain. As a preventive aspect, cryodenervation of thoracic nerves during the surgery when chest is open appears to be promising.
The pain which they develop could be due to
- Overzealous stretching of chest wall
- Injuring lower components of brachial plexus
- Incomplete union of sternum in view of less vascularity
- Adhesions between posterior surface of sternum and mediastinal structures
Management of Poststernotomy Pain
Many of them respond to anticonvulsants and antidepressant medications.
In refractory patients sympathetic blockade of T1 –T5 fibres gives good relief.
TENS can be tried in some patients.
Post Thoracotomy Pain
The common postsurgical pain encountered in thorax is post-thoracotomy pain. This happens because of injury or division of nerve root in corresponding intercostal space. Sometimes the nerve gets entrapped in the surgical scar and creates a nagging problem.
Whenever the nerve is damaged, sprouting of the injured nerve occurs. The leads to neuroma formation and resistant scar pain. These neruromas deveop a capacity to spantaneonly fire the impulses.
These impulses reach the dorsal horn of spinal cord which gets hyperexcited and leads to central sensitization.
Thorax consists of thoracic cage and its contents. The thoracic cage is a osseocartilagenous cage primarily meant for altering the intrathotacic pressure so that air can be sucked in during inspiration and expelled out during expiration. The thoracic cavity consists of major organs like lungs, heart, along with part of oesophagus, great vessels, lymphatic chain etc. the thoracic cage usually shields these vital structures from external injuries. Diaphragm separates thorax from abdomen.
One has to specifically look for tenderness is the scar which might give a clue regarding neuroma formation. Altered sensation or loss of sensation suggests deafferentation pain.
These neuromas can generate viscero sensory reflex. The internal viscera are connected embryologically to cutaneous manifestation throughout the entire body. By pressing or moving the various connective tissue elements of the somatosensory areas served by the same neurological tissue, one can produce visceral or autonomic symptoms. This alleviation of pain from cutaneous area might resolve abdominal or thoracic visceral pain that may appear to be remote from the side itself.
Management of Post-thoracotomy Pain
Often this problem responds to conservative management for 6 weeks with conventional analgesics. Unconventional analgesics like amitryptiline, carbamazepine, gabapentin, clonidine can also be used.
Sometimes local application of capsaicin cream can be useful.
The small subgroup in which symptoms persist beyond 6-8 weeks, the neuroma group responds very well to local infiltration with local anaesthetics and steroids.
Most often the problem responds to these measures. The local anaethetic is supposed to break afferent-efferent neuronal loop at the neuroma level. The steroid is supposed to inhibit fibroplasias leading to inhibition of normal healing. This might lead to scar thinning and loss of scar tenderness. This might provide pain relief. The temporary pain relief because of local anaesthetic might reassure the patient and intensity of pain might come down.
The patients in whom deafferentation nature is suspected, may or may not respond to conventional strategy of local infiltration. As an alternative one can try acupuncture or TENS.
Some refractory patients might require corresponding sympathetic segment block with local anaesthetics, which can be made into permanent block either neurolytic way or radiofrequency lesion.