However , intercostal nerve injury seems to be the most important pathogenic factor .
Chronic pain complaints after thoracic surgery represent a significant clinical problem in 25 - 60 % of patients .
Results from thoracic and other surgical procedures suggest multiple pathogenic mechanisms that include pre- , intra- , and postoperative factors .
This review attempts to analyse the methodology and systematic s of the studies on the  post-thoracotomy pain syndrome ( PTPS ) after lung cancer surgery in adults , in order to clarify the relative role of possible pathogenic factors and to define future strategies for prevention .
Role of cryoanalgesia in the control of pain after thoracotomy.
Thoracotomy causes severe postoperative pain , which is difficult to manage since the use of systemic analgesics often causes respiratory depression . Cryoanalgesia of the intercostal nerves has been advocated as an effective means of local analgesia without serious side effects . A prospect i ve r and omised blind trial to investigate the efficacy of the technique was carried out . A total of 53 patients undergoing thoracotomy  were allocated to either the trial or a control group . At thoracotomy the surgeon was informed of the patient 's trial allocation . The trial group received one minute of direct cryotherapy to at least five intercostal nerves related to the incision . All patients received methadone via the lumbar epidural route in a dose calculated according to their weight . A linear analogue assessment of postoperative pain was made by the patients as soon as they were sufficiently awake . An independent record of all postoperative analgesia was kept . After discharge from hospital further assessment s were made at least six weeks after operation . Statistical analysis of the scores of postoperative pain and analgesic consumption showed that there was no significant difference between the trial and the control group . There was , however , a suggestion of an increase in the long term morbidity , although these figures were not amenable to statistical analysis . Thus is has not been possible to demonstrate a role for cryoanalgesia in the control of post thoracotomy pain
However , intercostal nerve injury seems to be the most important pathogenic factor .
Chronic pain complaints after thoracic surgery represent a significant clinical problem in 25 - 60 % of patients .
Results from thoracic and other surgical procedures suggest multiple pathogenic mechanisms that include pre- , intra- , and postoperative factors .
This review attempts to analyse the methodology and systematic s of the studies on the  post-thoracotomy pain syndrome ( PTPS ) after lung cancer surgery in adults , in order to clarify the relative role of possible pathogenic factors and to define future strategies for prevention .