Comparison between posterolateral thoracotomy and vertical axillary thoracotomy regarding nerve impairment and its neurophysiologic implication

ABSTRACT

The aim of this study is to analyze the degree of intercostal nerve impairment in posterolateral and vertical axillary thoracotomy and verify that the severity of long standing post-thoracotomy pain is related to the degree of nerve damage. This study includes 45 patients operated upon at Cardio-thoracic surgery Department - Suez Canal University over one and a half year-duration [March 2004 through October 2005] 30 patients for posterolateral thoracotomy and 15 patients for vertical axillary thoracotomy. The needs to relieve the immediate postoperative pain were recorded. The neurophysiologic recordings were performed one month after thoracotomy either posterolateral or vertical axillary to assess the following [1] the presence of superficial abdominal reflexes [mediated in part by the intercostal nerves] [2] the somato-sensory evoked response after electrical stimulation of the surgical scar [3] the electrical thresholds for tactile and pain sensation of the surgical incision. The patients with posterolateral thoracotomy needed opiates to relieve early pain and showed a higher degree of intercostal nerve impairment compared to those produced by the vertical axillary thoracotomy as revealed by the disappearance of the abdominal reflexes, larger reduction in amplitude of the somatosensory evoked potentials and a higher increase of the sensory thresholds to electrical stimulation of both tactile perception and pain. This study is showing the pathophysiologic differences between the two approaches and suggests that the minor long lasting post thoracotomy pain among the vertical axillary thoracotomy patients is partly due to a minor nerve damage. We can also conclude that nerve injury and nerve impairment after PLT arc responsible for the increased needs for narcotic analgesics during the immediate postoperative period as well as the long lasting neuropathic pain later on. So, it is necessary to match specific treatment to the neuropathic pain generating mechanisms