Pain syndromes after missile-caused peripheral nerve lesions: part 1--clinical characteristics.

OBJECTIVE

To report on the clinical characteristics of pain and factors influencing pain intensity in patients with missile-caused nerve injuries.

METHODS

The prospective study included 326 patients with clinically significant pain syndromes including complex regional pain syndrome Type II, deafferentation pain, reinnervation pain, and neuralgic pain. Diagnostic procedures were analyzed, factors influencing the pain intensity were identified, and the patients' characteristics, pain characteristics, and other clinical symptoms and signs were compared between different types of pain syndromes.

RESULTS

The rate of painful injuries ranged from 17.3 to 22.9% for mixed nerves and from 2.6 to 4.6% for motor nerves. Peripheral nerve block and sympathetic block were useful and safe adjuvant diagnostic procedures, obtaining pain relief in 66.7% of patients with neuralgic pain and in 90.1% of patients with complex regional pain syndrome Type II. Pain started 2.6 days after injury in patients with complex regional pain syndrome Type II and 11.9 days after injury in patients with painful nerve adhesions (analysis of variance, P < 0.001). Permanent pain was more frequent (79.1%) than paroxysmal pain, superficial pain was more frequent (55.2%) than deep pain, and burning pain was the most frequent pain descriptor (43.6%). Ten factors were found to significantly influence the pain intensity (binary logistic analysis), including three independent predictors (multivariate analysis): type of pain syndrome (P < 0.001), multiple nerve damage in the injury site (P = 0.022), and onset of pain in the first two days after injury (P = 0.031).

CONCLUSION

Pain syndromes after missile-caused nerve injury differ significantly regarding time of pain onset, pain characteristics, and other symptoms and signs. The type of pain syndrome, multiple nerve damage, and early onset of pain are independent predictors of initial pain intensity. Although medical history and physical examination are the main diagnostic keys, nerve exploration preceded by a nerve block and sympathetic block are safe and useful adjuvant diagnostic procedures.