Effect of Co-Morbid Conditions on Persistent Neuropathic Pain after Brachial Plexus Injury in Adult Patients

BACKGROUND AND PURPOSE Neuropathic pain (NeuP) associated with traumatic brachial plexus injury (BPI) can be severe, persistent, and resistant to treatment. Moreover, comorbidity associated with NeuP may worsen the pain and quality of life. This study compared persistent NeuP after BPI between patients with and without co-morbid conditions (psychiatric dysfunction and other painful conditions) and tramadol usage as a second-line agent in combination with an antiepileptic and/or antidepressant during a 2-year follow-up. METHODS The medical records of patients diagnosed with BPI referred to a pain center between 2006 and 2010 were reviewed for 2 years retrospectively. Data regarding patient demographics, injury and surgical profiles, characteristics of NeuP and its severity, and treatment received were compared between patients with and without manifesting co-morbid conditions. The NeuP and pain intensity assessments were based on the DN4 questionnaire and a numerical rating scale, respectively. RESULTS Of the 45 patients studied, 24 patients presented with one of the following co-morbid conditions: myofascial pain (21%), psychiatric disorder (17%), phantom limb pain (4%), complex regional pain syndrome (21%), and insomnia (37%). Tramadol was required by 20 patients with co-morbidity and, 9 patients without co-morbidity (p<0.001). The mean pain score after 2 years was higher in patients with co-morbidity than in those without co-morbidity (p<0.05). CONCLUSIONS Persistent pain following BPI was more common in patients manifesting other painful conditions or psychiatric co-morbidity. A higher proportion of the patients in the co-morbid group required tramadol as a second-line of agent for pain relief.