Atypical chest pain: evidence of intercostobrachial nerve sensitization in Complex Regional Pain Syndrome.

BACKGROUND Atypical chest pain is a common complaint among Complex Regional Pain Syndrome (CRPS) patients with brachial plexus involvement. Anatomically, the intercostobrachial nerve (ICBN) is connected to the brachial plexus and innervates the axilla, medial arm and anterior chest wall. By connecting to the brachial plexus, the ICBN could become sensitized by CRPS spread and become a source of atypical chest pain. OBJECTIVE To evaluate the sensitivity of chest areas in CRPS patients and normal controls. DESIGN Prospective investigation of pressure algometry in chest areas to determine chest wall sensitivity. METHODS CRPS patients and normal controls volunteered to participate in our study. Each individual was examined to meet inclusion criteria. Patients' report of chest pain history was collected from every participant. Pressure algometry was used to measure pressure sensitivity in the axilla, anterior axillary line second intercostal space, mid-clavicular third rib, mid-clavicular tenth rib, and midsternal. Each of these measurements were compared to an intra-participant abdominal measure to control for an individuals generalized sensitivity. The ratios of chest wall sensitivities were compared between CRPS patients and normal controls. RESULTS A history of chest pain was reported by a majority (94%) of CRPS patients and a minority (19%) of normal controls. CRPS patients reported lifting their arm as a major initiating factor for chest pain. To pressure algometry, the ratios of CRPS patients were significantly greater than control subjects (p< 0.02 throughout), indicating increased chest wall sensitivity. LIMITATIONS This study is limited by the relatively small number of patients (n=35) and controls (n=21) used. CONCLUSION The results of this study support the idea that chest pain is greater in CRPS patients than normal controls. The ICBN could be the source of this sensitization by CRPS spread from the brachial plexus.