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This Article Full Text Full Text (PDF) All Versions of this Article: 298/1/G31    most recent ajpgi.00288.2009v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Hobson, A. R. Articles by Dukes, G. PubMed PubMed Citation Articles by Hobson, A. R. Articles by Dukes, G.

Neuroregulation and Motility

Neurophysiological evaluation of convergent afferents innervating the human esophagus and area of referred pain on the anterior chest wall

¹GSK Academic Discovery Performance Unit and Clinical Investigation Unit, Addenbrooke's Hospital, Cambridge; and ²The Wingate Institute of Neurogastroenterology, Centre for Gastroenterology, Queen Mary's School of Medicine and Dentistry, London, United Kingdom

Submitted July 17, 2009 ; accepted in final form October 15, 2009

Noxious stimuli in the esophagus cause pain that is referred to the anterior chest wall because of convergence of visceral and somatic afferents within the spinal cord. We sought to characterize the neurophysiological responses of these convergent spinal pain pathways in humans by studying 12 healthy subjects over three visits (V1, V2, and V3). Esophageal pain thresholds (Eso-PT) were assessed by electrical stimulation and anterior chest wall pain thresholds (ACW-PT) by use of a contact heat thermode. Esophageal evoked potentials (EEP) were recorded from the vertex following 200 electrical stimuli, and anterior chest wall evoked potentials (ACWEP) were recorded following 40 heat pulses. The fear of pain questionnaire (FPQ) was administered on V1. Statistical data are shown as point estimates of difference ± 95% confidence interval. Pain thresholds increased between V1 and V3 [Eso-PT: V1-V3 = –17.9 mA (–27.9, –7.9) P < 0.001; ACW-PT: V1-V3 = –3.38°C (–5.33, –1.42) P = 0.001]. The morphology of cortical responses from both sites was consistent and equivalent [P1, N1, P2, N2 complex, where P1 and P2 are is the first and second positive (downward) components of the CEP waveform, respectively, and N1 and N2 are the first and second negative (upward) components, respectively], indicating activation of similar cortical networks. For EEP, N1 and P2 latencies decreased between V1 and V3 [N1: V1-V3 = 13.7 (1.8, 25.4) P = 0.02; P2: V1-V3 = 32.5 (11.7, 53.2) P = 0.003], whereas amplitudes did not differ. For ACWEP, P2 latency increased between V1 and V3 [–35.9 (–60, –11.8) P = 0.005] and amplitudes decreased [P1-N1: V1-V3 = 5.4 (2.4, 8.4) P = 0.01; P2-N2: 6.8 (3.4, 10.3) P < 0.001]. The mean P1 latency of EEP over three visits was 126.6 ms and that of ACWEP was 101.6 ms, reflecting afferent transmission via A fibers. There was a significant negative correlation between FPQ scores and Eso-PT on V1 (r = –0.57, P = 0.05). These data provide the first neurophysiological evidence of convergent esophageal and somatic pain pathways in humans.

cortical evoked potentials; visceral; somatic