BACKGROUND: The phenotype of large diameter sensory afferent neurons changes in several models of neuropathic pain. We asked if similar changes also occur in "functional" pain syndromes. METHODOLOGY/PRINCIPAL FINDINGS: Acidic saline (AS. pH 4. https://www.jmannino.com/hot-price-Reebok-Classic-Leather-Weiss-Grun-Gold-great-price/