This target article examines the clinical and experimental
evidence for a role of peripheral and central hyperexcitability in
persistent pain in four key areas: cutaneous hyperalgesia, referred
pain, neuropathic pain, and postoperative pain. Each suggests that
persistent pain depends not only on central sensitization, but also
on inputs from damaged peripheral tissue. It is instructive to think
of central sensitization as comprised of both an initial central
sensitization and an ongoing central sensitization driven by inputs
from peripheral sources. Each of these factors, initial sensitization,
ongoing central sensitization, and inputs from peripheral sources,
contributes to the net activity in dorsal horn neurons and thus
influences the expression of persistent pain or hyperalgesia. Since
each factor, peripheral inputs and central sensitization (initial or
ongoing), can contribute to both the initiation and maintenance of
persistent pain, therapies should target both peripheral and central
sources of pathology.