Idiopathic breakthrough pain: a new hypothesis.

Breakthrough pain (BTP) in treated patients with chronic pain states is neither well defined nor well understood. BTP is generally defined as a transient exacerbation of pain experienced by a patient with relatively stable and adequately controlled baseline pain. It is usually categorized as spontaneous, with no known cause, or incident, when initiated by voluntary or involuntary movements, or therapeutic procedures. Since pain is related to survival, it possibly cannot be completely and permanently controlled. It is hypothesized that glia are at least partially responsible for inducing pain spikes by attempting to reactivate unresponsive neurons. Therefore, compounds that modulate microglia may offer potential alternative therapeutic options in the control of idiopathic BTP.