The Angry Backfiring C Syndrome (ABC) occurs when the sympathetic nerve fiber becomes angry, or backfires (like a car engine) in response to an underlying injury (usually ligament or other soft tissue).

The nerve itself spits out various vasodilating chemicals such as substance “p”, kinens and histamine. These chemicals inflame the tissues and cause pain. In addition, the C-fiber itself becomes hypersensitive because of its own actions.

When someone sprains an ankle, it would not be surprising if he complained of continued burning pain afterwards. It is also easy to imagine the ankle becoming warm, swollen, discolored, and painful to light touch. It is the vasodilating chemicals that cause this to occur. If persistent sympathetic pain develops, it is called the ABC syndrome.

RSD with Distant Effects is one of the most recently recognized forms of reflex sympathetic dystrophy. In this case, the afflicted person has sympathetic pain associated with true RSD or any of its subtypes and they have autonomically controlled symptoms related to the internal organs (the vicera). These include, but are not limited to rapid heart rate, change in bowel or bladder function, dizziness, or blurred vision.

Based upon our own clinical experience — not everyone agrees that the internal organs can become involved — the most common viscera affected include the heart, eyes, and teeth (see the somato-visceral pain chapter). One of the best explanations for the spread of pain from limb to limb is the “table cloth effect.” In this case, the fascia — the sticky stuff in between the skin and meat in chicken — gets pulled, just like a tablecloth, and causes kinks in distant places.

RSD with dystonic features represents yet another special category of sympathetic pain. In this case the person afflicted develops both features of reflex sympathetic dystrophy and a movement disorder. In mild cases there may be only a complaint of decreased balance or dexterity. In moderate cases there may be visible contractions of a single muscle (like a writer’s cramp) and in more severe cases an entire limb may move about uncontrollably.

While no one really knows for sure, it is thought that the over-activity of the C fiber causes “cross talk” to neighboring motor nerve fibers (like a short circuit) and causes the motor nerve to fire. It may also be due to a defect in the brainstem itself, neurological reflex arcs involving the peripheral muscle spindle and sympathetic nerve fibers, or central nervous system alterations that cause signals to be improperly routed.