Analyzing Visceral Nerve Disorders

Visceral pain is quite unique, according plenary speaker Gerald Gebhart, PhD.

What makes it so, is the fact that the each organ receives enervation from two nerves and all organs have an intrinsic enervation, he said, in his presentation, titled “Visceral Nociceptors-Silent and Otherwise-and Visceral Pain.”

Visceral nerve disorders are often categorized as functional, meaning the cause of what causes the discomfort or disorder is unknown. It is known, however, that these disorders are characterized by hypersensitivity and they seem to arise independent of any apparent tissue insult or injury, he said.

Managing these patients can be difficult, but growing research is steadily providing more insight into the disease process.

“The issue comes down to the fact that in the visceral realm, at least, many of these functional disorders are widely held to be centrally-mediated or maintained by central mechanisms,” he said.

Gebhart’s presentation focused on the concept that peripheral drive maintains pain and hypersensitivity in these functional disorders. For the presentation, Gebhart discussed data from a study on hypersensitivity in inflammatory bowel syndrome and the contributions of changes in receptive properties of colorectal nocicpetive endings. A hypothesis used for this study was that mechanically insensitive, or silent, afferents gain mechanosensitivity. The research suggested that mechanical sensitive afferent fibers are also sensitized and may also contribute to the process. While about 25% of these fiber endings are silent, it is suggested that when awakened they may contribute significantly to hypersensitivation, he said.

Among the evidence he presented for these concepts were that: colorectal hypersensitivity in pain and Irritable Bowl Syndrome is reversed by colorectal local anesthesia; similarly, another study illustrated that administering local anesthetics into the bladder of painful bladder system patients their VAS pain scores are reduced by more than 50% in almost all the patients, which can last up to 10 days.

Visceral pain is quite unique, according Gerald Gebhart, PhD plenary speaker at APS’ 29th Annual Scientific Meeting May 7.