<P> The vague and poorly defined sensation as well as its temporal nature, characteristic of visceral pain, is due to the low density of sensory innervation of viscera and the extensive divergence of visceral input within the central nervous system (CNS). The phenomenon of referred pain is secondary to the convergence of visceral afferent (sensory) nerve fibers entering the spinal cord at the same level as the superficial, somatic structures experiencing the pain . This leads to a misinterpretation of incoming signals by higher brain centers . </P> <P> There are two goals when treating visceral pain: to alleviate the current experience of pain and to address any underlying pathology, if and when identifiable . Treatment of the pain in many circumstances should be deferred until the origin of the symptoms has been identified . Masking pain may confound the diagnostic process and delay the recognition of life - threatening conditions . Once a treatable condition has been identified there is no reason to withhold symptomatic treatment . Also, if cause for the pain is not found in reasonable time then symptomatic treatment of the pain could be of benefit to the patient in order to prevent long - term sensitization and provide immediate relief . </P> <P> Symptomatic treatment of visceral pain relies primarily upon pharmacotherapy . Since visceral pain can result secondary to a wide variety of causes, with or without associated pathology, a wide variety of pharmacological classes of drugs are used including a variety of analgesics (ex . opiates, NSAIDs, benzodiazepines), antispasmodics (ex . loperamide), antidepressants (ex . TCA, SSRI, SNRI) as well as others (ex . ketamine, clonidine, gabapentin). In addition, pharmacotherapy that targets the underlying cause of the pain can help alleviate symptoms due to lessening visceral nociceptive inputs . For example, the use of nitrates can reduce anginal pain by dilating the coronary arteries and thus reducing the ischemia causing the pain . The use of spasmolytics (antispasmodics) can help alleviate pain from a gastrointestinal obstruction by inhibiting the contraction of the gut . There are issues associated with pharmacotherapy that include side effects (ex . constipation associated with opiate use), chemical dependence or addiction, and inadequate pain relief . </P> <P> Invasive therapies are in general reserved for patients in whom pharmacological and other non-invasive therapies are ineffective . A wide variety of interventions are available and shown to be effective, a few will be discussed here . Approximately 50--80% of pelvic cancer pain patients benefit from nerve blocks . Nerve blocks offer temporary relief and typically involve injection of a nerve bundle with either a local anesthetic, a steroid, or both . Permanent nerve block can be produced by destruction of nerve tissue . Strong evidence from multiple randomized controlled trials support the use of neurolytic celiac plexus block to alleviate pain and reduce opioid consumption in patients with malignant pain originating from abdominal viscera such as the pancreas . Neurostimulation, from a device such as a spinal cord stimulator (SCS), for refractory angina has been shown to be effective in several randomized controlled trials . A SCS may also be used for other chronic pain conditions such as chronic pancreatitis and familial Mediterranean fever . Other devices that have shown benefit in reducing pain include transcutaneous electrical nerve stimulators (TENS), targeted field stimulation, both used for somatic hyperalgesic states, external neuromodulation, pulsed radiofrequency ablation and neuraxial drug delivery systems . </P>

Visceral diseases of the abdomen and pelvis are most likely to refer pain to