The subjective experience of visceral pain and the neurobiological mechanisms that underlie it are substantially different from those of somatic pain, yet pain management strategies do not traditionally differ in their approaches. As a result, the treatment of visceral pain frequently results in suboptimal outcomes and adverse effects on the GI tract. In a review recently published in Pain Management, Anne E. Olesen of the Department of Gastroenterology and Hepatology of Denmark’s Aalborg University and colleagues suggest holistic alternatives to conventional pain management strategies with their exclusive focus on peripheral nociception.1
Frequently diffuse, poorly localized and associated with autonomic and emotional reactions and alterations in visceral function, visceral pain is common across a range of clinical populations. While visceral pain is often found in the presence of structural, biochemical or inflammatory abnormalities such as kidney stones, pancreatitis and colitis, it frequently occurs without evidence of tissue insult, leading to the diagnosis of functional disorders such irritable bowel syndrome, non-ulcer dyspepsia or bladder pain syndrome.2
In the review, Anne Olesen et al wrote that a positive relationship between patient and provider is pivotal to improving outcomes. Many patients with visceral pain have been through multiple rounds of diagnostic procedures with multiple specialists. Providers should acknowledge the reality of the patient’s symptoms even in the absence of a definitive diagnosis in order to build confidence and a strong therapeutic relationship. “Currently, investigational strategies frequently fail to demonstrate a cause for symptoms and, as such patients are frequently unhelpfully labeled as having underlying psychiatric issues, such as malingering or hypochondriasis. Consequently, patients can feel disenfranchised with healthcare providers, thereby limiting their engagement with treatment strategies,” the authors noted. Patients should receive education on the characteristics and biology of visceral pain in order to provide a context for interventions, and patients and providers should discuss and agree to realistic goals for treatment. This may serve to interrupt the often vicious cycle wherein patients become dissatisfied and move on to yet another specialist.
The writers of the review recommend the use of the World Health Organization’s “analgesic ladder” for patients with visceral pain, but include the caveat that strong opioids be reserved for patients with organic as opposed to functional visceral disorders. Originally developed for use in cancer pain, the ladder comprises 3 steps. The first step on the ladder involves the use of non-opioid analgesics. If pain increases or persists, clinicians initiate 2nd step treatment with non-opioids plus weak opioids. The third and final step consists of strong opioids in combination with non-opioids. The authors caution that health care providers be alert to the opioid side effects that are specific to visceral pain, such as opioid-induced bowel dysfunction. Laxatives should be prescribed at the same time as strong opioids.
Because a significant minority of patients with visceral pain do not achieve pain remission with standard analgesic interventions, the writers of the review recommend that adjuvant analgesics such as anticonvulsants or antidepressants be initiated early in patients when signs of central sensitization such as hyperalgesia and allodynia are evident. Unconventional pharmacological treatments such as ketamine, NGF antagonists, TRPV2 antagonists and linaclotide may eventually prove to be of benefit in visceral pain, but are yet to be validated with clinical trials. Nonpharmacological treatments including acupuncture or transcranial magnetic stimulation may also be considered, although data remain preliminary for both. The review authors also note that psychological treatments such as dynamic psychotherapy, cognitive behavioural therapy and hypnotherapy have demonstrated a degree of efficacy in visceral pain. In particular, gut-focused hypnotherapy may represent a valid treatment option.
The authors concluded “in order to optimize the management of chronic visceral pain, it is evident that a greater focus needs to be placed on managing aberrant central processing and psychological sequelae, rather than the current paradigm which is largely based on ameliorating peripheral nociception.”
Pain management specialists may have a significant role to play in treating patients with visceral pain. In an email interview with Clinical Pain Advisor, review co-author Søren Schou Olesen of Aalborg University Hospital noted that most gastroenterologists have limited experience in pain medicine and handling of complex pain problems. “Therefore, selected patients may benefit from a multidisciplinary approach from a specialised pain management unit, once conventional gastroenterological work-up and treatments are completed without a satisfactory result,” he noted.
1. Olesen AE, Farmer AD, Olesen SS, Aziz Q, Drewes AM. Management of chronic visceral pain. Pain Manag. June 2016.
2. Schwartz ES, Gebhart GF. Visceral Pain. In: Taylor BK, Finn DP, eds. Behavioral Neurobiology of Chronic Pain. Vol 20. Berlin, Heidelberg: Springer Berlin Heidelberg; 2014:171-197. http://link.springer.com/10.1007/7854_2014_315. Accessed June 30, 2016.