Management of Acute and Chronic Pain in cancer

Source of acute pain is related to metastatic spread of cance.Patients may have depression and anxiety.PathophysiologyOrganic causes:nociceptive and neuropathic pain.Nociceptive pain includes somatic and visceral pain and refers to pain due to peripheral stimulation of nociceptors in somatic or visceral structures.Somatic pain is related to tumor involvement of somatic structures.Visceral pain is related to lesions in hollow or solid viscus.Nociceptive pain is responsive to nonopioids and opioids.Neuropathic pain involves peripheral or central afferent neural pathways.Neuropathic pain respond poorly to opioids,but controlled with drug or invasive procedures.Trauma of surgery ,scars, injury of soft tissue and of sensory afferents that innervate the surgical area may be a cause of chronic pain. Multimodal analgesia with local anesthetics and gabapentin is effective in preventing acute and chronic pain and reducing analgesic consumption.ThreatmentDrugs are cornerstone of pain management because of its efficacy,rapid onset ,and relatively low cost.Mild to moderate pain: NSAID,s and acetaminophen.Moderate to severe pain is treated by addition of codeine.Sever pain:Morphine, fentanyl.TCA are effective in the absence of depression and have direct analgesic effects and cause potentiation of opioids.Anticonvuls:Chronic neuropathic pain. Corticosteroids decrease pain perception,have a sparing effect on opioid requirements,improve mood, increase appetite,and lead to weight gain.Neuraxial AnalgesiaNA with local anesthetics: Immediate pain relief in patients whose pain cannot be relieved with oral or i.v analgesics.It is not performed in local infection,bacteremia,systemic infection.In intractable pain,we use EA despite meningeal infection.The implantable systems use for management of pain.Patients are typically considered for neuraxial opioid administration when systemic opioid administration has failed.Neurolytic ProceduresIt intended to destroy sensory components of nerves.Important aspects of determining the suitability of destructive nerve blocks are location and quality of pain,the effectiveness of less destructive treatment modalities,life expectancy,the inherent risks associated with block,and availability of experienced anesthesiologists to perform procedures.Constant pain is more amenable to destructive nerve blocks than is intermittent pain.Neurolytic celiac plexus block used to treat pain originating from abdominal viscera.Block is associated with significant side effects,but analgesia usually lasts 6 months or longer.Neurosurgical procedures for managing pain are reserved for patients unresponsive to other less invasive procedures.Cordotomy ,Dorsal rhizotomy,Dorsal column stimulators or deep brain stimulators may be used in selected patients.