1、,Cancer Pain Syndromes Craig D. Blinderman, MD, MA Co-Director, MGH Cancer Pain Clinic MGH Palliative Care Service,Objectives,Review the definition of pain and basic pathophysiology Review the common causes of pain in cancer patients Review approach to managing pain,Defining Pain,Pain is defined as
2、an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage.,Merskey, H., Bogduk, N, ed. Classification of Chronic Pain, Second Edition. IASP Task Force on Taxonomy. 1994, IASP Press: Seattle. 209-214.,Taxonomy of Pain,Classi
3、fication may be based on: Anatomy Body System Temporal Characteristics Severity Etiology Pathophysiology Defined pain syndromes,Taxonomy of Pain,Clinically, it is useful to determine both the etiology and inferred pathophysiology in the assessment of the pain complaint, as this may suggest the use o
4、f specific therapies.,Taxonomy of Pain,Nociceptive Somatic Visceral Neuropathic Psychogenic Idiopathic,Nociceptive Pain,Nociceptive somatic pain Sustained predominantly by tissue injury or inflammation. Described as sharp, aching, stabbing, throbbing or pressure-like. Nociceptive visceral pain Poorl
5、y localized; described as crampy pain (e.g. obstruction of hollow viscus), or as aching and stabbing (e.g. pain secondary to splenomegaly).,Neuropathic Pain,Sustained by abnormal somatosensory processing in the PNS or CNS. Typically, described as “burning,” “shock-like,” “electrical.” May be paroxys
6、mal in nature. On physical examination, patients may have allodynia (pain induced by non-painful stimuli) and hyperalgesia (increased perception of painful stimuli).,Psychogenic Pain,Refers to pain that is believed to be sustained predominantly by psychological factors. Rare in the cancer population
7、.,Idiopathic Pain,In the absence of evidence sufficient to label pain as either nociceptive or neuropathic, we may use the term “idiopathic.” In patients with cancer, this term should lead to additional workup and a search for an underlying etiology and pathophysiology.,Basic Pathophysiology of Pain
8、,Transduction Conversion of thermal, chemical, mechanical stimulus to electrical activity at nociceptor Na channels Conduction Passage of action potential along the first order neuron to dorsal horn of spinal cord Transmission Transfer and modulation of input from one neuron to another Substance P,
9、Glutamate, Brain derived neurotropic factor Inhibitory interneurons Perception Awareness and meaning of pain Modulation Descending pathways inhibit transmission of nociceptive impulses e.g. Periaqueductal grey matter in midbrainnucleus raphae in medulla Norepinephrine, serotonin, endogenous opioids,
10、Ascending Tracts,Descending Tracts,Cortex,Midbrain,Medulla,Spinal Cord,Thalamus,Pons,Peripheral and Central Pathways for Pain,Modulation Descending pathways inhibit transmission of nociceptive impulsesPerception Awareness and meaning of painTransmission Transfer and modulation of input from one neur
11、on to another Conduction Passage of action potential along the first order neuron to dorsal horn of spinal cordTransduction Conversion of thermal, chemical, mechanical stimulus to electrical activity at nociceptor,Cancer Pain Syndromes,Syndrome: Definition,A temporal and qualitative convergence of s
12、ymptoms and signs, which conforms to a recognized patternAssociated with distinct etiologies, pathophysiologies, and prognostic and therapeutic implications,Cancer Pain Syndromes,Related to tumor involvement Accounts for 78% of pain problems in inpatient cancer population and 62% of outpatient cance
13、r population in MSKCC survey Metastatic bone disease, hollow viscous involvement and nerve compression or infiltration are most common causes Pain syndromes associated with cancer therapy 19% of pain problems in inpatient population and 25% in outpatient population Pain unrelated to cancer or therap
14、y Approx. 3% of inpatients have pain unrelated to their cancer and 10% in outpatient population Generalized pain in a dying cancer patient,Foley, KM. Pain syndromes in patients with cancer. Oxford Textbook of Palliative Medicine, 3rd Ed,Cancer Pain Syndromes: Temporal Patterns,Temporal Classificatio
15、n Acute Chronic Breakthrough Pain,Acute Cancer Pain,Defined by a recent onset and a natural history characterized by transience.May or may not be associated with overt pain behaviors.Usually caused by diagnostic or therapeutic interventions,Causes of Acute Cancer Pain,Diagnostic Interventions Acute
16、postoperative pain Therapeutic interventions Analgesic Techniques Associated with chemotherapy,Associated with radiotherapy Acute pain associated with hormonal therapy Acute pain associated with immunotherapy Acute pain associated with infection,Chronic Cancer Pain,Persists for one month or more bey
17、ond the usual course of an acute illness or injury Most commonly due to direct effects of the tumor Other causes: Due to cancer therapy (15-25%) Pathology unrelated to either the cancer or its treatment (5-15%),Causes of Chronic Cancer Pain,Related to tumor involvement Bone pain syndromes Headache a
18、nd Facial Pain Tumor involvement of the peripheral nervous system Visceral pain syndromes In neuroendocrine tumors with liver involvement this may be a major source of pain Somatic soft tissue pain syndromes Paraneoplastic pain syndromesPain syndromes associated with cancer therapy Post-chemotherapy
19、 pain syndromes Chronic pain associated with hormonal therapy Chronic post-surgical pain syndromes Chronic post-radiation pain syndromes,Therapeutic strategy for cancer pain,Non-pharmacological Modalities Cognitive behavioral interventions Massage, Physical Therapy Acupuncture Cutaneous techniques R
20、adiation Therapy Surgery Interventional procedures Anesthetic techniques,Pharmacotherapy Non-opioid analgesics NSAIDs Acetaminophen Dipyrone Opioid analgesics Codeine Morphine Oxycodone Fentanyl Hydromorphone Methadone Levorphanol Adjuvant analgesics Anticonvulsants Antidepressants Local anesthetic
21、agents GABA agonists NMDA antagonists Others,Summary,Cancer Pain may be due to the affects of the tumor on viscera, nerves, bones and soft tissue. Acute and Chronic Pain syndromes may also be due to the treatment of cancer Effective management of cancer pain requires recognizing syndromes and their inferred pathophysiology,
