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Neuropathic pain 1. Mechanism 2. Characteristic 3. Diagnosis 4. Treatment Neuropathic pain Mechanism of pain: caused by cancer nerve compression - nerve root compression caused by a collapsed vertebra total tumor mass = neoplasm + surrounding inflammation nerve infiltration by cancer nerve injury Neuropathic pain Mechanism of pain: caused by treatment postoperative (neurotomy) phantom limb pain, post-mastectomy pain radiotherapy (fibrosis) e.g. Brachial plexopathy chemotherapy - peripheral neuropathy (wincristine, cisplatine, taxol) Neuropathic pain Mechanism of pain: post-herpetic neuralgia diabetic neuropathy post-stroke pain uraemic neuropathy Neuropathic pain Pain characteristic: superficial burning pain spontaneous stabbing/shooting pain boring and radiating pain allodynia - pain caused by a stimulus which does not normally provoke pain hyperalgesia - an increased response to a stimulus which is normally painful Neuropathic pain Diagnosis: history clinical examination neurological examination MRI / CT Neuropathic pain Treatment: I. Adiuvant analgesics II. Corticosteroids III. Analgesics (opioids) IV. Neurolysis, spinal analgesia Neuropathic pain Corticosteroids (reduces total tumor mass) e.g. Dexamethason 16-24mg at the begining and then reduse dose Antidepressants - tricyclic antidepressants (amitriptyline, desipramine, doxepin, imipramine, clomipramine) SSRI (paroxetine, citalopram, fluoxetine) Neuropathic pain Amitriptyline is effective in migraine and other types of headache, chronic low back pain, post-herpetic neuralgia, fibromialgia, painful diabetic polyneuropathy, central pain, cancer pain. Superficial burning pain, allodynia = tricyclic antidepressants 10-25mg nocte at the begining; max 75mg relief may not occur for 4-5 days, for effect you have to wait even 1-2 weeks Neuropathic pain Anticonvulsants - carbamazepine, gabapentin, valproate, oxcarbazepine, lamotrigine spontaneous stabbing/shooting pain carbamazepine 200-1600mg; effect after 10-14 days adverse effects! gabapentin - 300-3600mg; effect after one week Neuropathic pain Other drugs: oral local anasthetics - mexiletine 450-600mg ; lignocaine infusions NMDA receptor antagonists - dextromethorphan, ketamine (in subanaesthetic doses), bupivacaine, methadon muscle relaxants - Baclofen 10-15mg >>75-100mg topical agents - capsaicin, lignocaine patch, EMLA benzodiazepines and neuroleptics spinal analgesia - epidural and intrathecal routes. A 4-step analgesic ladder used either alone or in conjunction with the WHO 3-step ladder Spinal analgesia Step 4 Class I antiarrhytmic or cetamine Step 3 Tricyclic antidepresant and anticonvulsant Step 2 Tricyclic antidepressant or anticonvulsant Step 1 Bone pain 1. Mechanism 2. Pain characteristic 3. Diagnosis 4. Treatment Bone pain Mechanism: metastases - breast, prostate, thyroid, kidney, lung, colon cancer infiltration of the bone pathologic fracture Bone pain Pain characteristic: - continuous, aching and localized pain - is exacerbated by movements and sneezing - may be unifocal multifocal generalized Bone metastases Symptoms: pain (75%) neurological symptoms pathologic fracture hypercalcaemia bone marrow failure Bone pain Diagnosis: history clinical examination rtg scintigram MRI / CT Bone pain Treatment: surgery - bone stabilisation, tumor excision radiation therapy - is usually considered when bone pain is focal and poorly controlled with an opioid chemotherapy (chemosensitive tumors) hormonotherapy (hormonosensitive tumors breast, prostate) Bone pain Radiopharmaceuticals that are absorbed at areas of high bone turnover - strontium-89, rhenium-186, samarium-153 strontium is only potentially effective in treatment of pain due to osteoblastic bone lessions or lession with an osteoblastic component e.g. prostate cancer metastases strontium - initial clinical response occurs in 7-21 days - the usual duration of benefit is 3-6 months Bone pain Non-steroidal anti-inflammatory drugs (NSAID) opioids corticosteroids bisphosphonates (clodronate, pamidronate) calcitonin neurolysis, spinal analgesia Bone pain Bisphosphonates - inhibit osteoclast activity and reduce bone resorption -provide analgesia and decrease the use of analgesics clodronate: - intravenous dose 600mg weekly - oral dose - 1600mg daily pamidronate: - intravenous dose 60-90mg every 3-4 weeks - is safe in patients with impaired renal function - adverse effect: occasional hypocalcaemia, nausea Bone pain Calcitonin: mechanism of action is unclear - increase endorphin levels in the central nervous system - interact with the serotonergic system - anti-inflammatory action - direct effect on osteoclasts calcitonin - subcutaneous - relatively low dose at the begining, then gradually increased to 200 IU - intranasal- 200 IU in one nostril; alternating nostril everyday Spinal cord compression Neurological emergency 3-5% of patients with advanced cancer 40% is associated with cancers of the breast, lung, prostate others are associated with: renal cell cancer, lymphoma, myeloma, melanoma, sarcoma, colorectal cancer very rarely spinal cord syndromes are due to epidural or cord metastases Spinal cord compression Mechanism of compression: - metastatic spread to vertebral body or pedicle - 85% - tumor extension through intervertebral foramina - 10% - intramedullary primary - 4% - haematogenous dissemination - epidural space - 1% Spinal cord compression Clinical presentation: pain (>90%) - pain of long duration which suddenly changes -pain is aggravated by lying down - pain may occur spontaneously - radicular pains are often exacerbated by neck flexion or straight leg raising, by coughing, sneezing or straining - funicular pain is less sharp, has a more diffuse distribution and is sometimes described as a cold unpleasant sensation Spinal cord compression Clinical presentation: - weakness > 75% - paraesthesiae - sensory loss (>50%) starting in the feet and moving proximally (is helpful in defining the level of the compression) - sphincter dysfunction >40% loss of sphincter function is a bad prognostic sign Spinal cord compression Diagnosis: - history - clinical examination - neurological examination - rtg - shows vertebral metastasis / collapse - MRI is the investigation of choice - CT with myelography may be helpful if MRI is not available Spinal cord compression Treatment: - high-dose steroids and radiation should be offered to all patients. Steroids can reduce pain and preserve neurological function; initial dosage - 100mg i.v.bolus (usually 2450mg) followed orally halving of the dose every third day until the end of radiation Spinal cord compression Treatment: - surgery is only occasionally indicated - solitary vertebral metastasis - neurological symptoms and signs progress despite radiotherapy and high dose dexamethason - vertebral body resection with anterior spinal stabilization is generally the operation of choice Corticosteroids in palliative care Special indications (Dexamethason 2x8mg 10-14 days): superior vena cava syndrome lymphadenopathy lymphangitis carcinomatosa obstruction of a hollow viscus (e.g. Bowel, ureter) postradiation inflamatory pericarditis exudative hypercalcaemia hormonal therapy Corticosteroids in palliative care Neuropathic pain bone pain neuropathic pain from infiltration or compression of neural structures increased intracranial pressure arthralgia neuromyopathy Corticosteroids in palliative care Other indications: anorexia cachexia difficulty with breathing nausea, vomiting fever