Transcript Neuropathic pain
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 lignocaine infusions - mexiletine 450-600mg ;
NMDA receptor antagonists - dextromethorphan, ketamine (in subanaesthetic doses), bupivacaine, methadon muscle relaxants - Baclofen 10-15mg >>75-100mg topical agents EMLA - capsaicin, lignocaine patch, 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
Tricyclic antidepressant
or
anticonvulsant
Step 1
Tricyclic antidepresant
and
anticonvulsant
Step 2
Class I antiarrhytmic
or
cetamine
Step 3
Spinal analgesia
Step 4
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 high bone turnover that are absorbed at areas of 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 24 50mg) 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