PAIN PAIN

By Dr. Cuong Ngo-MinhBy Dr. Cuong Ngo-Minh

Back to Basics Back to Basics April 14th 2010 April 14th 2010

ObjectivesObjectives

• To differentiate between Nociceptive from Neuropathic To differentiate between Nociceptive from Neuropathic types of pain on neural basis types of pain on neural basis

• To make a differential diagnosis of causes of pain. To make a differential diagnosis of causes of pain.

• To clinically assess pain and it’s impact on daily function by To clinically assess pain and it’s impact on daily function by history and search for most likely causehistory and search for most likely cause

• To create an individualized plan of management for To create an individualized plan of management for patients with acute or chronic pain. Use multiple modalities patients with acute or chronic pain. Use multiple modalities to relieve pain. to relieve pain.

• Select clients appropriately for referral to pain specialist, Select clients appropriately for referral to pain specialist, interdisciplinary approach. interdisciplinary approach.

Definitions 1Definitions 1• PAIN: «  an unpleasant sensory and emotional experience PAIN: «  an unpleasant sensory and emotional experience

associated with actual or potential tissue damage or described in associated with actual or potential tissue damage or described in terms of such damage » by the International Association for the terms of such damage » by the International Association for the Study of Pain. Study of Pain.

• A) Nociceptive pain is cause by DIRECT stimulation of peripheral A) Nociceptive pain is cause by DIRECT stimulation of peripheral nociceptors. nociceptors.

It is It is usuallyusually associated with associated with TISSUE DAMAGE TISSUE DAMAGE as well asas well as inflammation processes. Nociceptive pain is sub-categorized into inflammation processes. Nociceptive pain is sub-categorized into

A1) somatic which can be superficial (skin) or deep pain (eg tumor A1) somatic which can be superficial (skin) or deep pain (eg tumor infiltration, arthritis) infiltration, arthritis)

A2) visceral (eg. Pancreatitis, Crohn’s disease). A2) visceral (eg. Pancreatitis, Crohn’s disease).

Pathophysiology: SOMATIC pain signal start with the AFFERENTPathophysiology: SOMATIC pain signal start with the AFFERENT MYELINATED A-delta fibers (sharp pain) then goes to the C fibers MYELINATED A-delta fibers (sharp pain) then goes to the C fibers (delayed dull pain). Visceral pain (eg endometriosis): the afferent (delayed dull pain). Visceral pain (eg endometriosis): the afferent travel with sympathetic and parasympathetic fibers. travel with sympathetic and parasympathetic fibers.

Definitions 2Definitions 2• B) Neuropathic pain is caused by an injury to the peripheral or B) Neuropathic pain is caused by an injury to the peripheral or

central nervous system or is due to sensitazation of central pain central nervous system or is due to sensitazation of central pain neurons. neurons.

B1) Sympathetic via maintained sympathetic Efferent activity B1) Sympathetic via maintained sympathetic Efferent activity eg Complex regional pain syndrome type 1 – Reflex sympathetic eg Complex regional pain syndrome type 1 – Reflex sympathetic

dystrophy Pain wildly out of proportion to soft tissue or bone dystrophy Pain wildly out of proportion to soft tissue or bone injury but no nerve injury. Nerve block may help. injury but no nerve injury. Nerve block may help.

- Type 2 causalgia where pain wildly out of proportion to nerve - Type 2 causalgia where pain wildly out of proportion to nerve injury (by EMG-NerveConductionStudy).injury (by EMG-NerveConductionStudy).

B2) Non-Sympathetic via damage to peripheral nerve (eg. B2) Non-Sympathetic via damage to peripheral nerve (eg. Mechanical herniated disc, Neuroma of Morton, Infectious: post-Mechanical herniated disc, Neuroma of Morton, Infectious: post-herpetic neuralgia)herpetic neuralgia)

C) Central via Central nervous system Deafferation pain: no need C) Central via Central nervous system Deafferation pain: no need

for peripheral stimulus eg. Post stroke, spinal cord injury, for peripheral stimulus eg. Post stroke, spinal cord injury, Phantom Limb)Phantom Limb)

History for Pain 1History for Pain 1

• Use systematic questionnaire to find the cause of pain. Use systematic questionnaire to find the cause of pain. A) Where : point to area(s), localized/generalized, radiating A) Where : point to area(s), localized/generalized, radiating B) When/frequency: Acute vs chronic (more than 6 weeks) B) When/frequency: Acute vs chronic (more than 6 weeks)

Specific triggering factor/acute event vs progressive. Specific triggering factor/acute event vs progressive. C) Intensity: scale 1-10, Visual Scale/facial expression, mild-C) Intensity: scale 1-10, Visual Scale/facial expression, mild-

moderate-severe, Relieving and worsening factors moderate-severe, Relieving and worsening factors D) Type: constant vs intermittent , superficial vs deep, D) Type: constant vs intermittent , superficial vs deep,

sharp/dull, burning, electric shock sharp/dull, burning, electric shock E) Context: Work-related, MVA accident, F) Functional E) Context: Work-related, MVA accident, F) Functional

impairement: Work, Home, sleep, quality of life, FIFE impairement: Work, Home, sleep, quality of life, FIFE =Feelings Ideas Function Expectation-Emotions. Socio-=Feelings Ideas Function Expectation-Emotions. Socio-economic support.economic support.

History for Pain 2History for Pain 2

• Past Medical History: Cancer, Accident, Surgery, medical Past Medical History: Cancer, Accident, Surgery, medical illness (Diabetes, CVA, Neurological illness eg Multiple illness (Diabetes, CVA, Neurological illness eg Multiple sclerosis, neuropathy, Arthritis), Mental illness (depression, sclerosis, neuropathy, Arthritis), Mental illness (depression, anxiety, somatization,...). Drug users and addiction history.anxiety, somatization,...). Drug users and addiction history.

• List of medications prescribed (acetaminophen, Nsaids, List of medications prescribed (acetaminophen, Nsaids, narcotics, co-analgesic (amitriptilline, neurontin, pre-narcotics, co-analgesic (amitriptilline, neurontin, pre-gabelin,...), psychotropes eg Effexor) and overcounter gabelin,...), psychotropes eg Effexor) and overcounter medications. medications.

• Review of system to look for « red flags »Review of system to look for « red flags » Systemic symptoms of weight loss, diaphoresis, asthenia, Systemic symptoms of weight loss, diaphoresis, asthenia,

neurological symptomsneurological symptoms

Physical examination for PainPhysical examination for Pain Antalgic gait? Is pain intensity change with distraction? Reproductibiliy Antalgic gait? Is pain intensity change with distraction? Reproductibiliy

of pain? (use of PROVOCATIVE manoeuvers is KEY)of pain? (use of PROVOCATIVE manoeuvers is KEY)• Facial expression, vitals signsFacial expression, vitals signs

• Complete physical exam with more attention to painful structures, Complete physical exam with more attention to painful structures, according to clinical hypothesis coming from history and r/o sign of according to clinical hypothesis coming from history and r/o sign of cancer (localized or with metastasis), Range of motion, Trigger cancer (localized or with metastasis), Range of motion, Trigger points, guarding, reboundpoints, guarding, rebound

• Muscolo- Neurological exam, ? Swelling ? Redness ? Allodynia-Muscolo- Neurological exam, ? Swelling ? Redness ? Allodynia-HyperesthesiaHyperesthesia

search for signs to decide if nociceptive vs neuropathicsearch for signs to decide if nociceptive vs neuropathic• Mental status r/o sign of co-morbid mental illnessMental status r/o sign of co-morbid mental illness

• « perform complete physical examination regardless of complain »« perform complete physical examination regardless of complain »

Investigations and management for pain 1Investigations and management for pain 1

• Investigation are done to confirm or infirm hypothesis of Investigation are done to confirm or infirm hypothesis of diagnosis (eg Imaging, MRI L-Spine for Low back pain)diagnosis (eg Imaging, MRI L-Spine for Low back pain)

eg If suspect cancer of pancreas : CT abdomeneg If suspect cancer of pancreas : CT abdomen For neuropathy: EMG-NCSFor neuropathy: EMG-NCS

Refer to specialists appropriately to treat the cause of pain (eg Refer to specialists appropriately to treat the cause of pain (eg oncologist if cancer). For advise on pain relief for non-oncologist if cancer). For advise on pain relief for non-cancer pain, refer to pain specialists (re: Chronic Pain cancer pain, refer to pain specialists (re: Chronic Pain Management clinic) who can offer Injections (nerve blocks, Management clinic) who can offer Injections (nerve blocks, epidural...) and interdisciplinary team approachepidural...) and interdisciplinary team approach

Investigations and management for pain 2Investigations and management for pain 2

• For pain symptom relief, use multimodal (non-For pain symptom relief, use multimodal (non-pharmacologic and pharmacologic) approach. pharmacologic and pharmacologic) approach.

• Holistic approach, especially for total pain/ suffering. Holistic approach, especially for total pain/ suffering.

• Experience of pain differs from individuals affected by same Experience of pain differs from individuals affected by same disease/condition so treatment is in case by case basis. disease/condition so treatment is in case by case basis. Even for the same person, pain changes over time. Even for the same person, pain changes over time. Approach differs depending if Acute vs Chronic, Cancer Approach differs depending if Acute vs Chronic, Cancer pain vs Non-cancer pain.pain vs Non-cancer pain.

Investigations and management for pain 3Investigations and management for pain 3

• Non-pharmacologicNon-pharmacologic includes: physiotherapy-exercice, TENS, includes: physiotherapy-exercice, TENS, Adjustement of work activities, Acuponcture, Massotherapy, Adjustement of work activities, Acuponcture, Massotherapy, psychotherapy, surgery ...psychotherapy, surgery ...

• PharmacologicPharmacologic:1) Non- opioids: Acetaminophen, NSAIDS, steroids :1) Non- opioids: Acetaminophen, NSAIDS, steroids Opiods (codeine, tramadol, morphine, oxycodone, hydromorphone, Opiods (codeine, tramadol, morphine, oxycodone, hydromorphone,

fentanyl, methadone),fentanyl, methadone), ADJUVANT Tricyclic (eg amitryptilline), Anticonvulsant as adjuvant ADJUVANT Tricyclic (eg amitryptilline), Anticonvulsant as adjuvant

therapy (gabapentin, pregabelin, ...). Cannabinoids eg nabilone therapy (gabapentin, pregabelin, ...). Cannabinoids eg nabilone Always assess Benefice vs Risk/side effects ratio. Always assess Benefice vs Risk/side effects ratio.

• Use combination eg opioid long-acting, PRN short acting opioid Use combination eg opioid long-acting, PRN short acting opioid and adjuvant (eg pre-gabelin). Treat comorbid conditions: eg. and adjuvant (eg pre-gabelin). Treat comorbid conditions: eg. Antidepressant. Use laxatives with narcotics.Antidepressant. Use laxatives with narcotics.

Investigations and management for pain 4Investigations and management for pain 4• Narcotic use principles: Narcotic use principles:

1) Try non-narcotic treatment first, up to their maximum dose 1) Try non-narcotic treatment first, up to their maximum dose tolerated tolerated

2) Goal is NOT pain= 0 but pain relief to allow Functional status in 2) Goal is NOT pain= 0 but pain relief to allow Functional status in daily activities daily activities

3) Progressive titration of dose of narcotic. Use minimal dose that 3) Progressive titration of dose of narcotic. Use minimal dose that

relieve pain/ assure function. Titrate with short acting opiods eg relieve pain/ assure function. Titrate with short acting opiods eg hydromorphone. Once stable dose (not frequent PRN), use total hydromorphone. Once stable dose (not frequent PRN), use total daily dose and convert to long acting meds eg Hydromorphone daily dose and convert to long acting meds eg Hydromorphone Contin. Manage side effects: constipation, nausea, confusionContin. Manage side effects: constipation, nausea, confusion

4) Tolerance effect: Same dose not as efficient to relieve pain so 4) Tolerance effect: Same dose not as efficient to relieve pain so need to increase dose. Tolerance is different than addiction! need to increase dose. Tolerance is different than addiction! « Explain that the correct use of morphine is more likely to « Explain that the correct use of morphine is more likely to prolong a more rested, pain free life »prolong a more rested, pain free life »

5) Narcotics can be used for non-cancer pain: need narcotic contract 5) Narcotics can be used for non-cancer pain: need narcotic contract to avoid abuse.to avoid abuse.

Investigations and management for pain 4Investigations and management for pain 4

• Third party issues: Employer, Worker’s Comp or WSIB, Private Third party issues: Employer, Worker’s Comp or WSIB, Private Insurance and objective assessment of functional status.Insurance and objective assessment of functional status.

• Quality of life eg Palliative care. Capacity issues in end-stage Quality of life eg Palliative care. Capacity issues in end-stage disease. Caregiver stress.disease. Caregiver stress.

Euthanasia and Physician assisted suicide are illegal in Canada. Euthanasia and Physician assisted suicide are illegal in Canada. No maximum dose, use necessary dose of narcotics to relieve No maximum dose, use necessary dose of narcotics to relieve

pain (but document reasoning and monitor) and assure quality pain (but document reasoning and monitor) and assure quality of life. Counsel care givers.of life. Counsel care givers.

Summary for pain managementSummary for pain management

• History and physical to search for cause of pain. History and physical to search for cause of pain. Management differs from Acute vs Chronic pain, Cancer vs Management differs from Acute vs Chronic pain, Cancer vs Non-Cancer pain. Goal is to improve functional status. Non-Cancer pain. Goal is to improve functional status.

• Use multiple approach non-pharmacologic and Use multiple approach non-pharmacologic and pharmacologic modalities to relieve pain and co-morbid pharmacologic modalities to relieve pain and co-morbid conditions (eg depression). Set action plan with client and conditions (eg depression). Set action plan with client and caregivers. caregivers.

• Refer appropriately for diagnosis and management. Eg Refer appropriately for diagnosis and management. Eg pain specialist can do epidurals, nerve block or neurolysis pain specialist can do epidurals, nerve block or neurolysis

Consent, capacity, controversial ethical Consent, capacity, controversial ethical issues (Cleo 4.3, 4.10)issues (Cleo 4.3, 4.10)

• Capacity: ability to decide with understanding and appreciate Capacity: ability to decide with understanding and appreciate consequence (pro-cons) of decision. Capacity for health is different consequence (pro-cons) of decision. Capacity for health is different from financial capacityfrom financial capacity

• Capacity is affected by factors: severity of physical and psychological Capacity is affected by factors: severity of physical and psychological illness, effect of medications/ delirium, religious belief and values, fear illness, effect of medications/ delirium, religious belief and values, fear of death.of death.

• Issues of Euthanasia and Physician Assisted Suicide (illegal in Canada)Issues of Euthanasia and Physician Assisted Suicide (illegal in Canada)“ “ The candidate will be aware that they may be asked to comment on The candidate will be aware that they may be asked to comment on

unresolved or controversial ethical issues and will be able to name and unresolved or controversial ethical issues and will be able to name and describe relevant key issues and ethical principles”describe relevant key issues and ethical principles”

““Contrast resp. depression caused by opioids to resp rate 6-8bpm of Contrast resp. depression caused by opioids to resp rate 6-8bpm of dying patient in which resp depression is not caused by opioids but a dying patient in which resp depression is not caused by opioids but a natural part of dying process”. Titrate Rx to provide appropriate pain natural part of dying process”. Titrate Rx to provide appropriate pain control.control.

Ressources Ressources

1) 1) Managing pain. The Canadian Healthcare Professional’s Managing pain. The Canadian Healthcare Professional’s Reference by the Canadian Pain Society, Dr Jovey Editor Reference by the Canadian Pain Society, Dr Jovey Editor

2) Practice Based Learning program from McMaster University, 2) Practice Based Learning program from McMaster University, Module on Chronic Non Cancer Pain, Vol 11(10), August Module on Chronic Non Cancer Pain, Vol 11(10), August 20032003