Current Concepts and Strategies in Pain Management

Raymond G. Tatevossian, MDChair, Pain &Palliative Care Committee, PSJMC

Clinical Assistant Professor of Anesthesiology, USC Keck School Medicine

Lecture Objectives

• Current Understanding Of Pain Mechanisms

• Current Treatment Strategies

• Medication Update

• Controversies Surrounding Opioids

• Prudent Opioid Prescribing

• Advanced Interventional Techniques

Pain: The Statistics

• 2nd leading cause of medically related lost work days

• $100 billion/year cost to US economy • 42% adults experience daily pain• 50% of population see a doctor with “Pain”

as the chief complaint• 66% of US veterans report persistent pain

attributable to military service

Is All Pain “Bad?”

The Gift of Pain by Dr. Paul Brand• “The Beloved Enemy”

• Pain is evolutionarily necessary for survival– Acute pain is protective

The “Gift” of Pain--an Example• Mycobacterium leprae

– Disfigurement• Infectious processes or

painlessness?

• The Cat Test– Sensory Neuropathy

http://bhavanajagat.files.wordpress.com/

Classification of Pain

Acute

• Generally protective

• Relieved when healing complete

• Short duration

• Predictable pathology

• Predictable prognosis

• Tx with analgesics

Chronic

• Generally no useful fnctn.

• Persists after healing complete

• Long duration

• Unpredictable Pathology

• Unpredictable prognosis

• Tx multidisciplinary

Chronic Pain Conditions

Nocioceptive Pain:

• Osteoarthritis

Mixed Pain:

•Malignant pain

•Chronic headache

•Fibromyalgia

•Failed back surgery syndrome

Neuropathic Pain:

•CRPS 1 and CRPS 2

•Chronic abdominal pain

•Chronic pelvic pain

•Diabetic neuropathy

•HIV neuropathy

•Phantom limb pain

•Arachnoiditis

•Post herpetic neuralgia

•Post thoracotomy pain

•Trigeminal neuralgia

•Degenerative disc disease

Factors Contributing to Chronic Pain

“Chronic Pain Load”• Intensity of injury• Duration of injury• Repetitiveness of injury• Chronicity of underlying disease• Genetic predisposition

– BH4 enzyme production

• Other factors:- Psychological- Socioeconomic - Cultural

Mechanisms of Pain: NeuroplasticityHow does a Chronic Pain State Develop?

• Peripheral Sensitization- Injury causes release of

“sensitizing soup” - Reduction in threshold and

increase response of nocioceptors

• Central Sensitization- Membrane excitability, synaptic

recruitment and decreased inhibition

- Uncoupling of pain from peripheral stimuli

http://www.aafp.org/afp/2001

Treatment: Multiple Options

Traditional Step Approach

http://www.nationalpainfoundation.org/images/ImplantableTherapy

Multimodal Pain Management

Goals of Treatment• Reduce pain

• Increase activity level

• Improve quality of life

• Pre-emptive analgesia

• Stay within “Therapeutic Window”– Avoid undertreatment

– Avoid toxicity

• How?– Synergism with Meds

• Morphine + Gabapentin

– Apply multimodal pain strategies when possible

Analgesic Medication UpdateFDA Advisory Panel Recs/Trends:• Acetaminophen- max daily dose,

max single dose

• Vicodin, Percocet - ban in current form

• Propoxyphene (Darvocet)- push for phased withdrawal

Abuse Deterrent Opioids:• Morphine ER+ Naltrexone (Embeda)

• Oxycodone IR+ Naltrexone (Oxytrex)

• Oxycodone IR + Niacin (Acurox)

Emerging Analgesic Medications• IV Acetaminophen

(Paracetamol) – opioid sparring, phase 3

completed

• Tapendatol (Nucynta) -opioid agonist, NE reuptake

inhibitor GI effects, ER phase 3

• Hydromorphone Extended Release (Exalgo)– FDA approved 3/1/2010,

awaiting REMS

Opioids--The Evolving Controversy

Past: Decreased Scrutiny

• 1990: Pain becomes “fifth vital sign”• 1990: Intractable Pain Act

– “no physician or surgeon shall be subject to disciplinary action …for prescribing controlled substances for intractable pain”

• Medical Board CA defines under treatment of pain as “inappropriate prescribing”

• Bergman vs Chin: $ 1.5 million dollars awarded for under treatment of pain

• 2000-2005 a 35-50% increase in opioid prescribing

Opioids--The Evolving Controversy

Present: Increased Scrutiny

• Most common class of medication prescribed – 800% increase in 10 years

• Fatal opioid poisonings have tripled 1999-2006• Food & Drug Administration Act (2007)

– Creation of REMS for new and existing drugs

• McLellan and Turner, Annals On Internal, Editorial, Jan 2010

- “prescribing opioids at high doses is both dangerous amd questionable” - White House Office of National Drug Control Policy

Opioids--The Evolving Controversy

Future:

• Goals – Avoid undertreatment AND avoid abuse

• Know appropriate prescribing stratagies– immediate release vs. sustained release formulations– neuropathic vs nocioceptive pain – malignant vs. chronic non-cancer pain– Urine toxicology screen– Opioid contract/Prescription monitoring

Strategic Opioid Prescribing

Prescription Monitoring • CURES (CA)

• Pharmacists, physicians, and law enforcement officials

• Real time, S II – IV

• https://pmp.doj.ca.gov/pmpreg

Opioid Contract• Call it “Opioid Consent”

• Discuss risks and benefits of opioids

• Educational

• Establish rules of prescribing

Intrathecal Drug Delivery Systems

AKA: Pain pump

Mechanism of Action:• Drug delivered directly to the

intrathecal space

Drugs:• Morphine• Baclofen• Ziconotide (Prialt®)• Bupivicaine• Clonidine• Ketamine

http://www.medtronic.com/IN/images/intro_intrathecal1.gif

Intrathecal Drug Delivery Systems

PROS• Short reversible trial• Delivery of drug

directly to the site of action

• 1mg IT Morphine = 300 gm oral Morphine

• Cancer Pain: pain, toxicity, survival 6mo

CONS• Short reversible trial opioid benefit with

time (40% failure with time)

• Contraindications to placement

• Complications (granuloma)

Spinal Cord Stimulation• Production of electrical

field over dorsal columns by epidurally placed electrodes

• Gate Control Theory– Gate exists in dorsal horn that governs pain

signal transmission – Closing gate decreases pain

• Parasthesia produced over painful body area

Spinal Cord Stimulation

Grade A Evidence• Failed Back Surgery• Arachnoiditis

Grade B Evidence• CRPS I• CRPS II

Other Indications• Phantom limb, post herpetic

neuralgia, spinal cord injury

www.medscape.com

References1. Arthritis Foundation. (2000) Pain in America. http://www.arthritisfoundation.org2. American Pain Foundation. http://www.painfoundation.org.3. National Institutes of Health. NIH Guide: New Directions in Pain Research: Bethsea.1998.4. Brand P and Yancey P. The Gift of Pain. Michigan: Zondervan Publishing House, 1997.5. Turk D. Pain Hurts-Individuals, Significant Others, and Society. APS Bulletin. 2006;16:1. 6. Payne J. Pain medications: What you need to know about acetaminophen, darvon, and darvocet. US News and

World Report 2009.7. Jamison R and Clark D. Opioid Medication Management:Clinician beware. Anesthesiology 2010; 112:777-8.8. Tucker K. Promoting good pain management in california. California Health Law News 2004;22:1-4.9. McLellan T. Chronic noncancer pain management and opioid overdose: Time to change prescribing practices.

Annals of Internal Medicine 2010;152:123-4.10. http://cdc.gov/nchs/data/databriefs/db22.htm11. http://www.painmed.org/pdf/rems_comments.pdf12. Cousins M, Carr D, et al. Neural blockade in clinical anesthesia and pain medicine. New York: LWW, 2009.13. American Society of Anesthesiologists Task Force on Chronic Pain Management. Practice guidelines for

chronic pain management: an updated report by the ASA. Anesthesiology 2010;112:810-33.14. Gilron I, Bailey J, et al. Morphine, gabapentin, or their combination for neuropathic pain. NEJM

2005;352:1324-34.15. Smith T, Staats P, et al. Randomized clinical trial of an implantable drug delivery system compared with

comprehensive medical management for refractory cancer pain:impact on pain, drug-related toxicity, and survival. J of Clinical Oncology. 2002;20:4040-9.

16. Barolat G, Massaro F, et al. Mapping of sensory responses to epidural stimulation of the intraspinal neural structures in man. J. Neurosurg 1993;78:233-239.