Hayek Post Surgical Pain

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Persistent Postsurgical Pain:Risk Factors and Prevention

Division of Pain Medicine

Department of Anesthesiology

University Hospitals ofCleveland

Salim Hayek, MD,PhD
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Persistent Postsurgical Pain:

Risk Factors and Prevention

Salim M. Hayek, MD, PhD

Division of Pain Medicine

Department of AnesthesiologyUniversity Hospitals of Cleveland


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Conflicts of Interest

None Relevant


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Persistent Postoperative Pain


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Learning Objectives

Physiology & Pathophysiology of Pain

Nociceptive vs. Neuropathic Pain

Predictors of Chronic Postsurgical Pain

Targets for Prevention of PersistentPostsurgical Pain


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Postoperative Pain

Pain

Score

POD10 32 54 6 180

PPP

Persistent Postsurgical Pain (PPP) = Pain >

3-6 mo after surgery


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Kehlet H et al., Lancet. 2006 May 13;367:1618-25

PPP--Incidence

Compares in its scale to morbidity of other forms of neuropathicpain such as post-herpetic neuralgia and post-stroke pain (5-10%)


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PPPA significant problemEtiologiesOngoing Inflammation

Neuropathic Pain: surgicalinjury to peripheral nervesDrug seeking/psychogenic


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Immediate Post-op

Activation ofnociceptors

Inflammation~ injury to nerves

Around-the-Clock

Medication

Breakthrough Pain

Most patients respond well to opiates and COX inhibitors.If nerves are injured during surgery, a neuropathiccomponent of the pain might develop immediately and then

persist in the absence of any peripheral noxious stimulusor ongoing peripheral inflammation


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PAIN = 2 subtypes

Pain: nociceptive or neuropathicNociceptive: tissue insultnociceptor

activationNeuropathic: pathological lesion or

dysfunction of the nervous system

Neuropathic pain treatmentdiffers from that of nociceptivepain


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Inflammatory PainThe phenomena, although evoked within a

matter of minutes, outlast the precipitatingtissue injury for several hours or days

However, they are generally reversible Inflammatory pain is the pain that, in the

absence of any peripheral nerve damage,drives acute postoperative pain until the

surgical wound has healedIf a focus of ongoing inflammation persists,

however, so will the pain


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Neuropathic Pain

Occurs as a result of a primary lesionor dysfunction in the nervous system

Key feature: combination of sensoryloss with paradoxical hypersensitivity

spontaneous pain, dysesthesia,

hypersensitivity, including allodyniaand hyperalgesia and hyperpathia


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Jung BF et al., Pain 2003; 104: 1-13Rasmussen PV et al., Pain 2004; 110: 461-469

Surgical nerve injury PPP

Postsurgical chronic pain closely resemblesneuropathic pain in most patients

Major nerves trespass the surgical fieldof most of the surgical proceduresassociated with chronic pain, and damageto these nerves is probably a prerequisitefor the development of postsurgicalchronic pain


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Aasvang E & Kehlet H. Br J Anaesth 2005; 95: 69-76

Inflammatory vs. Neuropathic

In a subset of patients, a continuousinflammatory response, such as after

inguinal mesh hernia repair, can contributeto a maintained inflammatory pain

Differentiation of neuropathic from non-

neuropathic causes of postsurgical pain isessential


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Inflammatory vs. Neuropathic


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Rogers ML, Eur J Cardiothorac Surg 2002; 21: 298-301Benedetti F, Thorac Cardiovasc Surg 1998; 115: 841-847

Neuropathic Pain following Surgery

Signs of neurological damage, in the formof hypoesthesiamastectomy

hernia repair

mandibular osteotomy

Use of a rib retractor blocks intercostalnerve conduction by 50100% (EMG)degree of nerve damage correlates with

intensity of chronic pain


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Neuronal Plasticity & Pain

2 kinds of plasticity:Reversible changes in the software of the

system, operates during inflammatory pain

After nerve injury, the hardware itself isaltered

no simple continuum from acute to

chronic pain that correlates with theduration or intensity of peripheral injury


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Neuropathic Pain Changes

Up regulation of 2 subunit of Ca2+ ChNeuroimmune sequelae pain sensitivityDegeneration of nerve cut end/infl. cells

Release of TNF- signaling moleculesMicroglia are activated in the spinal cord

Interruption of nerve contact with target

small unmyelinated neurons death (excitotoxic)inhibitory interneurons death

even cortical changes in gray mater


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PPPEtiologies

Ongoing InflammationNeuropathic Pain: surgical

injury to peripheral nerves

Drug seeking/psychogenic


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PPP--Risk Factors

Nerve Injury

Genetic Susceptibility

Preceding Pain

Psychosocial Factors

Age & Sex


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Mikkelsen T et al., Anesth Analg. 2004 Jul;99(1):146-51Jaaskelainen SK et al., Neurology. 2004 Jun 8;62(11):1951-7

Nerve Injury

Seems to be necessary--in most cases

Most patients with post-surgical

nerve damage no painSevere nerve damage after mandibular

osteotomy neuropathic pain only in 10%

Nerve damage alone: Not sufficientfor the development of PPP


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Genetic Susceptibility

Inconsistent pain response likely heritableGeneration of painExperience of painResponse to analgesics

Rats: Susceptibility to neuropathic painClinical evidence

High COMT activity TMJ painMelanocortin-1 receptor gene (associated with

red hair/fair skin) greater female specific -opioid analgesia


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Preceding PainCorrelates with development of PPPSevere pre-amputation pain phantom

limb pain1

Intensity of acute post-operative paincorrelates with PPP followingBreast surgery2

Thoracotomy3

Inguinal herniorrhaphy4

1. Nikolajsen L et al., Lancet. 1997 Nov 8;350(9088):1353-72. Tasmuth T et al., Pain. 1996 Dec;68(2-3):343-7

3. Katz J et al., Clin J Pain. 1996 Mar;12(1):50-54. Callesen T et al., Br J Surg. 1999 Dec;86(12):1528-31


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Psychosocial Factors

Modulators of the pain responseExpectation of post-op painFear of post-operative pain

Pre-operative anxietyPast memoriesSocial environment

WorkLevels of physical activityCatastrophizing


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Poobalan AS et al., Clin J Pain. 2003 Jan-Feb;19(1):48-54Katz J et al., Pain. 2005 Dec 15;119(1-3):16-25

Age & Sex

Older patients undergoingherniorrhaphy have a lower

risk for developing PPP thanyoung patients

Women have morepostoperative pain than men


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Prevention Strategies

Surgical TechniqueAvoid intraoperative nerve injury

Careful dissection inflammatory responses

Use minimally invasive techniques


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Grant AM et al., Br J Surg. 2004 Dec;91(12):1570-4Macrae WA, Br J Anaesth. 2001 Jul;87(1):88-98

Prevention StrategiesSurgical Technique

HerniorrhaphyLaparoscopic technique can risk of nerve

damageLight weight mesh ~less inflammation

MastectomyPreservation of intercostal brachial nerve could

decrease chronic painIncreased use of sentinel lymph node biopsy

might ALNDThoracic SurgeryThoracoscopic techniques >> rib retractorsIntracostal suture / muscle sparing


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SNRIAntidepressants

NMDA blockers

Neurogenic soup

blockers


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Hayek Post Surgical Pain

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