neuropathic paintx
TRANSCRIPT
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ALBERTO RIVERA SANCHEZ MD FAAPMR, ABPM, ABDA
PAIN MANAGEMENT SUB SPECIALIST
Managing Neuropathic Pain
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Neuropathic pain Prevalence of 2-40% (Harden 2015)
3.75 million with chronic NP in the US (IASP 1997)
The most common studied NP syndromes are: DMPN PHN
Other causes:○ SCI○ Phantom Pain○ CRPS○ Post CVA○ Nerve Injury
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Neuropathic pain 33% of pain patients seen in tertiary
facilities have anxiety disorders (Von Korff, et al 1996)
40-60% meet the criteria for depressive disorder (Banks, 1996)
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FDA Approved Med’s for NP Carbamazepine Lidocaine patches Gabapentin Pregabalin (PHN, DMPN) Capsaicin Duloxetine (DMPN) Tapentadol ER (DMPN)
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Off label Med’s for NP Anti-depressants Anti-epileptics Anti-arrythmic
Evidence for their safety and efficacy is lacking
Benbow 1999, Kost 1996, Karlsten 1997, Carter 1997
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Central Sensitization Excitatory neurotransmitters (e.g. glutamate,
substance P, neurokinin A or CGRP) stimulate the dorsal horn neurons
Repeated pain stimuli activate the NMDA receptors (“wind-up”), which induce prolonged postsynaptic action potentials
Activation of the NMDA receptors raises intracellular Ca++
Expression of c-fos and c-jun genes leading to increased protein synthesis
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Peripheral Sensitization
1° afferent nerve terminals (A-delta, C Fibers) hyperexcitability
Bradykinin, histamine, PG’s, cytokines, and substance P lower their action potential threshold
Mediators increase the gain of the inflammatory milieu
Spine 1997N. Harden 2015
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Hyperalgesia Increased pain from a stimulus that
normally provokes pain (IASP 2012)
Treatment:Topical lidocaine 2.5% / prilocaine 2.5%Gabapentin (Pain 2002)
IV Lidocaine (Neurology 2000)
Capsaicin (Scholten 2015)
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Allodynia Pain due to a stimulus that does not
normally provoke pain (IASP 2012) Treatment
Gabapentin (Eur Neurol 1998)
Pregabalin (J Pain 2008 )
Ketamine (Pain 1994)
IV Lidocaine (J Pain Symp Mgt 1999)
IV Morphine (Neurology 1991)Tramadol (Pain 1999)
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Shooting pain Pain that seems to travel like lightning from
one place to another Treatment:
Amitriptyline (Neurology 1987)
Carbamazepine (Campbell et al. 1966)
Gabapentin (Eur Neurol 1998)
Imipramine (Neurology 2003)
Lamotrigine (Pain 1997)
IV Phenytoin (Anesth Analg 1999)
Venlafaxine (Neurology 2003)
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TCA’s and Other Psych Med’s in NP
Help in NP due to Na+ channel blocking Risk of sedation and anticholinergic
effects
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Capsaicin Selective stimulator of C-fibers Cause Substance P release Depletes Substance P Apply 3-4 times/day for 4-8 weeks Capsaicin 8% relief may last 12 weeks Start with tramadol or lidocaine cream
(Pain Ther 2014)
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GABA, Pregabalin and NP
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Pregabalin Side Effects
Infection peripheral edema, Fatigue constipation, weight gain blurred vision ataxia, dizziness headache diplopia
Drowsiness tremor visual field loss xerostomia accidental injury
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Gabapentin and Opioids
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Gabapentin Increases the concentration of GABA in
the Brain Modifies Ca2+ currents Excreted 95% unchanged in the urine Good for NP No direct anti-nociceptive effect
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Gabapentin Side Effects
Sedation Fever Fatigue Ataxia Nystagmus Dizziness Drowsiness Weight gain due to increased apetite
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Ketamine
Amantadine and Dextromethorphan are effective for DMPN (Pain 1998, Neurology 1997)
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Herbal supplements Cannabis Plant Extract (AAPM&R 2015)
FMS NP RA Spasticity related pain
Side effects Dizziness Drowsiness Fatigue Legal issues
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Herbal supplements Alpha Lipoic Acid 600mg daily L-carnitine 1000mg daily Vitamin B complex Vitamin D once a week CoQ10---FMS—150-300mg daily (PMR Journal 2015)
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Non pharmacologic Tx PT OT Pain psychology Cognitive behavioral therapy Ergonomic evaluation Aqua therapy Work conditioning/hardening
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Interventional Pain Management Spinal Cord Stimulators Intercostal nerve blocks Peripheral nerve blocks Caudal Epidural injections Sphenopalatine Ganglion Blocks Radiofrequency Neurotomy Stellate Ganglion Blocks
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Conclusion The best management option is:
• Multimodal Therapy
Consider the patient’s comorbidities Listen to your patient complaints