Neuropathic Pain

From Anvita Health Wiki

Contents 1 More Specific Terms 2 Introduction 3 Etiology 4 Pathology 5 Clinical-manifestations 6 Diagnostic-procedures 7 Complications 8 Management 9 More General Terms 10 Additional Terms 11 References

More Specific Terms

• complex regional pain syndrome
• complex regional pain syndrome type 1; reflex sympathetic dystrophy; RSD; hand shoulder syndrome
• neuralgia

Introduction

• Pain that results from a disturbance of function or pathologic change in a nerve; in one nerve mononeuropathy; in several nerves, mononeuropathy multiplex; if diffuse & bilateral, polyneuropathy.

Etiology

• ( neuropathic pain syndromes):
• peripheral nervous system

• postherpetic neuralgia
• trigeminal neuralgia
• painful diabetic polyneuropathy
• post- amputation ( phantom limb pain)
• common in patients with peripheral neuropathy [9]

• central nervous system

• post- stroke pain (central pain)
• myelopathic/ radiculopathic pain

• multiple sclerosis
• spinal stenosis
• arachnoiditis
• root sleeve fibrosis

• sympathetic nervous system

• reflex sympathetic dystrophy
• causalgia ( complex regional pain syndromes)
• lumbosacral plexopathy

Pathology

• spontaneous & paroxysmal discharges of pain fibers

• injury to peripheral nerves
• nociceptive receptors become highly sensitive to mechanical stimulation

• loss of central inhibitory modulation

• spinal pain afferents may become spontaneously active if cut off from their normal input

• interaction of sympathetic nervous system with somatic afferent nociceptive receptors
• primary afferents may develop sensitivity to norepinephrine
• Na+ channel alpha subunit SCN10A may play a role

Clinical-manifestations

• pain is referred to body region innervated by damaged nerves
• sensory deficit is generally present in the area of the patient's pain
• qualities

• burning
• shooting
• stabbing
• paroxysmal
• vice-like
• electric- shock like

• paresthesias
• pain may be triggered by light touch
• pain is often severe & refractory to conventional pain management
• typically affects distal extremities
• often worse at night [9]

Diagnostic-procedures

• lidocaine test

Complications

• increased risk of suicide ( hazzard ratio = 1.4)

Management

• analgesia

• antidepressants

• tricyclic antidepressants (first line) [9]
• duloxetine (first line) [9]
• bupropion ( sustained-release) 150-300 mg QD [3]

• anticonvulsants

• valproic acid
• gabapentin (first line) [9]
• topiramate [5]
• carbamazepine
• phenytoin
• lamotrigine
• oxcarbazine
• tiagabine
• zonisamide
• levetiracetam

• combination of nortriptyline + gabapentin more effective than either agent alone [7]
• opiates (oral or parenteral)
• mexiletine
• clonazepam [5]
• lidocaine infusion when opiates are not effective
• botulinum toxin A injections may be effective [6]

More General Terms

• chronic pain
• chronic neurologic disease

Additional Terms

• gabapentin (Neurontin, Gralise)
• lidocaine test
• mexiletine (Mexitil)
• valproic acid; n-dipropylacetic acid (Depakene, Depakote, Divalproex, Mylproin, Valontin, Stavzor)

References

1. Pain Management, The American Medical Association, Overview of Physiology, Assessment & Treatment, 2003
2. Harrison's Principles of Internal Medicine, 14th ed. Fauci et al (eds), McGraw-Hill Inc. NY, 1998, pg 55
3. Journal Watch 22(1):10, 2002 Semenchunk et al, Neurology 57:1583, 2001
4. Harden RN, Houle TT, Remble TA, Lin W, Wang K, Saltz S. Topiramate for phantom limb pain: a time-series analysis. Pain Med. 2005 Sep-Oct;6(5):375-8. PMID: [1]
5. UpToDate 13.3 [2]
6. Yuan RY et al. Botulinum toxin for diabetic neuropathic pain: A randomized double-blind crossover trial. Neurology 2009 Apr 28; 72:1473. PMID: [3]
7. Gilron I et al, Nortriptyline and gabapentin, alone and in combination for neuropathic pain: a double-blind, randomised controlled crossover trial Lancet 2009 Oct 10; 374:1252. PMID: [4] doi:10.1016/S0140-6736(09)61081-3 [5]
   - Jensen TS and Finnerup NB Neuropathic pain treatment: a further step forward The Lancet, 30 September 2009 PMID: [6] doi:10.1016/S0140-6736(09)61205-8 [7]
8. Veterans Administration Memorandum Dec 24, 2009 Recent VHA Findings regarding chronic pain conditions and suicide risk
9. Medical Knowledge Self Assessment Program (MKSAP) 15, American College of Physicians, Philadelphia 2009
10. National Guideline Clearinghouse
    - EFNS guidelines on neuropathic pain assessment. European Federation of Neurological Societies ngc-guideline: [8]
    - EFNS guidelines on pharmacological treatment of neuropathic pain. (European Federation of Neurological Societies) ngc-guideline: [9]
    - EFNS guidelines on neurostimulation therapy for neuropathic pain. (European Federation of Neurological Societies) ngc-guideline: [10]
    - Pharmacologic management of neuropathic pain: evidence-based recommendations. ngc-guideline: [11]
    - The use of gabapentin and tricyclic antidepressants in the treatment of neuropathic pain in cancer patients: a clinical practice guideline. ngc-guideline: [12]
    - Spinal cord stimulation for chronic pain of neuropathic or ischaemic origin. National Institute of Health and Clinical Excellence (NICE) ngc-guideline: [13]
    - Neuropathic pain. The pharmacological management of neuropathic pain in adults in non-specialist settings. National Institute for Health and Clinical Excellence (NICE) ngc-guideline: [14]

neuropathic pain