48 herpes zoster and postherpetic neuralgia 49 phantom pain
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48. Herpes zoster and postherpetic neuralgia 49. Phantom pain. 마취통증의학과 R2 민진기. Herpes zoster and postherpetic neuralgia. Objective of this chapter overview of epidermiology, natural Hx, pathophysology, treatment, and prevention of herpes zoster and postherpetic neuralgia

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48. Herpes zoster and postherpetic neuralgia 49. Phantom pain

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48 herpes zoster and postherpetic neuralgia 49 phantom pain

48. Herpes zoster and postherpetic neuralgia49. Phantom pain

마취통증의학과

R2 민진기


Herpes zoster and postherpetic neuralgia

Herpes zoster and postherpetic neuralgia

Objective of this chapter

overview of epidermiology, natural Hx, pathophysology, treatment, and prevention of herpes zoster and postherpetic neuralgia

Herpes zoster- viral inf. that is accompanied by acute pain in majority of pts.

PHN- diagnosed when HZ pain persists


Herpes zoster epidermiology

Herpes zosterepidermiology

Reactivation of virus and its spread from single dorsal root or cranial nerve ganglion to corresponding dermatome and neural tissue of same segment

Annually in approximately 500,000 in USA

During lifetime of as much as 20~30%of population


Epidermiology

epidermiology

As many as 50% of those living until 85 years of age

Marked increase in incidence with aging

Also significantly increased in pts. with supressed cell-mediated immunity

Can be transmitted during vesicular phase of rash  primary inf. in seronegative individual


Natural history

Natural history

Prodrome bregins several days before rash onset

Thoracic dermatome- 50~70% of all case cranial, cervical, and lumbar- each 10~20%

Rash vesicle  crust healed: 2~4 weeks


Natural history1

Natural history

Acute pain gradually resolves before or shortly after rash healing in most case

Dermatomal pain without rash zoster sine herpete: finding of VZV DNA in CSF

Neurological disorder- motor neropathy, cranial polyneritis, transverse myelitis, cerebral angiitis, storoke after ophalmic zoster

Ophthalmological Cx- 2~6%: keratitis, uveitis, iridocyclitis, panophthalmitis and glaucoma


Treatment

Treatment

Acyclovir, famciclovir, and valacyclovir- inhibit viral replication, reduce duration of viral shedding, hasten rash healing, decrease severity and duration of acute pain

Most important Cx- chronic pain( can be refractory)

:prevention of PHN important clinical goal

Inhibit viral replication limit degree of neural damage PNH 가능성 줄어듬


Treatment1

treatment

Antiviral Tx in HZ significantly reduce risk of prolonged pain but not prevent PHN in all pts.


Treatment2

treatment

Supplemently

Corticosteroid

Tricyclic antidepressant

Nerve block

Combinig antiviral therapy with effective relief of acute pain in pts. with HZ will further lessen the risk of PHN


Prevention

prevention

A live, attenuate varicella vaccine- effective in protecting against varicella and its complications

Incidence of varicella- substantially reduced in regions where vaccine is accepted


Post herpetic neuralgia epidemiology and natural history

Post herpetic neuralgiaepidemiology and natural history

Definition- variable: from any pain persisting after rash healing to pain that has persisted at least 6 months after rash onset


Epidemiology and natural history

Epidemiology and natural history

Herpes zoster- sharp, stabbing pain

PHN- burning pain

Risk factor of PHN

old age(well estabilished)

pts. with more severe acute pain

pts. with painful prodrome

greater severity and duration of HZ rash


Epidemiology and natural history1

Epidemiology and natural history

Other putative risk factor of PHN

greater sensory abn. in affected dermatome

generalized subclinical sensory deficits

diabetes

more pronounced cell-mediated and humoral immune response

MRI brain stem and cervical cord abn.

EMG motor abn., psychological distress, fever


Pathophysiology

pathophysiology

Greater neural damage more development of PHN

Post-mortem study,

dorsal horn atropy and pathological change on affected side, not on un affected side,also not in pts. with history of HZ whose pain did not persist


Treatment3

treatment

1) Tricyclic antidepressants

2) Gabapentin

3) Lidocaine patch 5%

4) Tramadol

5) Opioid analgesics

2), 3), 4)- first line treatments

1), 5)- second line treatments: greater caution in often elderly with PHN


Gabapentin

gabapentin

Second-generation antiepileptic drug

Side effect- somnolence, dizziness and mild peripheral edema

gait and balance problem, cognitive impairment in elderly

To reduce side effect and increase pts. compliance, should be initiated low dosage


Tramadol

tramadol

Norepinephrine and serotonin reuptake inhibitor with major metabolites that is mu-opioid agonist

Increased risk of seizure in pts. treated with tramadol

Serotinin syndrome may occur with SSRIs and MAO inhibitors

To decreased likelihood of side effect, should be initiated at low dosage


48 herpes zoster and postherpetic neuralgia 49 phantom pain

TCAs

Reduce pain in diabetic neuropathy and postherpetic neuralgia

Amitriptyline- clinically most widely used TCAs

Despite efficacy of TCAs in treatment of PHN, cardiac toxicity and side effect profile reguire caution in elderly

Side effect- dry mouth(m/c), constipation, sweating, diziness, disturbed vision, and drowsiness


Beyond first and second line treatment

Beyond first and second-line treatment

Sympathetic nerve block- temporary pain relief but typically do not provide longer-lasting benefits

Intrathecal administration of methylprednisolone

Spinal cord stimulation

demonstrated long-term benefits in 82%

Conclusion: comprehensive treatment approach


Key points

Key points

  • HZ (shingles)- reactivation of VZV which establishes latency in sensory ganglia after primary infection (chicken pox)

  • Vesicular rash heals within 2~4 weeks and is accompanied by pain in majority in pts.

  • Older age- increased risk due to age associated decline in VZV specific cell mediated imminity

  • Antiviral Tx inhibit viral replication, reduce duration of viral shedding, hasten rash healing, decrease duration of pain


Key points1

Key points

  • Peripheral, sympathetic, and epidural nerve block appear to relieve acute pain in HZ, but their role in PHN is uncertain

  • PHN- pain that continues after healing of rash. can last for years

  • Risk factor of PHN- older age, more intense acute pain, more severe rash, prodrome before rash

  • Qualitatively different type of pain that characterize PHN have different underlying mechanism


Phantom pain

Phantom pain

Amputation of limb painful and nonpainful sequelae such as phantom sensation, telescoping, stump pain and phantom pain

Postamputation pain delay rehabilitation, limit use of prosthetic devices, and profound influence on quality of life of amputee


Phantom sensation

Phantom sensation

Nonpainful sensation perceived as emanating from missing body part

Common after surgery with 90% during first 6 months after surgery

Excision of other body part( tongue, bladder, rectum, breast, and genitalia) may also present with phantom sensation


Phantom sensation1

Phantom sensation

Kinetic sensation- perception of movements in amputated body region (flexion and extension of toes)

Kinesthetic perception- distorted representation in size or position of missing part (perception that hand of foot is twisted)

Extroceptive perception- paresthesia, tingling, touch, pressure, itching, heat, cold, wetness


Phantom sensation2

Phantom sensation

Complete paraplegic and quadriplegic pts. also have phantom sensation

Commonly experienced in distal portion of limb (hand and feet)- possibly due to rich innervation of these region and large cortical representation of these region


Telescoping

telescoping

Perception of progressive shortening of phantom body part resulting in sensation that distal part of limb is becoming more proximal

Feel a hand close to stump, but not forearm of distal arm

Occur in two-thirds of limb amputees


Phantom pain1

Phantom pain

Perception of painful, unpleasant sensation in distribution of missing or deafferented body part

Occur in two-thirds of post amputation pts. in first 6 months after surgery

Extereoceptive like pain (knifelike or sticking) proprioceptive type of pain (squeezing and burning)


Phantom pain2

Phantom pain

Frequecy, duration, and severity decrease during first 6 months and did not change significantly

One factor that increase incidence of phantom pain- pain in limb before amputation


Stump pain

Stump pain

Pain localized to residual body part

Incidence of stump pain more than 2 years after amputation- about 20%

Usually secondary to local pathologic process such as inf., lesion of skin, soft tissue, or, bone, or local ischmia


Theoletical mechanism

Theoletical mechanism


Treatment stump pain

Treatmentstump pain

First step- to identify specific etiology for pain

Examined for localized tender spot (neuroma), ulcer, bony abn.,evidence of ischemia, recurrence in case of malignancy

TENS- beneficial in 25~50% of pts.


Stump pain1

stump pain

Pain by somatic mechanism: NSAIDs, COX-2 antgonist, and/or opioids

Pain by neuropathic mechanism: TCAs, anticonvulsants

Specific rectifiable pathology-protruding bone, bony exostosis, wound inf., poorly healed wounds surgical treatment


Phantom pain treatment

Phantom pain treatment

Education, and counseling of pts. on consequences of amputation, rehabilitation process, prosthetic option

Preemptive epidural or peripheral nerve block

Wide variety of medication- opioid, calcitonin, ketamine

Physical therapy

Psychological intervention

Neurostimulation

Ablative procedure


48 herpes zoster and postherpetic neuralgia 49 phantom pain

Flow rates are for gravity flow of one unit of packed cells diluted with 250 mL normal saline passing through catheters of equal length.

Hagen-Poisseuille equation에 따르면 flow rate는 압력의 변화와 r의 4제곱에 비례하며 점성이나 line의 길이에는 반비례한다.


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