Herpes Zoster and PHN

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Herpes Zoster and PHN
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Herpes Zoster

• Historic Aspect
• Incidence
• Pathology
• Clinical manifestion
• Different diagnosis
• Therapy

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Historic Aspect

• Herpes Zoster(shingles) is an acute infectious
  disease caused by herpes zoster virus belonging
  to the DNA group of viruses.
  
• It primarily affects the posterior spinal root
  ganglion of the spinal nerves.
  
• Greek language herpes means to chronic
  cutaneous diseases , zoster means a belt.
  
• Herpes zoster describes the girdle-like vesicular
  eruption of the disease in the trunk.

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Incidence

• Overall incidence of HZ 131 per 100,000
  person-years.
  
• No gender difference.
• Directly related to age 75 years and older
  younger than 14 years-tenfold
  
• Dermatomes thoracic dermatomes and the opthalmic
  division of the trigeminal nerve.
  
• More common and severe in immunosuppressed
  patients(Lymphoma, chronic lymphocytic leukemia,
  radiation therapy, chemotherapy, lupus
  erythematosus.)
• A small percentage of patients(5) have a
  recurrence of HZ.-same dermatome.
  

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Pathology

• The virus that causes varicella gains to the
  sensory nerves in skin and passes to the dorsal
  ganglion cell in which it lies dormant.
  
• Latent virus becomes reactivated often immune
  mechanisms are impaired.
  
• An intense necrotizing reaction is seen in the
  dorsal root ganglia, peripheral nerves, dorsal
  horn of the spinal cord.

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Clinical Consideration

• Symptoms and Signs
• Differential Diagnosis
• Immunologic response
• Therapy
• complication
• Conclusion

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Symptoms and Sign 1

• Commences with pain,paresthesia,and dysesthesia
  in the afflicted dermatome,followed in a few
  days(4-5days) by vesicular eruption.
  
• At first the pain is mild but may increase in
  intensity over the succeeding days.
  
• Pain sharp, shooting,dull,aching,burning
• Systemic symptoms(5)
• ( fever,malaise,headache, nausea,stiff
  neck,regional or diffuse adenopathy)
  
• Localized erythema and swelling,red
  papules,vesicles,blebs, pustules,crust,(2-3wk)
  
• Erythema , bleb, sharp pain resolve during 3rd
  wks.
  
• Scales of the encrusting blebs begin to fall off
  leaving irregular pink scar (5th wks)
  
• Older patients are more severe pain in the acute
  stage than younger patients.
  

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Symptoms and Sign 2

• Ophthalmic zoster
• Opthalmic division of the trigeminal nerve
• Ramsay Hunt syndrome
• Varicella Zoster of the geniculate ganglion.
• 7th cranial nerve involve-unilateral facial
  paralysis
  
• Sacral Zoster(S2, S3, S4 dermatomes)
• Neurogenic bladder with urinary hesitancy or
  retention.

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Opthalmic Zoster

• First branch of the Fifth nerve(V1)

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Dermatomes
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Mandibular branch of the Fifth nerve(V3)
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Third cervical nerve(C3)
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Thoracic 4th nerve(T4)
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Thoracic 4th nerve(T4)
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Thoracic 6th nerve(T6)
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Thoracic 10th nerve(T10)
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The 3rd lumbar nerve(L3)
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Closeup view of lesion
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On the back thoracic nerve
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On the back thoracic nerve
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Fingers digital nerves
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Disseminated Herpes
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Differential diagnosis

• Herpes simplex
• Poison ivy
• Zoster sine herpete
• painful disease can occur without cutaneous
  vesicles
  
• Cellulitis

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Immunologic response
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Goals of therapy

• Abort segmental infection
• Prevent viral spread beyond the primary unit
• Prevent tissue injury(cytolysis)
• Prevent postherpetic neuralgia

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Therapy

• 1) Nerve Blocks
• 2) Antiviral agents
• 2) Antiinflammatory agents
• 3) Systemic analgesics and ajuvant
• agents
• 4) Miscellaneous techniques

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Nerve block

• Local anesthetic infiltration-skin lesion
  healing, PHN-incidence severity-reducing
  
• Peripheral sympathetic nerve block
• restoration of intraneural bl flow,
  preservation of large fibers
  
• Reducing the development ofPHN

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Antiviral Agents

• Acyclovir 800mg five times a day
• Valacyclovir 1g three times a day
• Famciclovir 500mg three times a day
• Decrease pain
• Hasten healing of the rash
• Reduce the duration of PHN
• Act to competitively inhibit DNA polymerase,
  terminating DNA synthesis and viral replication
  

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corticosteroid

• Pain relief in the acute phase
• Shorten the time to fall crusting of lesions
• Frequantly used prior to the development of
  antiviral agents
  
• Adverse events-not recommend

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Systemic analgesic and ajuvant agents

• Acetaminophen,NSAID,Opioid
• Low dose tricyclic antidepressant
  therapy(amitriptyline 10-25mg po before bedtime)

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Complication

• Neuralgia
• Facial or oculomotor palsy
• Paralysis of motor nerves
• Myelitis
• Meningoencephalitis
• Postherpetic Neuralgia
• Systemic toxicity-dissemination
• Fever,Chills,
• Bacterial sepsis,
• Varicella pnumonias

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Postherpetic neuralgia

• Pain persisting beyond the crusting of lesions or
  beyond 4wks, 6wks, 2mons, or 6mons.
  
• Similar to herpes zoster neuralgia
• Burning, aching, itching,
• severe paroxysm of stabbing or burning pain
• Allodynia-87 of PHN
• Hyperesthesia, dysesthesia, anesthesia

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Therapy of PHN

• Antidepressant
• Neuroleptics
• Anticonvulsants
• Opioids
• Topical agents
• Nerve blocks
• Tens
• Acupuncture

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Nerve block

• Local infiltration
• Somatic nerve block
• Sympathetic nerve block
• Epidural block
• Neurolytic block

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Local infiltration

• EpsteinSQ infiltration(steroid)-64 pain relief
• Tio,Moya,Verasan,-SQ infiltration of 0.25
  bupivacaine 0.2 triamcinolone alone 70
  improve

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Somatic nerve block

• Sensory nerve blocks are in early attempts to
  relieve its pain.success in managing pain in
  early stages of the disease-results are limited.
  
• Nerve blocks are primarily used in postherpetic
  neuralgia for diagnosis and prognosis,esp as a
  prognostic block before neurolytic block.
  
• Steroid injected around the dorsal nerve block.
  Steroids injected around the dorsal nerve have
  had unpredictable and limited success.

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Sympathetic nerve block

• Bonica reported good temporary-0.2pucaine(somati
  c sympathetic block)-4days interval-PHN(under
  2month)-best result.
  
• Colding-concluded that sympathetic blocks for
  established PHN were no value.

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Miscellous therapy of PHN

• acupuncture

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Conclusion

• Prompt tx shortens the progressive course and
  decreases severity
  
• Correlation between the age of the patient and
  the response to therapy
  
• Older patients do not respond to therapy and
  specifically to sympathetic nerve blocks.
  
• 40 of patients remain totally refractory or
  unsatisfactorily relieved.
  
• 50(approx) of patients improve over the years
  one-half of these are receiving no tx
  
• Strategies to prevent the onset of HZ in addition
  to the attempt to prevent the onset of PHN after
  the onset of HZ