management of post herpatic neuralgia,,,, pain management

1. HERPES ZOSTER & P.H.N
Dr. Ravi Shankar Sharma
DARADIA

2. INTRODUCTION
• Viral infection caused by the reactivation of the
varicella-zoster virus (VZV).
• Primary varicella infection - chicken pox.
• Neuronal destruction and inflammation pain
interference with daily activities
• Does not cross midline
• Immunocompetent  single dermatome affected
Immunocompromised  multiple dermatomes/
visceral dissemination / cutaneous dissemination

5. ETIOPATHOGENESIS
•Neurogenic
inflammation
•Haemorrhagic
necrosis
•Neuronal loss
& scarring
Primary VZV infection ( chicken pox )
virus remains dormant in DRG & cranial N nuclei
CMI for VZV decreases with age
VIRAL REPLICATION in DRG

6. Anti dromic conduction of virus to dermo
epidermal junction via cutaneous nerves
•Demyelination
•Increase in the electrical
activity of peripheral
nociceptors
Inflammation and tissue
necrosis leading to rash
PERIPHERAL NERVES
SKIN

7. Pathophysiology PHN

8. PHASES
• Prodrome
• Rash
• Pain

9. PRODROME
• Precedes the appearance of rash by 3 – 7
days
• Result of viral replication and inflammation
• Flu like symptoms malaise, fatigue,
headache, fever, neck stiffness
• U/L dermatomal pain / altered sensation /
pruritis

10. RASH
Maculopapular rash
7
days
2–3weeks

11. PAIN
• It can precede or accompany the rash
• Burning / throbbing / stabbing / electric shock
like pain which may be constant or intermitent
• Associated with hyperaesthesia and allodynia
• Interfere with sleep, physical and emotional
functioning

12. DERMATOMAL DISTRIBUTION
• Thoracic – upto 50%
• Cranial – 10 – 20 %
• Cervical -- 10 – 20 %
• Lumbar – 10 – 20 %
• Sacral – 2 – 8 %
• Generalised - < 1 %

13. CLINICAL VARIANTS
• Herpes zoster ophthalmicus – ophthalmic
division of trigeminal nerve
• Herpes zoster oticus – VII cranial nerve
• Zoster sine herpete – dermatomal pain
without rash

14. LAB DIAGNOSIS
• VIRAL CULTURE: (1 to 2 weeks)
• DIRECT IMMUNOFLOUROSCENCE : ( 3 hours)
• VIRAL DNA TESTING(PCR): ( 1 day )
100 %sensitivity in old crusted lesions
• BIOPSY: reserved for difficult to diagnose cases.
- ballooning degeneration
- acantholysis of keratinocytes
- leukoclastocytic vasculitis

15. DIFFERENTIAL DIAGNOSIS
• Coronary artery disease,
• Pleurodynia
• Costochondritis (Tietze’s syndrome)
• Pericarditis,
• Cholecystitis
• Acute abdominal diseases.
• Disc diseases.
• Nerve diseases and Myofascial pain.

16. TREATMENT
Objectives :
• Reduction of severity and duration of the pain.
• To limit viral replication.
• Recovery of epidermal defects and prevention
of secondary infections.
• Reduction or prevention of PHN.

17. TREATMENT – ACUTE HERPES ZOSTER
CONSERVATIVE MANAGEMENT
• Patient education
- avoid contact with individuals who are sero
negative for VZV
- keep rash clean and free of adhesive
dressings to prevent secondary infections

18. ANTI VIRAL THERAPY:
- Inhibit viral DNA polymerase and hence its
replication
- must be given to all herpes zoster patients
- beneficial when given within 72 hrs of onset of
rash
Those who benefit even > 72 hrs :
- ophthalmic zoster
- immunocompromised
- neurological damage

19. Benefits of antiviral therapy
• Inhibition of viral replication
• Reduce duration of viral shedding
• Hastens rash healing
• Decrease the degree of neural damage
• Decrease the severity and duration of acute pain
• Decrease duration of PHN
• Decrease incidence of PHN

21. CONSERVATIVE MANAGEMENT contd
• ANALGESICS:
- mild pain – NSAIDS / acetaminophen / weak
opioids
- moderate pain – strong opioids ( effective in
reducing pain )
• CO ANALGESICS: gabapentin , pregabalin , TCA’S may
be used

22. CONSERVATIVE MANAGEMENT contd
• CORTICOSTEROIDS:
- reduce inflammatory features of acute zoster
- possibly prevent injury to affected neurons
- effective when used in combination with antivirals
- no effect on the healing of rash
- no effect on the occurrence of PHN

23. INTERVENTIONS
• Single shot epidural with local anaesthetic + STEROID
(level B evidence)
• Continuous epidural with LA
• Paravertebral blocks
• Sympathetic blocks
• SCS

25. PREVENTION
• VZV vaccination for children
• VZIG – for immunocompromised seronegative
patients who are exposed to chicken pox /
herpes zoster
• Herpes zoster vaccination for adults

26. POST HERPETIC NEURALGIA

27. INTRODUCTION
• POST HERPETIC NEURALGIA : dermatomal
pain persistent > 120 days after the onset of
rash
• PHN risk factors:
- age > 50 yrs
- painful prodrome
- severe acute pain / rash

28. PATHOPHYSIOLOGY
VIRAL REPLICATION 
NEURAL DAMAGE AND
INFLAMMATION
(GANGLIONITIS)
SENSITIZATION
PERIPHERAL C FIBRES
 burning,
hyperalgesia, allodynia
CENTRAL  involves
NMDA R & Glutamate
R / EPHAPTIC
conduction
DEAFFERENTIATION
Loss of large and small
diameter fibers
Ectopic discharges
Collateral sproutings

29. CLINICAL FEATURES
• sharp shooting, electric shock like pain
- continuous burning / throbbing pain
• tactile allodynia ( most deblitating )
- hyperalgesia
• Musculoskeletal pain
• Sensory abnormalities :
- hypoaesthesia, altered temperature sensation,
paraesthesia, dysaesthesia, chronic pruritis

31. DIAGNOSIS OF PHN
• h/o rash f/b dermatological pain
• h/o rash  12 months pain free  dermatomal
pain
• Lab diagnosis :
- quantitative sensory testing
- skin biopsy
- NCV

32. TREATMENT
OBJECTIVES :
• To alleviate pain
• To Improve quality of life

33. CONSERVATIVE MANAGEMENT
• ANTICONVULSANTS:
- Gabapentin : alpha 2 delta L type voltage gated
Ca++ channel blocker
- start with 300mg / day (max dose upto 3600mg /
day )
- Pregabalin : alpha 2 delta L type voltage gated
Ca++ channel blocker
- start with 150 mg / day ( max upto 600 mg/day)
- better tolerated

34. CONSERVATIVE MANAGEMENT contd
• ANTI DEPRESSANTS:
- TCA’s : amitryptyline / nortryptyline
• Provides moderate to excellent pain relief .
(used esp in those suffering with insomnia)
desipramine – less sedating
- SNRI’s : not FDA approved
duloxetine is still used

35. CONSERVATIVE MANAGEMENT contd
• OPIOIDS: Tramadol & Oxycodone useful
CLINICAL RECOMMENDATIONS:
• Use lowest effective dose
• Initiate with short acting opioids
• Convert to long acting
• Proactively combat nausea and constipation

37. INTERVENTIONAL MANAGEMENT
• SYMPATHETIC NERVE BLOCKS :
- Good evidence
- it reduces sympathetically mediated neuronalinflammation
• SPINAL CORD STIMULATION : good evidence
• POOR EVIDENCE :
- Continuous epidural for one week
- intercostal N block
- transforaminal DRG
- intra thecal opioids
• PRF leisoning
• Narrow band UVB

38. PREVENTION OF PHN
• Vaccination
• Anti viral therapy
• Pharmacotherapy – alleviate pain
• Sympathetic blocks

39. PREVENTION OF PHN
• Vaccination
• Early antiviral therapy
• Early treatment of neuropathic pain

40. Thank YOU