II. Epidemiology
-
Incidence following Herpes Zoster
- Age over 80 years: 30%
- Age 60-65 years: 20%
- Age <50 years: Uncommon (only <20% of neuralgia cases are under age 50 years)
III. Pathophysiology
- Most common complication following Herpes Zoster infection
- Virus replication destroys Basal Ganglia
IV. Risk Factors
- Advanced age
- Female gender
- Severe prodrome or severe rash
- Severe acute pain with the acute zoster outbreak
- Prodromal pain prior to acute rash development
- Zoster Ophthalmicus
- Immunosuppression
- Diabetes Mellitus
- Systemic Lupus Erythematosus (SLE)
V. Symptoms
- Pain in Dermatomal Distribution persists >90 days after Herpes Zoster rash resolves
- Burning or electric-shock pain
- Hyperalgesia
- Allodynia
VI. Management: Topical
-
Lidocaine 5% patch (Xylocaine, or OTC 4% patch at $2/patch)
- Apply (up to 3 patches/day) to affected area for 12 hours of every 24 hours (must have 12 hours free)
- Expensive alternatives (e.g. ZTlido 1.8% at $9/patch), but unlikely to result in better efficacy
- (2018) presc lett 25(11): 66
- Evidence of benefit is marginal
-
Capsaicin cream (Zostrix) 0.075% cream
- Apply to affected area three to four times daily
- Also marginal evidence for use
VII. Management: Neuro-Psychiatric medications
-
General
- Amitriptyline more effective than Gabapentin, but adverse effects limits tricyclic use
- Gnann (2002) N Engl J Med 347:340 [PubMed]
-
Tricyclic Antidepressants
- Agents
- Efficacy
- As effective and better tolerated than Opioids
- Raja (2002) Neurology 59:1015-21 [PubMed]
- Serotonin-Norepinephrine Reuptake Inhibitors (SNRI)
- Anticonvulsants
- Gabapentin (Neurontin) titrate up to 600-1200 mg three times daily
- Pregabalin (Lyrica) titrate up to 200 mg three times daily
VIII. Management: Refractory Postherpetic Neuralgia
- See also Chronic Pain Management
- Transcutaneous Electric Nerve Stimulation (TENS)
- Biofeedback
- Nerve Block
- Opioid Analgesics
- Intrathecal Methylprednisolone 60 mg at L2-L3
- Good to excellent pain relief in refractory cases
- Relief persists longer than 2 years
- References
IX. Course
- Typical duration: 30 days to 6 months
- Some cases may persist years