What is it?

Postherpetic neuralgia is the most common chronic complication of herpes zoster. It is a neuropathic pain caused by damage to sensory nerves during varicella-zoster virus infection.

How often does it occur?

About 20% of patients with herpes zoster report pain still present after 3 months, and 15% have persistent pain after 2 years from onset.
The risk increases with age: from 8% in patients aged 50-54 years to 21% between 80-84 years.

Typical Symptoms

• Continuous burning pain
• Paroxysmal shocks
• Allodynia (pain from just light touch of the skin)
• Itching or hypoesthesia in the affected skin area (dermatome)

Diagnosis

• History of herpes zoster + pain persisting for ≥90 days
• Clinical neurological evaluation
• No specific diagnostic tests required

Treatments

Topical Treatment

• Lidocaine 5% patches
• High-concentration capsaicin patch (8%)

Systemic Treatment

• Tricyclic antidepressants (amitriptyline, nortriptyline)
• Gabapentin or pregabalin
• Opioids (only in refractory cases and under close supervision)

Neurostimulation

When local treatments or medications are not enough, neuromodulation can be considered, a technique that uses electrical impulses to “calm” pain signals:

• Transcutaneous electrical nerve stimulation (TENS)
  A portable device that sends small electrical impulses through the skin.
  It can help reduce pain without medication.
• Spinal cord stimulation (SCS)
  A minimally invasive procedure indicated in some cases resistant to medications.
  A small electrode is implanted near the spinal cord to block pain.

Interventional Therapies

Not routinely recommended: insufficient evidence for sympathetic blocks or intrathecal injections.

Prevention

Herpes zoster vaccination is the only effective way to prevent postherpetic neuralgia.
It reduces the incidence of zoster by 51% and PHN by 66%.