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%.