13.1.2.2 Trigeminal post-herpetic neuralgia

Previously used term:

Post-herpetic trigeminal neuropathy.

Description:

Unilateral facial pain persisting or recurring for at least 3 months in the distribution(s) of one or more branches of the trigeminal nerve, with variable sensory changes, caused by herpes zoster.

Diagnostic criteria:
  1. Unilateral facial pain in the distribution(s) of a trigeminal nerve branch or branches, persisting or recurring for >3 months and fulfilling criterion C
  2. Herpes zoster has affected the same trigeminal nerve branch or branches
  3. Pain developed in temporal relation to the herpes zoster infection1
  4. Not better accounted for by another ICHD-3 diagnosis.
Note:

Usually, pain will have developed while the rash was still active, but on occasion later, after rash has healed. In such cases, pale or light purple scars may be present as sequelae of the herpetic eruption.

Comments:

Despite its long-preferred name, post-herpetic neuralgia is actually a neuropathy or neuronopathy: significant pathoanatomical changes have been shown in the nerve, ganglion and nerve root. In 13.1.2.2 Trigeminal post-herpetic neuralgia, there is also evidence of the inflammation extending into the trigeminal brainstem complex.

Following acute herpes zoster, post-herpetic neuralgia is more likely in the elderly.

The first division of the trigeminal nerve is most commonly affected in 13.1.2.2 Trigeminal post-herpetic neuralgia, but the second and third divisions can be involved also.

Typically the pain of post-herpetic neuralgia is burning and itching, the latter sometimes very prominent and extremely bothersome. Also typically, patients with postherpetic neuralgia show a clear sensory deficit and brush-evoked mechanical allodynia in the trigeminal distribution involved. Many patients however show little sensory loss, and instead demonstrate heightened responses to thermal and/or punctate stimuli.