Postherpetic neuralgia
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Synopsis
Herpes zoster infection can occur from reactivation of the herpes varicella-zoster virus or from primary infection. In two-thirds of adults, reactivation is characterized by severe pain and paresthesias in a dermatomal distribution, followed 1-2 weeks later by the appearance of a vesicular rash. The thoracic, cervical, and trigeminal dermatomes are most commonly involved. Approximately 25% of patients have residual neuropathic pain lasting greater than 4 months following resolution of the rash, a condition known as postherpetic neuralgia (PHN).The risk of developing PHN increases with age. In patients with persistent pain following rash resolution, pain and temperature sensation are hyper-acute, leading to severe pain even with light touch (allodynia) or episodes of unpredictable shooting or stabbing pain. PHN is a clinical diagnosis. Neuralgiform symptoms can persist from weeks to a lifetime.
Related topics: varicella, disseminated herpes zoster
Codes
ICD10CM:B02.29 – Other postherpetic nervous system involvement
SNOMEDCT:
2177002 – Postherpetic neuralgia
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Differential Diagnosis & Pitfalls
- Trigeminal neuralgia
- Migraine headache
- Cluster headache
- SUNCT (short-lasting unilateral neuralgiform headache with conjunctival injection and tearing)
- Paroxysmal hemicranias
- Peripheral neuropathy (eg, diabetic neuropathy, drug-induced neuropathy, lateral femoral cutaneous neuropathy)
- Mononeuritis multiplex
- Nerve tumor (eg, schwannoma)
- Traumatic nerve injury
- Contact dermatitis (allergic, irritant), eczema, or skin irritation
- Radiculitis (see radiculomyelitis)
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Last Reviewed:07/30/2018
Last Updated:04/11/2021
Last Updated:04/11/2021