Postherpetic neuralgia

A chronic pain condition following shingles

Postherpetic neuralgia
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Synonyms	PHN
Pronounce
Field	Neurology, Pain management
Symptoms	Burning, stabbing, or shooting pain that persists after resolution of shingles rash; sensitivity to touch (allodynia); numbness or itching
Complications	Chronic pain, depression, sleep disturbance, reduced quality of life
Onset	Typically begins after shingles rash resolves (weeks to months after initial infection)
Duration	Lifelong or prolonged in some cases
Types	Localized to the area affected by shingles, usually thoracic or trigeminal distribution
Causes	Nerve damage following varicella-zoster virus reactivation (herpes zoster)
Risks	Age >60 years, severe shingles rash, delayed treatment of shingles, immunosuppression
Diagnosis	Clinical history and symptoms following shingles; physical examination
Differential diagnosis	Diabetic neuropathy, trigeminal neuralgia, other causes of chronic nerve pain
Prevention	Shingles vaccine (e.g., Shingrix)
Treatment	Topical lidocaine, capsaicin cream, nerve blocks, cognitive behavioral therapy
Medication	Gabapentin, pregabalin, tricyclic antidepressants (e.g., amitriptyline), opioids (for severe cases)
Prognosis	Variable; may resolve over months or become chronic and debilitating
Frequency	Affects ~10–20% of people with shingles; risk increases with age
Deaths	Rare, usually due to complications like severe depression or suicide in extreme cases

Postherpetic neuralgia (PHN) is a chronic pain condition that occurs as a complication of herpes zoster, commonly known as shingles. It is characterized by persistent nerve pain in the area where the shingles rash appeared, even after the rash has healed. PHN is the most common long-term complication of shingles and can significantly affect a person's quality of life.

Pathophysiology

Postherpetic neuralgia results from damage to the nervous system caused by the varicella-zoster virus (VZV), the same virus that causes chickenpox. After a person recovers from chickenpox, the virus remains dormant in the dorsal root ganglia of the spinal cord. Years later, the virus can reactivate, leading to shingles. In some individuals, the nerve damage from the viral reactivation results in chronic pain, known as postherpetic neuralgia.

Symptoms

The primary symptom of postherpetic neuralgia is pain in the area where the shingles rash occurred. This pain can be described as burning, stabbing, or aching. Other symptoms may include:

• Allodynia: Pain from stimuli that do not normally provoke pain, such as light touch or temperature changes.
• Hyperalgesia: Increased sensitivity to painful stimuli.
• Itching or numbness in the affected area.

Risk Factors

Several factors increase the risk of developing postherpetic neuralgia, including:

• Age: Older adults are more likely to develop PHN.
• Severity of the shingles rash: A more severe rash increases the risk.
• Delay in antiviral treatment: Early treatment of shingles with antiviral medications can reduce the risk of PHN.

Diagnosis

Diagnosis of postherpetic neuralgia is primarily clinical, based on the patient's history of shingles and the presence of persistent pain in the affected area. A thorough medical history and physical examination are essential to rule out other causes of chronic pain.

Treatment

Treatment of postherpetic neuralgia focuses on pain management and improving quality of life. Options include:

• Anticonvulsants: Medications such as gabapentin and pregabalin can help reduce nerve pain.
• Antidepressants: Tricyclic antidepressants like amitriptyline may be effective in managing pain.
• Topical treatments: Lidocaine patches or capsaicin cream can provide localized pain relief.
• Opioids: In some cases, opioids may be prescribed for severe pain, but they are generally used with caution due to the risk of dependence.

Prevention

The most effective way to prevent postherpetic neuralgia is through vaccination. The shingles vaccine, such as Shingrix, is recommended for older adults to reduce the risk of developing shingles and its complications, including PHN.

Prognosis

The prognosis for individuals with postherpetic neuralgia varies. While some people experience a gradual reduction in pain over time, others may have persistent pain for months or even years. Early intervention and effective pain management strategies can improve outcomes.

Related pages

• Herpes zoster
• Varicella-zoster virus
• Chronic pain
• Neuropathic pain

External links

Classification	ICD-10: B02.2, G53.0 , G44.847 Mm ICD-9-CM: 053.19
External resources	MedlinePlus: 007423 eMedicine: neuro/317

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