Postherpetic Neuralgia Overview

Herpes zoster (shingles) is considered to be one of the most painful common medical conditions. But approximately 1 in 6 patients with shingles end up experiencing a new and enduring level of pain when they develop postherpetic neuralgia (PHN).

The condition is defined as recurring or persistent long-term nerve pain in an area of the body that has suffered an outbreak of shingles, which is caused by the varicella zoster virus (VZV). The virus initially causes chickenpox in an individual, then goes dormant in their dorsal root ganglia for decades. When it reactivates, it moves to the skin to resurface as a blistering rash, damaging the sensory nerves that register pain and pressure along the way.

PHN is the result of that nerve damage, and the most common chronic complication of shingles. Its onset typically begins after the shingles blisters crust over and start to heal, but it can also occur in individuals with no rash. The dermatomal pain associated with PHN lasts at least 90 days after the appearance of the shingles rash, but can extend unremittingly for months or years.

Statistics show that approximately 1 out of every 3 people in the United States will develop shingles in their lifetime, or an estimated 1 million cases each year. The CDC notes that between 10% and 18% of them will experience PHN, and that the risk increases with age.¹

“An older adult with shingles is more likely to develop PHN and have longer lasting and more severe pain than a younger person with shingles. People younger than 40 rarely experience PHN,” according to the CDC.¹ 

DelveInsight's "Postherpetic Neuralgia - Market Insights, Epidemiology, and Market Forecast-2030" reports on PHN epidemiology in 7 major countries, including the United States. It observes that people over the age of 60 have about a 60% chance of developing PHN after having shingles. That number rises to 75% for individuals who are 70 or older.2

The level of pain associated with PHN is reflected by the types of treatments that are used. It typically requires an individualized, multi-pronged approach using a combination of options.

Transdermal patches containing lidocaine or capsaicin can be applied directly to the affected area of skin for temporary pain relief. Anticonvulsants like gabapentin and pregabalin are used to stabilize abnormal electrical activity caused by injured nerves. The antidepressants nortriptyline, amitriptyline, duloxetine, and venlafaxine target key brain chemicals that determine how the body interprets pain. Opioid painkillers—including tramadol, oxycodone, and morphine—can also be prescribed in low doses if closely monitored. 

The only way to avoid both shingles and PHN is through vaccination. Shingrix has been approved by the FDA for adults 50 years and older. It also received a preferred recommendation from the CDC’s Advisory Committee on Immunization Practices for the prevention of shingles and related complications.

Shingrix has an efficacy rate of over 90% in clinical tests, far surpassing that of the only other shingles vaccine on the market, Zostavax. It also has been shown to induce persistent immune responses in older adults who are at greatest risk.

References

1. CDC. Shingles (Herpes Zoster). Complications of Shingles. Page last reviewed July 1, 2019. Accessed July 6, 2020. https://www.cdc.gov/shingles/about/complications.html.

2. Postherpetic Neuralgia Market Size & Share, Epidemiology and Forecast till 2030. Press Release. DelveInsight. Accessed July 6, 2020. http://www.digitaljournal.com/pr/4653939.