Herpes Zoster & Post Herpetic Neuralgia- For the Pain Boards & your Patients!

In this episode of the Pain Exam Podcast, Dr. David Rosenblum provides a comprehensive review of herpes zoster and postherpetic neuralgia (PHN), focusing on pathophysiology, diagnosis, and treatment options. Dr. Rosenblum explains that postherpetic neuralgia affects approximately 25% of patients with acute herpes zoster, causing debilitating unilateral chronic pain in one or more dermatomes. He discusses the three phases of herpes zoster: acute (up to 30 days), subacute (up to 3 months), and postherpetic neuralgia (pain continuing beyond 3 months). Dr. Rosenblum identifies risk factors for developing PHN, including older age, female sex, immunosuppression, prodromal pain, severe rash, and greater acute pain severity. He details the pathophysiology involving peripheral and central sensitization, and explains different phenotypes of PHN that can guide treatment approaches. For treatment, Dr. Rosenblum reviews various options including antiviral medications (which should be started within 72 hours of onset), corticosteroids, opioids, antidepressants (particularly tricyclics and SNRIs), antiepileptics (gabapentin and pregabalin), topical agents (lidocaine and capsaicin), and interventional procedures such as epidural injections and pulsed radiofrequency. He emphasizes that prevention through vaccination with Shingrix is highly effective, with 97% effectiveness in preventing herpes zoster in patients 50-69 years old and 89% effectiveness in those over 70. Dr. Rosenblum mentions that he's currently treating a patient with trigeminal postherpetic neuralgia and is considering a topical sphenopalatine ganglion block as a minimally invasive intervention before attempting more invasive procedures.