Viruses – Post Herpetic Neuralgia
One of the most common complications of shingles is the development of Post Herpetic Neuralgia, which is a very common skin disorder that I encounter daily in my The Woodlands dermatology and Conroe dermatology offices. As the varicella zoster virus lays dormant in the dorsal root ganglion and travels along the nerves to cause an outbreak in a dermatomal pattern, nerve damage and destruction can occur with shingles. This can be a debilitating pain that is long lasting from months to years. The pain is described as neuropathic pain, which burns and feels like bolts of electricity. Allodynia is very common, which is pain due to normally innocuous stimuli such as wind blowing against the skin. The incidence of Post Herpetic Neuralgia increases in elderly patients and those with severe outbreaks of shingles. Patients over age 70 have a 75% chance of developing Post Herpetic Neuralgia. The most common areas of the body affected with shingles that develop Post Herpetic Neuralgia are the face (trigeminal nerve) and the arms (brachial nerve). The sooner a patient is initiated on antiviral medicines when an outbreak occurs, the less likely Post Herpetic Neuralgia will occur. Narcotics and topical anesthetics are usually ineffective in treating the pain of Post Herpetic Neuralgia. A lideocaine patch can provide some relief in patients and can be cut to fit the area of pain. Gabapentin should be initiated with the antiviral regimen when a patient is first diagnosed with shingles to decrease the likelihood of developing Post Herpetic Neuralgia. Gabapentin 300mg 3x/day for one month is the standard course and can be titrated to 900mg 3x/day. Lyrica 75mg 2x/day is another option, which has a similar mechanism to Gabapentin. If a patient continues to have pain, other medicines can be added to their regimen. Amitriptyline is a tricyclic antidepressant, which is effective in combination with Gabapentin for treating Post Herpetic Neuralgia. Oral steroids can also offer some benefit. In patients recalcitrant to medical therapy, a referral to a pain management specialist can be of benefit as nerve blocks can be performed.