By Adam Shuster, DO Pain Management Consultants of SWFL –
Shingles is one of the most common neuropathic pain syndromes affecting adults in the United States. Roughly 20% of the population will experience shingles in their lifetime. Shingles is cause by a viral infection (Herpes Zoster). Usually, pain may start five to seven days prior to eruption of a rash. The typical pain produced by shingles is neuropathic in nature.
That means the pain involves the nervous system, usually the dorsal root ganglion, but may also affect other nerves as well. Shingles pain is usually described as burning, lancinating, itching, and can be accompanied by numbness or a tingling sensation. The most commonly affected area involves the thoracic dermatomes, but can also affect the 5th cranial nerve, also known as the trigeminal nerve. The rash and painful symptoms tend to occur in the distribution of the affected spinal nerve.
Herpes is hallmarked by its unilateral presentation, rash, and painful symptoms. The acute herpes infection is a result of an inflammatory reaction at the dorsal root ganglia and peripheral nerves. Early treatment (within 72 hrs) with an antiviral medication such as Acyclovir, can not only shorten the course of shingles and decrease painful episodes during the acute infection, but it also decreases the chances of developing postherpetic neuralgia.
Postherpetic neuralgia is classified as a patient having herpetic pain which continues 3-4 months after the rash has disappeared. It is more common in the elderly and approximately 50% of adults aged over 70 are at risk for developing postherpetic neuralgia.
There are many treatments for postherpetic neuralgia. Injections such as a thoracic or lumbar epidural steroid injection can be helpful. There are a variety of medications which can be used as well. Narcotics may be helpful in the acute setting, but are often paired with antidepressants or anticonvulsants, as narcotics alone may be inadequate to control pain.
Antidepressants and anticonvulsants are used to decrease symptoms involving pain, burning, numbness, or tingling. Lidocaine ointment, or a lidocaine patch (Lidoderm) may be applied to the affected area. This is a very safe and often helpful treatment. For postherpetic neuralgia, a newer medication called Qutenza can be topically applied and can offer pain relief for months at a time.