Herpes Zoster & HPN
Herpes Zoster, Post Herpetic Neuralgia, and Zoster Vaccine Live
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‘Prevention is worth a pound of cure” is particularly true for older adults who are at risk for developing post herpetic neuralgia (PHN) and herpes zoster (HZV). PHN is the post sequelae that can occur in people who have had a previous bout of herpes zoster, also known as shingles. HZV is an infection attributable to the human herpes virus-3, also known as the varicella zoster virus. The varicella zoster virus lives dormant within trigeminal, dorsal root, or geniculate nerve ganglia, of those who have previously had chicken pox. Once reactivated within the patient’s body, HZV can ensue.
About of HZV typically runs its course over two to four weeks. It often begins with a prodrome of burning pain, pruritis, and tingling sensation. Next, a maculopapular rash can develop, along a unilateral dermatome, that evolves into draining vesicles, which eventually crust over and heal. Nerve fibers affected and damaged by this virus, however, can become dysfunctional, propagating inappropriate pain signals to the brain that can remain for at least three months or longer, even after the lesions have resolved.
This resultant complication, PHN, is experienced by approximately twenty percent of people who have encountered HZV. These particular patients tend to be those who are immunosuppressed such as diabetics, those with certain cancers, those who chronically use corticosteroids, and those receiving radiation or chemotherapy. HZV affecting the eye can be a risk factor for PHN, as well. Additionally, the patients tend to be older. This is most likely due to the reduction of cell mediated immunity as people age. It has been noted that incidence of HZV and PHN strongly increases in people as they age. In fact, thirty percent of people aged fifty five and over have experienced HZV, while those sixty years old and beyond have up to a fifty percent chance of developing PHN. A stressor, in the patient’s life, can often be a precipitating factor that will cause the virus to reactivate.
The pain of PHN although occasionally mild, is more often severe, described as sharp and stabbing or achy and deep in nature. Less often, the discomfort may continue to feel pruritic or as a tingling or numb sensation. It may be aggravated by something as simple as clothing touching the affected area or even unpleasant stimuli. Although, for some, PHN can be a self-limiting acute complication, resolving within weeks, for others it can become chronic, continuing for months to even years, with reliance on medications for symptom alleviation.
Medications that are used to shorten the vesicular phase and other symptoms of HZV include the oral antivirals such as famiclovir (Famvir), acyclovir (Zovirax), and valacyclovir (Valtrex). However, these tend to be the most beneficial when taken within seventy-two hours of appearance of the rash. Symptoms of PHN, on the other hand, tend to be reduced by the use of analgesics such as acetaminophen (Tylenol) or NSAIDs when milder or narcotics when pain is more severe. Tricyclics such as desipramine (Norpramin), amitriptyline (Elavil), nortriptyline (Pamelor), and imipramine (Tofranil), as well as lower dosed anti-convulsants such as carbamazapine (Tegretol), pregabalin (Lyrica), gabapentin (Neurontin), and phenytoin (Dilantin) can be used to reduce discomfort too. Additionally, topical agents such as lidocaine (Lidoderm) and capsaicin (Zostrix) and even nerve blocks may be used to control the symptoms of PHN.
Although, the thought of possibly experiencing HZV and subsequently PHN can be a frightening one, there is a way to reduce the risk of this happening. In 2006, the zoster vaccine live (Zostavax) was approved, licensed, and introduced by the Federal Drug Administration (FDA). Its purpose is to reduce the risk of reactivation of the varicella zoster virus in those who retain the dormant virus within their bodies. For those patients, usually over the age of seventy, who unfortunately experience HZV despite vaccination, the vaccine can still decrease the risk of developing PHN.
A study on the effectiveness of zoster vaccine live (Zostavax), conducted by the FDA, demonstrates its utility. It included a randomized sample of approximately 38,000 elderly people aged sixty years and older, from across America. These people were then divided into two groups; those that received the vaccine and those who were given a placebo. These groups were then followed for a period of three years. During that time, it was noted that of people aged eighty and above, the vaccine was eighteen percent effective, though it was forty-one percent effective for those aged 70 to 79 years old. The vaccine’s greatest effectiveness was discovered in the youngest members of the group, those aged 60-69 years old, at sixty-four percent. Overall, for the entire group, effectiveness of the zoster vaccine live was determined to be approximately fifty percent. Additionally, in terms of length of time during which patients experienced pain, those people in the vaccinated group felt pain for two days less than those in the group who received the placebo.
Even though overall effectiveness of the zoster vaccine live for the elderly population aged sixty and over is approximately fifty-fifty, for those in whom the vaccine achieves its purpose, its use is well worth it. Not everyone, however, is able to receive the vaccine. Acceptable candidates include those who are aged fifty and over, do not have an allergy to gelatin, neomycin, and have no allergies to any components of the vaccine itself. The vaccine should not be taken by any people who are actively ill with fever, immunodeficient or immunosuppressed, as the vaccine consists of a live, attenuated virus. It may be possible for those who obtain the vaccine to transmit the virus to those who have never had the chickenpox.
The most common adverse effects related to the vaccine are redness, pain or swelling at the administration site and headache, while anaphylaxis is the most serious. It is given as a single dose, subcutaneous injection, into the upper arm. However, the zoster vaccine live should not be administered at the same time as the pneumococcal vaccine polyvalent (Pneumovax 23), due to a diminished immune response to the zoster vaccine live. If the Pneumovax 23 vaccine is needed, it should be separated from administration time of the zoster vaccine live by at least four weeks. As of June 2011, it remains uncertain if the zoster vaccine live’s effectiveness extends beyond four years, and thus the need for booster vaccination is yet to be decided.
In my practice, I educate my patients regarding the importance of zoster vaccine live as a preventative measure against HZV and PHN. Once, I had a 68 year old male patient who came in to see me because of a painful rash on his left ear. He stated that it had become increasingly painful over several days, followed by a rash that developed the previous day and from which a clear drainage seeped. Though he reported no loss of hearing, he was worried because he did not want his hearing to be affected. He did, however, mention that his ear did ring intermittently.
After a physical exam that included a check not only of his left ear, but also his right one, his nose, throat, face, head, and neck, I determined that the rash appeared to be HZV based on its appearance, being linearly patterned, small vesicles on a red base that ran superiorly and laterally to the lobule of the ear and distal to the middle canal of the ear. As this was my first experience of a “herpes zoster oticus,” I consulted with my physician colleague, who confirmed the diagnosis.
After informing the patient of his diagnosis, I discussed how the rash was contagious at this time, until the drainage subsided and the vesicles crusted over. He was worried about passing this on to his wife, but I reassured him that he would not, as he told me that she had had the chicken pox as a child. However, I did tell him over the next seven days to avoid people who may not have ever had the chicken pox, as they would be susceptible to catching the virus. We further discussed starting the patient on famiclovir, a medicine that I informed him would be beneficial to healing the rash. Because the patient had normal kidney function, I was able to start him on a dose of 500mg, three times a day, to be taken over the next seven days. I informed him of possible side effects such as headache, nausea and vomiting and asked him to call me if he were to experience any other symptoms. I also put him on corticosteroid otic drops, in order to help with the inflammation and discomfort.
Lastly, I gave him the name and contact information of a local ear, nose and throat (ENT) physician, with whom to make an appointment that week, so as to ensure that there would be no complications to his hearing. The patient agreed to all of this. I asked him to follow up with me in a week’s time.
On follow up, the patient’s rash was mostly healed with few crusted vesicles remaining. He stated that the pain and the ringing in his ear had subsided. His hearing was fine and that the ENT did not foresee any complications. At that point, I advised him to return, perhaps in a month or two to get the zoster vaccine live. Given that this patient was over the age of fifty, healthy overall without any immunosuppression and not immunodepressed, I informed him of how this vaccine could possibly prevent him from developing PHN, a complication of recurrent pain that could develop because of his recent zoster experience. He agreed to this, as he stated that the pain that he had was awful and he never wanted to experience it again. In fact, I also encouraged his equally healthy seventy year old wife, who had accompanied him on the visit, to consider getting vaccinated, as she had had the chicken pox as a child and was therefore at risk of developing the HZV and PHN herself. Both of them thought this to be a good idea and both made subsequent appointments for this purpose.
Although, the zoster vaccine live is not able to prevent the acquisition of HZV or even PHN in everyone who receives it, its effects for those in whom it works can bring much peace of mind and body. As Wayne Gretsky put it, “You miss one hundred percent of the benefits of the shots you never take”.
Karen Digby, CNP_BC, CWS
Published on January 29, 2013
Karen Digby is a nurse practitioner specializing in geriatrics. She received her training from New York University and the University of Michigan in Ann Arbor. In over ten years of practice, Karen has obtained a wealth of experience in various aspects of health care including home care, outpatient/ambulatory care, dementia care, subacute care, hospice, assist living and long-term care. Due to her expertise in geriatrics, Karen was selected as an item writer, by the American Nurses Credentialing Center, for the Gerontological Nurse Practitioner Board Certification Examination. She also co-authored an article on “Falls in the Elderly” in the Plastic Surgical Nursing Journal. Additionally, Karen is certified as a Wound Care Specialist through the American Academy of Wound Management.
- Post-herpetic neuralgia. http://emedicine.medscape.com/article/1143066-overview
- Stankus, SJ., Dlugpolski, M., Packer, D. Management of Herpes Zoster (Shingles) and Post herpetic Neuralgia. American Family Physician. 2000. Apr 15; 61 (8):2437-244.
- http://www.ucsfhealth.org/conditions/post-herpetic_neuralgia/index.html Post-herpetic neuralgia
- http://www.fda.gov/BiologicsBloodVaccines/Vaccines/QuestionsaboutVaccines/ucm070418.htm Vaccines, blood & biologic
- http://www.fda.gov/downloads/BiologicsBloodVaccines/Vaccines/ApprovedProducts/UCM132831.pdf Proposed prescribing information