Introduction:
The varicella-zoster virus initially causes chickenpox in childhood, and later in life, it can reactivate, leading to Herpes Zoster (HZ), commonly known as shingles, especially in older adults and those with weakened immune systems. Herpes zoster typically manifests as a one-sided rash along a specific nerve pathway. It can be followed by post-herpetic neuralgia (PHN), which is severe and persistent pain even after the rash has cleared. PHN is more common in older individuals and can be quite debilitating.
Effective management of HZ in the elderly involves timely diagnosis, antiviral treatment, and adequate pain relief. If PHN develops, a long-term pain management strategy is necessary. There is a moderately effective vaccine available, recommended for older individuals to reduce the risk of HZ and its complications.
What Are the Causes of Herpes Zoster in Older Adults?
Varicella-Zoster Virus (VZV) is a human neurotropic alpha herpes virus with double-stranded DNA. In its primary infection, chickenpox, symptoms can range from subclinical to presenting with fever and vesicular skin lesions. During this phase, the Varicella-zoster virus establishes a latent state in various ganglia along the nervous system, including dorsal root ganglia, cranial nerve ganglia, and autonomic nerve ganglia. This latency is achieved through retrograde axonal transport from the initial skin lesions or hematogenous spread during viremia.
Reactivation of VZV, which results in herpes zoster (shingles), occurs months to years later. This can manifest as typical dermatomal shingles or more severe disseminated zoster. Reactivation happens when VZV overcomes the immune controls and travels along the affected ganglia and nerves to reach the skin.
Several risk factors contribute to VZV reactivation, including older age, immunocompromised conditions like HIV-1 infection, lymphoma, leukemia, organ transplants, and immunosuppressive medications. Reduced VZV-specific cell-mediated immunity plays a role in reactivation, especially in these risk factors. Depression, sleep disturbances, female gender, weight loss, physical trauma, Caucasian race, diabetes mellitus, and a previous history of shingles increase the risk of VZV recurrence. Additionally, a family history of shingles, particularly among first-grade relatives, raises an individual’s risks of developing shingles in a dose-dependent manner.
What Are the Symptoms of Herpes Zoster in Older Adults?
Varicella-zoster virus (VZV) reactivation leads to herpes zoster (HZ), characterized by a unilateral dermatomal rash. The rash evolves from a maculopapular stage to vesicular-pustular lesions and eventually crusts within two to four weeks. The extent of the rash can vary, involving a single dermatome or adjacent dermatomes, depending on the affected sensory ganglia. Older adults may have atypical rash appearances, including smaller patches or maculopapular without vesicles. The prodromal phase preceding the rash is marked by neuropathic pain and sometimes systemic symptoms like fever and photophobia. Herpes Zoster Ophthalmicus (HZO) affects the eye and may present with a characteristic “Hutchinson sign” on the nose.
Ocular manifestations include conjunctival inflammation, corneal issues, uveitis, and more. Herpes zoster can affect cranial nerves, leading to various clinical symptoms. VZV can cause myelitis, resulting in limb weakness, incontinence, and sensory deficits, with varying outcomes in immunocompetent and immunocompromised individuals. Recurrent VZV infections can manifest as encephalitis and meningitis, sometimes without a rash. Visceral zoster can affect internal organs and is more common in immunocompromised individuals. Disseminated HZ is defined by multiple vesicles outside primary and adjacent dermatomes, more common in immunocompromised individuals.
Post-herpetic sequelae following herpes zoster include:
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Post-herpetic Neuralgia (PHN): Defined as pain persisting for at least 90 days after HZ diagnosis or rash onset. Incidence ranges from five to 30 percent and is more common in older adults, affecting 50 percent of those over 85. PHN is the most debilitating HZ sequelae, impacting all aspects of an individual’s life. Risk factors include prodromal symptoms, severe pain and rash, older age, immunosuppression, diabetes, and zoster opthalmicus. The pain can be constant, intermittent, or triggered by stimuli, described as burning, throbbing, stabbing, or shooting. Allodynia, where normal touch causes severe pain, is particularly distressing. PHN leads to anxiety, depression, weight loss, sleep disturbances, social isolation, and difficulties in daily activities.
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Secondary Bacterial Infection: If clinical symptoms persist beyond one to two weeks and the rash worsens, it is suspected. Often due to Staphylococcal infections and can rarely progress to septicemia. In zoster ophthalmicus (HZO) may present with yellowish drainage and eye crusting.
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Other Dermatologic Complications: Rarely benign and malignant skin lesions can develop at the previous HZO site months to years later. These include post-zoster granulomatous dermatitis, vasculitis, lymphoid proliferations, and various skin cancers.
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Residual Neurological Manifestations of VZV: Neurologic signs and symptoms can occur during active VZV infections or as chronic deficits following VZV encephalitis or meningitis. Outcomes range from complete recovery to severe disability or death. Transverse myelitis, polyneuropathy, and Guillain-Barre syndrome can result from VZV infections.
How to Diagnose Herpes Zoster in Older Adults?
Herpes zoster is diagnosed based on the patient’s history and the characteristic dermatomal appearance of the rash. However, laboratory-based diagnostic tools can be used for confirmation in cases with atypical clinical presentations.
Early vesicular lesions provide the highest yield for clinical specimens. If vesicular fluid cannot be obtained, acceptable alternatives include lesion scrapings, crusts, tissue biopsy, saliva, cerebrospinal fluid (CSF), and blood.
The most sensitive and specific method for diagnosis is detecting varicella-zoster virus (VZV) DNA using polymerase chain reaction (PCR). VZV DNA PCR has high sensitivity and specificity, making it the gold standard for diagnosis. Quantitative PCR is widely available and provides a rapid diagnostic test. A positive PCR in CSF indicates central nervous system (CNS) involvement, while a positive salivary VZV DNA PCR supports the diagnosis of enteric zoster. Positive VZV DNA PCR from blood or oropharyngeal samples is useful in atypical presentations or zoster sine herpete.
VZV culture is highly specific but less sensitive and can take one to two weeks for results. Serological tests, which detect antibody titers against VZV, may show a rise during an episode of Hz but are not very sensitive or specific. A low serum-CSF ratio of anti-VZV IgG can also support the diagnosis of ongoing CNS VZV infection and vasculopathy.
The Tzanck smear, one of the earliest diagnostic tools for VZV, involves scraping the base of a vesicle and staining the material for the presence of multinucleated giant cells and intranuclear inclusions.
What Is the Treatment for Herpes Zoster in Older Adults?
The treatment for herpes zoster involves:
Antiviral Agents:
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Antiviral therapy for acute herpes zoster is recommended for patients who meet certain criteria, including those over 50, individuals with moderate to severe rash or pain, non-truncal involvement, and immunocompromised patients.
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Initiating antiviral treatment within 72 hours of rash onset reduces viral shedding, new lesion formation, and the severity and duration of acute pain. Delayed treatment is still recommended if there is evidence of new lesions or complications.
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Hospitalization with intravenous acyclovir should be considered for specific high-risk groups, such as stem cell transplant recipients, individuals with suspected visceral dissemination, and those with eye involvement (herpes zoster ophthalmicus).
Corticosteroids:
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Corticosteroids can help manage pain in acute HZ and can be used in cases of VZV-induced facial paralysis and cranial polyneuritis to reduce inflammation and swelling. Steroids should be used alongside antivirals.
Analgesics:
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Mild pain in HZ can be treated with Acetaminophen and NSAIDs (non-steroidal anti-inflammatory drugs). Opioid analgesics are used for severe acute HZ pain; Tramadol is an alternative but should be used cautiously in patients with a history of seizures or those specific medications.
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Tricyclic antidepressants (TCAs) like Amitriptyline, Nortriptyline, and Desipramine can help control pain but may have side effects. Gabapentin and Pregabalin, anticonvulsants are used to manage neuropathic pain in both acute HZ and PHN.
Topical Therapy:
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Topical Lidocaine provides well-tolerated pain relief in PHN. Topical Capsaicin is an alternative to PHN.
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Regional or local anesthetic nerve blocks can also be considered.
Herpes Zoster Ophthalmicus (HZO) Therapy:
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In cases of suspected HZO, ophthalmology should be consulted.
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Antiviral treatment typically lasts seven to ten days, but older adults and immunocompromised individuals may require a longer course.
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Artificial tears can improve eye lubrication, and Erythromycin ointment may prevent secondary infection.
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Topical steroids should be used cautiously and under ophthalmologist supervision, as imprudent use can worsen the corneal disease.
Conclusion:
Herpes zoster in older adults presents unique challenges and considerations. It can lead to significant pain and complications, particularly postherpetic neuralgia (PHN). Prompt diagnosis and appropriate management, including antiviral therapy and pain control, are crucial in improving outcomes for older individuals affected by HZ. Close monitoring and tailored treatment plans are essential, especially for those with comorbidities or immunocompromised conditions.
