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Herpes Zoster (Shingles)

Edwin Y. Choi, MD, Lea S. Choi, DO and Shane L. Larson, MD Reviewed 06/2019
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Subject: Herpes Zoster (Shingles)

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BASICS

DESCRIPTION

  • Results from reactivation of latent varicella-zoster virus (VZV) (human herpesvirus type 3) infection

  • Postherpetic neuralgia (PHN) is defined as pain persisting at least 1 month after rash has healed. The term zoster-associated pain is more clinically useful.

  • Usually presents as a painful unilateral vesicular eruption with a dermatomal distribution

  • System(s) affected: nervous; integumentary; exocrine

  • Synonym(s): shingles

EPIDEMIOLOGY

Incidence

  • Incidence increases with age—2/3 of cases occur in adults age ≥50 years. Incidence is increasing overall as the U.S. population ages.

  • Herpes zoster: 4/1,000 person-years

  • PHN: 18% in adult patients with herpes zoster; 33% in patients ≥79 years of age

  • Individual lifetime risk of 30% in the United States

Prevalence

~1 million new cases of herpes zoster annually in the United States 
Pregnancy Considerations

May occur during pregnancy

 
Geriatric Considerations
  • Increased incidence of zoster outbreaks

  • Increased incidence of PHN

 
Pediatric Considerations
  • Occurs less frequently in children

  • Has been reported in newborns infected in utero

 

ETIOLOGY AND PATHOPHYSIOLOGY

Reactivation of VZV from dorsal root/cranial nerve ganglia. Upon reactivation, the virus replicates within neuronal cell bodies, and virions are carried along axons to dermatomal skin zones, causing local inflammation and vesicle formation. 

RISK FACTORS

  • Increasing age

  • Immunosuppression (malignancy or chemotherapy)

  • Physical trauma

  • Female

  • HIV infection

  • Spinal surgery

GENERAL PREVENTION

  • Herpes zoster vaccination (Shingrix) is approved and recommended by the CDC for adults 50 years and older (1).

  • Shingrix is recommended for adults who previously received Zostavax and is the preferred vaccine.

  • Live VZV vaccine (Zostavax) (recommended for >60 years) is contraindicated in immunosuppressed persons, patients with HIV and CD4 counts <200, patients undergoing cancer treatment, and patients with hematologic or lymphatic (1),(2).

  • Patients with active zoster may transmit disease-causing varicella virus—typically through direct contact.

COMMONLY ASSOCIATED CONDITIONS

Immunocompromised states, HIV infection, posttransplantation, immunosuppressive drugs, and malignancy 

DIAGNOSIS

HISTORY

  • Prodromal phase (sensory changes over involved dermatome prior to rash)

    • Tingling, paresthesias

    • Itching

    • Boring “knife-like” pain

    • Allodynia and hyperalgesia

  • Acute phase

    • Constitutional symptoms (e.g., fatigue, malaise, headache, low-grade fever) are variable.

    • Dermatomal rash

PHYSICAL EXAM

  • Acute phase

    • Rash: initially erythematous and maculopapular; evolves to characteristic grouped vesicles usually in one dermatome but may affect two to three adjacent dermatomes

    • Thoracic and lumbar dermatomes are most commonly involved sites (2).

    • Vesicles become pustular and/or hemorrhagic in 3 to 4 days.

    • Weakness in distribution of rash (1%)

    • Rash crusts and resolves by 14 to 21 days.

  • Possible sine herpete (zoster without rash) and other chronic disorders associated with VZV without the typical rash

    • Herpes zoster ophthalmicus (HZO). Vesicles on tip of the nose (Hutchinson sign) indicate involvement of the external branch of cranial nerve V; associated with increased incidence of HZO

  • Chronic phase

    • PHN is the most common complication (15% overall; increases with age).

    • 1–5% of cases may affect the motor nerves, causing weakness (zoster motorius), facial nerve (e.g., Ramsay Hunt syndrome), spinal motor radiculopathies.

    • Lesions usually heal 2 to 4 weeks after onset, but scarring and pigmentation changes are common (2).

DIFFERENTIAL DIAGNOSIS

Rash 
  • Herpes simplex virus

  • Coxsackievirus

  • Contact dermatitis

  • Superficial pyoderma

DIAGNOSTIC TESTS & INTERPRETATION

Initial Tests (lab, imaging)

Rarely necessary. Clinical appearance is distinct. 

Follow-Up Tests & Special Considerations

  • Viral culture

  • Tzanck smear (does not distinguish from herpes simplex, and false-negative results occur)

  • Polymerase chain reaction

  • Immunofluorescent antigen staining

  • Varicella-zoster–specific IgM

Test Interpretation

  • Multinucleated giant cells with intralesional inclusion

  • Lymphatic infiltration of sensory ganglia with focal hemorrhage and nerve cell destruction

TREATMENT

GENERAL MEASURES

  • Treat to control symptoms and prevent complications.

  • Antiviral therapy decreases viral replication; lessens inflammation, nerve damage; and reduces the severity and duration of long-term pain.

  • Prompt analgesia may shorten the duration of zoster-associated pain.

  • Calamine and colloidal oatmeal may help reduce itching and burning.

MEDICATION

First Line

  • Acute treatment

    • Antiviral agents initiated within 72 hours of skin lesions help relieve symptoms, speed resolution, and prevent or mitigate PHN (3)[A].

    • Antivirals do not significantly reduce the incidence of PHN (4)[A].

    • Valacyclovir: 1,000 mg PO TID for 7 days

    • Famciclovir: 500 mg PO TID for 7 days

    • Acyclovir: 800 mg q4h (5 doses daily) for 7 days

    • In children, oral acyclovir is the drug of choice.

  • Analgesics (acetaminophen, NSAIDs)

  • Corticosteroids do not prevent PHN but may accelerate resolution of acute neuritis.

    • Tricyclic antidepressants (TCAs); amitriptyline 10 to 25 mg at bedtime and other low-dose TCAs relieve pain acutely and may reduce pain duration; dose may be titrated up to 75 to 150 mg/day as tolerated.

    • Lidocaine patch 5% (Lidoderm) applied over painful areas (limit three patches simultaneously or trim a single patch) for up to 12 hours may be effective.

    • Gabapentin: 300 to 600 mg TID for pain; limited by adverse effects

    • Capsaicin cream and other analgesics may be useful adjuncts. Use opioids sparingly.

    • Capsaicin 8% patch or plaster provides pain relief for patients with PHN (5)[C]; better tolerated when initially applied with topical anesthetic

    • Pregabalin: 150 to 300 mg/day divided BID or TID reduces pain; use is limited by side effects.

  • Prevention of PHN and zoster-associated pain: Nothing prevents PHN entirely, but treatment may shorten duration and/or reduce severity.

    • Antiviral therapy with valacyclovir, famciclovir, or acyclovir given during acute skin eruption may decrease the duration of pain.

    • Low-dose amitriptyline (25 mg at bedtime) started within 72 hours of rash onset and continued for 90 days may reduce PHN incidence/duration.

    • Paravertebral blockade: Nerve blocks during the acute phase shorten the duration of pain; somatic blocks, paravertebral blocks, and repeated/continuous epidural blocks can be used to prevent PHN (6)[A].

    • Insufficient evidence to suggest that corticosteroids reduce incidence, severity, or duration of PHN

  • Precautions

Second Line

Numerous therapies have been advocated, but supporting evidence to routinely recommend is lacking. 

COMPLEMENTARY & ALTERNATIVE MEDICINE

Cupping therapy (traditional Chinese medicine) shows potential benefit, but evidence is conflicting. 

ADMISSION, INPATIENT, AND NURSING CONSIDERATIONS

  • Outpatient treatment, unless disseminated or occurring as complication of serious underlying disease requiring hospitalization

  • Consultation with ophthalmology for ophthalmic involvement (VZO).

ONGOING CARE

FOLLOW-UP RECOMMENDATIONS

Refer to ophthalmology if concern that ophthalmic branch of the trigeminal nerve is involved. 

Patient Monitoring

Follow duration of symptoms—particularly PHN. Consider hospitalization if symptoms are severe; patients are immunocompromised; >2 dermatomes are involved; serious bacterial superinfection, disseminated zoster, or meningoencephalitis develops. 

DIET

No special diet 

PATIENT EDUCATION

  • The rash typically lasts 2 to 3 weeks.

  • Encourage good hygiene and proper skin care.

  • Warn of potential for dissemination (dissemination must be suspected with constitutional illness signs and/or spreading rash).

  • Warn of potential PHN.

  • Warn of potential risk of transmitting illness (chickenpox) to susceptible persons.

  • Seek medical attention if any eye involvement.

PROGNOSIS

  • Immunocompetent individuals should experience spontaneous and complete recovery within a few weeks.

  • Acute rash typically resolves within 14 to 21 days.

  • PHN may occur in patients despite antiviral treatment.

COMPLICATIONS

  • PHN

  • HZO: 10–20%

  • Superinfection of skin lesions

  • Meningoencephalitis

  • Disseminated zoster

  • Hepatitis; pneumonitis; myelitis

  • Cranial and peripheral nerve palsies

  • Acute retinal necrosis

REFERENCES

1
Centers for Disease Control and Prevention. Shingles (herpes zoster). https://www.cdc.gov/shingles/vaccination.html. Accessed October 18, 2018. https://www.cdc.gov/shingles/vaccination.html. Accessed October 18, 2018. ??[View Abstract on OvidMedline]
2
Saguil A, Kane S, Mercado M, et al. Herpes zoster and postherpetic neuralgia: prevention and management. Am Fam Physician.  2017;96(10):656–663. [View Abstract on OvidMedline]
3
McDonald EM, de Kock J, Ram FS. Antivirals for management of herpes zoster including ophthalmicus: a systematic review of high-quality randomized controlled trials. Antivir Ther.  2012;17(2):255–264. [View Abstract on OvidMedline]
4
Chen N, Li Q, Zhang Y, et al. Vaccination for preventing postherpetic neuralgia. Cochrane Database Syst Rev.  2011;(3):CD007795. [View Abstract on OvidMedline]
5
Massengill JS, Kittredge JL. Practical considerations in the pharmacological treatment of postherpetic neuralgia for the primary care provider. J Pain Res.  2014;7:125–132. [View Abstract on OvidMedline]
6
Kim HJ, Ahn HS, Lee JY, et al. Effects of applying nerve blocks to prevent postherpetic neuralgia in patients with acute herpes zoster: a systematic review and meta-analysis. Korean J Pain.  2017;30(1):3–17. [View Abstract on OvidMedline]

ADDITIONAL READING

Langan SM, Smeeth L, Margolis DJ, et al. Herpes zoster vaccine effectiveness against incident herpes zoster and post-herpetic neuralgia in an older US population: a cohort study. PLoS Med.  2013;10(4):e1001420. [View Abstract on OvidMedline] 

SEE ALSO

  • Bell Palsy; Chickenpox (Varicella Zoster); Herpes Eye Infections; Herpes Simplex

  • Algorithm: Genital Ulcers

CODES

ICD10

  • B02.9 Zoster without complications

  • B02.29 Other postherpetic nervous system involvement

ICD9

  • 053.9 Herpes zoster without mention of complication

  • 053.10 Herpes zoster with unspecified nervous system complication

SNOMED

  • 4740000 Herpes zoster (disorder)

  • 2177002 Postherpetic neuralgia (disorder)

CLINICAL PEARLS

  • Antiviral therapy within 72 hours of the onset of rash is most effective.

  • Patients with active herpes zoster can transmit clinically active disease (chickenpox) to susceptible individuals.

  • Shingrix is the recommended vaccine for healthy adults 50 years and older, including those who previously received Zostavax, to prevent shingles and related complications.

 
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