What is the recommended treatment for unilateral herpes zoster involving the cervical dermatomes C2 to C5?

Treatment of Unilateral Herpes Zoster Involving Cervical Dermatomes C2-C5

For uncomplicated herpes zoster affecting cervical dermatomes C2-C5, initiate oral valacyclovir 1 gram three times daily for 7-10 days, continuing until all lesions have completely scabbed. 1, 2, 3

Initial Assessment and Risk Stratification

Before initiating therapy, evaluate for features that would mandate escalation to intravenous treatment:

• Facial or ophthalmic involvement (C2-C3 distribution raises concern for cranial nerve complications including vision-threatening disease) 1
• Multi-dermatomal spread (≥3 dermatomes indicates disseminated disease) 1
• Severe immunosuppression (active chemotherapy, HIV with CD4 <100, organ transplant, high-dose corticosteroids >40 mg prednisone daily) 1
• Visceral involvement (hepatitis, pneumonia, encephalitis) 4, 1
• Hemorrhagic or necrotic lesions 1

Standard Oral Antiviral Therapy

First-Line Treatment

Valacyclovir 1 gram orally three times daily for 7-10 days is the preferred regimen due to superior bioavailability and convenient dosing compared to acyclovir. 1, 2, 3 Treatment must be initiated within 72 hours of rash onset for optimal efficacy in reducing acute pain, accelerating lesion healing, and preventing postherpetic neuralgia. 1, 5

Alternative Oral Regimens

• Acyclovir 800 mg orally five times daily for 7-10 days remains effective but requires more frequent dosing, potentially reducing adherence. 1, 2, 3
• Famciclovir 500 mg orally three times daily for 7 days offers equivalent efficacy with better bioavailability than acyclovir. 1, 6

Critical Treatment Endpoint

Continue antiviral therapy until all lesions have completely scabbed, not just for an arbitrary 7-day period. 1, 2 Immunocompromised patients may develop new lesions for 7-14 days and heal more slowly, requiring treatment extension well beyond the standard 7-10 days. 1

Indications for Intravenous Acyclovir

Switch to intravenous acyclovir 10 mg/kg every 8 hours if any of the following are present: 4, 1, 2

• Disseminated disease (≥3 dermatomes, visceral involvement, or hemorrhagic lesions)
• Facial/ophthalmic involvement with risk of cranial nerve complications (particularly relevant for C2-C3 dermatomes)
• CNS complications (encephalitis, meningitis, Guillain-Barré syndrome)
• Severe immunosuppression
• Lack of clinical improvement after 7-10 days of appropriate oral therapy (suspect acyclovir resistance)

High-dose IV acyclovir remains the treatment of choice for VZV infections in severely compromised hosts. 4, 1

Renal Dosing Adjustments

Baseline renal function must be assessed before initiating therapy, as valacyclovir is eliminated primarily by the kidneys. 1 For creatinine clearance 30-49 mL/min, reduce valacyclovir to 1 gram every 12 hours; for CrCl 10-29 mL/min, reduce to 1 gram every 24 hours; for CrCl <10 mL/min, reduce to 500 mg every 24 hours. 1, 3

Monitoring During Treatment

• Renal function: Obtain baseline serum creatinine and monitor weekly during IV acyclovir therapy. 1
• Treatment failure: If lesions have not begun resolving within 7-10 days, suspect acyclovir resistance and obtain viral culture with susceptibility testing. 1
• Adequate hydration: Ensure patients maintain hydration to reduce risk of crystalluria and acyclovir-induced nephropathy (occurs in up to 20% of patients). 1

Management of Acyclovir-Resistant VZV

For confirmed acyclovir-resistant herpes zoster (rare in immunocompetent patients but occurs in up to 7% of immunocompromised patients), switch to foscarnet 40 mg/kg IV every 8 hours until clinical resolution. 1, 2 All acyclovir-resistant strains are also resistant to valacyclovir, and most are resistant to famciclovir. 1

Immunosuppression Management

In patients with disseminated or invasive herpes zoster, temporarily reduce or discontinue immunosuppressive medications when clinically feasible. 1, 2 Re-introduction of immunosuppressive agents should occur only after all vesicular lesions have crusted, fever has resolved, and the patient has shown clinical improvement on antiviral therapy. 1

Common Pitfalls to Avoid

• Do not discontinue antiviral therapy at exactly 7 days if lesions are still forming or have not completely scabbed—short-course therapy designed for genital herpes is inadequate for VZV infection. 1
• Do not use topical antivirals—they are substantially less effective than systemic therapy and are not recommended. 4, 1
• Do not delay treatment beyond 72 hours of rash onset—efficacy in reducing postherpetic neuralgia diminishes significantly. 1, 5
• Do not apply corticosteroid creams to active shingles lesions—this can increase risk of severe disease and dissemination, particularly in immunocompromised patients. 1

Infection Control

Patients with herpes zoster should avoid contact with susceptible individuals (those without prior chickenpox or vaccination) until all lesions have fully crusted, as the virus can be transmitted via direct contact with lesions or aerosolized vesicular fluid. 1 Cover lesions with clothing or dressings to minimize transmission risk. 1

Prevention of Future Episodes

After recovery from the current episode, administer the recombinant zoster vaccine (Shingrix) for all adults aged ≥50 years, regardless of prior herpes zoster episodes. 1, 2 The vaccine provides >90% efficacy in preventing future recurrences and should be given as a two-dose series. 1