Herpes Zoster

Herpes zoster (from Greek zoster — belt) is a viral disease characterized by the appearance of grouped painful vesicular eruptions on the skin.

It does not occur due to primary infection, but as a result of local reactivation of the chickenpox virus (Varicella-zoster virus), which has been dormant in the human body for years.

Etiology and pathophysiology

During primary infection (usually in childhood), the virus causes classic chickenpox. After recovery, the pathogen does not leave the body. Along the course of the nerve fibers, it ascends and permanently resides in the sensory ganglia (dorsal ganglia) or the nuclei of the cranial nerves. There it enters a latent (dormant) state, restrained by the immune system cells.

With age (usually after 50 years) or against the background of weakened immune defenses, the virus “awakens,” begins to actively multiply, and descends back along the axon of the affected nerve to the skin. This process causes damage to the epidermis in the innervation zone of this nerve.

Conditions that provoke virus reactivation include:

• stress — severe psycho-emotional or physical tension;
• hypothermia — exposure to low temperatures on the body;
• oncology — presence of malignant neoplasms;
• HIV infection — viral infection of the immune system;
• corticosteroid use — long-term use of hormonal medications.

Clinical significance

Before the rash appears (prodromal period), some patients may experience pain along the course of the involved nerve. Then, redness and characteristic vesicles appear at this location.

The main clinical sign of herpes zoster is the strict unilateral and linear nature of the eruptions (they run in a band along the course of the nerve, not crossing the midline of the body). Specific antiviral drugs (acyclovir, valacyclovir) are used for treatment (within the first 72 hours).

The most common and serious complication is postherpetic neuralgia — acute unstable or persistent debilitating pain of varying intensity that can persist for months or years after complete skin healing in the affected area.

To relieve pain syndrome, the following are usually used:

• gabapentin and pregabalin — anticonvulsants (anticonvulsants);
• cyclic antidepressants — drugs for modulating pain response;
• botulinum toxin injections — local injections to reduce pain intensity.