9 Treating shingles and oral and genital herpes
Shingles
Shingles is an infection of a dermatomal or cranial nerve by the herpes zoster virus. The herpes virus establishes a latent infection in the nerve that lasts for the life of the host and may become active at times of stress or immune system compromise (Steiner 2007). The pain usually begins during the viral prodrome and can last up to 3 weeks before red raised lesions and blisters break out along the course of the nerve. Herpes simplex virus 1 (HSV1) is part of the same family of viruses and causes “cold sores” or lesions around the mouth. Herpes simplex virus (HSV2) lies dormant in the genitals and causes recurrent outbreaks of lesions in the genital or anal area. All are related to the varicella or chickenpox virus and the Epstein–Barr virus is included in this class of viruses (Liu 2006).
Herpes zoster, or shingles, is caused by the varicella zoster virus (VZV) and may be found in individuals of any age. It is more common in immunocompromised HIV-AIDS patients and bone marrow transplant recipients and in the elderly who have an 8–10-fold increase of incidence compared to those under age 60, presumably due to reduction of T-cell mediated immunity seen with aging. Diabetes mellitus, surgery, spinal anesthesia, malignancies, and conditions associated with immune suppression such as steroid therapy, and immune-suppressive agents serve as predisposing factors and triggers for the appearance of VZV or shingles (Steiner 2007).
The immediate pain reduction and lasting pain relief suggest that something is happening to interfere with either viral structure or replication. The mechanism for this effect is unknown. Several mechanisms have been proposed but none have been tested. The herpes family of DNA viruses has a double stranded DNA molecule located within an icosapentahedral capsid surrounded by an amorphous protein material which is in turn encapsulated by an envelope that consists of polyamines, lipids and glycoproteins. The glycoproteins give the virus its distinctive properties and provide the antigens to which the host immune system can respond (Steiner 2007).
Post-herpetic neuralgia (PHN) is more difficult to treat and does not respond to the protocols for shingles. The virus is gone within weeks of the active infection and the neuralgia may be caused by viral damage to the nerve. The treatment for PHN is focused on inflammation, calcium influx into the nerve and scar tissue between the nerve and the surrounding fascia, and reduction of central amplification created by deafferentation of the peripheral nerve. Thoracic nerve roots have sympathetic involvement which complicates PHN symptoms and treatment. The protocols for neuropathic pain discussed in Chapter 3 may be useful in PHN but it can be challenging to treat.
Shingles diagnosis
The majority of shingles cases in the elderly occur in thoracic nerve roots although any dorsal root ganglion may be involved (Bradley 2000). Thoracic nerve pain may present as abdominal pain or chest pain and may be mistaken for pain of visceral origin. A sensory examination for skin hyperesthesia, the first sign of nerve irritability, is a simple way to determine neural involvement and may avoid expensive and invasive diagnostic testing aimed at discovering a visceral cause for the pain.