Herpes Zoster Infection
(Acute posterior Ganglionitis or Shingles)
By Maxime Coles MD
Herpes Zoster affects nearly 1 million patients a year in the USA with a preference for the septuagenarians and up. Herpes Zoster Infection (Acute posterior Ganglionitis or Shingles) is the result of a re-activation of the Varicella Virus from a latent phase, in a posterior dorsal root ganglion.
Primary Varicella infection presents with a viral prodrome followed by a characteristic maculopapular rash in a dermatomal pattern, 48 hours after. The rash often progresses into painful vesicles and bullae during the following two weeks. Other symptoms like fatigue, malaise, and fever may be encountered
The virus lies dormant in the dorsal root ganglion and may reactivate years later generally between the 5th and seventh decade of life. Re-activation may increase in the elderly especially because of age related decline in immunity or immunosuppression.
Chickenpox and Herpes Zoster are both caused by the Varicella-Zoster virus (Human Herpesvirus type 3). Chickenpox may represent the acute and invasive phase while the Herpes Zoster (Shingles) represent a re-activation to the latent phase.
Herpes zoster inflames the sensory root ganglia, the skin of the associated dermatome, and sometimes the posterior and anterior horns of the gray matter, meninges, and dorsal or ventral roots. Herpes zoster frequently occurs in elderly and HIV-infected patients, but it is more severe in immunocompromised patients because their cell-mediated immunity is decreased. Unfortunately, there are no clear-cut precipitants.
Lancinating pain following the apparition of crops of vesicles with an erythematous base is significant, 48 hours after the eruption. The site is generally unilateral, hyper esthetic in the thoracic or lumbar area where a few satellite lesions can be found. These lesions usually continue to form for about 3 to 5 days. Herpes Zoster may disseminate to other areas of the body and visceral organs especially in Immuno-compromised patients.
Geniculate Zoster (Ramsay syndrome, Herpes Zoster Oticus} involve the Geniculate ganglion. Ear pain, facial paralysis or vertigo can occur. Vesicle can erupt in the external auditory canal disturbing the taste buds of the anterior two thirds of the tongue.
Ophthalmic herpes zoster will involve the Gasserian ganglion and generate pain with vesicular eruption around the eye and the forehead, in the distribution of the ophthalmic division of the 5th cranial nerve. Vesicles noted on the tip of the nose (Hutchinson sign) indicate the involvement of the nasocillary branch.
Herpes Zoster in the distribution of the Trigeminal Nerve is uncommon like in the intraoral zoster with a unilateral distribution.
Post Herpetic Neuralgia is seen in less than 5% of patients with Herpes zoster but elderly may present with persisting and recurrent pain in a determined area (postherpetic neuralgia) lasting months, years or even lasting permanently creating a disability.
Finally, Herpes Zoster may be associated to motor neuropathy (ZAM) with paresis, a rare complication that can be found in only 3% of the cases. Generally, paresis may follow the eruption 2-3 weeks after. In a study, weakness was prolonged to almost a year. The mechanism is unknown, but many believe that it is a distant mediated neuropathic process. Nerve conduction studies have demonstrated a conduction block with fibrillation potentials in affected muscles, resolving eventually, suggesting a certain degree of demyelination. Many researchers have reported a higher risk in developing motor neuropathy among patients suffering of Diabetes Mellitus from 5.8% to 12.9% in the general population. It becomes imperative this need for physicians in general, to be aware of the clinical aspect of Herpes Zoster Motor Neuropathy.
The diagnosis of Herpes Zoster can be suspected in presence of the typical and pathognomonic rash involving a well determined dermatome. The “Tzanck” test became popular in confirming the infection and in detecting multinucleate giant cells, found in Herpes Simplex or Herpes Zoster. Herpes Simplex has the tendency to recur. The Viruses can be differentiated by culture or PCR but the detection of Antigen from a biopsy sample can be useful.
Many believe that antiviral medication should then be started during the time of the prodrome or at least in the 72 hours after the apparition of the maculopapular rash or vesicles, for better results. Treatment may be only symptomatic or antiviral like Acyclovir, Famciclovir, Valacyclovir can be used with wet compresses. The addition of systemic analgesic is often suggested but It is recommended to refer a patient suffering from an Ophthalmic Herpes Zoster to an ophthalmologist and one with an Optic Herpes Zoster to an otolaryngologist.
Antiviral Therapy with oral medications decreases the severity and the duration of an acute eruption. It may also decrease the rate of serious complications especially for the immunocompromised patient. The incidence of postherpetic neuralgia will be reduced by this way. Famciclovir 500 mg three times a day for 7 days, and Valacyclovir 1g three times a day for 7 days are preferred to acyclovir 800 mg 5 times a day for 7 to 10 days. The use of Corticosteroids will not decrease the postherpetic neuralgia. In severely immunocompromised patients, Acyclovir is recommended in the dose of 10-15 mg/kg IV each 8h for at least 2 weeks for adults but only 7 days for children below 12 years.
The safety of the antiviral therapy during pregnancy is not well established. Congenital Varicella can result from Maternal Varicella and the need to treat a mother outweigh any risk to the Fetus. Acyclovir and Valacyclovir should be used in pregnant women during the late stages.
Postherpetic neuralgia can be difficult to treat because the pain can radiate along a single spinal nerve causing radiculopathies, cranial neuropathies, myelitis, aseptic meningitis. Gabapentin, cyclic antidepressants and topical capsaicin or lidocaine ointment can improve the condition. Opioid analgesics and intrathecal Methylprednisolone has been used to control intractable pain. Researchers have demonstrated Botulinum toxin to be beneficial in reducing pain. In cases of Motor Neuropathy, the prognosis is generally good with a full recovery and re-gain of muscle functioning in the next 6 months to a year is expected in more than half of the patient who suffer from the disease. A period of rehabilitation may facilitate the recovery.
There is slightly an increase risk in developing Cancer after Shingles infection. The mechanism is unclear and mortality from this complication does not appear to increase as a direct result of the presence of the virus.
A new Herpes Zoster vaccine, live-attenuated, is now recommended for immunocompetent adults older than 50 years old in 2 doses apart during a 2-6 months period. This protocol was recommended by the advisory Committee on Immunization Practices. A newer vaccine, live-attenuated, with long lasting protection is recommended for adults immunocompetent but contraindicated in immunocompromised patients.
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