Shingles

What is Shingles?

Shingles, also known as Herpes Zoster, is a viral disease caused by the reactivation of the Varicella-Zoster virus. This virus stays dormant in nerve cells after causing Chickenpox. While Chickenpox is common in children, Shingles usually occurs in adults or older people.

Shingles happens when the body’s immune system isn’t able to control the virus that’s lying dormant. This means that people with strong immune systems rarely get Shingles. The illness is not harmless and can manifest in different ways. Sometimes, even after the Shingles has gone away, patients can experience moderate to severe continuing pain, known as postherpetic neuralgia.

What Causes Shingles?

When reactivated, the virus multiplies within nerve cells. The virus particles, or virions, are then transported from the nerve cells to the skin areas associated with that particular nerve cluster. Once in the skin, the virus triggers inflammation and causes blisters. Shingles pain is due to this inflammation of the affected nerves by the virus.

Things that might activate the herpes zoster virus include:

• Emotional stress
• Use of certain drugs that weaken the immune system
• Having an acute or chronic illness
• Being exposed to the virus
• Having a type of cancer

Risk Factors and Frequency for Shingles

Herpes zoster, or shingles, affects 1.2 to 3.4 out of each 1000 healthy people each year. However, it is more common in those over the age of 65, affecting 3.9 to 11.8 of each 1000 people. The disease does not appear more frequently in any particular season. The rate of recurrence is highest in those with weakened immune systems.

• Herpes zoster affects 1.2 to 3.4 out of 1000 healthy people every year.
• In people over the age of 65, the number goes up to 3.9 to 11.8 out of 1000 each year.
• There’s no specific season in which herpes zoster is more common.
• The recurrence rate is highest in those with weakened immune systems.

Signs and Symptoms of Shingles

• Zoster characteristically presents with a prodrome of fever, malaise, and excruciating burning pain followed by the outbreak of vesicles that appear in one to three crops over three to five days.
• Lesions are distributed unilaterally within a single dermatome.

Clinically, lesions start as closely grouped erythematous papules which, rapidly become vesicles on an erythematous and edematous base and may occur in continuous or interrupted bands in one, two, or more contiguous dermatomes unilaterally. Dermatomes commonly involved are thoracic (53%), cervical (20%), and trigeminal (15%) including ophthalmic and lumbosacral (11%).

The three phases of the infection include:

• Preeruptive stage presents with abnormal skin sensations or pain within the dermatome affected. this phase appears at least 48 hours prior to any obvious lesions. At the same time, the individual may experience headaches, general malaise, and photophobia.
• The acute eruptive phase is marked by the vesicles and the symptoms seen in the pre-eruptive phase. The lesions initially start as macules and quickly transform into painful vesicles. The vesicles often rupture, ulcerate and eventually crust over. Patients are most infectious in this stage until the lesion dry out. Pain is severe during this phase and often unresponsive to traditional pain medications. The phase may last 2-4 weeks but the pain may continue.
• Chronic infection is characterized by recurrent pain that lasts more than 4 weeks. Besides the pain, patients experience paresthesias, shock-like sensations, and dysesthesias. The pain is disabling and may last 12 months or longer.

Shingles oticus is also known as Ramsay Hunt syndrome type II. It is due to the spreading of the virus from the facial nerve to the vestibulocochlear nerve which involves the ear and causes hearing loss and vertigo (rotational dizziness).

Zoster may occur in the mouth if the maxillary or mandibular division of the trigeminal nerve is affected. Clinically, it presents with vesicles or erosions occurring over the mucous membrane of the upper jaw (palate, gums of the upper teeth) or the lower jaw (tongue or gums of the lower teeth). Oral involvement may occur alone or in combination with the lesions on the skin over the cutaneous distribution of the same trigeminal branch.

Due to the close relationship of blood vessels to nerves, the virus can spread to involve the blood vessels compromising the blood supply, and causing ischemic necrosis. Complications such as osteonecrosis, tooth loss, periodontitis, pulp calcification, pulp necrosis, periapical lesions, and tooth developmental anomalies can occur due to it.

The ophthalmic division of the trigeminal nerve is the most commonly involved branch which causes ophthalmic zoster. The skin of the forehead, upper eyelid, and orbit of the eye may be involved. It is seen in approximately 10% to 25% of cases presenting with features of, keratitis, uveitis, and optic nerve palsies. Complications in the form of chronic ocular inflammation, loss of vision, and debilitating pain can occur.

The involvement of the CNS is not uncommon. since the virus resides in the sensory root ganglia, it can affect any part of the brain causing cranial nerve palsies, muscular weakness, diaphragmatic paralysis, neurogenic bladder, Guillain Barre syndrome, and myelitis. In severe cases, patients may develop encephalitis.

Complications of herpes zoster include secondary bacterial infection, post-herpetic neuralgia, scarring, nerve palsy, and encephalitis in the case with disseminated zoster.

1. Disseminated zoster is defined as more than twenty skin lesions developing outside the primarily affected area or dermatomes directly adjacent to it. Besides the skin, other organs may also be affected, causing hepatitis or encephalitis making this condition potentially lethal.
2. Post-herpetic neuralgia is the persistence of pain after a month of onset of herpes zoster. It is the commonest side effect seen in elderly patients with involvement of the ophthalmic division of trigeminal nerve.
3. Complications like cranial neuropathies, polyneuritis, myelitis, aseptic meningitis, or partial facial paralysis occur due to the involvement of the nervous system.

During pregnancy, varicella may lead to infection in the fetus and complications in the newborn, but chronic infection or reactivation, in other words, herpes zoster, is not associated with fetal infection.

Zoster sine herpete is an entity with a pain in the involved dermatome without any skin lesions.

Testing for Shingles

• Herpes zoster is clinically diagnosed with burning pain, characteristic morphology, and typical distribution.
• Herpes simplex virus can occasionally produce a rash in a pattern called as zosteriform herpes simplex.[7][8][9]

Tests for varicella-zoster virus include the following:

• The Tzanck smear of vesicular fluid shows multinucleated giant cells. It has lower sensitivity and specificity than direct fluorescent antibody (DFA) or Polymerase chain reaction (PCR).
• Varicella-zoster virus-specific IgM antibody in blood is detected during the active infection of chickenpox or shingles but not when the virus is dormant
• Direct fluorescent antibody testing of vesicular fluid or corneal fluid can be done when there is eye involvement.
• PCR testing of vesicular fluid, a corneal lesion, or blood in a case with eye involvement or disseminated infection.

Molecular biology tests based on in vitro nucleic acid amplification (PCR tests) are currently considered the most reliable. Nested PCR test has high sensitivity, but is susceptible to contamination leading to false-positive results. The latest real-time PCR tests are rapid, easy to perform, as sensitive as nested PCR, have a lower risk of contamination, and also have more sensitivity than viral cultures.

Differential Diagnosis

Cutaneous lesions of herpes zoster need to be differentiated from herpes simplex, dermatitis herpetiformis, impetigo, contact dermatitis, candidiasis, drug reactions, and insect bites. Preceding pain without the development of skin lesions in herpes zoster is different from cholecystitis and biliary colic, renal colic, trigeminal neuralgia, or any dental infection.

Herpes zoster tends to involve only one side of the oral cavity, which distinguishes it from other oral blistering conditions. In the mouth, it presents initially as vesicles that break down quickly to leave ulcers that heal within 10 to 14 days. The prodromal pain before the rash may be confused with a toothache which leads to unnecessary dental treatment.

Treatment Options for Shingles

• Antiviral therapy hastens the resolution of lesions, decreases acute pain, and helps to prevent post-herpetic neuralgia especially in elderly patients.
• Acyclovir 800 mg, five times daily for five days
• Valacyclovir 1 gm three times daily for five days
• Famciclovir 500 mg three times daily for seven days
• Topical antibiotic creams like mupirocin or soframycin help to prevent secondary bacterial infection.
• Analgesics help to relieve the pain.
• Occasionally, severe pain may require an opioid medication.
• Topical lidocaine and nerve blocks may also reduce pain.

Post-herpetic neuralgia commonly occurs in elderly patients, and once the lesions have crusted, they can use topical capsaicin and Emla cream.

What else can Shingles be?

When a doctor is diagnosing a skin condition, there are a range of potential causes that they need to consider. Some possibilities might include:

• Cellulitis (skin infection)
• Chickenpox
• Cnidaria envenomation (jellyfish or other stinging sea creature venom)
• Contact stomatitis (mouth inflammation due to certain irritants)
• Outbreaks related to the herpes simplex virus (which causes cold sores or genital herpes)
• Ecthyma (skin infection leading to sores)
• Erysipelas (skin infection typically on the legs)
• Erysipeloid (skin condition caused by certain bacteria)
• Folliculitis (inflammation or infection of hair follicles)
• Human cowpox infections (a rare and generally mild disease caused by a virus)
• Irritant contact dermatitis (an itchy skin reaction caused by some substances)
• Insect bites
• Lichen striatus (a skin condition often found in children that presents as a band of small pink or red bumps)
• Mucosal candidiasis (a yeast infection in the mouth, throat, or other areas)

All these conditions can lead to similar symptoms; thus, they require appropriate checks and tests for correct diagnosis.