28 Aug
2018

What is Shingles?


shingles

Shingles is a painful blistering rash caused by reactivation of varicella, the chickenpox virus. Herpes zoster is the correct term

Chickenpox or varicella is the primary infection with the virus, Herpes zoster, also called ‘varicella-zoster’. During this widespread infection, which usually occurs in childhood, the virus seeds to nerve cells in the spinal cord, usually of nerves that supply sensation to the skin.

The virus remains in a resting phase in these nerve cells for years before reactivating. It then grows down the nerves to the skin to produce shingles (zoster). This can occur in childhood but is much more common in adults, especially the elderly.

Shingles patients are infectious (resulting in chickenpox), both from virus in the lesions and in some instances the nose and throat.

Who gets shingles?

Anyone who has previously had chickenpox may subsequently develop shingles. They can be male or female, young or old. In general, it is more common in older adults and certainly tends to be more severe in this group.

Shingles is more common and more severe in patients with poor immunity. Blisters can occur in more than one area and the virus may affect internal organs, including the gastrointestinal tract, the lungs and the brain.

Chickenpox or shingles in the early months of pregnancy can harm the fetus, but luckily this is rare. Chickenpox may infect the fetus in later pregnancy, and then develop into shingles as an infant.

It is not clear why shingles affects a particular nerve fibre. Pressure on the nerve roots may set it off, or by radiotherapy at the level of the affected nerve root, by spinal surgery, by an infection such as sinusitis or by an injury (not necessarily to the spine).

Patients report occasional clusters of shingles. Experts suggest that contact with someone who has chickenpox or shingles may cause one’s own virus to reactivate.

Clinical features

The first sign of shingles is usually pain, which may be severe, in the areas of one or more sensory nerves, often where they emerge from the spine. The pain may be just in one spot or it may spread out. The patient usually feels quite unwell with fever and headache. The lymph nodes draining the affected area are often enlarged and tender.
Within one to three days of the onset of pain, a blistering rash appears in the painful area of skin. Sometimes, especially in children, shingles is painless.

It starts as a crop of closely-grouped red bumps in a continuous band on the area of skin supplied by one, occasionally two, and rarely more neighbouring spinal nerves. New lesions continue to appear for several days, each blistering or becoming pustular then crusting over. Shingles occasionally causes blisters inside the mouth or ears, and can also affect the genital area.

The pain and general symptoms subside gradually as the eruption disappears. In uncomplicated cases, recovery is complete in 2-3 weeks in children and young adults, and 3 to 4 weeks in older patients.

Occasionally pain is not followed by the eruption – shingles “sine eruptione”. These cases can be difficult to identify because there is no characteristic rash.

Regions

The chest (thoracic), neck (cervical), forehead (ophthalmic) and lumbar/sacral sensory nerve supply regions are most commonly affected at all ages but the frequency of ophthalmic shingles increases with age. Rarely the eruption may affect both sides of the body.

In elderly and undernourished patients the blisters are deeper. It may take many weeks to heal and scarring may follow. Muscle weakness arises in about one in twenty patients because it affects the muscle nerves as well as the sensory nerves. Facial nerve palsy is the most common result. There is a 50% chance of complete recovery and in time some, one can expect improvement in nearly all cases.

Post-herpetic neuralgia (after-pains)

We define post-herpetic neuralgia as persistence or recurrence of pain more than a month after the onset of shingles. It becomes increasingly common with age affecting about a third of patients over 40 and is particularly likely if there is facial infection. The pain may be continuous and burning with increased sensitivity in the affected areas, or a spasmodic shooting type, or, rarely, of an itchy, crawling variety. The overlying skin is numb or exquisitely sensitive to touch. Sometimes, instead of pain, the neuralgia results in a persistent itch (neuropathic pruritus).

Treatment

If you think you may have shingles, see your doctor as soon as possible. Antiviral treatment can reduce pain and the duration of symptoms, but it is much less effective if started more than one to three days after the onset of the shingles.

• Rest and pain relief are important – try paracetamol initially
• One should apply a bland, protective application to the rash. Try povidone iodine or calamine lotion.
• Capsaicin cream may be helpful for pain relief for post-herpetic neuralgia.
• Oral antiviral medication is recommended in the following circumstances:
• Facial shingles
• Those with poor immunity
• The elderly
• Antiviral medication available for shingles on prescription include:
• Aciclovir (this is the only one available in New Zealand)
• Valaciclovir
• Famciclovir
• In severe or extensive cases aciclovir may be given intravenously for a few days.
• In some circumstances, systemic steroids may also be recommended.
• One may need oral antibiotics for secondary infection, usually flucloxacillin or erythromycin.

Treatment of post-herpetic neuralgia

Post-herpetic neuralgia may be difficult to treat successfully. It may respond to any of the following.

• Local anaesthetic applications eg lignocaine
• Topical capsaicin
• Tricyclic antidepressant medications such as amitriptyline
• Serotonin and norepinephrine reuptake inhibitors such as duloxetine and venlafaxine, which are well tolerated and safe
• Anti-epileptic medication such as carbamazepine, sodium valproate or gabapentin and pregabalin
• Transcutaneous electrical nerve stimulation and acupuncture may relieve pain in some patients
• Botulinum toxin injections into the affected area

A medical professional may prescribe opioids such as morphine for severe intractable pain. Nonsteroidal anti-inflammatories are generally unhelpful.

If you have significant discomfort but simple analgesics such as paracetamol do not control it, seek your doctor’s advice. You may get a referral to a Pain Clinic at your local hospital.

Prevention

Because the risk of severe complications from shingles is more likely in older people, those aged over 60 years might consider zoster vaccine.

Experts have produced a herpes zoster vaccine which can prevent varicella reactivation. The vaccine (called Zostavax®) is estimated to be 14 times more potent than the chickenpox vaccine and can be given to people aged 50 years or older. People with weakened immune systems should receive this treatment. The herpes zoster vaccine can reduce the incidence of shingles by half. In people who do get shingles despite being vaccinated, the symptoms are usually less severe and after-pains are less likely to develop.

© 2018 Dr Dilshaad Asmal, Dermatologist

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