This is, potentially, a very distressing condition, though not
necessarily so. It is caused by the chicken pox virus. After
an attack of chicken pox, the varicella herpes virus lays dormant
in the spinal cord, perhaps for many years. At some time in
the future, most commonly in the middle-aged and older, the
virus migrates from the spinal cord down, usually one, sensory
nerve (the nerve enabling touch, pain, hot and cold to be experiences),
and produces the typical rash on the skin. One does not catch
shingles. The potential to develop the disease has existed ever
since the individual had contracted chicken pox perhaps sixty
or seventy years earlier. Because, almost always, only one sensory
nerve is affected, then only one side of the body is affected
and the doctor can tell from a sensory map, a dermatome chart,
which nerve it is. When several dermatomes are involved at once,
the diagnosis might be questioned, but if confirmed, then the
patient must be fully investigated to exclude, or otherwise,
some serious underlying cause. Younger people, even children
may be affected but, generally, the attacks are not as severe,
or as painful, as they are in older people.
Classically the first warning of shingles is pain, before the rash has appeared. This is called pre-herpetic neuralgia. It can vary in time from a couple of days to a couple of weeks. It can be confusing, often mistaken for something else, and, particularly as shingles so often affects the chest, can be misconstrued as pleurisy or even angina. The disease is confirmed by the appearance of blistering spots on the affected dermatome. The rash can vary considerably in severity. Broadly speaking, the worse the rash, the worse the pain but it is not all uncommon to see a severe rash with little pain and an almost negligible rash with great pain – and this does not mean the person affected is making a fuss! Very often the worse cases are those that affect the face and can cause blindness and facial paralysis. The rash dries up and scabs over in 2 or 3 weeks but the pain can remain for a long time (post-herpetic neuralgia). This can be severe, difficult to treat, and, in some unfortunates, life long.
The doctor will prescribe painkillers and an anti-viral drug such as aciclovir. Anti-viral drugs are not as effective against viruses as antibiotics are against bacteria but they are worth giving not least because they may reduce the amount of post-herpetic neuralgia. Patients with shingles are infectious, for some days after the rash appears, and can give chicken pox (not shingles) to those with no varicella immunity. The treatment of post-herpetic neuralgia involves all kind of medications including analgesics, antidepressants, anticonvulsant drugs as used in epilepsy and the local application of capsaicin products. |
