Shingles can be painful. Or not. And when it’s painful, it can be very very painful. It all goes back to a childhood infection.
It is chickenpox reincarnated. Here are the pathophysiologic links that lead to shingles.
- A person catches chickenpox, usually a mild disease producing a rash. This is called varicella, and it’s caused by a herpes virus. (The herpes virus family is a ubiquitous predator of humans.)
- Under attack by the person’s antibody defenses, the virus retreats to a what amounts to a protective cave, a nerve cell.
- The virus hibernates, perhaps poking its head out once in a while, only to get smacked down by the person’s antibody defenses.
- The person, now called the host, gets older. The host’s antibody defenses get weaker.
- The virus pokes its head out, finds it can replicate, and does so. It propagates down the nerve cell and out to adjacent skin, producing pain and an inflammatory rash. This is herpes zoster. Most people call this condition shingles. The virus and inflammation damage sensory nerves, especially key nerve junctions along the spinal canal.
- The rash fades, but pain may persist. This is called post-herpetic neuralgia, which means pain that occurs after a herpes event and is related to a nerve. Some also call this condition shingles.
Shingles Rash is Characteristic
Usually only one nerve junction is involved. The rash is associated with the area served by that one nerve junction, so it is seen on the skin in the area related to that nerve. This means it follows a dermatome. Dermatomes do not cross over the midline, so the rash is one-sided. Note: dermatomes are constructs, not anatomically pure. The field covered by a nerve does not abruptly and precisely stop at the midline, so crossover is typical. Often the rash stretches from the back bone around the body on one side to about the midpoint in front. This suggests half a girdle, and the word shingles comes from Latin for girdle. The rash look like chickenpox: redness, tiny bubbles.
Because the pain may precede the rash by several days, the condition may be misdiagnosed at first. Pain along the mid-abdomen may resemble gall bladder pain, for example.
Often the pain is mild. But the pain may get worse even as the rash fades. It can be knife-like, or like extreme soreness. The skin over the area may be very sensitive. People may not even want clothing to touch it.
Shingles is Not Contagious and Can be Prevented
There are live viruses in the rash. These are the chickenpox viruses. Chickenpox can be transmitted from the rash. After a person gets chickenpox, they may get shingles if/when their antibody defenses get weak.
Vaccine that prevents shingles (varicella vaccine) will, obviously, prevent the associated post herpetic neuralgia.
Sources:
Barbara G. Jericho MD: Postherpetic Neuralgia: A Review. The Internet Journal of Pain, Symptom Control and Palliative Care 2010 : Volume 8 Number 1
(US) Centers for Disease Control
James Cooper - I'm on the faculty of a health science department at a large university. Most of my articles derive from conferences or presentations ...
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