Question: Please discuss carotidynia, including its cause and treatment. I am a woman, 64, who has been tentatively diagnosed with the condition. I have never endured such intense pain, even from my heart attacks. How does carotidynia differ from temporal arteritis?

- Mrs. N.

Answer: The carotids (kuh-ROT-ids) are arteries running up the sides of the neck to deliver blood to the brain. When they become inflamed and distended, we call the resulting pain "carotidynia."

You cannot exaggerate the pain of carotidynia. The artery area is excruciatingly tender to the touch, and pain radiates over the face, neck, ear and head.

The exact cause of carotidynia is sometimes elusive.

Hot packs over the painful area along with anti-inflammation drugs might be all that you need until the episode runs its course. Some patients need cortisone drugs to disarm the inflammation.

"Temporal arteritis" describes a specific inflammation of arteries at the sides of the head, often part of a complex and widespread process throughout the body. Temporal arteritis requires administration of cortisone to prevent damaging consequences.

Temporal arteritis is sometimes associated with polymyalgia rheumatica, a special kind of widespread muscle ache. It, too, responds to the timely administration of cortisone drugs.

Facial pain also might signal an infected ear, a misaligned jaw joint or something else altogether.

You need specific answers to any problem that continues to produce pain.

The report I'm sending you discusses temporal arteritis. Others can order "Polymyalgia and Its Companion Ills" by writing: Dr. Donohue - No. 45, Box 5539, Riverton, NJ 08077-5539. Enclose $3 and a self-addressed, stamped (55 cents) No. 10 envelope.

Question: Every time I get a tetanus shot, my arm aches for three or four days, and it turns swollen and red. Can you explain why? What's in the shot?

- Mrs. T.

Answer: The tetanus shot contains a harmlessly dilute toxin, a poison made by the tetanus germ. If you have ever seen a lockjaw patient struggling through a muscle-spasm episode, you realize how important it is to be protected against the infection.

"Lockjaw" is the other name for tetanus. It is not a pretty sight. The victim cannot open his mouth, and the severity of the attendant muscle spasms elsewhere can actually damage bones.

I'm curious. How often do you get tetanus shots? You need updating of protection once every 10 years. Your reaction sounds a lot like overimmunization.

If you get a three-day ache from a normal protection shot, then you might help by applying heat over the injection area.

Some people do react too exuberantly to the shot. Even so, it's a small price to pay for the protection and peace of mind it affords.