Hydrotherapy: Pain

Pain seems to be a very common word in every language or dialect around the world, for pain is a universal human experience. Almost every person that comes to the Desert Spring Therapy Center in Desert Hot Springs, California, comes with a complaint of pain.

What is Pain?

Dorland Medical Dictionary describes pain as a more or less localized sensation of discomfort, distress, or agony, resulting from the stimulation of specialized nerve endings.¹ Goodman classifies pains into four main categories. They are: cutaneous (from the skin), deep somatic (pertaining to structures of the body wall or cavity), visceral pain (body organs), and lastly referred pain (from a part of the body some distance away).²

Let us examine carefully where pain really comes from. Cutaneous pain is felt on or in the skin and the skin may be very tender. However the pain may not originate on the skin for it may come from the organs underneath or may even be referred from another location in the body.

Deep somatic pain relates to a body cavity like the chest or the abdominal cavity. It may originate from bone, nerve, muscle, tendon, ligaments, peritoneum (membrane lining the abdominal cavity), cancellous (sponge) bone, arteries, and joints.

It is interesting to note that the membranes covering body organs, like the pleura that cover the lungs, are insensitive to pain but that which covers the walls of the cavity where the organs are located is highly sensitive and well supplied with nerve endings. This type of pain may be associated with involuntary action such as sweating, lack of color (as paleness), or when stimuli due to internal causes excite the nervous system.

The visceral pain comes from internal organs themselves, such as the heart, spleen, great blood vessels, or groups or organs that make up a system such as the digestive, respiratory, or reproductive systems.

Because the membranes covering the organs are generally insensitive to pain, one may have diseased organs but not be aware of pain until the disease progresses and involves the lining and the walls of the cavity where the organ is located in the body. When organs are involved with pain, it is usually associated with signs and symptoms of illness. Disease of the abdomen may elicit pain in the low back or skin over the abdomen.

Referred pain seems to be felt in an area other than its origin. For example, pain from appendicitis may often occur in areas other than that of the appendix, or the pain or angina pectoris, from the heart, may be referred to the left arm, sometimes to both arms, or to the ear, jaw, back, or even the teeth.³

As with any illness, we need first to find the cause. This means getting an adequate diagnosis. Then we can go to work intelligently to “nip it in the bud” by removing the cause. Once this is determined, applications of heat and /or cold are tremendously effective in relieving pain.

How Do Heat and Cold Work?

Heat is a counterirritant; this helps explain its analgesic effect. “A counterirritant is defined as a superficial irritant that is intended to relieve some other irritant.” One explanation is this: let’s imagine two sensory messages arriving in the central nervous system (grand central station of the nervous system), at the same time. Their impulses are transmitted by different sizes or types of nerve fivers. Interaction between them may modify the quality and intensity by their acting on each other, and thus help relieve the pain.

In one early study, Gammon and Starr found that heat applied on the skin should not exceed 104 F, and it should be applied directly over the site of the origin of the painful stimulus. They also discovered that heat (from a hot water bottle, a fomentation, or other sources) should be applied periodically, five minutes on and ten minutes off, and repeated for most effective results.

Another way heat removes pain is through the increased blood flow, bringing increased oxygen to the oxygen-deficient part. It washes away pain-producing chemicals and reduces the painful swelling caused by excess fluid or edema.

Heat also relaxes the muscle fibers; thus relieving muscle spasms. It changes the state of tonus of the muscle, influencing blood flow by changing the intramuscular tension and releasing the “squeezed” blood vessels of a spasm.

The mental attitude of the patient toward heat may be helpful in relieving pain. A severely burned person may question the beneficial effects of heat. But continuous flow of warm water in a tub, or a wet sheet pack on the skin of the body, lessens tension and induces sleep because it gives a sense of security. Let the person receiving the treatment have an understanding that the benefits of heat will be helpful to overcome pain.⁴

When tissues are cooled, the metabolic rate is decreased (according to the van’t Hoff principle). That is, the use of oxygen and all the nutritional substances, as well as the production of lactic acid, and pain causing chemicals and all waste products by the tissues involved, including that of nerves, is decreased. Thus, there is a decrease of sensation. Even anesthesia can be achieved by trained personnel in appropriate situations.

Cold, as from an ice massage, can be used to stop pain receptors from starting pain, to lessen the production of pain chemicals, to stop nerve conduction of pain, or to reduce referred pain. Generally speaking, cold works better for early small burns, sprains, or trauma. Later, heat works better to boost circulation and encourage healing.

Because of this anesthetic effect, with decreased pain perception, such therapies as exercise, stretching, and massage to a part, can be given without eliciting too much pain.⁵

And remember—we may be encouraged by the sure promise of a new world where there will be no more pain.

Disclaimer: The information in this article is helpful and is educational. It is not the author’s or authors’ or Wildwood Health Institute’s intent to substitute the blog article for diagnosis, counseling, or treatment by a qualified health professional.

Copyright through December 2023. All rights reserved by Wildwood Sanitarium, Inc. 

1. Dorland’s Pocket Medical Dictionary, 25th Edition, WB Saunders Company, Philadelphia, PA, 1995[↩]
2. Goodman CC and Snyder KS. Differential Diagnosis in Physical Therapy, Send Edition, WB Saunders Company, Philadelphia, PA, 1995[↩]
3. Goodman CC and Snyder KS. Differential Diagnosis in Physical Therapy, Send Edition, WB Saunders Company, Philadelphia, PA, 1995[↩]
4. Adams RH. Heat for the relief of pain. The Physical Therapy Review, 40 (2), 1960[↩]
5. Dail CW and Thomas CS. Simple Remedies for the Home, Teach Services, Brushton, NY, 1991[↩]