Heat Tones Down Central Nervous System Pain

Intuitively, heat is soothing for sore muscles, it helps them relax. In fact, heat was the number two nondrug therapy identified in a 2004 survey of Fibromyalgia Network Members. But, can the application of heat realistically tone down the central nervous system pain that is the hallmark of fibromyalgia? Based on recently published data on patients with low back pain, the answer is “yes” and heat will even help with sleep.¹

A team in Germany used brain electroencephalogram (EEG) activity as an objective measure of the amount of noxious signals bombarding the brain due to the painful muscles in the lower back. By recording EEG activity, the researchers were able to detect whether the pain processing load in the central nervous system declined with use of heat applied to the lower back. This is of particular interest for people with fibromyalgia because signals entering the central nervous system are amplified, leading to an enhanced pain state. Although medications that target this central nervous system pain are usually prescribed, side effects often limit the dose that fibromyalgia patients can tolerate.

Identifying nondrug therapies that are capable of reducing the noxious signals into the central nervous system, but with little or no side effects, would greatly benefit people with fibromyalgia. Such therapies could be used in addition to medications to help tone down the pain.

The study consisted of two groups, each with 15 people complaining of low back pain. The control group received a bottle of a nonsteroidal anti-inflammatory drug (NSAID, such as ibuprofen) and were told they could take the medication for pain, if needed. The treatment group received four heat wraps, one to be worn each day for up to 8 hours during the next four consecutive days. In addition, this group also received the same NSAID with instructions that they may take it for pain, if needed. Subjects also completed questionnaires each day to evaluate pain, sleep, stress, work performance, and relaxation level.

All participants returned to the study center on day 2 and day 4 so that the researchers could measure their EEG activity. The amount of brain activity detected by the EEG at the highest end of the frequency range was tallied for each participant. Brain signals at the high frequency represent alerting and stressful stimuli, which is an objective measure of the relative degree of pain a person is experiencing. A drop in this value indicates that fewer noxious signals are entering a person’s central nervous system to produce pain.

Not only did the high frequency EEG values drop significantly for the heat wrap group, this objective reduction in pain occurred mostly during the first two days. Compared to the control group, the authors state, “the heat wrap therapy was more effective in reducing pain, decreasing stress at work, and increasing quality of sleep.”

Although people with fibromyalgia hurt all over, a patient’s most painful area can be the driving factor for determining a person’s overall pain level.² Applying heat to the region of most intense pain may not only “feel good,” it can also bring down your fibromyalgia pain to more tolerable levels. And, if the widespread pain is keeping you awake at night, take a long hot bath or shower just before bedtime (better yet, sit in a hot tub). For local pains, apply topical heat to the area during the day or at night (e.g., microwavable heat wraps, heating pads, or ThermaCare wraps by Procter and Gamble).

1. Kettermann B, et al. Clin J Pain 23(8):663-8, 2007.
2. Staud R, et al. Rheumatology 45(11):1409-15, 2006.