Closing the gate on pain: Body and Mind
Pain clinics offer victims a variety of means to take active control of their Suffering. Sarah Hoill gave birth to her first baby seven years ago, but she cannot remember much about it. At the time she was under the influence of pethidine injections and entonox (“gas and air”), which made her feel so groggy that she felt she wasn’t really participating in her own delivery.
Second time around and three years later the Hills replaced the pethidine with a privately hired TENS machine, with more rewarding results, and by the time their youngest was born in 1992, TENS machines transcutaneous electrical nerve stimulators could be found in most delivery suites around the country. Today their use is actively promoted by midwives, and the Natural Childbirth Trust encourages people to hire TENS machines and instructions, for use at home as well as in hospital, for the four weeks around the expected date of delivery. The hire cost is about Pounds 30.
TENS machines are also used with varying degrees of success in other situations, most commonly by people who suffer from chronic pain which is localised in one part of the body. They were first developed in the late 1960s, and the most basic kind is a small, portable, battery-operated electronic box that can be worn on a belt without getting in the way of day-to-day activities. Two or more electrodes are stuck to the skin with tape or self-adhesive pads, about three inches apart, on or near the painful area.
Shirley Sawyer, who runs the TENS Clinic at Musgrove Park Hospital in Taunton, says: “It is usually a matter of trial and error to find the most effective spot for any individual patient, but in my experience about 60 per cent of people who come to us for a two-week trial get some relief from TENS. The most common problems patients present us with are lower back pain and sciatica, but we also have some success with painful shoulder or knee joints.”
When a TENS machine is switched on, it sends out a steady stream of electrical signals which are felt as a pulsating or tingling sensation. The device is thought to work on the principles of the “gate theory” of pain. In its simplest form, this suggests that pain is felt when an unpleasant stimulus causes an electrical message to travel along nerve fibres to the spinal cord, and from there up to the brain. A series of “gates” within the spinal cord determine whether these messages get through to the brain. If a gate is open, more pain messages pass through and the person experiences higher levels of pain. Factors which tend to open a gate are stress, tension, thinking about pain and immobility. Factors which close a gate and prevent pain messages being transmitted include relaxation, distraction, exercise and mobility.
TENS machines are also thought to close the gate. The stream of regular electrical pulses from the TENS activates some of the larger nerve fibres, which transmit the sensation of “touch”, and this has the effect of closing the gate and inhibiting pain messages from getting to the brain. It is similar to what happens when you rub a part of your body when it hurts, or put it under a cold tap.
TENS machines cannot offer relief if the nociceptive system the part of the nervous system which transmits pain becomes damaged. The nervous system used to be considered a fixed “wiring” system, but now it is thought of more as a “plastic”, changeable, living system. If tissue is damaged, the pain fibres in that region can become muddled up, sometimes permanently.
The results can be alarming. The pain receptors in the damaged area may become so hyper-sensitive that even the slightest touch in that area is sent off mistakenly as a severe pain message and this hyper-sensitivity may last for years, long after the original damage has occurred and healed. Some people who have such tender skin or allodynia are suffering from post-herpetic neuralgia, a condition where nerves have been damaged by the shingles virus. In this case, because of the allodynia, the TENS electrodes are often not tolerated in the very region which is painful.
Most hospitals hold regular pain clinics. Some patients have suffered from chronic pain for several years before they are referred to a pain clinic, while others may be referred within weeks of sustaining an injury or developing a painful medical condition. Not surprisingly more than 50 per cent of people who attend pain clinic are unable to work, and many will have to endure some pain for the rest of their lives.
For this reason, Dr Barry Nicholls, the consultant anaesthetist who runs the pain clinic at Musgrove Park Hospital, recognises that people with chronic pain often respond much better to a long-term psychological approach to pain management than to the more traditional, short-lived relief.
Dr Nicholls tries to explain to patients that he may not be able to offer a diagnosis, nor find the cause of their pain. Many will already have been around the usual circuit of GPs and specialists and will have been fully investigated a long time before they get to see him. Part of his job, as he sees it, is to explain that while conventional medicine in a sense has failed them, they can be taught to manage their pain in a way that is very effective in the long term.
“I try to explain it by comparing the pain they feel with ripples in a pond caused by throwing a stone in. The original stone has disappeared under the water, but ripples remain on the surface. Searching for the stone by sticking your hand in simply causes more ripples and disturbances. It can be the same when you look for the cause of chronic pain.”
TENS machines can also play a valuable role in pain management programmes. Unlike injections and pills, and even acupuncture and osteopathy which are all interventions performed by others, keeping patients in a very passive state TENS machines can be used and controlled solely by the patient, placing them in a much more powerful and active position.
It is this “active control” that clinical psychologist Patrick Hill is seeking to harness at the pioneering pain management department at the Gloucestershire Royal Hospital. This department is just one facet of Gloucester’s health psychology service itself one of only a handful which exist in the NHS.
As Dr Hill explains: “The focus of the health psychology service is not to find people with psychological disturbances, but to take people with a health problem and to apply a psychological, rather than just a medical approach to it in this case, to their pain.”
The pain management service has devised a number of courses for patients with chronic pain which last from four to eight weeks. The courses facilitate the process which helps people to change from being “passive patients” to “active copers”, and are designed to emphasise the importance of pain management, rather than cure.
The whole process concentrates on empowering people through their perception of control by exercise, relaxation, practical strategies, goal setting and psychological techniques. For the longer term, the multi-disciplinary team who run the course try to ensure that people are equipped to carry on working independently so that when the course finishes, they are able to be self-supporting and self-reliant.
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