Advances and instrumentation in diagnosis and treatment of trigger points in human myofascial pain: veterinary implications

C. RECENT ADVANCES IN TP/MYOFASCIAL SYNDROME THERAPY IN HUMANS AND ANIMALS

Conventional treatment of lameness in athletic animals includes physiotherapy, rest, analgesic and anti-inflammatory medication, topical application of liniments, poultices, hot- or cold- packs, dressings or support bandages etc. Severe damage to fascia, tendons or muscles may need surgery. Treatment of equine back-pain may involve change of saddle or rider or the use of better saddle-pads. In spite of conventional measures, many horses and greyhounds take weeks or months to regain the potential for full athletic performance.

Direct injury, overstretching and viral diseases are the main cause of TPs. Active TPs can become passive following a period of rest or conventional treatment. Passive TPs are easy to reactivate (Verhaert 1985). Therefore, it is advisable to search for TPs in patients recovering from such incidents, even those patients which appear to be clinically normal. All TPs should be treated by first-aid or professional methods.

Animal TPs are easy to find by palpation. Finger or probe pressure or electrical stimulation of TPs is very painful: their palpation usually causes dogs to howl, snap or bite (Janssens 1984, 1987) and cattle or horses to vocalise, buck, kick, cringe, yield or go down or take definite aversive action (Kothbauer and Meng 1983; Cain and Rogers 1987). All TPs should be eliminated. Fully healthy tissue contains no TPs.

If multiple TPs are present and if pain is generalised, one must be selective in the choice of points for treatment. Treatment of many TPs in one session can be very painful. The human patient may not return for follow-up treatment and the animal patient may be much more difficult to handle in subsequent sessions. One can manage such cases as follows:

a. Humans with multiple TPs are best treated at special AP points (such as LI 4, LV03, ST36, PC06, BL23) for 1-3 sessions before TP therapy begins. In many cases, these preliminary sessions help to localise the clinical pain, making the selection of TPs easier.

 

b. Animals with multiple TPs: The special AP points ((a), above) are easy to locate and needle in dogs. However, in horses and cattle, LI 4 and LV 3 are difficult to locate or needle and ST36, PC06 are difficult to needle. In those species, one can use BaiHui (lumbosacral space), TH15, BL23 in the preliminary sessions.

 

 

With manageable numbers of TPs at presentation (or following preliminary AP sessions), one may start with the less painful TPs. These tend to be older, less active and associated with earlier symptoms than those of the current problem. Their palpation may refer little pain. Their elimination often eliminates the current problem also. If not, the more recent TPs are treated later on (Verhaert 1985).

Where there are few TPs to be treated, the most important ones to treat are the most painful ones. These are usually the most recent, are active and, on palpation or needling, refer pain to the patient's subjective problem area. Elimination of the more recent active TPs may shift the patient's pain pattern to that of older (less active or, now, passive) TPs. These may be treated later, if they persist.

Many methods are used to treat TPs. They include "stretch and spray", massage/vibration, TP injection, dry needling, electro-AP, TENS, laser and other methods.

TP "stretch and spray" technique: This is a method suggested by Travell and Simons. The muscle(s) containing the TPs are stretched (painful) and sprayed by an aerosol coolant (ethyl chloride or similar substances). It may be suitable for TPs in limb muscles in humans and dogs but has little practical application in horses because of the pain involved and the mass and power of the muscular system in horses.

TP massage/vibration: This is a common form of first-aid and is used 1-2 times/ day in physiotherapy. It is very useful to prescribe Do It Yourself or First-Aid massage (by a friend, partner, animal handler etc) daily between TP therapy sessions.

Massage/vibration can be given by hand or by mechanical instruments. Because of the mass of the equine muscular system, massage is best done by "fisting" the TPs for 4-6 minutes/day. Massage can be combined with rubs or liniments containing physical stimulants/rubefacients (such as alcohol, menthol, mustard, turpentine, acetic acid, salicylate) or penetrating agents/ dispersants (DMSO: operator should wear gloves !). Moss recommended massaging in adrenalin cream in humans.

TP injection is very successful and takes little time. It was the original method used in German Neural Therapy. Melzack (1977) said that short acting local anaesthetic blocks of TPs often give prolonged, sometimes permanent, relief of some forms of myofascial or visceral pain. It is the most suitable method for busy medical and veterinary practitioners, if the patient can tolerate it. Cain and Rogers (1987) have used TP and AP point injection successfully in equine patients for many years.

The solution for injection can be saline; Impletol (Bayer, Germany); 0.5-1% procaine or xylocaine; solutions containing Vit B1, B12, salicylate, DMSO; homoeopathic preparations etc. Many different types of solution are used, with similar results. Some clinicians feel that better results are obtained with saline or slightly irritant solutions than with those containing local anaesthetics. They explain this by longer periods of TPstimulation post- injection.

It is important to "hit" the centre of the TP. Chronic, fibrotic TPs may be difficult to penetrate. This can be very painful to the patient and (in humans) usually refers pain to the patient's subjective pain area. Needle sizes vary from 10-40 mm, depending on the depth of the point. Needles are 21-25 gauge. The volume injected at each TP depends on the tissue to be injected. In dogs and humans, volumes are 0.25-5 ml; in horses 1-10 ml.

Fischer believes that vigorous needling and injection is necessary to break down the scar (fibrous) tissue in chronic myofascial TPs. However, this belief is not shared by others. For instance, Janssens (1984, 1987) treated TPs using 5 minutes simple needle insertion/session in some dogs and injection in others. He could see no clear difference between the methods. Pontinen has used TENS, Laser and simple AP successfully to release TPs in humans and Rogers has used electro AP successfully to release TPs in horses with myofascial pain.

Scars are usually injected with small volumes, 0.1-0.2 ml/point and all tender points along the scar are injected. A dental syringe and 25 gauge needle are used. Alternatively, the French Dermojet (high pressure) spray-injector can be used.

TP dry needling: This is the usual method of stimulating AhShi points and AP points. Sterile 28-34 gauge AP needles or fine hypodermic needles are inserted into the centre of the TPs. They are left in-situ for 5-20 minutes, with or without manipulation (pecking, rotation). It is suitable for relaxed, placid patients but requires a longer session time than injection. Janssens (1984, 1987) has reported good results with simple needling in dogs. The method may not be suitable for very nervous, active or dangerous patients.

TP Electro-AP: This method is similar to dry needling but the needles are stimulated by an AP electro-stimulator. It has been used successfully by Pontinen in humans and Rogers in dogs and horses. It requires a longer session time than injection.

TP TENS: Transcutaneous Electrical Nerve Stimulation can be used to treat TPs in humans (Pontinen 1987). Skin electrodes are lubricated with a saline jelly and are taped over the TPs and connected to the stimulator. Output frequency is usually set in the range 1-10 Hz. Output is increased gradually until a strong but comfortable stimulus is attained. The muscles underneath usually show a visible twitch. Session time is usually 20 minutes. Patients can be treated at the clinic 1-2 times/week or can be given a personal, portable TENS instrument and shown which points to stimulate and how to operate the instrument. In that case, TPs are treated daily for 10-60 minutes. The results are excellent.

TENS in animals poses many problems. Little has been published on the use of TENS on animal TPs. The hair may need to be clipped and electrodes are more difficult to keep in place than in humans. A variation of TENS, using AP stimulators connected to gauze bandages soaked in saline solution and applied to AP points on the limbs or painful joints/bones has been used successfully by some veterinary acupuncturists. The use of TENS in animals needs to be supervised at all times.

TP Laser: Laser is an electromagnetic energy in the visible or infrared light range. The beam but can be interrupted (modulated) at variable frequencies and intervals by mechanical or electronic means. Mid-power lasers (5-30 mW/cm sq), mainly class 3A and 3B are used.

The most common is the Gallium Arsenide (Ga-As) or diode laser, emitting invisible light (902 nM) in the infra-red range. The depth of penetration increases with wavelength (Kolari et al 1988). Thus, cold laser is most effective when the tissues to be treated are superficial and infrared laser penetrates deeper than HeNe (red) laser.

Laser is usually given 2-8 times, at intervals of 1-3 days. At each session, the laser is applied for 20-120 seconds to or around the rim of the lesion and to each of the AP points or TPs selected for the case. Irradiation time depends on output power and depth of point. High output lasers and superficial points need less irradiation time. Airaksinen et al 1988 and Pontinen 1987 reported good results in TP therapy in humans.

Although Laser has been used successfully to treat back pain in horses (Martin and Klide 1987) and many veterinary acupuncturists are using lasers, there is little published on the use of laser on animal TPs. It is possible that lasers for human use may not be powerful enough to reach deeper TPs in large animals. More powerful veterinary lasers are being tested now.

Laser irradiation of scars, especially if concentrated on tender points, keloids and areas of marked adhesion, can produce dramatic clinical improvement in these cases.

Other methods have been used to treat TPs. They include heat, cold, faradism, ultrasound and moxibustion. Ultrasound and faradism are said to give poor results (Melzack et al 1977; Melzack 1978; Brook and Stenn (1983), Janssens 1984).