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Pointing light at musculoskeletal and neurological conditions: clinical applications 115

Figure 9.4 Paraspinal muscle
contracture treatment in a patient
with chronic intervertebral disk
disease (IVDD) and spondylosis.

the muscle from different angles, as well as its tendons. medicine – an exception would be traditional Chinese

For instance, if you are treating the gracilis muscle for veterinary medicine, especially for equine patients.
contracture, you have to include the area from its origin Myofascial pain is often underestimated and undi-
in the pubic symphysis to the insertion in the cranial agnosed, and has implications in patient biomechanics
border of the tibia. And for this particular treatment, and quality of life. These “contraction knots” may cause

you probably also want to include the semitendino- lameness, restriction of range of movement, and auto-
sus muscle, from the tuber ischiadicum to the medial nomic signs. So although treating the TPs may not be
surface of the tibia. You may even want to treat both enough for the patient, it is necessary to treat them if
hindlimbs. Measuring the area – or making a good esti- we want to provide the best analgesia. Laser therapy is
mate of it – will give you an accurate idea of how much one of the therapeutic modalities that can help allevi-
energy you need if you want to stay within a certain ate this pain. Let’s have a quick review of how TPs are
2
dose range. In this example, if the area is 600 cm and formed to understand why.
2
you want to use a dose of 8 J/cm , you should prob- Local factors, as well as central and biomechanical
ably create or customize a program that will eventually factors, are considered in the etiopathogenesis of TPs.
deliver around 4800 J – the preset programs for the Locally, they are the result of abnormal depolarization
knee or the hip usually deliver only around 700–2500 J of motor end plates. Just to refresh a little bit, in the
since they are designed for smaller areas. motor end plate we have a presynaptic neuron, a syn-

aptic space, and a postsynaptic muscle fiber. The neuro-

9.4.1 Trigger points transmitter of this connection is acetylcholine, or Ach.
So increased contraction may be due to increased lib-
During soft-tissue palpation, you may find trigger eration of Ach in the presynaptic neuron, or to excess

points (TPs), which are considered a form of myofascial activity or number of postsynaptic Ach receptors. Any
pain. A TP is felt as a taut tender band or nodule, which of these will lead to spontaneous electrical activity,
elicits a local twitch on palpation and a pain response which is actually measurable. [304]
(called the “jump sign” in humans) either in that spot Sustained contraction leads to compression of local
or in a referred area. TPs and their corresponding areas sensory nerves and vessels, with subsequent hypoxia.

of referred pain have been mapped in humans, but this This, together with the increased adenosine triphos-
inter-area link is not usually described in veterinary phate (ATP) demand (because the muscle is contracted)

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