Those who have suffered the fairly common discomfort of a "muscle knot" know the pain associated with such constricted muscles. These often show up in skeletal muscles as tight bands of muscle fiber. The condition is so common that it has been given its own name, being referred to within medical circles as a myofascial trigger point.
While there is no conclusive, definitive reason why muscle knots appear, a number of theories exist, as do a number of treatment options. It is known that something triggers a tightening reaction of the muscle, after which that same muscle fails to relax. As a result, the small area of muscle in question begins to ache and may become sensitive to the touch. If left untreated, this trigger point can begin to affect surrounding nerves, can worsen as a result of a diminished blood supply to the area (which can initiate a spiral cycle known as metabolic crisis), and may end up resulting in referred pain (a type of pain that occurs when nerve signals from several areas of the body "feed" the same nerve pathway leading to the spinal cord and brain).
Trigger points can be caused by many things, including traumatic injury, muscle tension, muscle spasms, over exertion, pinched spinal nerves, and hormonal deficiencies. If a collection of trigger points becomes large enough, the resulting chronic pain condition becomes known as myofascial pain syndrome (MPS). New research indicates a strong correlation between fibromyalgia tender points and myofascial trigger points.
A trigger point injection (TPI) can be used as an effective treatment of involved muscles in many areas of the body, the most common being the neck, back and shoulders. During the procedure, a small needle is inserted into the affected area using x-ray guidance (fluoroscopy), and a local anesthetic (sometimes with a steroid anti-inflammatory) is injected. The injection of medication will numb the trigger point, alleviating any associated pain. The ultimate goal is to have the muscle relax to a normal, inactive state.