Trigger point dry needling, also referred to as intramuscular stimulation (IMS) and/or intramuscular therapy (IMT) is an invasive procedure in which an dry needles are inserted into the skin and muscle.  It is a physical therapy modality used in conjunction with other therapies to treat myofascial pain.
Dry needling involves insertion of filament needles into the muscle that have contracted and become shortened.  These shortened muscles compress and irritate the nerves. The aim of dry needling is to achieve a local twitch response to release muscle tension and pain. Dry needling is an effective treatment for chronic pain, such as chronic low back pain and sciatica symptoms.
A healthy muscle feels very little discomfort with insertion of this needle. However, if the muscle is sensitive, shortened or has active trigger points within it, the subject will feel pain as a sensation like a muscle cramp -‘the twitch or cramping response’. This sensation lasts only a few seconds.
Intramuscular dry needling can reduce pain, while increasing flexibility and range of motion by:
•stretching receptor in the muscle by stimulation, producing a relaxation or lengthening
•the needles cause a small injury that draws blood to the area, initiating the natural healing process
•the treatment creates an electrical potential in the muscle to make the nerve function normally again
The number of treatments required depends on several factors: your general health, the duration and extent of your condition, how much scar tissue there  is and how quickly your body can heal.  The rate of healing also depends on the condition of your nerves.  If the pain is of recent origin, one treatment may be all that is necessary.  The average person responds very well within 4 to 6 treatments.
IMS has a remarkable success rate, as proven by the elimination of symptoms and signs, even for chronic pain.