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 (Article published in TOGS September  2006 edition)

 

Trigger point injections in chronic pelvic pain

Dr.Shobhana Mohandas.MD.DGO. FICOG.Dip.Endoscopy: Chief  Gynaecologist  & Endoscopic surgeon

Sun Medical Centre, Unit of Trichur Heart Hospital,Thrissur.

 

Chronic pelvic pain is a common vexing problem faced by the gynaecologic patient the world over.  Aetiological factors for this problem are varied. Pelvic pain could be caused by pelvic inflammatory disease, pelvic adhesions, pelvic venous congestion, endometriosis, ectopic pregnancy, fibroids, ovarian cysts, or neoplasms.  In the acute phase, medical or surgical treatment may be required for any of these aetiologic factors.  Once the acute phase treatment is over, the patient, sometimes, may be left with a nagging pain which she may describe as: “I get pain when I strain to bend, or turn”,or. “ I get pain when I press on my abdomen”.  This type of pain may ensue commonly after abdominal surgery, like LSCS or abdominal hysterectomy, but may also follow treatment for acute pelvic inflammatory disease. 

On examination, pelvic examination will reveal non-tender uterus and ovaries. On examining the abdomen, on pressing the abdomen, tenderness will be elicited in specific spots in the abdomen, anywhere from the umbilical area to the pubic symphysis.  These are patients with pain in the abdominal wall, produced by fibrotic bands in the abdominal wall, which could be called, “Trigger Points”. The pain is usually mild, but irritating to the patient and may cause physical and mental agony.  The treating physician, quite often, for want of finding sufficient physical findings, may refer to it, as “functional”.  Such “Trigger Points” could be managed successfully with local injections of anaesthetic into the specific points.  What follows is a description of this less researched modality of treatment for chronic pelvic pain. 

 

Background: The first medical textbook that took the position that muscles cause pain was published by J. Travell and D.G. Simons in 1983.  As discussed in this text, the hallmark of myofascial pain is the

presence of one or more trigger points in muscles. Trigger points are hyperirritable bundles of fibers within a muscle which become "knotted" and inelastic, unable to contract or relax, due to an injury.  A focus of hyper-irritability in a tissue that, when compressed, is locally tender and, if sufficiently hypersensitive, gives rise to referred pain and tenderness, and sometimes to referred autonomic phenomena and distortion of proprioception.  An oxidative-dysoxygenative dysfunction (ODD) was proposed by Majid Ali as the systemic molecular pathogenetic model of fibromyalgia for all of its symptom-complexes.   The three primary molecular phenomena in ODD are oxidosis, dysoxygenosis (abnormal oxygen metabolism), and acidosis.  Trigger point sites show accumulation of fat droplets designated "fat dusting"; variations in width and intensity of staining of muscle fibers; nuclear enlargement and endomysial as well as perimysial nuclear clustering; fiber degeneration, contracture knots (club-like enlargement of myofibrils in vicinity of empty sarcolemmic tubes); and interstitial infiltration of metachromatic mucopolysaccharides. Ultrastructural abnormalities in TP tissues include the following: mitochondrial swelling, moth-eaten appearance of myofibrils, giant (double length) sarcomeres, disrupted sarcomeres, and excess collagen in advanced cases on histopathology.  The ODTP hypothesis (Oxidative dysoxygenative trigger point hypothesis) proposes that tender points develop as a result of accumulation of pools of oxidized and stagnant lymph (as well as oxidized and denatured blood components) within muscles, tendons and ligaments. Removal of such oxidized lymph clears the way for healing.

 

Selecting a patient with chronic pelvic pain for Trigger point injections:

 

When abdominal pain is chronic and unremitting, with minimal or no relationship to eating or bowel function but often a relationship to posture (i.e., lying, sitting, standing), the abdominal wall should be suspected as the source of pain.  Pain that is the same or increased when the abdominal wall is tensed generally indicates an origin in the abdominal wall.  Pain caused by intra-abdominal causes should be ruled out by noting the absence of associated symptoms like nausea, vomiting, diarrhea, physical findings like tender masses in the pelvis, etc.  Abdominal wall pain is chronic, nagging and non-progressive.  Tenderness originating from inside the abdominal cavity usually decreases when a supine patient tenses the abdominal wall by lifting head and shoulders off the examining table. In contrast, pain originating from the abdominal wall is unchanged or increased by this maneuver (positive Carnett's sign).  A tender trigger point in the abdominal wall is frequently no more than 1 or 2 cm in diameter. However, it is not unusual for the pain to spread over a wide area or to be referred.  In a gynaecologic practice, this sort of pain usually follows abdominal surgery.

 In about 100 cases for whom Trigger point injections were tried at Elite Mission Hospital by the author, most of the cases were patients who had undergone previous surgery.  Trigger point injections can also be used as a diagnostic test in ruling out other causes of pelvic pain.  If the pain totally subsides with TPI(Trigger point injections) no subsequent treatment need be given.  If not, a diagnostic/therapeutic laparoscopy may be needed in indicated cases. 

How do Trigger point injections work?

Trigger point injections act by the following mechanisms:

1)     Mechanical disruption of the abnormal contractile elements, which may result in the relief of muscle tautness and hyperirritability

2)     Fluid injections, which may dilute nerve-sensitized substances that may be present

3)     Muscle fiber damage, which may release intracellular potassium, causing a depolarization block of nerve fibers

4)     Feedback mechanisms between the central nervous system and the trigger point, which may be interrupted and

5)     Focal necrosis caused by the anesthetic agent, which could contribute to the destruction of the trigger point. 

 

 

 

How are trigger point injections given?

There are not very many research articles on Trigger point injections and many workers use various methods in giving these injections.  The method used by the author in treating about 100 patients in the past 5 years is described below.  The patient is selected carefully, making sure there is no acute abdominal cause of pain.  She is given realistic expectation of how much pain relief to expect after trigger point injections. On palpation of abdomen, there should be tender areas on touch and pelvic examination should not reveal any areas of tenderness.  All the fornices should be palpated deeply and bimanually in a careful manner to look for deep seated areas of tenderness.  If there are areas of tenderness, it is caused by pelvic infection/endometriosis/pelvic venous congestion.  They should be treated as such.

The selected patient is asked to lie supine.  A 20 cc syringe is filled with 2cc containing 100mg hydrocortisone (1 vial of Primacort) , 3-4 cc 2% Lignocaine, and about 15cc distilled water. Steroids presumably reduce inflammation or result in the thinning of connective tissue around painful nerve roots.  A lignocaine sensitivity test should be done for patients who have not previously undergone testing for hypersensitivity.  The patient is asked to show where her pain usually comes.  The tender area is localized, if possible with a finger. It is not always possible to localize with a finger.  The area is swabbed with methylated alcohol and a 21 guage needle attached to the 20 cc syringe is then inserted in the abdominal wall.  The patient is asked to report pain , when a painful point is reached.  For example, the needle is inserted in one point and the patient is asked, “Do you have pain?” She may say no.  The needle is withdrawn a little bit, and re-inserted in another direction.  When a trigger point is reached, she would wince with pain and say, “ Oh yes, it is painful”

1-1.5cc of the solution in the syringe is injected at that point and the injection is usually very painful.  The needle is again withdrawn a little without taking it out of the skin and reinserted in other areas to look for other trigger points.  In this manner, all the trigger points in this area are injected with 1cc of diluted lignocain-cum-hydrocortisone. 

The needle is now taken out of the skin and other tender areas sought on the skin.  The procedure is repeated there.  The depth of the needle is not fixed and may depend on the thickness of the abdominal wall. 

Response:

Apart from 2-3 patients, treated by the author, all patients have been cured of pain.  The patient continues to have pain at the points where the needle was inserted for 3-4 days, but after that she stays  totally pain free.  No patient has been given repeat injections under the author’s care, although many other workers have mentioned repeat injections in studies involving trigger point injections in many sites in the body. 

 3 elderly patients had vaso-vagal syncope after the treatment.  It subsided with rest and IV- fluids.  There was no need for hospital admission. 

Conclusion:

Trigger point injection therapy is a very effective therapy for abdominal pain of myofascial origin.  It should be tried in all patients with pelvic pathologiesbefore going in for surgical remedies, if the pain seems to have a myofascial component to it in addition to the abdominal pathology.  This will lead to the patient being more satisfied post-surgically.  It should be tried in all post surgical patients complaining of chronic nagging pain.  Immediataely after surgery, a reasonable time should be given for the post-surgical inflammatory response to subside.  But if it persists for a long time, instead of asking the patient to put up with the pain or labeling her functional, a trial of trigger-point therapy would go a long way in alleviating the suffering of the patient. 

Bibliography:

Saud Suleiman: The Abdominal wall : an overlooked cause of pain: American Family Physician . Vol. 64/No. 3 :August 1, 2001.

     Laurie Barclay: ACOG Issues New Guidelines for Chronic Pelvic Pain : Obstet Gynecol. 2004;103:589-605.

Rueben.S.Ingber: Position Paper on Trigger Point Injections [Fibromyalgia and Myofascial Pain News: www.immunesupport.com

James Carter,John Slocumb: OBGYN.net Conference Coverage From IPPS - Simsbury, Connecticut - April/May, 1999: www.obgyn.net.

Shobhana Mohandas: Chronic Pelvic Pain: Desk top Reference in Gynaecology: 2000: PUbl: Jaypee Brothers.

Majid Ali: Oxidative-Dysoxygenative Trigger Points in Fibromyalgia  Pathogenesis, Diagnosis, and Resolution : J of Integrative Med 1999;3:38-47.



 

 

 

 


 


 

 

 

 

 

 

 

 


 

 

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