Trigger Point Injection Brian Shian, MD, FHM Department of Family Medicine University of Iowa Hospitals and Clinics Objectives Discuss the definition and diagnosis criterial Explore possible pathophysiology Identify the role of Ultrasound in evaluation and treatment Review agents used for local injection Demonstrate ultrasound guided injection What is a Trigger Point (TrP)? A TrP is generally considered a localized spot in theskeletalmusclewithwhichofthefollowing characteristic? A. Tenderness under palpation B. Palpable nodule in a taut band C. Tenderness, referred pain and twitch with compression D. No consensus Travell, Janet; Simons David; Simons Lois (1999). Myofascial Pain and Dysfunction: The Trigger Point Manual (2 vol. set, 2nd Ed.). USA: Lippincott Williams & Williams 1
Trigger Point Discrete, focal, hyperirritable spots located in a taut band of skeletal muscle. Painful on compression and can produce referred pain, referred tenderness, motor dysfunction, and autonomic phenomena. Hypothetical and unproven etiology Simons DG, Travell JG, Simons LS. Travell & Simons' Myofascial pain and dysfunction: the trigger point manual. 2d ed. Baltimore: Williams & Wilkins, 1999:5. Related Terms Taut band Active trigger point Latent trigger point Key trigger point Satellite point Jump sensation or sign Margulis, RK. Tandem Point(SM) Therapy: An integrated acupressure approach for myofascial pain. NIH Grand Rounds, March 17, 2000. http://www.tandempoint.com/p2.htm Myofascial Pain Syndrome (MPS) Coined by Dr. Travell & David Simons in 1982 No laboratory test to assist the diagnosis Diagnosis is currently made by identifying a TrP in a person whose pain is consistent with the pain of a TrP and whose pain is reproduced in part by activation of the TrP. Travell J, Simons D. Myofascial Pain and Dysfunction, Vol. 1: The Trigger Point Manual, the Upper Extremities. Baltimore: Williams & Wilkins; 1982. 2
Pathophysiology Integrated Hypothesis: A disruption of Ach metabolism equilibrium caused persistent muscle contraction which cause muscle injury Injured muscle release substance to activate muscle nociceptors and cause pain This theory remains conjecture in the face of conflicting data Quintner JL, etc. A critical evaluation of the trigger point phenomenon. Rheumatology (Oxford). 2015 Mar;54(3):392 9. TrP: Intertester Reliability Nice DA, etc. Intertester reliability of judgments of the presence of trigger points in patients with low back pain. Arch Phys Med Rehabil. 1992 Oct;73(10):893 8. TrP Under POCUS Sikdar S, et al. Assessment of Myofascial Trigger Points (MTrPs): A New Application of Ultrasound Imaging and Vibration Sonoelastography 30th Annual International IEEE EMBS Conference Vancouver, British Columbia, Canada, August 20 24, 2008 3
Proposed Diagnosis Criterials Based on a Delphi study, a panel agreed that two palpatory and one symptom criteria for the identification of a TrP: I. a taut band II. a hypersensitive spot III. referred pain I and II applied to both active and latent TrPs III could include pain, or other sensations, such as tingling or numbness. A TrP should meet at least two criterial Fernandez de las Pe~nas C, Dommerholt J.International consensus on diagnostic criteria and clinical considerations of myofascial trigger points: A Delphi Study. Pain Med 2017;19(1):142 50. Common Trigger Point Locations Occipital area Upper back Lower back Abdominal wall Facial TMJ Pfenninger GL, Fowler GC. (1994). Procedures for Primary Care Physicians. St. Louis, MO: Mosby, Inc. Trigger Point Management Non invasive compression spray and stretch TENS High intensity focused US Invasive Local injection Acupuncture Dry needling 4
Trigger Point Injection (TPI) A common treatment modality Mechanic effect Chemical effect Vasodilation Dilution & removal toxic material Inhibit Ach release Pfenninger GL, Fowler GC. (1994). Procedures for Primary Care Physicians. St. Louis, MO: Mosby, Inc. TPI Indication Unexplained localized pain Migraine Renal colic Primary dysmenorrhea Nocturnal cal cramps Fibromyalgia? TPI Contraindication Injection site infection Concomitant use of an anticoagulation Hemorrhagic syndrome Septicemia Resuscitation equipment not available Significant psychiatric disturbance Pfenninger GL, Fowler GC. (1994). Procedures for Primary Care Physicians. St. Louis, MO: Mosby, Inc. 5
TPI Complications Local complication Myositis ossificans Intramuscular hematoma Wrong structure Neurovascular injury Wrong depth: Intrathecal injection Pneumothorax Descending necrotizing mediastinitis Local anesthetic Injection Agents Bupivacaine, ropivacaine w/wo dexamethasone New local anesthetics Saline 5 HT3 receptor antagonist tropisetron Botulism toxin A/Dysport Levosulpiride Special Site Injection Great occipital nerve Anterior abdominal cutaneus nerve Lumbar plexus Pudendal nerve Dorsal ramus of spinal nerve 6
ACNES Injection Predict Injection Failure Hopwood MB, Abram SE. Factors associated with failure of trigger point injections. Clin J Pain. 1994 Sep;10(3):227 34. Dry Needling Patients treated with dry needling had postinjection soreness of significantly greater intensity and longer duration than those treated with lidocaine injection Hong CZ. Lidocaine injection versus dry needling to myofascial trigger point. The importance of the local twitch response. Am J Phys Med Rehabil. 1994 Jul Aug;73(4):256 63. 7
Other Interventions Myofascial release Bloodletting Extracorporeal Shock Wave Therapy Kinesiology taping EMG guided trigger point injections POCUS Role To identify trigger points To rule out other pathologies To localize key structures or organs To safely guide local injection POCUS Guided TrP Injection Demo 8
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