This Session by Simon Strauss

Transcription

1 This Session by Simon Strauss Myofascial Pain. Part A Myofascial Pain. Part B Pain Assessment Tools. Part C

2 Definitions and Language of Pain Allodynia- 1. A lower than normal pain threshold. 2. A clinical situation where pain results from a stimulus which should normally be painless. 3. Pain upon palpation at less than 4kg/cm 2 or less at a site, which does not cause pain at the same anatomic site in normal individuals. Dysesthesia- Unpleasant sensations ranging from numbness to pins and needles.

3 Definitions and Language of Pain Hyperalgesia: A greater than normal response to a stimulus expected to cause pain in a normal individual. Fibromyalgia: Chronic widespread Allodynia. Nociception: The neurochemical process by which pain signals are transmitted from the periphery to the CNS and perceived by the individual

4 Definitions and Language of Myofascial Pain Myofascial Trigger Points (MTrPs) : May be active or latent An active Myofascial trigger point is a focus of hyper-irritability in a muscle or its fascia that causes the patient pain.

5 Definitions and Language of Myofascial Pain An active Myofascial trigger point causes pain and tenderness at rest or with motion that stretches or loads the muscle. It prevents full lengthening of the muscle, as well as fatigue and decreased strength. Pressure on an active MTrP induces / reproduces some of the patient s pain complaint and is recognised by the patient as being some or all of his or her pain.

6 Definitions and Language of Myofascial Pain A Latent Myofascial Trigger Point: does not cause pain during normal activities. It is locally tender, but causes pain only when palpated. It also refers pain on pressure. It can be associated with a weakened shortened more easily fatigued muscle. A Palpable / Taut Band: is a group of muscle fibres that is associated with MTrPs and is identifiable by its rope-like consistency.

7 Definitions and Language of Myofascial Pain Twitch response: a transient contraction of part of the involved muscle in response to needling or snapping palpation Jump Sign: A general pain response of the patient, who may wince, vocalise or jump in response to pressure on a MTrP. Involved muscle: A muscle that contains one or more MTrPs

8 Myofascial Pain Syndromes Can be thought of as Pain Syndromes that are caused by and are maintained by one or more active Trigger Points and their associated reflexes

9 Myofascial Pain Syndromes The Trigger Point is the Pain Generator

10 Myofascial Pain Syndromes Prevalence Unselected and Control Groups Danish study of 1504 people, aged 30-60, 37% of males and 65% of females had localised myofascial pain. 100 male and 100 female airforce personnel (Av. Age 19) 45% of males and 54% females had focal neck muscle tenderness ( latent trigger points). 269 female student nurses. 45% had TrPs in masseter, 35% had TrPs in trapezious. 28% had myofascial pain at the time of examination.

11 Myofascial Pain Syndromes Prevalence Unselected and Control Groups Lumbogluteal muscles: Assessment of 100 asymptomatic control subjects. Revealed latent TrPs in 45% of Quadratus Lumborum, 41% of Gluteous Medius, 11% of Gluteous Minimus, 5% of Piriformis.

12 Myofascial Pain Syndromes Prevalence Anecdotal evidence suggests that Ballerinas, Swimmers, Runners and indeed any group of athletes that uses a group of muscles in a prolonged or repeatedly forceful manner are likely to have latent trigger points and therefore can be toppled into a Myofascial pain state.

13 Myofascial Pain Syndromes Prevalence Patient Groups Community pain medical center. 96 Patients studied by a neurologist: 93% had at least part of their pain caused by myofascial TrPs and in 74% of the patients myofascial TrPs were considered to be the primary source of Pain.

14 Myofascial Pain Syndromes Prevalence Patient Groups Comprehensive pain center 283 consecutive admissions to a comprehensive pain center: The diagnosis made independently by a Neurosurgeon and a Physiatrist based on physical examination as described by Travell and Simons assigned a primary organic diagnosis of myofascial pain in 85% of the cases.

15 Myofascial Pain Syndromes Prevalence Percentage of Patients with another diagnosis who also had Myofascial TrPs contributing to their pain problems Diagnosis Number Myofascial TrPs % with Source Cervicogenic Headache Reflex sympathetic Dystrophy % Lin et al 84 82% Lin et al Fibromyalgia % Finestone et al

16 Myofascial Trigger Points Clinical Features History of spontaneous pain associated with acute overload or chronic overuse of the muscle. The mildest symptoms are caused by latent TrPs which cause no pain but cause some degree of functional disability. More severe involvement results in pain related to the position or movement of the muscle. The most severe level involves pain at rest.

17 Myofascial Trigger Points Palpable Band. Clinical Features A cord like band of fibres is present in the involved muscle. INJURY This can be difficult to identify when there are overlying muscles or thick subcutaneous tissue.

18 Myofascial Trigger Points Spot Tenderness Clinical Features A very tender small spot which is found in a Taut Band. The sensitivity of this spot (TrPs) can be increased by increasing the tension on the muscle fibres of the taut band.

19 Jump Sign Myofascial Trigger Points Clinical Features Pressure on the tender spot causes the patient to physically react to the precipitated pain by exclaiming or moving. Ah-Shi - Oh yes! This reaction indicates the level of tenderness but is also dependent on the pressure exerted by the examiner.

20 Myofascial Trigger Points Pain Recognition Clinical Features Digital pressure on or needling of the tender spot induces / reproduces some of the patient s pain complaint and is recognised by the patient as being some or all of his or her pain. Ah-Shi - Oh yes! This finding by definition identifies an active trigger point. This replication of the patient s pain may require sustained pressure (5-60 seconds) on the TrP.

21 Myofascial Trigger Points Twitch Response Clinical Features Is a transient contraction of the muscle fibres of the taut band containing the trigger point. The twitch response can be elicited by snapping palpation of the trigger point. Or more commonly by precise needling of the trigger point.

22 Myofascial Trigger Points Clinical Features Elicited referred pain and or tenderness An active MTrP refers pain in a pattern characteristic of that muscle -Usually to a site distant to the TrP. 85% of TrPs project distally. [The area of the referred pain is often tender and may contain satellite trigger points.] Latent TrPs also refer pain on pressure but usually require more pressure to do so.

23 Myofascial Trigger Points Clinical Features Restricted Range of Movement. Full stretching of the affected muscle is often involuntarily restricted by pain. Inactivation of the associated MTrP releases the taut band that is (? reflexly) restricting the muscle.

24 Myofascial Trigger Points Muscle Weakness Clinical Features The patient is unable to demonstrate normal muscle strength on static testing of the affected side as compared to the contra-lateral non-affected side. The involved muscle is also more easily fatigued.

25 Myofascial Trigger Points Postulated Explanations of Clinical Features Clinical Feature Palpable Band Spot Tenderness Jump Sign Pain Recognition Twitch Response Referred Pain and Tenderness Restricted Range of Movement Muscle Weakness Possible Explanation Continuos abnormal release of Calcium from sarcoplasmic reticulum Sensitisation of nociceptors in vicinity of motor endplate Severity of Trigger Point tenderness Aggravation of the Trigger point Spinal reflex activation of motor units Excitation of sleeping nociceptors Increase release of acetylcholine in neuromuscular junctions due to mechanical stress with related increase of sensitising substances Reflex inhibition of involved muscle

26 Myofascial Trigger Points Pathogenic Factors Acute overload Overwork - Fatigue (Including postural stress) Chilling Gross Trauma Other Trigger Points Emotional distress Joint or nerve damage Visceral disturbance

27 Chart outlining the natural course of Myofascial pain caused by Trigger Points Pathogenic Factors STRESS Taut Band Latent TrPs Active TrPs Perpetuating Factors Spontaneous Recovery Persistence without progression Additional TrPs & Chronicity