Clinical and Health Affairs
Myofascial Trigger Points: What Physicians Should Know about these Neurological Imitators
By Jack E. Hubbard, Ph.D., M.D.
Abstract
Myofascial trigger points (MFTPs) are a common cause of chronic neck and back pain. They also can cause a wide spectrum of associated symptoms. This review focuses on neurological symptoms—headache, dizziness, and sensory disturbances—that are frequently caused by musculoskeletal MFTPs. The discussion considers the diagnosis, pathophysiology, and treatment of MFTPs as well as the proposed mechanisms that generate the neurological symptoms. Physicians should consider these neurological imitators in patients who have such symptoms with no apparent cause.
Since they were first described by Travell and colleagues in 1942,1 myofascial trigger points (MFTPs) have been recognized as a common cause of chronic neck and back pain.2,3 Less well-known by both primary care physicians and neurologists is the fact that MFTPs also can cause a wide spectrum of associated symptoms. For example, in a survey of 164 patients with MFTPs of the head and neck, Fricton reported neurological, gastrointestinal, musculoskeletal, and otological symptoms in 10% to 40%.4 This article describes MFTPs and the neurological symptoms most commonly generated by them—headache, dizziness, and sensory disturbances. It also discusses the mechanism behind and treatment of these symptoms.
Myofascial Trigger Points
Myofascial trigger points are localized segments of muscle that have been subjected to trauma by acute injury or microtrauma from repetitive stress; in some cases, they are the result of a systemic illness.2,3 Any skeletal muscle can develop trigger points, which can be identified by careful examination of the affected muscle groups for knots that are 2 mm to 5 mm in diameter and tight bands that are painful when palpated.2,3 Diagnosis is based on the patient’s history and examination; there are no laboratory tests or imaging studies that can confirm the presence of MFTPs.3 The criteria for diagnosing MFTPs is somewhat controversial,5 and debate exists over whether or not they are true pathologic entities.6,7
Although some theories suggest that MFTPs are on the same spectrum of disorders as fibromyalgia,8 MFTPs and fibromyalgia are not one and the same. MFTPs are localized areas of injury and discomfort, whereas fibromyalgia pain is more diffuse and thought to reflect a central pain syndrome.9 Also, MFTPs can be objectively identified during a careful examination of the patient; whereas diagnosing fibromyalgia relies on the subjective responses of the patient as he or she is examined for sensitive trigger zones.9,10 Finally, and most importantly, MFTPs are more easily treated than fibromyalgia.10
Trigger points are quite common, especially in the cervical musculature, and are most often found in patients 31 years to 50 years of age, with a greater incidence in women than men.2,3 Several studies have reported that up to 85% of back pain and 54.6% of neck pain and headaches are caused by myofascial pain.11,12 Most frequently developing in the axial musculature (neck and back), trigger points are associated with poor posture and can develop insidiously from occupational activities (eg, cradling a telephone handset between the head and shoulder or sitting in an awkward position in front of a computer) or vocational activities (eg, bending one’s head for a prolonged period of time while knitting or reading). Acute injury such as whiplash from a motor vehicle accident is another common cause of trigger points.2 In some cases, a specific cause cannot be identified.
The pathophysiology of MFTPs remains speculative, however. One theory is that muscle injury or stress disrupts the sarcoplasmic reticulum, releasing free calcium ions.2 In the presence of adenosine triphosphate, ionic calcium causes the actin and myosin of the muscle fibers to lock into place. This action results in diminished blood flow and release of painful substances such as serotonin, histamine, kinins, and prostaglandins in the injured area.13
Neurological Symptoms
Myofascial trigger points frequently produce neurological complaints. Physicians should be aware of the possibility of MFTPs when patients present with headache, dizziness, or a number of sensory symptoms.
■ Headache
Headache is a frequent consequence of neck injury; conversely, neck pain is common in patients who suffer from headaches.14-18 Headaches occur in 55% to 66% of patients who sustain a whiplash-type injury to the neck, and neck pain is reported in 73% of patients with migraine.14,19 Although the cause of headache following a whiplash injury is often the result of cervical facet dysfunction,20 MFTPs may develop afterward and account for persistent headache in many patients.2,21
The mechanism of headaches generated or exacerbated by MFTPs most likely involves the trigeminocervical complex.22 Constant nociceptive input from cervical muscle trigger points converge on the trigeminal nucleus caudalis in the upper cervical spinal cord.16 Such continuous stimulation results in temporal and spatial summation of pain signals to the trigeminal pathways, which relay sensory information from the head and face.17
Myofascial trigger points typically cause tension headaches that originate either directly from the trigger points in the muscles of the head such as the temporalis or indirectly from the cervical musculature.3 These headaches can be severe and debilitating, raising concerns of an expanding intracranial mass or infection. Trigger points also can precipitate migraine headaches or contribute to their worsening. Continuous nociceptive input stimulates the trigeminovascular pathways, which can increase the frequency and/or severity of migraine headaches.22,23 As early as 1981, the head and neck muscles were recognized as important for migraine generation.19 Trigger points can influence their frequency, severity, and treatment.16,23 With appropriate trigger-point therapy, migraine headaches often come under better control, decreasing in both frequency and severity.23
Patients referred to our clinic because of frequent migraine headaches (one to three per week) or those who do not respond to appropriate preventive and/or abortive therapy often have cervical MFTPs. With specific myofascial therapy to the cervical musculature, patients report that the frequency of their migraine attacks decreases significantly, eliminating the need for preventive medications. When they do experience migraine, they find that their headaches generally respond more effectively to medications such as triptans or other abortive therapy. Also, those patients who experience daily tension headaches that are present with the superimposed migraine pattern see improvement as well.
■ Dizziness
A frequent complaint of patients with cervical MFTPs is dizziness. They describe it in nonspecific terms such as feeling off balance and unsteady or like they are walking on a cloud. In Fricton’s study of 164 patients with cervical MFTPs, 23.1% reported experiencing dizziness.4 Interestingly, these patients also were found to have other otological symptoms such as tinnitus (42.1%), ear pain (41.5%), and reduced hearing (17.7%). Nausea also was common, but vomiting was not.4,24
Often such patients indicate that their dizziness worsens with prolonged or repetitive bending of the head and neck. For instance, Travell and Simons noted patients reporting that they feel as if they will pitch over backwards when looking up and tend to fall forward when looking down.24 Patients with such symptoms are usually referred for neurological or otolaryngological evaluation. Although most patients with this cervicogenic vertigo have concomitant neck pain and/or headaches, some, especially those who are elderly, will deny any neck discomfort or report only minor stiffness.
Such patients should have a careful examination for trigger points in the cervical area. In my experience, when the trigger points are treated with appropriate myofascial therapy, dizziness resolves. The mechanism of the dizziness is likely related to excessive proprioceptive input from the cervical muscles,3,25,26 especially the clavicular division of the sternocleidomastoid muscle and the trapezius muscle.24,27 Travell and Simons theorize that dizziness results from proprioceptive information from the cervical musculature that helps orient the body.24 Because of its attachment to the mastoid process, the sternocleidomastoid muscle also may refer pain deep into the ear and cause tinnitus.24
■ Sensory Symptoms
More than a quarter of patients with cervical MFTPs experience sensory symptoms in the upper extremities and face such as numbness and tingling.4 Pain also can be referred distally from MFTPs in patterns that do not follow dermatomal, myotomal, or sclerotomal patterns.3,28 Dorsher suggests that pain referred from MFTPs follows the distribution of acupuncture meridians.28
The distribution of sensory symptoms caused by MFTPs depends on the location of the trigger points. Cervical trigger points can refer numbness and tingling to either the face or head or to the upper extremities.3 Upper extremity motor impairment such as weakness or incoordination also can arise from pain generators in the neck.25 Trigger points in the lumbar region can refer sensory symptoms to the legs.29,30 Thoracic trigger points may mimic thoracic radiculitis. Patients who have such symptoms are often referred for neurological evaluation to rule out other causes such as multiple sclerosis or neuropathy. Sensory symptoms and findings caused by MFTPs closely mimic those of a radiculopathy. I once saw a 35-year-old patient who experienced recent onset of neck pain as well as pain and numbness in her left arm, which she described in a C7 pattern. Her neurological examination was significant for diminished sensation over the dorsal forearm and hand, weakness in the triceps muscle, and a decrease in the triceps reflex. Her presentation was most consistent with a C7 radiculopathy. She also had prominent cervical trigger points on the left side, but I was convinced that she had a large C6-7 herniated disc on the left and would require decompressive surgery. Her cervical MRI scan was normal, however. After starting on a course of myofascial therapy, all of her symptoms resolved and her follow-up neurological examination was normal.
The referral of sensory symptoms distant from trigger points is likely because of changes in processing within the brain and spinal cord.23 For example, Niddam and colleagues demonstrate modulatory activity of the periaqueductal gray of the midbrain in the brainstem with myofascial trigger point pain.31 Other suggested mechanisms include convergence-projection to the central centers, branching of primary afferent nociceptors from the affected muscle, convergence-facilitation from the trigger point, image projection to supraspinal levels, and sympathetic activity neuronal spread.2
Treatment
Successful treatment of MFTPs usually eliminates or significantly reduces the associated neurological symptoms. The goal in trigger-point management is to restore muscle fiber length in the affected segments.3 Management of MFTPs includes both nonpharmacologic and pharmacologic therapies.
■ Nonpharmacologic Therapy
Myofascial trigger-point therapy is a manual technique that involves applying pressure to a trigger point to release the pathologic contraction of the muscle segment and to stretch the segment to restore normal muscle fiber length. The duration of treatment varies from person to person, but an initial course is usually twice a week for three to four weeks. To be effective, trigger-point therapy must be performed by a physical therapist who is skilled in manual therapy with myofascial release techniques.32
Traditional physical therapy that initially involves vigorous exercise and traction often does not help and sometimes causes symptoms to worsen. Acupuncture, stress management, and relaxation techniques, when combined with myofascial therapy, also can help patients with pain caused by MFTPs.33-35
■ Pharmacologic Treatment
There is no pharmacologic agent that is specific for treating myofascial trigger points. Any pharmacotherapy must be administered in conjunction with physical therapy and can be given orally, topically, or by injection. Oral medications such as spasmolytics (muscle relaxants) can improve muscle function.35,36 Nonspecific agents—tricyclic antidepressants, nonsteroidal anti-inflammatory drugs, anticonvulsants, and opioids—generally are used for pain control. Topical agents include local anesthetics or nonsteroidals in patch or gel form. Local anesthetics with or without corticosteroids, neurolytic agents, or botulinum toxin can be injected directly into trigger points to break up the localized muscle knots.36,37 Some investigators conclude that simple dry needling of the trigger points can be effective.38
Follow-up Care
A post-treatment program is necessary to maintain the achieved clinical improvement. Myofascial therapy may not entirely eliminate symptomatic active trigger points, which are characterized by a local twitch response followed by pain during palpation, but it may convert them to asymptomatic latent points, which can be reactivated by reinjury.35,38 To prevent this from happening, patients need to make appropriate ergonomic changes in their day-to-day activities to avoid repetitive stress to the injured muscles.39 For example, patients with cervical myofascial trigger points should use a headset when having long conversations on the telephone or change their position to avoid bending their heads while knitting or reading. In addition, a strengthening and conditioning regimen for the affected muscle groups, usually taught by a physical therapist, is beneficial.
Conclusion
Myofascial trigger points are pathologic changes within muscle segments that are usually caused by trauma such as a motor vehicle accident, repetitive movements, or remaining in a static position for a prolonged period. Identified on examination as painful knots and taut bands within the affected muscle, trigger points are capable of producing neurological symptoms including headache, dizziness, and sensory disturbances. As such, they can imitate more serious neurological disorders such as intracranial mass, vestibular neuronitis, nerve injury, radiculopathy, and multiple sclerosis. Patients who present with such neurological symptoms that are not explained by any other cause should have the appropriate musculature carefully examined for trigger points. With appropriate treatment, pain and symptoms associated with trigger points can improve over time. MM
Jack Hubbard is a neurologist with the Minneapolis Clinic of Neurology and an adjunct professor of neurology at the University of Minnesota.
The author thanks Jessica Heiring, M.D., for her suggestions for this manuscript. Disclosure Dr. Hubbard is a member of the Minneapolis Clinic of Neurology, which employs physical therapists who treat patients with myofascial trigger points.
References
1. Travell J, Rinzler S, Herman M. Pain and disability of the shoulder and arm; treatment by intramuscular infiltration with procaine hydrochloride. JAMA. 1942;120(6):417-22.
2. Rachlin E. Trigger points. In: Rachlin E, Rachlin I. Myofascial Pain and Fibromyalgia. Trigger Point Management. 2nd ed. St. Louis, MO: Mosby; 2002:203-16.
3. Travell J, Simons DG. Background and principles. In: Travell J, Simons DG. Myofascial Pain and Dysfunction. The Trigger Point Manual. Baltmore, MD: Williams and Wilkins; 1983;2:5-44.
4. Fricton JR. Myofascial pain syndrome. Characteristics and epidemiology. In: Fricton JR, Awad EA. In: Advances in Pain Research and Therapy. Vol 17. Myofascial Pain and Fibromyalgia. New York, NY: Raven Press; 1990;5:107-27.
5. Tough EA, White AR, Richards S, Campbell J. Variability of criteria used to diagnose myofascial trigger point pain syndrome—evidence from a review of the literature. Clin J Pain. 2007;23(3):278-86.
6. Argoff C. Targeting an “invisible” condition: How to treat myofascial pain syndrome. Practical Neurology. 2004;August:65-6.
7. Behr T. Problems with myofascial pain syndrome and fibromyalgia syndrome. Neurology. 1996:46(3):593-7.
8. Bennett RM. Myofascial pain syndromes and the fibromyalgia syndrome: A comparative analysis. In: Advances in Pain Research and Therapy. Vol. 17. Myofascial Pain and Fibromyalgia. New York, NY: Raven Press; 1990;2:43-65.
9. Yunus M, Inanici F. Fibromyalgia syndrome: Clinical features, diagnosis, and biopathophysiologic mechanisms. In: Rachlin E, Rachlin I. Myofascial Pain and Fibromyalgia. Trigger Point Management. 2nd ed. St. Louis, MO: Mosby; 2002:3-31.
10. Dunteman ED. Fibromyalgia and myofascial pain syndromes. Practical Pain Management. 2004;July/August:26-9.
11. Fishbain DA, Goldberg M, Steele R, Rosomoff H. DSM-III diagnoses of patients with myofascial pain syndrome (fibrositis). Arch Phys Med Rehabil. 1989;70(6):433-8.
12. Fricton JR, Kroening R, Haley D, et al. Myofascial pain syndrome of the head and neck: A review of clinical characteristics of 164 patients. Oral Surg Oral Med Oral Pathol. 1985:60(6):615-23.
13. Shah JP. New frontiers in the pathophysiology of myofascial pain. Pain Practioner. 2009;winter:40-2.
14. Binder A. The diagnosis and treatment of nonspecific neck pain and whiplash. Europa Medicophys.2007;43(1):79-89.
15. Drottning M. Cervicogenic headache after whiplash injury. Curr Headache Rep. 2003;7(5):384-6.
16. Nelson J. Cervical myofascial trigger points in headache disorders. Practical Pain Management. 2008;September:59-60.
17. Mueller L. Cervicogenic headache: a diagnostic and therapeutic dilemma. Headache and Pain. 2003;14(1):29-37.
18. Marcus DA. Headache and musculoskeletal abnormalities: A guide to treatment approaches. Headache and Pain. 2007;18(2):58-66.
19. Tfelt-Hansen P, Lous I, Olesen J. Prevalence and significance of muscle tenderness during common migraine attacks. Headache. 1981;21(2):49-54.
20. Yin W, Bogduk N. The nature of neck pain in a private pain clinic in the United States. Pain Med. 2008;9(2):196-203.
21. Romano TJ. Trauma and chronic soft tissue pain. AJPM. 2003;13(3):98-105.
22. Bartsch T, Goadsby PJ. The trigeminocervical complex and migraine: current concepts and synthesis. Current Headache Reports. 2003;2:149-54.
23. Giamberardino MA, Tafuri E, Savini A, et al. Contribution of myofascial trigger points to migraine symptoms. J Pain. 2007;8(11):869-78.
24. Travell J, Simons DG. Sternocleidomastoid muscle. In: Travell J, Simons DG Myofascial Pain and Dysfunction. The Trigger Point Manual. Baltimore, MD; Williams and Wilkins; 1983;7:202-18.
25. Woodhouse A, Vasseljen O. Altered motor control patterns in whiplash and chronic neck pain. BMC Musculoskelet Disord. 2008;9:90-106.
26. Paulus I, Brumagne S. Altered interpretation of neck proprioceptive signals in persons with subclinical recurrent neck pain. J Rehabil Med. 2008;40:426-32.
27. Good MG. Senile vertigo caused by curable cervical myopathy. J Am Geriatr Soc. 1957;5:662-7.
28. Dorsher PT. Myofascial referred-pain data provide physiologic evidence of acupuncture meridians. J Pain. 2009;10(7):723-31.
29. Dunteman ED. Myofascial elements of low back pain. Practical Pain Management. 2005;March:29-34.
30. Travell J, Simons DG. Myofascial Pan and Dysfunction. The Trigger Point Manual. Vol. 2. The Lower Extremities, Baltimore, MD: 1992.
31. Niddam DM, Chan RC, Lee SH, Yeh TC, Hsieh JC. Central modulation of pain evoked from myofascial trigger point. Clin J Pain. 2007;23(5):440-8.
32. Paris B. The practical application of trigger point work in physical therapy. In: Rachlin ES, Rachlin IS. Myofascial Pain and Fibromyalgia. Trigger Point Management. St. Louis, MO: Mosby; 2002;28:525-43.
33. Audette JF, Blinder R. Acupuncture in the management of myofascial pain and headaches. Current Headache Reports. 2003 2: 173-9.
34. Kraus H. Muscle deficiency. In: Rachlin ES, Rachlin IS. Myofascial Pain and Fibromyalgia. Trigger Point Management. St. Louis, MO: Mosby 2002;15:437-65.
35. Travell J, Simons DG. Apropos of all muscles. In: Travell J, Simons DG. Myofascial Pan and Dysfunction. The Trigger Point Manual. Baltimore, MD;: Williams and Wilkins; 1983;3:45-102.
36. Wheeler AH. Myofascial pain disorders: theory to therapy. Drugs. 2004;64(1):45-62.
37. Scott NA, Guo B, Barton P, Gerwin RD. Trigger point injections for chronic non-malignant pain: a systematic review. Pain Med. 2009;10(1):54-69.
38. Rachlin ES. History and physical examination for myofascial pain syndrome. In: Rachlin ES, Rachlin IS. Myofascial Pain and Fibromyalgia. Trigger Point Management. St. Louis, MO: Mosby;2002;10:217-30.
39. Abdel-Moty E, Khalil TM, Steele-Rosomoff R, et al. The role of ergonomics in the prevention and management of myofascial pain. In: Rachlin ES, Rachlin IS. Myofascial Pain and Fibromyalgia. Trigger Point Management. St. Louis, MO: Mosby; 2002;20:561-87.