Myofascial Trigger Points in Neck and Shoulder Muscles and Widespread Pressure Pain Hypersensitivtiy in Patients With Postmastectomy Pain Evidence of Peripheral and Central Sensitization Carolina Ferna ´ndez-Lao, PT, MSc,* Irene Cantarero-Villanueva, PT, MSc,* Ce ´sar Ferna ´ndez-de-las-Pen ˜as, PT, MSc, PhD,w zy Rosario Del-Moral-A ´ vila, MD,J Lars Arendt-Nielsen, DMSc, PhD,y and Manuel Arroyo-Morales, MD, PT, PhD* Objective: To describe the presence of widespread pressure pain hyperalgesia and myofascial trigger points (TrPs) in neck and shoulder muscles in patients with postmastectomy pain. Methods: Twenty-nine women (mean age: 50±8 y) with postmas- tectomy pain and 23 matched healthy controls (mean age: 50±9 y) participated. Pressure pain thresholds (PPT) were bilaterally assessed over the C5-C6 zygapophyseal joint, the deltoid muscle, the second metacarpal, and the tibialis anterior muscle. TrPs in the upper trapezius, suboccipital, levator scapulae, sternocleidomas- toid, scalene, infraspinatus, and pectoralis major muscles were explored. TrPs were considered active if the local and referred pain reproduced symptoms and the patient recognized the pain as familiar. Results: Twenty-five (86%) patients reported neck pain whereas 20 (69%) patients showed shoulder/axillary pain. The results showed that PPT levels were significantly decreased bilaterally over the C5-C6 zygapophyseal joint, deltoid muscle, second metacarpal, and tibialis anterior muscle in patients with postmastectomy pain as compared with controls (all sites, P<0.001). No significant differences in the magnitude of PPT decrease between sites were found (P=0.222). The mean number of active TrPs for each woman with postmastectomy pain was 5.4±1.8. Healthy controls only had latent TrPs (0.5±0.6). Patients with postmastectomy pain showed a greater number of TrPs than controls (P<0.001). In all muscles, there was significantly more active TrPs in patients with postmastectomy pain as compared with controls (P<0.001). Active TrPs in the pectoralis major (n=27, 93%), infraspinatus (n=23, 79%), and upper trapezius (n=19, 65%) muscles were the most prevalent in the affected side in the postmastectomy group. The number of active TrPs was positively correlated with neck (r s =0.392, P=0.036) and shoulder/axillary (r s =0.437, P=0.018) pain intensity. Conclusions: Our findings revealed bilateral widespread pressure pain hypersensitivity in patients with postmastectomy pain. In addition, the local and referred pain elicited by active TrPs reproduced neck and shoulder/axillary complaints in these patients. These results suggest peripheral and central sensitization in patients with postmastectomy pain. Key Words: postmastectomy pain, trigger points, pressure pain, sensitization (Clin J Pain 2010;26:798–806) B reast cancer is the most common form of cancer among women. 1 A recent study found that since 1980, the breast cancer incidence rate has increased by 2.9% per year in Spain. 2 Further, with increasing longevity and effective therapies, the population of cancer survivors also increases. For instance, it is estimated that there are 2 millions of breast cancer survivors in the United States. 3 Screening programs and advances in therapeutic and diagnostic approaches raised survivors to close to 70% 5 years after diagnosis 4 Regional or localized pain is the most frequent impairment after breast cancer treatment (20% to 65%), 5 with a strong relationship to self-perceived disability and quality of life. 6 In fact, shoulder disability seems to be a frequent complication to the treatment of breast cancer (35%). 7 The presence of persistent pain beyond the period of “normal” healing after mastectomy surgery is called “postmastectomy pain” and it is generally attributed to the damage of peripheral nerves during the operative procedure. 8 Further, the pain is neuropathic in character as it is described as burning, electric shock-like, or stabbing. 9 A retrospective study found a prevalence of 43% of postmastectomy neuropathic pain in a sample of 408 women who had received mastectomy surgery. 10 Finally, the presence of pain before and soon after the surgery is a mayor predictive factor for chronic pain after breast surgery. 11 There is increasing evidence suggesting that postmas- tectomy pain can also be related to other sources different from nerve injury, such as myofascial tissue. 12 In this context, Simons et al 13 suggested that muscle/myofascial trigger points (TrPs) can play an important role in postmastectomy pain. TrPs are defined as hyperirritable tender spots in a taut band of a skeletal muscle that are Copyright r 2010 by Lippincott Williams & Wilkins Received for publication March 9, 2010; revised April 6, 2010; accepted April 9, 2010. From the *Department of Physical Therapy, Universidad Granada; JOncology Radiotherapy Service, Hospital Virgen de las Nieves, Servicio Andaluz de Salud, Granada; zEsthesiology Laboratory, Universidad Rey Juan Carlos; wDepartment of Physical Therapy, Occupational Therapy, Rehabilitation and Physical Medicine, Alcorco´n, Madrid, Spain; and yDepartment of Health Science and Technology, Centre for Sensory-Motor Interaction (SMI), Aalborg University, Aalborg, Denmark. The study was funded by a project grant (FIS 08-ETES-PI0890418) from the Spanish National Institute of Health, Madrid, Spain. Reprints: Ce´sar Ferna´ndez-de-las-Pen˜as, PT, MSc, PhD, Facultad de Ciencias de la Salud, Department of Physical Therapy, Occupa- tional Therapy, Rehabilitation and Physical Medicine, Universidad Rey Juan Carlos, Avenida de Atenas s/n, 28922 Alcorco´n, Madrid, Spain (e-mail: cesar.fernandez@urjc.es). ORIGINAL ARTICLE 798 | www.clinicalpain.com Clin J Pain  Volume 26, Number 9, November/December 2010