A Comparison of Scar Infiltration, Scar Deactivation, and Standard of Care for the Treatment of Chronic, Post-Surgical Pain After Cesarean Section in the Primary Care Setting: A Comparative Effectiveness Trial.

While there is not a clearly established and widely accepted pathophysiological cause to this post-operative pain, studies have estimated that between 7-33% of patients experience chronic peri-incisional pain after Cesarean section with Pfannenstiel incision - a type of abdominal surgical incision that allows access to the abdomen and the most common method for performing Cesarean sections today - defined as pain persisting beyond the period of expected healing, approximately 3 months.

Management of chronic peri-incisional pain after Cesarean section requires an extensive workup including laboratory testing (CBC, ESR, Urinalysis, STI testing) and imaging (transvaginal ultrasonography and abdominal CT) to rule out organic causes. Once a visceral etiology from postoperative pain has been excluded, there is not a well-established guideline dictating standard of care, however treatment can include analgesics such as Acetaminophen or Non-Steroidal Anti-inflammatory Drugs, and in refractory cases suggestive of neuropathic pain Tricyclic Antidepressants, Gabapentin, Pregabalin, and Serotonin-Norepinephrine Reuptake Inhibitors can be used. If medicinal therapy fails to manage symptoms, consultation for pain management specialists and/or surgical evaluation is often considered.

Scar deactivation is used as standard of care for treatment and resolution of scar associated pain in patients with a history of Cesarean section by medical acupuncturists, both abdominal and/or low back pain that began after the cesarean section. Scar infiltration with lidocaine has been used in numerous clinical settings, masquerading under different names. Referred to as Neural Therapy in Germany, the technique of injecting short-acting local anesthetic into the dermal subcutaneous junction of scar tissue has been widely applied; however there is limited readily available clinical trial evidence supporting its reported effectiveness. Theoretically, it is postulated that the anti-inflammatory effects of local anesthetics play a role in mitigating the autonomic nervous system disruption of interference fields caused by scar tissue. Local anesthetics promote anti-inflammatory activity through a variety of mechanisms including reversibly inhibiting leukocyte adhesion by interfering with the action of integrins and leukocyte adhesion molecule-1, limiting leukocyte migration, reversible inhibition of phagocytosis, inhibition of phospholipase A2, inhibition of prostaglandins, inhibition of thromboxane release, inhibition of leukotriene release, inhibition of histamine release, reduction in free radical formation, and inhibition of cytokine release. Additionally, Lidocaine injection is proposed to alleviate nerve entrapment within fascia through hydrodissection, a technique being effectively utilized in the management of carpal tunnel syndrome.

Scar deactivation is the technique of inserting acupuncture needles at a 30-45 degree angle into the superficial fascia to surround a scar. It is postulated that needle insertion into connective tissue produces analgesia through a multifaceted process encompassing the disruption and remodeling of extracellular matrix in loose connective tissue, alterations in gene expression affecting neurotransmitter levels, and cellular signaling pathways impacted in response to fibroblast and mast-cell involvement. In traditional Chinese medicine, injuries resulting in scar tissue formation are thought of as areas of blood and subsequently Qi stagnation. Disruptions in the flow of Qi at the point of scar tissue can result in abnormal skin sensations such as pain, itching, and numbness in addition to systemic effects. A case report has demonstrated effective pain relief in with an acupuncture protocol utilizing scar deactivation technique.