Background and Clinical Significance: Serratus Anterior Muscle Pain Syndrome (SAMPS) is an underdiagnosed cause of anterior chest wall pain, often attributed to myofascial trigger points of the serratus anterior muscle (SAM) or dysfunction of the Long Thoracic Nerve (LTN), leading to significant disability and affecting ipsilateral upper limb movement and quality of life. Current diagnosis relies on exclusion and physical examination, with limited treatment options beyond conservative approaches. This case report presents a novel approach to chronic SAMPS, successfully diagnosed using Sonoguided Digital Palpation (SDP) and treated with ultrasound-guided hydrodissection of the LTN using 5% dextrose in water (D5W) without local anesthetic (LA), in a patient where conventional treatments had failed. Case Presentation: A 72-year-old male presented with a three-year history of persistent left chest pain radiating to the upper back, exacerbated by activity and mimicking cardiac pain. His medical history included two percutaneous coronary interventions. Physical examination revealed tenderness along the anterior axillary line and a positive hyperirritable spot at the mid axillary line at the 5th rib level. SDP was used to visualize the serratus anterior fascia (SAF) and LTN, and to reproduce the patient’s concordant pain by palpating the LTN. Ultrasound-guided hydrodissection of the LTN was then performed using 20–30cc of D5W without LA to separate the nerve from the surrounding tissues, employing a “fascial unzipping” technique. The patient reported immediate pain relief post-procedure, with the pain reducing from 9/10 to 1/10 on the Numeric Rating Scale (NRS), and sustained relief and functional improvement at the 12-month follow-up. Conclusions: Sonoguided Digital Palpation (SDP) of the LTN can serve as a valuable diagnostic adjunct for visualizing and diagnosing SAMPS. Ultrasound-guided hydrodissection of the LTN with D5W without LA may provide a promising and safe treatment option for patients with chronic SAMPS refractory to conservative management, resulting in rapid and sustained pain relief. Further research, including controlled trials, is warranted to evaluate the long-term efficacy and generalizability of these findings and to compare D5W to other injectates.

Background/Objectives Serratus Anterior Muscle Pain Syndrome (SAMPS), often attributed to myofascial trigger points of the serratus anterior muscle (SAM) or dysfunction of the Long Thoracic Nerve (LTN), can lead to significant disability, affecting upper limb movement and quality of life. Current diagnosis relies primarily on exclusion and physical examination. Treatment options are largely limited to physical therapy and pharmacological interventions, alt-hough myofascial trigger points injection have been reported. In this manuscript, we present the case of a male patient referred to our rehabilitation clinic by a cardiologist due to persistent pain in the left chest radiating to the upper back, shoulder and arm that failed conservative treatments. We provide technical notes detailing the ultrasound-guided diagnosis through dyanamic sonoguide digital palpation of the LTN to reproduce the patient's SAMPS, along with techniques for ultrasound-guided hydrodissection of the LTN. Method We describe in detail the dynamic sonoguide digital palpation of the LTN as a supportive diagnostic tool for reproducing the patient's SAMPS. Ultrasound-guided hydrodissection is a minimally invasive technique aimed at treating nerve-related pain and dysfunction by injecting fluid around a nerve or in areas where the nerve may be compressed or irritated. We outline the settings and specifics of the ultrasound-guided hydrodissection of LTN technique, utilizing 20 to 30cc of 5% dextrose in water (D5W) without local anesthetics (LA). Results Dynamic sonoguide digital palpation effectively reproduced the patient's SAMPS. The patient reported a significant reduction in pain immediately after the LTN was successfully hydrodissected from the serratus anterior fascia and surrounded by D5W. Notably, the pain relief was not attributable to LA, as no LA was injected near the LTN or in the fascia. The pain-relieving effects persisted for 12 months following the procedure. Conclusion Dynamic sonoguide digital palpation of the LTN can serve as effective diagnostic maneuver to assist in visualizing and diagnosing SAMPS. Hydrodissection of the Long Thoracic Nerve may provide a promising treatment option for patients with SAMPS, resulting in rapid pain relief. The technical notes included may aid practitioners in accurately diagnosing and treating this condition using ultrasound-guided techniques.