Diagnosis of Thoracic Outlet Syndrome Using Electrophysiologically Guided Anterior Scalene Blocks

CT-Guided Injection of the Anterior and Middle Scalene Muscles: Technique and Complications

“…5 Two previous studies illustrate that a higher percentage of patients with a positive scalene block respond favorably to surgical decompression. 12,16 If ergonomic modifications, exercise, and physiotherapy do not improve the symptoms, surgery may be an option. In our study, the rate of successful surgical outcome did not vary according to positive or negative anesthetic injections into the ASM/MSM, 30/43 (70%) versus 5/7 (71%), respectively.…”

“…Localization techniques for scalene injections include palpation and external visible anatomic landmarks, 13,17 EMG guidance, 12 sonographic guidance, 11,18,19 and fluoroscopic guidance. 18,20 Success rates by these means are expected to be very operator-dependent based on experience, whereas CT guidance lends a simplicity and accuracy that would allow a shorter learning curve.…”

“…9 The anesthetic injection allows the first rib to descend by relaxing the scalene muscle and thereby decompressing the BP. 6,[9][10][11] The anterior scalene block has been the most helpful test to confirm the diagnosis of NTOS 5,6,[11][12][13][14][15] and to predict the response to surgery, because it may mimic the results of first-rib resection and anterior scalenectomy. 6,[10][11][12]14,16 However, to be predictive, the injection should avoid anesthesia of the BP and sympathetic chain, and the patient should be both medically and psychologically stable.…”

“…6,[9][10][11] The anterior scalene block has been the most helpful test to confirm the diagnosis of NTOS 5,6,[11][12][13][14][15] and to predict the response to surgery, because it may mimic the results of first-rib resection and anterior scalenectomy. 6,[10][11][12]14,16 However, to be predictive, the injection should avoid anesthesia of the BP and sympathetic chain, and the patient should be both medically and psychologically stable. 13 Different methods have been used to guide the scalene injection, including the use of anatomic landmarks, 13,17 EMG, 12 sonography, 11 combinations of EMG and sonography, 18 EMG and fluoroscopy, 18 and CT most recently.…”

“…6,[10][11][12]14,16 However, to be predictive, the injection should avoid anesthesia of the BP and sympathetic chain, and the patient should be both medically and psychologically stable. 13 Different methods have been used to guide the scalene injection, including the use of anatomic landmarks, 13,17 EMG, 12 sonography, 11 combinations of EMG and sonography, 18 EMG and fluoroscopy, 18 and CT most recently. 9,10 CT-guided injection of the scalene muscle is a novel technique, 9 which has not been previously evaluated in the radiology literature, to our knowledge.…”