Abstract: Scalene muscle injections are used to confirm the diagnosis of neurogenic thoracic outlet syndrome and predict the response of patients to surgery. We performed a retrospective study to determine if relief of pain was related to brachial plexus blockade in these patients.
Methods: We reviewed the charts of 12 patients who had anterior and middle scalene muscle injections, for neurogenic thoracic outlet syndrome, between April 2009 and September 2010. The injections were performed under ultrasound guidance wherein 2 to 5 mL of 0.25% bupivacaine was injected into the belly of the anterior and scalene muscles. The following were noted: (1) sites of preprocedure pain; (2) volume injected into each of the anterior and middle scalene muscles; (3) presence of numbness after injection; and (4) presence and duration of pain relief.
Results: All 12 patients had relief of their pain. Six of the twelve patients developed numbness, which ranged from blockade of the C4-5, C6-7, and C4-T1 dermatomes. In the patients who developed numbness, there was no relationship between the duration of numbness and the duration of pain relief or the location of numbness and the location of pain relief.
Conclusions: The relief from scalene muscle injections in patients with neurogenic thoracic outlet syndrome is not related to blockade of the brachial plexus. ▪