Severe Scapular Pain Following Unintentional Cervical Epidural Air Injection

This a unique case of severe scapular pain following unintentional epidural space air injection during epidural steroid injection.A 70-year-old woman presented for a fluoroscopically guided C7-T1 interlaminar epidural steroid injection. Three injection attempts were made using the loss of resistance with air technique. On the first attempt the epidural space was entered, but contrast injection showed that the needle was intravenous. On the second attempt an equivocal loss of resistance with air was perceived and 5 mL of air was lost from the syringe. The needle was withdrawn and redirected, and upon the third needle passage the contrast injection showed appropriate epidural space filling up to the C4-5 level. Injection of betamethasone mixed in lidocaine was initially uneventful.However, 20 minutes post-injection the patient experienced sudden sharp and continuous pain along the medial edge of the scapula. After failing to respond to multiple intravascular analgesics, the patient was transferred to the emergency room. Her pain subsided completely following an intravenous diazepam injection. Cervical spine computerized tomography showed obvious air in the posterior epidural space from C4-5 to C6-7 as well as outside the spinal canal from (C4-T2). Having recovered fully, she was discharged the following morning. In reviewing the procedure, the equivocal loss of resistance on the second passage was actually a true loss of resistance to epidural space and air was unintentionally injected. Surprisingly, severe scapular pain resulted in a delayed manner after the steroid solution was injected. The authors theorize that unintentional prefilling of the epidural space with air prior to the injection of the subsequent steroid mixture added sufficient pressure to the epidural space to cause right-sided C4 nerve root stretching/entrapment and ensuing radicular pain to the right scapular border. The subsequent intravenous diazepam provided cervical muscle relaxation and facilitated foramina passage of air out of the spinal canal.This case demonstrates that under certain conditions entry of air into cervical epidural space can lead to unexpected, albeit temporary, neurological symptoms.