STUDY DESIGN: The article presents and discusses 4 cases in which symptomatic epidural gas developed after different surgeries on the lumbar spine. OBJECTIVE: To raise spinal surgeons' awareness of this potential problem. SUMMARY OF BACKGROUND DATA: Vacuum phenomenon (gas accumulation in an intervertebral disc) is relatively common. Gas can also spontaneously enter and collect in the epidural space, but symptomatic epidural gas after spinal surgery is very rare. To date, only 5 such cases after lumbar surgery have been reported. METHODS: The primary disorders in the 4 new cases were disc extrusion at L2-L3 (Case 1), disc degeneration and herniation at L4-L5 (Case 2), stenosis of the lumbar spinal canal (Case 3), and disc herniation at L5-S1 with spinal canal stenosis (Case 4). The corresponding surgeries performed were L2-L3 microdiscectomy, L4-L5 microdiscectomy with instrumentation, right unilateral hemilaminotomy with complete instrumentation, and L5-S1 microdiscectomy. All 4 patients developed unexpected postoperative complaints of low back and radicular pain. Each was investigated with computed tomography and magnetic resonance imaging. The images revealed epidural gas collections compressing the thecal sac and/or nerve roots. RESULTS: Conservative management was effective in all but 1 case. In the latter case, computed tomography-guided needle aspiration was performed, but this did not resolve the problem. Surgery led to a favorable outcome, and follow-up lumbar computed tomography showed no epidural gas. CONCLUSION: Epidural gas after lumbar surgery is very rare but can cause unexpected postoperative back or radicular pain. Combined computed tomography and magnetic resonance imaging should be used to identify the problem and rule out other disorders. Conservative treatment should be the first-line approach but surgery is often necessary if this does not resolve the problem.
STUDY DESIGN: The article presents and discusses 4 cases in which symptomatic epidural gas developed after different surgeries on the lumbar spine. OBJECTIVE: To raise spinal surgeons' awareness of this potential problem. SUMMARY OF BACKGROUND DATA: Vacuum phenomenon (gas accumulation in an intervertebral disc) is relatively common. Gas can also spontaneously enter and collect in the epidural space, but symptomatic epidural gas after spinal surgery is very rare. To date, only 5 such cases after lumbar surgery have been reported. METHODS: The primary disorders in the 4 new cases were disc extrusion at L2-L3 (Case 1), disc degeneration and herniation at L4-L5 (Case 2), stenosis of the lumbar spinal canal (Case 3), and disc herniation at L5-S1 with spinal canal stenosis (Case 4). The corresponding surgeries performed were L2-L3 microdiscectomy, L4-L5 microdiscectomy with instrumentation, right unilateral hemilaminotomy with complete instrumentation, and L5-S1 microdiscectomy. All 4 patients developed unexpected postoperative complaints of low back and radicular pain. Each was investigated with computed tomography and magnetic resonance imaging. The images revealed epidural gas collections compressing the thecal sac and/or nerve roots. RESULTS: Conservative management was effective in all but 1 case. In the latter case, computed tomography-guided needle aspiration was performed, but this did not resolve the problem. Surgery led to a favorable outcome, and follow-up lumbar computed tomography showed no epidural gas. CONCLUSION: Epidural gas after lumbar surgery is very rare but can cause unexpected postoperative back or radicular pain. Combined computed tomography and magnetic resonance imaging should be used to identify the problem and rule out other disorders. Conservative treatment should be the first-line approach but surgery is often necessary if this does not resolve the problem.