Surgical Treatment of Extra-Foraminal Gas Containing Pseudocyst Compressing L5 Nerve Root by Using Unilateral Biportal Endosopy: A Case Report.

BACKGOUND: Most gaseous lumbar pseudocysts have been previously reported to be located in the spinal canal and successfully treated by several therapeutic methods. By comparison, a gas containing pseudocyst in lumbar extra-foraminal area is very rare. Here, the authors report a case of symptomatic gas containing cyst located in lumbar foramen. It was successfully treated with unilateral biportal endoscopic (UBE) surgery.

CASE DESCRIPTION: a 75-year-old man presented with severe left leg pain and tingling sensation refractory to conservative treatment that aggravated with weight bearing and position change. Computed tomography and magnetic resonance imaging showed a gas containing cyst compressing the left L5 nerve root ganglion in the foramina area at L5-S1 level. Gaseous extra-foraminal pseudocyst was successfully removed by UBE surgery via para-spinal approach. Vivid and clear endoscopic operative imaging of pseudocyst in detail was obtained during operation. The patient's symptom was significantly improved after the operation.

CONCLUSIONS: Gas containing pseudocyst in lumbar foraminal area is not common. Combined use of pre-operative MRI and CT can help diagnose gaseous pseudocyst and differentiate other pathologies. UBE technique which provides good operative visualization and delicate operative manipulation is a less invasive therapeutic method to treat foraminal gas containing pseudocyst.