Clinical outcomes with endoscopic resection of lumbar extradural cysts

Lumbar extradural cysts may be associated with sciatica-type back and leg pain. The symptoms of clinical pain syndrome from synovial cysts are sometimes difficult to differentiate from those of lumbar disc herniation or spinal canal stenosis and may be identified to be a pain source when visualized endoscopically. The authors analyzed the clinical outcomes with their endoscopic resection to better establish clinical indications and prognosticators of favorable results.

Two-year Macnab outcomes, VAS scores, and complications were analyzed in a series of 48 patients treated with the endoscopic removal of extradural cyst encountered during routine transforaminal and interlaminar decompression for foraminal and lateral recess stenosis causing lumbar radiculopathy.

There were 26 female and 22 male patients. The extradural cysts were most commonly encountered at L4/5 level in 26 patients (72.2%) followed by the L5/S1 level in 8 patients (22.2%), and in 2 patients (5.6%) at the L3/4 level, respectively. One patient underwent T9/10 decompression. At minimum 2-year follow-up, all patients were improved. Excellent results according to the Macnab criteria were obtained in 19/48 (39.6%) patients, good in 18/48 (37.5%), and fair in 11/48 (22.9%), respectively. The average preoperative VAS score for leg pain was 8.06±1.57 and reduced at a statistically significant level (P<0.000) postoperatively to 1.92±1.49, and 1.77±1.32 at final follow-up, respectively. The percentage of patients with unlimited walking endurance had improved at a statistically significant level (P<0.0001) from 33.3% preoperatively (16/48) to 81.3% (39/48) postoperatively. One patient had a recurrent disc herniation, and another patient did not improve. Two patients underwent fusion during the follow-up period. Patients with Fair outcomes had a statistically significant association (P<0.001) with facet instability as suggested by axial T2-weighted magnetic resonance imaging (MRI) findings of thickened ligamentum flavum, facet joint hypertrophy, and bright white fluid-filled joint gap of >2 mm.

Endoscopic resection of extradural spinal cysts during routine decompression for symptomatic foraminal and lateral recess stenosis is feasible with favorable clinical outcomes in the majority of patients. Fair outcomes were associated with advanced instability of the involved lumbar facet joint complex.