Readmissions After Outpatient Transforaminal Decompression for Lumbar Foraminal and Lateral Recess Stenosis.

BACKGROUND: The objective of this study was to analyze readmission rates after outpatient transforaminal endoscopic decompression surgery for lumbar foraminal and lateral recess stenosis done in an ambulatory surgery center. Endoscopic lumbar spinal surgery is gaining popularity for the treatment of lumbar disc herniations. Recent advances in surgical techniques allow for percutaneous endoscopically assisted bony decompression for neurogenic claudication symptoms due to spinal stenosis. The surgery can be done under local anesthesia and sedation. Patients may be discharged home within hours from surgery, and complications are rare. However, readmissions for recurrent disc herniations, failure of pain relief, dysesthetic leg pain, nerve root injuries with foot drop, and facet and pedicle fractures have been reported.
METHODS: A retrospective study of 1839 consecutive patients with an average mean follow up of 33 months (range 24 to 85 months) that underwent percutaneous endoscopic surgery at 2076 levels between 2006 and 2015 was conducted with the intent of identifying factors associated with emergency room or hospital readmission following endoscopic foraminotomy and microdiscectomy. Only patients with unilateral radiculopathy due to either herniated disc or lateral recess stenosis were included in this study. Preoperatively, disc migration was graded by direction and distance from the disc space according to Lee's radiologic 4-zone classification. The type of disc herniation was classified either as extruded or contained. Contained herniations were further subclassified as disc protrusions versus disc bulges. In addition, the preoperative disc height was recorded. Bony spinal foraminal stenosis and lateral recess stenosis were graded on preoperative magnetic resonance imaging and computed tomography scans into mild, moderate, and severe by dividing the lumbar neuroforamen into 3 zones: (a) entry zone, (b) midzone, and (c) exit zone. Surgical outcomes were classified according to the Macnab criteria. In addition, reduction in visual analog scores (VASs) were assessed. The treating physician (KUL) performed all surgeries.
RESULTS: According to the Macnab criteria, excellent and good results were obtained in 82.2% of patients with extruded disc fragment (331/1839). In this group, the mean VAS decreased from 5.9 ± 2.5 preoperatively to 2.4 ± 1.8 at the final follow up (P < .01). Patients with contained disc herniations (648/1839) had excellent and good results 72.7% of the time. In this group, the mean VAS decreased from 7.2 ± 1.6 preoperatively to 3.1 ± 1.5 at the final follow up (P < .01). In the spinal stenosis group (860/1839), 75% of patients had excellent to good results. There were no major approach-related complications. Sixty-nine patients had extravasations of irrigation fluid into the subcutaneous tissues (3.8%). Eight patients developed spinal headaches (0.4%). Two patients developed foot drop on the surgical side immediately postoperatively (0.1%). Reherniations of extruded discs occurred in 9 patients (2.7% recurrence rate). Failure of pain relief without significant improvement of walking endurance occurred in 29 patients with bony stenosis in the central canal, lateral recess, and entry zone of the neuroforamen (3.3%). Reherniations were associated with preserved disc height of >6 mm (P < .02). Dysesthetic leg pain due to dorsal root ganglion irritation occurred in 229 patients (12.4%) and was unrelated to case frequency but was associated with severe foraminal stenosis (P < .01). All 229 patients improved with supportive care. Facet or pedicle fractures did not occur in this series. There were 26 acute care (within 6 weeks from surgery) postoperative emergency room visits [16 of which resulted in readmission to a hospital over the 9-year study period (0.86%): 9 for dysesthetic leg pain, 2 for wound infections, and 5 for poorly controlled incisional pain].
CONCLUSIONS: Transforaminal endoscopic decompression can be successfully carried out in an outpatient surgery center setting. Readmissions due to reherniations, postoperative complications, or poor pain control are uncommon.