Clinical and Radiological Comparison between Ipsilateral and Contralateral Side Canal Decompression Using an Unilateral Laminotomy Approach

OBJECTIVE To compare the clinical and radiological outcome of both sides using the unilateral approach. METHODS Unilateral laminotomy was performed to achieve bilateral decompression. Thirty-nine patients who underwent this procedure were analyzed prospectively using the Oswestry Disability Index (ODI), the visual analog scale (VAS) pain score to evaluate symptoms in both legs, and the radiological morphometric index to calculate the anteriorposterior diameter and midcanal width. The incidence of complications from this approach was then evaluated. RESULTS The mean follow-up time was 12.2 months. The mean ODI was 48.4 preoperatively and 14.2 postoperatively. The mean dural sac widening of the ipsilateral side (187.0%) was significantly larger (p<0.01) than that of the the contralateral side (145.6%). The VAS improvement ratio ([preoperative VAS score-postoperative VAS score]/[preoperative VAS score]×100) for the pain in each leg was 75.4%(ipsilateral side) and 73.7%(contralateral side). While the VAS improvement ratio for pain in each side was significantly reduced, the difference in the VAS ratio between sides was statistically insignificant (p=0.64). There were 2 cases (5.1%) of dural tearing during the procedure, 1 case (2.6%) of transient paresthesia of nerve roots, and 2 cases (5.1%) of transient paresthesia of the contralateral nerve root. The transient paresthesias of nerve roots never lasted more than 2 weeks. CONCLUSION This technique allows for significant decompression of the contralateral canal and excellent clinical outcomes without troublesome complications. Although ipsilateral the dural sac widening was significantly larger than contralateral side, the difference in the clinical outcome between sides was statistically insignificant.