Are There Differences Between Patients with Extreme Stenosis and Non-extreme Stenosis in Terms of Pain, Function or Complications After Spinal Decompression Using a Tubular Retractor System?

BACKGROUND: Micro-tubular decompression in extreme lumbar spinal stenosis is challenging because it is technically difficult to achieve adequate decompression. Whether the results of micro-tubular decompression related to pain, function, and complications in lumbar spinal stenosis of the extreme and non-extreme varieties are different has not yet been conclusively established. QUESTIONS/PURPOSES: Are there differences between patients with extreme stenosis and non-extreme stenosis in terms of (1) VAS back or leg pain, (2) Oswestry Disability Index (ODI), or (3) complications when they were treated with spinal decompression using a tubular retractor system? METHODS: Between January 2007 and January 2017, one surgeon performed 325 single-level lumbar micro-tubular decompressions without fusion. Of those, 43% (140 of 325) had extreme stenosis (defined as the absence of cerebrospinal fluid signal and a grey homogeneous dural sac with unrecognizable rootlets and posterior epidural fat in T2 weighted axial MRI image) and the rest had non-extreme stenosis. During this time, we used tubular retractors for these procedures in patients with simple lumbar spinal stenosis who had persistent symptoms despite conservative treatment for neurogenic claudication. No alternate form of decompression was performed in the study period. Patients with complex lumbar spinal stenosis associated with a deformity or instability who were treated with instrumented fusion were excluded. A total of 14% (20 of 140) patients in the extreme stenosis group and 15% (28 of 185) patients in the non-extreme stenosis group were lost to follow-up before 2 years; the remaining 120 patients with extreme stenosis and 157 patients with non-extreme stenosis were analyzed at a mean follow-up of 33 ± 5 months in this retrospective, comparative study. The groups were not different at baseline in terms of preoperative VAS score for back pain, age, gender, BMI or the percentage who had diabetes or who smoked. However, patients with extreme stenosis had higher preoperative ODI scores and higher preoperative VAS score for leg pain compared with the non-extreme group. There was a higher proportion of men in the non-extreme stenosis group (56% [104 of 185] versus 50% [71 of 140]; p = 0.324). Study endpoints were VAS score for leg and back pain, ODI, and complications, all of which were ascertained by chart review. With the numbers available, we could detect with 80% power at p < 0.05 a difference of 0.93 cm of 10 cm on a 10-cm VAS scale for VAS leg pain; a difference of 1.00 cm of 10 cm on a 10-cm VAS scale for VAS back pain and a difference of 2.12 cm of 100 cm on a 100-cm ODI scale. RESULTS: In terms of pain, both groups improved after surgery, but there was no between-group difference in terms of the VAS scores at the most recent follow-up. VAS back pain improved from a mean of 3 ± 1 to 2 ± 1 in the extreme stenosis group and from 3 ± 1 to 1 ± 1 in the non-extreme stenosis group (p = 0.904); VAS leg pain improved from 7 ± 1 to 1 ± 1 versus 6 ± 1 to 1 ± 1, respectively (p = 0.537). ODI scores likewise improved in both groups, with no between-group difference in the ODI scores at latest follow-up (66 ± 7 to 19 ± 2 in the extreme stenosis group versus 59 ± 5 to 19 ± 2 in the non-extreme stenosis group (p = 0.237). Complications in the group with extreme stenosis occurred in six patients (incidental dural tears in two patients, urinary retention in three patients, and Syndrome of Inappropriate Anti Diuretic Hormone secretion (SIADH) in one patient); complications in the non-extreme stenosis occurred in two patients (incidental dural tears in two patients). CONCLUSIONS: The results in terms of improvement in VAS for leg and back pain and ODI scores were not different between patients with extreme and non-extreme stenosis. Micro-tubular decompression can be thus considered an alternative for patients with extreme stenosis. Future studies, ideally multicentre, comparative trials, are needed to confirm our preliminary results. LEVEL OF EVIDENCE LEVEL: III, therapeutic study.

Feasibility and Outcomes of Tubular Decompression in Extreme Stenosis.

STUDY DESIGN: Retrospective cohort study. OBJECTIVES: To report the feasibility, nuances, technical tips as well as outcomes of managing single-level grade D (extreme stenosis) and to compare the outcomes with nonextreme stenosis using the tubular retractor system. SUMMARY OF BACKGROUND DATA: Minimally invasive decompression in extreme stenosis is a challenge due to technical difficulty, feasibility of adequate decompression, and a steep learning curve. METHODS: Consecutive patients from January 2007 to January 2017 presenting with neurogenic claudication secondary to single-level spinal stenosis operated using tubular retractors were included in the study. The patients were divided into two groups; extreme-stenosis and nonextreme stenosis. The outcomes of surgery were evaluated and compared using visual analogue score (VAS) for leg and back pain, Oswestry disability index (ODI), and MacNab's criteria. RESULTS: A total of 325 patients (out of 446 patients after excluding the multilevel cases) fulfilled the inclusion criteria. One hundred forty patients were cases of extreme stenosis and 185 were nonextreme stenosis. The mean VAS for back and leg pain for extreme stenosis improved from 3.23 ±â€Š1.30 to 2.15 ±â€Š0.91 and 7.33 ±â€Š0.78 to 1.66 ±â€Š1.03 respectively as compared with nonextreme stenosis where the mean VAS for back and leg pain improved from 3.01 ±â€Š1.15 to 1.86 ±â€Š1.10 and 6.57 ±â€Š1.00 to 1.54 ±â€Š1.12 respectively. The mean ODI changed from 66.47 ±â€Š7.53 to 19.95 ±â€Š2.90 in extreme stenosis as compared with nonextreme stenosis where mean ODI changed from 59.05 ±â€Š5.08 to 19.88 ±â€Š2.67. As per MacNab's criteria 102 (of 120 patients) and 139 (of 157 patients) reported excellent and good outcomes in extreme and nonextreme stenosis respectively. CONCLUSION: Tubular decompression is feasible in patients with extreme-stenosis with no difference in the outcomes as well as complication rates when compared with a cohort of nonextreme stenosis. LEVEL OF EVIDENCE: 3.