Long-term Clinical Outcomes After Bilateral Laminotomy or Total Laminectomy for Lumbar Spinal Stenosis

A Single-institution Experience

Andrea Pietrantonio, MD; Sokol Trungu, MD; Isabella Famà, MD; Stefano Forcato, MD; Massimo Miscusi, MD, PhD; Antonino Raco, MD, PhD

Disclosures

Neurosurg Focus. 2019;46(5):e2 

In This Article

Discussion

The incidence of LSS ranges between 3.9% and 11% of the general population, and its prevalence is steadily growing in our aging society. LSS may be a developmental or an acquired disease, the last one being far more common, and generally has a slowly progressive course. LSS is caused by a compression of the neural elements from different structures of the spinal canal: ligamentum flavum hypertrophy and disc bulging may lead to central stenosis, whereas facet hypertrophy and settling are associated with recess or foraminal compression. These degenerative changes are mostly age related and may produce a vascular and/or mechanical compression on the neural roots.[2,12,24]

Classically, the surgical treatment of lumbar stenosis has been represented by a wide posterior decompression of the spinal canal: until the last few years, the standard procedure has been a wide laminectomy with a partial or complete removal of the articular processes.[6,8,10] This procedure destroys the entire posterior bony arch and posterior ligamentous complex, and it detaches the paraspinal muscles bilaterally, thus damaging significantly the posterior stabilizing structures of the spine. Not surprisingly, the short-term neurological outcome after a laminectomy is generally good, because of the wide decompression achievable, but concerns regarding postoperative instability and subsequent low-back pain in the medium and long term have been raised. Different studies have reported a higher iatrogenic instability following laminectomy compared to minimally invasive decompression.[1,7,20] On the basis of these and other experiences, a new trend in spine surgery, consisting of minimizing the normal tissue trauma while ensuring the same clinical, radiological, and neurological outcome, has progressively emerged.[13,16]

Unilateral and bilateral laminotomy for decompression of the lumbar spine was introduced in 1981 by Getty et al. as less invasive surgical options.[5] Laminotomy involves the partial removal of bone from the inferior aspect of the superior lamina, the superior portion of the inferior lamina, and the medial aspect of the facet joint, and it also entails the excision of the ligamentum flavum; the spinous process and supra- and interspinous ligaments are preserved.[18,25,26] The unilateral approach for bilateral decompression preserves the contralateral structures (lamina and facet joint) and ensures enough contralateral decompression by drilling the base of the spinous process and by tilting the microscope and the operating table.

Different studies showed no difference in clinical outcome between bilateral laminotomy and laminectomy.[9,19,22] In their multicenter observational study, Nerland et al. compared minimally invasive microdecompression and open laminectomy for the treatment of central lumbar stenosis and reported similar outcome scores at 1-year follow-up and a shorter hospital stay for the minimally invasive group. Considering the similar effectiveness of these techniques, the authors concluded that minimally invasive decompression should be favored when there are concerns about later instability.[15] Several studies showed that minimally invasive techniques ensure at least the same results as the standard open technique; moreover, results are better in terms of clinical improvement, LOS, blood loss, time to mobilization, use of medications, and patients' satisfaction in the short and medium term.[4,14,17]

Defining instability as sagittal plane translation ≥ 5 mm on dynamic radiographs, Thomé et al. reported a frequency of iatrogenic instability following laminectomy and unilateral laminotomy for bilateral decompression of 8.8% and 5.1%, respectively. Conversely, none of their patients treated with bilateral laminotomy showed radiographic and clinical evidence of postoperative instability.[23] On the other hand, in the retrospective study of Costa et al., 3 of 374 patients (0.8%) treated via unilateral laminotomy for bilateral decompression experienced postoperative back pain suggestive of iatrogenic instability.[3] In 2010, Lee et al. used cadaveric lumbar spine models to study the range of motion after bilateral laminotomy and facet-sparing laminectomy; the analysis per level demonstrated a roughly 2-fold increase in motion after laminectomy compared with bilateral laminotomies (14.3% in bilateral laminotomies vs 32.0% in full laminectomies). Moreover, stiffness was decreased by an average of 11.8% after 3-level laminotomies and by 27.2% after 3-level laminectomies.[11]

As a result of all these experiences and because of the concerns for late instability and the comparable clinical outcome, the classic wide laminectomy with facetectomy has been more frequently replaced with minimally invasive techniques. This is also our experience—in recent years fewer cases of laminectomies have been performed by our group for degenerative diseases, whereas the number of patients treated with bilateral laminotomies has continuously increased. Our results confirm the evidence emerging in the literature in the last few years and reported in this paper: in the laminotomy group, LOS and intraoperative blood loss were less.

Regarding complications, we observed a little increase in the frequency of dural tears in the laminotomy group. We found it more difficult to repair the leakage with sutures, because the smaller operative corridor makes both the suturing and the identification of the tear more challenging. However, the use of sealant and a more prolonged postoperative bed rest have proved to be effective in preventing CSF leakage. A higher incidence of incomplete decompression requiring reintervention was observed in the laminotomy group (3.7% vs 1%); we explain this as an error in surgical indication, because all these patients showed a severe foraminal stenosis that would have been better treated with a wide artrectomy and fusion from the beginning. No patient with postoperative instability was seen in the laminotomy group, as compared to the laminectomy group, in which 15 patients (14.3%) underwent fixation for iatrogenic listhesis and back pain.

Regarding clinical outcomes, the success rate of the 2 techniques was similar, although a slightly better outcome and higher patient satisfaction after bilateral laminotomy can be seen; in the medium to long term, bilateral laminotomy proved to be equally effective in improving pain and function if compared to standard decompression. However, the main advantages of this less invasive technique consist of the reduction of postoperative instability, ensuring at the same time an adequate degree of decompression.

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