From the Desk of Freyr Gauti Sigmundsson, MD
Caring for patients with lumbar spinal stenosis (LSS) with predominant back pain is a well-known continuous challenge. Most spinal surgeons meet and operate on many patients with spinal stenosis. Typically these patients have leg pain and pseudoclaudication as well as varying degree of back pain. They probably are told that the operation is for the leg and buttock pain experienced while walking. Often the patient asks “will my back pain get better or not?”
We are of course reluctant to answer the question as the prognosis as to the back pain is quite difficult to predict. In the Swedish Spine Register, most patients benefit from surgery also in terms of back pain although the benefit is not as pronounced as for leg pain. The residual back pain is frustrating for surgeons and patients alike and many surgeons want to address the back pain more aggressively. Some surgeons subsequently feel that adding spinal fusion to the decompression can improve outcomes as it addresses the back pain although no studies have before showed this to be the case. Adding fusion in the absence of defined deformity (spondylolisthesis or scoliosis) is very controversial(1). Spinal stenosis with predominant back pain without overt instability should in our opinion not routinely lead to fusion despite the results from our study but prompt the search for symptoms characteristic for mechanical low back pain and MRI signs of relevance i.e. facet joint fluid/degeneration and Modic changes. Patients experiencing low back pain when walking and increasing with walking distance would in our opinion NOT be candidates for fusion despite predominant back pain. It must also be taken into consideration that patients scheduled for spinal stenosis surgery generally show disc degenerative changes on adjacent levels and the fusion as such could initiate a future adjacent level disease.
The results from our register analysis have had some immediate effect in our clinical practice. Most importantly we can advise our patients with predominant back pain better as they can be informed that they are less likely to be satisfied and can expect to have considerable residual symptoms. The results of our study have also heightened awareness about patients with predominant back pain and also prompted us to search for mechanical pain generators to address with fusion. It is probably fruitful (but not included in our study) to analyze the type of back pain experienced by LSS patients. Back pain relieved by flexion in concordance with relief of leg pseudoclaudication probably responds favorably to decompression surgery while chronic back pain from facet joint arthrosis / disc degeneration probably will not be affected by decompression. It is also likely that root pain in the buttocks is characterized as back pain by many patients. The myriad of back pain constellations in spinal stenosis underscores the importance of how we ask about back pain and how we define predominant back pain. The studies establishing inferior outcomes in patients defined as having predominant back pain have mainly derived pain predominance by evaluating the ratio of pain,(2–4) while asking multiple questions about pain, particularly a percent question (how much in back versus leg), might perhaps better establishes predominant pain(5).
Agreeing with Dr. Pearson, we believe fusion is not warranted only because of predominance of back pain. However, the patients who might benefit from fusion are probably those with severe back pain.
1. Deyo RA, Nachemson A, Mirza SK. Spinal-fusion surgery - the case for restraint. N Engl J Med 2004;350(7):722–6.
2. Kleinstück FS, Grob D, Lattig F, et al. The influence of preoperative back pain on the outcome of lumbar decompression surgery. Spine 2009;34:1198–203.
3. Pearson A, Blood E, Lurie J, et al. Predominant leg pain is associated with better surgical outcomes in degenerative spondylolisthesis and spinal stenosis: results from the Spine Patient Outcomes Research Trial (SPORT). Spine 2011;36:219–29.
4. Sigmundsson FG, Jönsson B, Strömqvist B. Preoperative Pain Pattern Predicts Surgical Outcome more than Type of Surgery in Patients With Central Spinal Stenosis Without Concomitant Spondylolisthesis: A Register Study of 9,051 Patients. Spine 2013;39:E199-E210.
5. Wai EK, Howse K, Pollock JW, et al. The reliability of determining ”leg dominant pain”. Spine J 2009;9:447–53.