Sunday, April 20, 2014
Lumbar Radiculopathy and Numbness: An Understudied Symptom
Studies of lumbar radiculopathy have typically focused on pain and function as outcomes, with very little reported on the time course and degree of improvement of numbness. While pain tends to be the most bothersome radicular symptom for most patients, numbness and paresthesia can also be troublesome. Based on anecdotal experience, surgeons have traditionally told patients that numbness improves slowly and unpredictably, though there has not been much data supporting this belief. In an effort to fill the knowledge gap surrounding numbness after surgery for lumbar radiculopathy, Drs. Huang and Sengupta reviewed the pain diagrams of 85 surgical patients with lumbar radiculopathy due to disk herniation and/or spinal stenosis. In addition to pain, patients were also asked to shade areas on the pain diagram corresponding to numbness and paresthesia. All patients had baseline pain diagrams as well as at least two more post-operative pain diagrams over one year of follow-up. Additionally, patients were stratified based on whether they reported radicular symptoms for more or less than 6 months. The authors reported that pain improved fastest and to the greatest degree, with marked improvement in the first 6 weeks, beyond which there was minimal improvement. Numbness and paresthesia never improved significantly from baseline, though there were trends towards improvement over the course of an entire year. The Oswestry Disability Index and SF-36 physical function scores improved significantly out to three months and then plateaued. Patients with a longer duration of symptoms tended to improve slower than patients with symptoms for less than 6 months. These findings effectively confirmed what surgeons knew from anecdotal experience—pain improved the most rapidly and completely while numbness and paresthesia tended to improve slowly and incompletely.
The authors have made an excellent first step in quantifying difficult to measure outcomes such as numbness and paresthesia. No prior study has done such a complete analysis of these symptoms, and the results of this study will be valuable to surgeons and other spine providers counseling patients about their likely outcomes following surgery. The current method of quantifying the number of pixels on a computer-based pain diagram is novel, and future studies should evaluate exactly what this is measuring. Further stratification based on the underlying diagnosis (i.e. disk herniation vs. stenosis) would also be interesting as the current subgroup analysis focused on duration of symptoms. Given that all of the short term symptom patients had disk herniation while the long term patients were a mixture of disk herniation and stenosis, some of the differences observed could be driven by differences in pathology rather than in duration of symptoms. Weakness is another bothersome symptom that has not been well-studied, and future rigorous studies evaluating the time course and degree of improvement of weakness in lumbar radiculopathy would also be important. Data on the natural history of numbness in patients treated non-operatively would also be interesting. The current paper offers an important evidence base for discussions about how pain and numbness will likely change following surgery for lumbar radiculopathy, and such discussions should help create realistic patient expectations.
Please read Drs. Huang’s and Sengupta’s article on this topic in the April 15 issue. Does this affect how you counsel your lumbar radiculopathy patients pre-operatively? Let us know by leaving a comment on The Spine Blog.
Adam Pearson, MD, MS
Associate Web Editor