• Shellie A.B. Christensen, Ph.D.

WHY PAIN RADIATING DOWN THE LEG IS WORTH TRACKING

The location of low back pain can differ due to the underlying cause or the severity of symptoms. According to a 2016 study published in Pain Practice, the severity of low back pain is higher when pain radiates down the entire leg (Hüllemann et al., 2016). Further, surgery and medication intake are more common for patients experiencing radiating pain extending past the knee or to the ankle.


RADIATION PATTERNS IN LOW BACK PAIN

The main finding for the 2016 study in patients with low back pain is four different pain radiation distances.

  1. Well localized pain in the lumbar region

  2. Pain radiating to the thigh

  3. Pain radiating between the knee and ankle

  4. Pain radiating to the feet

Diagnoses for the patients in the study include sciatica, unspecified low back pain and radiculopathy. However, the diagnoses, of which there were many, are only a part of the picture. The pain drawings together with the questionnaires revealed much more.

Assessments of pain intensity, sleep disturbance, depression, disability and utilization of the health services gave additional insight. Worse pain conditions associated with pain radiating into both legs (bilateral pain), particularly to the thigh. While low back pain patients with pain radiating beyond the knee or into the feet showed neuropathic pain.

PAIN EXTENDING DOWN THE LEG IS A CRUDE DESCRIPTION

A much earlier study of chronic low back pain patients divided the lower limbs into four regions: buttocks, thigh, calves, and ankle/feet. Based on these divisions, the authors found pain intensity, back-specific function, and physical health assessments are generally worse in those with extensive leg pain (Prins et al., 2013). Extensive, meaning two or more regions. However, this may be a very crude estimate and depiction of leg pain. Patients’ experiences can vary greatly. For example, a patient may report multiple and discrete pain locations in the lower extremities or a singular continuous line from the low back to the lower femoral region or beyond. Thus the pain drawing in combination with appropriate physical examinations is more powerful.

For example, Hüllemann and colleagues (2016) suggested that patients with pain radiating to the feet may indicate an L5 or S1 root compression. Patients with localized low back pain (axial pain) show an increase in neuropathic pain components as measured 3 – 6 months later. This study is the first to identify what may be critical transitions characterized by severe low back pain.

Instead, encourage patients to precisely report the area and location of the pain. Recording whether the pain is present on both legs and assessing pain qualities will also be insightful.

In summary, by extracting the generalized pain location (buttocks, thigh, calves, and ankle/feet), insight into the severity of low back pain and behaviour, such as poor sleep, becomes evident. However, tracking change may give a more accurate understanding. Does the patient’s pain continue to spread? Is there an increase in the presence of neuropathic-pain-like symptoms, and how quickly are the changes occurring? Considering that these studies found so much insight by examining the patient at one specific point in time - imagine what we could learn with two, three or ten more time points?

REFERENCES

Hüllemann P, Keller T, Kabelitz M, Freynhagen R, Tölle T, Baron R. Pain Drawings Improve Subgrouping of Low Back Pain Patients. Pain Pract. 2017 Mar;17(3):293-304. doi: 10.1111/papr.12470. Epub 2016 Jun 23. PMID: 27334429.


Prins MR, van der Wurff P, Groen GJ. Chronic low back pain patients with accompanying leg pain: the relationship between pain extent and pain intensity, disability and health status. J Back Musculoskelet Rehabil. 2013;26(1):55-61. doi: 10.3233/BMR-2012-00350. PMID: 23411649.