Lower Back Pain: Pearls, Pitfalls, and Practical Tips

Whether you are working in primary care, urgent care, or the emergency department, chances are you see a patient complaining of lower back pain during every shift. It’s one of the most common reasons patients seek care, but also a chief complaint that leads to over-testing, over-treating, and is one of the driving factors behind the opioid epidemic.

While lower back pain is a bread-and-butter complaint, there is also a lot to unpack when trying to find the best practices. In this two-part series, we are going to dive into the evidence behind the essential themes of lower back pain: imaging, medications, and follow-up treatment.

Part 1: The Donut of Truth

The need for emergent imaging comes down to a few very specific and very important questions that you should be asking every patient with lower back pain. These are the “cannot miss” red flags that, regardless of the setting, all clinicians should be asking their patients and documenting in their EMR. Any concerning findings should prompt a discussion about emergent imaging.

Nerve/Spinal cord compression:

• Urinary retention: New urinary retention is an early finding that is concerning for cauda equina syndrome, and can be easy to miss. While the most textbook answer is that difficulty voiding is different than true urinary retention, any new changes in bladder function should raise a red flag to consider further investigation.

• Fecal incontinence: This is a symptom that is very important to ask patients about, as they will likely not associate it with their back pain or injury, and may hide it due to embarrassment.

• Saddle anesthesia: This symptom easily goes unnoticed by patients unless you specifically ask them, especially in patients with severe acute pain. The best way to address this is to ask if they feel any numbness or difference when wiping themselves. I have personally had patients who did experience this, but at the moment did not think anything of it, as the severity of their back pain was all-consuming.

• Lower extremity weakness: The most critical physical assessment finding that should be documented for any patient with lower back pain is their lower extremity strength. Ask the patient to “push down on the gas pedal” with both feet against your hands’ resistance, as well as having them “pull up” against your hands with both feet to assess the strength of dorsal and plantar flexion of the feet. You should be able to clearly document that the patient has “5/5 strength to bilateral lower extremities.” Anything less than this should be a red flag that may warrant a trip to an MRI.

Acute Spinal Fracture

For patients presenting with back pain after a traumatic event such as a fall or MVC, the concern is primarily for a spinal fracture. In these cases, CT will be the test of choice, as plain film X-rays have poor sensitivity for spinal fractures. While there are factors such as osteoporosis or chronic steroids that put patients at higher risk for fractures, the key finding on exam that should raise your concern for a spinal fracture is the presence of focal midline spinal tenderness on exam. This should be clearly documented on your exam, and its presence should raise your suspicion for an acute fracture.

Another red flag should be any patients with a known malignancy presenting with new non-traumatic back pain. This could very well be from a pathological fracture or a new lesion. Similar to cauda equina syndrome, any exam findings that are concerning for spinal cord compression should be escalated. For patients with known malignancy whose only complaint is non-radicular pain, CT is usually appropriate when the primary concern is a pathologic fracture or bony metastasis.

For patients over the age of 65 presenting with back pain following even a ground-level fall, have a low threshold to get CT imaging. This is primarily due to the increased incidence of fractures in the elderly, combined with the poor sensitivity of plain film XRs.

Compression fractures are common in the elderly and may not always present with midline spinal tenderness. Elderly patients may also downplay recent falls due to fear of losing the ability to live independently. Loss of function may be gradual in the elderly, and what may have initially been a mild compression fracture may now be significant following even what may seem to be a minor fall. Don’t assume that an elderly patient’s decreased mobility is just due to arthritis or “wear and tear,” especially after a fall. It can be difficult to assess subtle mobility changes in the elderly, another reason why the threshold to order CT imaging of the spine should be very low in this population.

Spinal Epidural Abscess

The final “cannot miss” diagnosis for patients with lower back pain is also the scariest.

Patients with a spinal epidural abscess (SEA) can quickly decompensate, and the risk of permanent paralysis is well documented in the literature. The classic triad of presenting symptoms (fever, back pain, neurologic deficits) is rare during initial evaluation, which in part is why this very serious condition should always be at the back of your mind whenever you see a patient complaining of back pain.

Risk factor “red flags:”

• IV Drug Use (IVDU): The classic SEA presentation taught in school is a patient with a history of IVDU presenting with new back pain. Any patient with a known or reported history of IVDU with new back pain should warrant immediate further evaluation.

• Diabetes: Due to the large prevalence of DM, this risk factor can easily go unnoticed, especially when it is buried within a long list of other co-morbidities. This is an example of why it is so important to have a standardized approach to both exam and documentation when evaluating a patient with back pain. Having a macro with a built-in checklist of pertinent negatives and positives will help you remember to address easy-to-forget risk factors such as DM.

• Recent spinal procedures: While IVDU is classically associated with SEA, remember that any invasive spinal procedure, even something as commonplace as an epidural steroid injection, puts the patient at risk for developing SEA, especially if they have other comorbidities. As part of your standard exam for all patients presenting with back pain, remember to ask about ANY recent spinal procedures or surgeries.

• Immunosuppression: Whether it is due to cancer, an autoimmune disease, or an organ transplant, any patient with a history of immunosuppression presenting with new back pain should raise a red flag for further investigation.

Start With the Labs

For patients with a suspected SEA, the first step is ordering labs. A normal WBC alone is not diagnostic, and patients may present with elevated WBCs due to the continued prevalence of steroids as a treatment for acute lower back pain. A normal lactate is likewise reassuring, but not diagnostic to rule out SEA.

The most important labs in this situation are inflammatory markers. If a patient has a normal ESR and CRP, the likelihood of a SEA is far less likely, but labs alone cannot definitively rule out a SEA, especially in high-risk patients.

Keep the Imaging Broad

The gold standard for a definitive diagnosis of SEA is an MR with contrast of the spine. For patients with a high suspicion for SEA, MR imaging should be obtained ASAP, as delays in imaging are associated with poor outcomes, and patients can quickly progress to permanent paralysis.

A final note for patients with suspected SEA is the importance of imaging multiple levels of the spine. There are multiple cases of malpractice suits due to missed lesions in adjacent levels of the spine, which resulted in significant delays in treatment and subsequent permanent paralysis. When the suspicion for SEA is high, have a low threshold to get MR imaging of multiple levels, and remember this is a contrasted study.

Final Thoughts

We see lower back pain every day, and without diligence, a patient with serious pathology can slip through the cracks. The best way to avoid this? Have a standardized approach to every patient with back pain. Create a checklist of essential questions and physical exam findings, and then just rinse and repeat. The most foolproof way to keep from missing badness is to have a macro or dot phrase that auto-populates a checklist to make sure that you have addressed all of the essential negatives and positives.

Next month, we will explore what the evidence says about the right and wrong ways to treat acute back pain. When are steroids the right call, what is the right dose of NSAIDs, and how to avoid sending patients down the slippery slope of opioids.