Originally published December 2014
Back pain is often a diagnostic dilemma that goes unresolved. While it is one of the most common reasons Canadians seek care1,2 studies have found that most of the time no physiologic cause for the pain is established.3 This is because many conditions that cause back pain are self-limited and improve without treatment. On rare occasions, however, serious conditions present with back pain as a primary symptom. Failing to properly assess patients with back pain and effectively rule out these diagnoses can lead to serious outcomes.
Ordering imaging for patients with uncomplicated back pain is typically not effective and may cause harm.4 That is why campaigns aimed at reducing unnecessary testing and treatment, such as Choosing Wisely (choosingwiselycanada.org), recommend against imaging for new cases of back pain in most patients who are not experiencing "red flag" symptoms or signs.5 Canadian and international clinical practice guidelines describe evidence-based conservative approaches to managing back pain.
The CMPA analyzed medico-legal cases, closed between 2008 and 2013, that involved a patient with a primary complaint of back pain and documented peer expert criticism of the diagnostic assessment. The most common missed diagnosis was cauda equina syndrome — neurological impairment that results from compression of the nerve roots in the spinal canal below the termination of the spinal cord. This condition, which has many potential causes, including disc herniation, spinal stenosis, and lesions, requires urgent surgery to prevent lasting damage.
Other missed back conditions included vertebral fracture and other spinal pathologies. Non-spinal conditions that presented with back pain included renal disease; malignancies such as lymphoma and bone metastases; cardiovascular events (most often rupturing abdominal aortic aneurysm [AAA]); and infections, such as epidural abscess, discitis, or osteomyelitis.
Frequently, experts attributed the missed diagnosis to the physician's failure to appreciate the significance of the patient's presentation. This included missing red flags, such as fever, weight loss, neurological symptoms, or certain characteristics of the pain. There were also situations of physicians not following up on abnormal laboratory findings, such as an elevated white cell count or erythrocyte sedimentation rate. In some cases, physicians were criticized for not re-evaluating patients who returned with pain that persisted, progressed, or did not respond to treatment as expected.
Case 1: Failing to recognize red flags leads to cauda equina syndrome
An orthopaedic surgeon refers his patient, a 28-year-old woman with long-standing sciatica, to a neurosurgeon, after MRI shows a worsening of her lumbar disc protrusion (right L5–S1) and spinal stenosis. The appointment is made for a few months later, but the patient visits the emergency department (ED) the following week with severe right leg pain with weakness and urinary urgency.
The ED physician performs a neurological exam and finds only an absent right deep tendon knee reflex and some diminished muscle strength of the right extensor hallucis longus. She diagnoses acute multi-level radiculopathy with motor impairment. She admits the patient to hospital under the care of her family physician (FP), who is notified by telephone of her condition.
The FP refers the patient to an anesthesiologist for pain management with epidural steroid injections. When the anesthesiologist examines the patient before administering the injection, he notes loss of sensation in her right lateral lower leg with weakness and diminished knee reflex. He administers the injection, and the patient is discharged the next day. At a follow-up appointment with her FP a few days later, the patient reports an episode of urinary incontinence. The physician advises her to go immediately to the nearest tertiary hospital ED to be assessed by a neurosurgeon. The patient undergoes an emergency laminectomy and decompression for cauda equina syndrome; however, she is left with permanent neurological deficits including bladder and bowel dysfunction.
The patient files a legal action against all physicians involved in her care. Experts are critical that the FP did not urgently refer the patient to a neurosurgeon when she was first admitted through the ED, and that the anesthesiologist did not appreciate the severity of the patient's symptoms when he examined her.
Many cases involved incidents of physicians not fully considering elements of patients' history or co-morbidities that might put them at risk for a serious outcome. In a few cases vascular causes of back pain, such as a rupturing AAA, were not included in the differential diagnosis for patients with obvious risk factors. Conversely, other cases involved physicians who mistakenly attributed a patient's symptoms to a past or pre-existing condition, thereby failing to consider other differential diagnoses.
Case 2: Anchoring delays malignancy diagnosis
A 14-year-old boy visits the ED complaining of back spasms and continuing back pain since participating in a mountain bike race one week earlier. He has already visited a chiropractor and physiotherapist, and he is taking an NSAID and muscle relaxant prescribed by his FP, all with no improvement.
On examination, the ED physician notes dorsolumbar spasms, no tenderness, and no masses. When asked, the patient denies having bladder or bowel problems. The physician diagnoses severe muscle spasms and orders an analgesic and muscle relaxant. When he assesses the patient 30 minutes after receiving the medications, his pain is gone, and he is discharged with instructions to follow up with his FP in the morning.
The next day the patient has difficulty walking and visits another physician, who promptly refers him to the children's hospital after a neurological exam finds pronounced leg weakness. The patient is ultimately diagnosed with anaplastic large cell lymphoma at T8–T10 and undergoes treatment.
A legal action is filed against the ED physician. Experts are critical that he did not perform a complete neurological assessment or ask the patient about symptoms of numbness or weakness.
Inappropriate prescribing of narcotics for pain control was commonly associated with diagnostic issues. In some of these cases, the use of narcotics was central when the drugs contributed to addiction or related to serious patient outcomes. In others, their use obscured the progression of neurological symptoms making diagnosis more difficult.
Cognitive biases such as attribution error (a form of stereotyping: explaining a patient's condition on the basis of their disposition or character rather than seeking a valid medical explanation) may have contributed to the inadequate assessment of a patient's back pain, particularly in cases where physicians were found to be too quick to fix on a particular diagnosis, or conclude that a patient was malingering. In a few cases epidural abscesses were missed in patients with a history of drug addiction, despite their representing a high-risk group for this complication.
Managing medico-legal risk
When assessing patients with complaints of back pain, consider the following risk management actions which are based on the experts' opinions in the cases analyzed:
- Be aware of the current evidence-based conservative approaches to managing the care of patients with back pain, which include guidance on the use of medication for pain management.
- Take a complete and appropriate physical examination, and evaluate for red flags associated with back pain that might indicate the need for urgent diagnostic imaging or referral to a specialist.
- Keep an open mind when patients explain the source of their symptoms.
- Pause and reflect on the differential diagnosis, being careful to consider possibilities that may be threatening to life or limb.
- Reflect on whether cognitive biases are influencing your diagnosis.
- Advise your patients of the symptoms and signs that should alert them to seek further medical attention.
- When patients return with the same or worsening symptoms, re-evaluate your diagnostic assumption and repeat the physical examination, with neurological exam.
- Ensure your documentation reflects a thorough assessment, history taking, differential diagnosis, and discharge instructions.
- Cassidy, J.D., Carroll, L.J., Côté, P., "The Saskatchewan health and back pain survey. The prevalence of low back pain and related disability in Saskatchewan adults," Spine (1998) Vol. 23 No. 17, p.1860
- Deyo, R.A., Mirza, S.K., Martin, B.I., "Back pain prevalence and visit rates: estimates from U.S. national surveys, 2002." Spine (2006) Vol. 31 No. 23, p.2724
- Deyo, R.A., Rainville, J., Kent, D.L., "What can the history and physical examination tell us about low back pain?" Journal of the American Medical Association (1992) Vol. 268 No. 6, p.760
- Srinivas, S.V., Deyo, R.A., Berger, Z.D., "Application of "less is more" to low back pain." Archives of Internal Medicine (2012) Vol. 172 No. 13, p.1016
- Choosing Wisely Canada. Imaging tests for lower back pain: When you need them—and when you don't. Accessed July 7, 2014 from: http://www.choosingwiselycanada.org/materials/imaging-tests-for-lower-back-pain-when-you-need-them-and-when-you-dont/