Approach to back pain: Clinical sciences

Back pain is a very common and potentially challenging condition to diagnose. The vast majority of patients have musculoskeletal pain without a specific underlying condition, and improve within a few weeks. Although back pain is most often benign and self-limited, in some cases it could also be a sign of more severe disease, so these patients require prompt evaluation and treatment.

Okay, if your patient presents with back pain, you should first perform an ABCDE assessment to determine whether your patient is unstable or stable. If they’re unstable, stabilize their airway, breathing, and circulation. Next, obtain IV access and put your patient on continuous vital sign monitoring, including heart rate, blood pressure, and pulse oximetry. Finally, if needed, don’t forget to provide supplemental oxygen!

Here’s a clinical pearl! Unstable patients with back pain might present in a few ways. First, your patient might have sepsis due to underlying discitis, osteomyelitis or abscess. In this case, don’t delay starting IV fluids, obtain an MRI and cultures, and initiate empiric antibiotics! Another common cause of back pain in unstable patients is from a visceral source, such as bowel perforation leading to acute peritonitis. These patients might present with hypotension and abdominal pain that radiates to the back, so in this case, start IV fluids, empiric antibiotics, and consult the surgery team. And finally, your unstable patient might have back pain from a vascular source, such as a ruptured aortic aneurysm. So, if your patient presents with hypotension, sudden and severe back pain described as “ripping” or “tearing”, then immediately start IV fluids, obtain a CT angiogram, and consult the vascular surgery team!

Now that we’ve addressed unstable patients, let’s go back and discuss stable ones. If your patient is stable, perform a focused history and physical examination. Your patient will report back pain, while the physical exam might reveal tenderness to palpation of the spinous and paraspinous structures, or tenderness to palpation in the abdominopelvic region. At this point, diagnose back pain! Next, assess for red flags including age of onset before 20 or after 55 years of age; severe or progressive motor and sensory loss; urinary retention or incontinence; history of cancer or spinal surgery; significant trauma that precedes the onset of pain; prolonged steroid use; and history of HIV.

If red flag symptoms are present, obtain a spinal X-ray and assess for the underlying cause. First, let’s focus on cauda equina syndrome! The cauda equina is the bundle of nerves at the lower end of the spinal cord, resembling a horse's tail. This region is crucial for transmitting nerve signals to and from the legs and pelvic organs. Thus, compression or damage of the cauda equina can lead to significant neurological symptoms.

Your patient will report progressive motor or sensory loss in the lower limbs, new urinary retention, or urinary or fecal incontinence. They might also have a history of a spinal tumor or disc herniation.

Physical exam typically reveals motor deficits and saddle anesthesia, meaning loss of sensation around the buttocks, perineum, and inner thighs. You will also note absent or decreased anal sphincter tone. Spinal X-ray may show loss of intervertebral space, which may indicate posterior intervertebral disc bulging, or could show spondylolysis and stenosis of the vertebral canal. With these findings, consider cauda equina syndrome and order an MRI. If it shows compression of the cauda equina nerves, which is often seen between the levels of L1 to L5, you can diagnose cauda equina syndrome!

Moving on to infection! These patients may have a history of a surgical procedure, intravenous substance use, or immunosuppression such as patients with prolonged steroid use or HIV. Physical exam typically reveals elevated body temperature and you may even observe a wound. Spinal X-ray might show discitis or osteomyelitis, where there is boney destruction, loss of intervertebral disc space, and surrounding soft tissue stranding, but keep in mind that they’re often negative. So, regardless of the x-rays, with these findings you should still consider an infection causing back pain, and order an MRI and blood cultures! If the MRI shows an epidural abscess, discitis, or osteomyelitis, and blood cultures return positive, then diagnose an infection.

Okay, let’s move on to malignancy and metastatic spinal disease! This patient may have a history of cancer, unexplained weight loss, and night sweats. Physical exam typically reveals tenderness to palpation localized to paraspinous tissues. Spinal imaging might show a vertebral tumor or metastatic lesions. If these findings are present, consider malignancy and obtain a biopsy! If the biopsy is positive for malignant cells, diagnose malignancy or metastatic spinal disease.

Here’s a clinical pearl! Biopsy can also help determine if the tumor is primary or metastatic. Lung, prostate, and breast cancers are the three most common cancers that tend to spread to the spine.

Next, let’s take a look at spinal fractures. History usually reveals an elderly patient with localized back pain that worsens with bending. They might have a history of trauma, corticosteroid use, or osteoporosis. Additionally, physical exam reveals localized tenderness to palpation over the spinous process, while the spinal X-ray typically shows a vertebral deformity.

At this point, consider a spinal fracture and order a spine CT and MRI. CT is preferred to evaluate bony abnormalities and confirms the diagnosis of vertebral fracture, while MRI is better for visualizing soft tissue abnormalities like spinal canal stenosis and impingement of neural elements! With these findings you can diagnose spinal fracture as a cause of back pain.