Back Pain in the ER and What Doctors Are Really Looking For
Back Pain Red Flags You Should Not Ignore
The Case I Never Forgot
During residency, a middle aged mechanic came into the emergency department with low back pain. He had spent the day working underneath a car, twisting and lifting, and he was certain he had strained a muscle. The explanation sounded reasonable. Physical labor. Awkward posture. Sudden discomfort.
But his pain felt different. It was deep, constant, and worse at night. Imaging revealed metastatic prostate cancer, meaning cancer that had spread from the prostate through the bloodstream into the vertebral bones of the spine. The first serious pathology encountered in training is never forgotten. It permanently reshapes how ordinary complaints are evaluated.
Back Pain Is Common but Broad
Back pain is one of the most frequent chief complaints in emergency medicine. Most cases involve the lumbar spine, the lower portion of the back responsible for bearing body weight and allowing movement. The majority are mechanical in origin, meaning they arise from strain or irritation of muscles, ligaments, or intervertebral discs, which are the cushioning structures between vertebrae.
Mechanical pain typically worsens with movement and improves with rest. It does not produce true neurological deficits such as weakness, numbness, or loss of reflexes. Although uncomfortable and sometimes disabling, it is usually not dangerous. The challenge lies in identifying the minority of cases that signal something far more serious.
Risk Stratification Comes First
Evaluation begins with risk assessment. A history of trauma, even minor trauma in older adults, raises concern for vertebral compression fracture, which is a collapse or crack in one of the spinal bones. A history of cancer is particularly important because many malignancies, including prostate, breast, and lung cancer, commonly metastasize to the spine.
Other critical risk factors include immune suppression, diabetes, intravenous drug use, and recent spinal procedures. These increase the risk of spinal epidural abscess, an infection that forms a collection of pus in the epidural space, the area between the spinal cord and the surrounding bone. If untreated, such infections can compress the spinal cord and result in permanent neurological injury.
When Pain Radiates
Back pain that radiates down the leg suggests radiculopathy, a condition caused by irritation or compression of a spinal nerve root. The most common cause is a herniated disc, which occurs when the inner gel like material of an intervertebral disc protrudes through its outer layer and presses against a nerve.
This may produce sciatica, characterized by sharp, electric pain that travels from the lower back into the buttock and down the leg along the sciatic nerve. Most cases improve with anti inflammatory medications, physical therapy, and time. However, objective muscle weakness indicates more significant nerve compromise and may require urgent imaging.
Red Flags That Demand Urgency
Certain symptoms immediately elevate concern. Fever in combination with back pain raises suspicion for vertebral osteomyelitis, infection of the spinal bone, or spinal epidural abscess. Severe back pain in a patient taking anticoagulants, commonly known as blood thinners, raises concern for spinal epidural hematoma, a collection of blood that can compress neural structures.
Loss of bladder control, bowel incontinence, or numbness in the saddle region, the area that would contact a saddle while sitting on a horse, suggests cauda equina syndrome. Cauda equina syndrome occurs when the bundle of nerve roots at the base of the spinal cord becomes compressed. It is a surgical emergency because prolonged compression can cause permanent loss of function.
Imaging Is Selective
Most uncomplicated low back pain does not require imaging. Magnetic resonance imaging, or MRI, is the preferred study when evaluating soft tissues, spinal cord compression, infection, or metastatic disease. Computed tomography, or CT, is more useful for detecting fractures of the vertebrae.
Imaging is guided by clinical findings and risk factors. Degenerative changes such as disc bulges and mild arthritis are common with aging and often unrelated to symptoms. Treatment decisions are based on the overall clinical picture rather than imaging findings alone.
Mechanical Pain and Prognosis
Mechanical back pain results from strain, inflammation, or age related degenerative disc disease, which refers to gradual wear and tear of the intervertebral discs. Although the term “degenerative” sounds alarming, it often reflects normal aging rather than dangerous pathology.
These cases respond to anti inflammatory medications, gradual mobilization, physical therapy, and time. Reassurance is appropriate once dangerous causes have been excluded. However, the memory of serious pathology reinforces the importance of careful evaluation before offering that reassurance.
THE BOTTOM LINE
• Back pain is common and most often caused by muscle strain or degenerative changes
• Red flags such as fever, weakness, bowel or bladder dysfunction, trauma, or cancer history require urgent evaluation
• The priority in emergency medicine is to rule out spinal cord compression, infection, fracture, or metastatic disease before labeling pain as simple strain
Written by a Board-Certified Emergency Medicine Physician