Most of us will have lower back pain in our lives (80–90% lifetime prevalence) and it accounts for 2–3% of ED visits (so quite a bit).
As with everything in EM, there are benign and serious causes and we need to differentiate between the two. The serious causes include diagnoses in the back and those in the abdomen or retroperitoneum.
- Benign: muscular and ligament strain, sciatica (posterolateral disk herniation) and spinal stenosis
- Serious back: cancer, spinal epidural abscess, vertebral osteomyelitis, infectious diskitis, spinal epidural hematoma and giant (central) disk hernation (cauda equina syndrome).
- Serious non-back: AAA, renal stones, renal infarct, tumor, pancreatitis, pancreatic cancer, PUD, cholecystitis, retroperitoneal hemorrhage, psoas abscess
RED FLAGS FOR BACK PAIN
Be sure to document a good history and physical.
Epidural abscess: ***no fever, ***not immunocompromised, ***no IVDA, ***no known h/o bacteremia
Epidural tumor: ***no history of systemic cancer or weight loss
Epidural hematoma: ***no recent anticoagulation or recent spinal anesthesia
Fracture: ***not older age (> 55), ***no prolonged steroid use, ***no trauma, ***no abrasion/contusion to back
General: ***no new frequent falls or ataxia, ***no 3 wk of midline pain, ***no nocturnal pain, ***no sphincter incontinence or urinary urgency, ***no bilateral leg symptoms
- Physical examination
- Motor: ***no weakness in legs (or arms)
- Sensory: ***no sensory level or saddle anesthesia
- Reflexes: ***no diminished or hyperreflexic reflexes in the
- Babinski sign (abnormal/upward)
- Sphincter dysfunction: ***no lax rectal tone (rectal optional but perform in intermediate or high risk patients)
- Post void residual: ***no more than > 100 cc’s (if urinary symptoms)
Given the above, the patient would be classified as
- HIGH RISK: Hx and PE red flags
- MED RISK: Hx but no PE red flags
- LOW RISK: no Hx or PE red flags
Lab testing is rarely useful. WBC, bands and percentage of neutrophils can all be normal in patients with spinal epidural abscess. Though ESR and CRP are non-specific, if normal they can help rule out infectious causes. Normal inflammatory markers don’t rule out disk herniation or epidural hematoma, though.
Imaging of the back should be carefully ordered. X-rays are of no value (if no trauma). MRI’s increased cost. Order these in high risk patients. You can get an outpatient MRI in medium risk patients (talk with the PMD, neurology or surgery to get follow-up, though).
If no further work up is required, discharge the patient home with pain medications and set their expectations.
Discharge Instructions for Low Back Strain
Provide proper instructions to patients who are sent home with lower back pain. First, they should have their expectations properly set. Second, more serious causes of back pain can present insidiously. The patient should know to return if things worsen.
You have been diagnosed with a lumbosacral back strain. This pain can often last 4–6 weeks, but should improve with proper care.
- Application of heat can be minimally helpful (10 minutes on and 20 minutes off to prevent burns).
- Bed rest should be of short duration (about 2 days) to hasten recovery.
- Exercise is not recommended until your symptoms are completely better, but you should resume your normal daily activities.
- Motrin 800 mg by mouth three-times a day with food for pain. You can take Norco for pain not relieved with Motrin. Muscle relaxants are helpful if there is a significant degree of spasm. These latter two medications can make you sleepy so avoid the use of heavy machinery, driving or complex decision making while on these medications.
- It is very important you follow up with your primary care doctor in 1–2 weeks.
- While our most likely suspicion for the cause of your back pain is a lumbosacral strain, more serious causes can initially present similarly. Therefore, return immediately if you develop any of the following symptoms:
- Numbness or weakness or arms or legs
- Increasing pain
- Inability to go to the bathroom normally
- Numbness in the perineum (“the crotch”)
Serious causes of back pain
Spinal Epidural Abscess (SEA)
This has been increasing in incidence due to more diabetes, IVDA, immunosuppressants and invasive spinal procedures. The traditional triad (back pain + fever + neurologic symptoms) is, of course, often absent. The most common finding is severe, unrelenting back pain. If they have such severe pain and a risk factor, you should really consider SEA and order an MRI of the entire spine with and without gadolinium.
Treatment usually consists of antibiotics and surgical decompression, but in those without neurologic symptoms some considering waiting on surgery. Let the surgeon make that call. Consult the neurosurgeon, regardless.
Again the presenting symptoms is unrelenting back pain. Look also for weakness and UMNL (hyperreflexia – probably best to check the knee and ankle). By the time you get bowel and bladder dysfunction, it is too late. Sometimes they don’t have a known primary tumor and this is the first presentation of the cancer. The tumor often presents in any part of the spine.
- Thoracic 60%
- Lumbosacral 30%
- Cervical 10%
The primary sources are from lung, breast and multiple myeloma. But non-Hodgkins lymphoma often presents with extramural spinal cord compression, as well.
Treatment is chemotherapy, radiation and surgery. Call the oncologist and surgeon. Steroids can also be used, so discuss with the consultants.
Spinal Epidural Hematoma
The main risk factors are a recent spinal instrumentation (though in one study, none of the OB epidurals caused a SEH) or use of anti-coagulants in a patient with back pain. Sometimes a venous hemorrhage can occur from an increase in abdominal or thoracic pressure resulting in an spontaneous SEH in the anti-coagulated patient.
Patients present with severe back or neck pain, radiculopathy and neurologic symptoms.
They will likely need surgical decompression and most likely anti-coagulant reversal. Call the neurosurgeon!
Giant Lumbar Disk Herniation
Central disk herniation (33%–75% antero-posterior hernation) is different from sciatica (smaller postero-lateral herniation) and results in cauda equina syndrome. This can be provoked by minimal trauma (like twisting, heavy labor) or the trauma may be absent.
Indications for surgery include cauda equina syndrome, progressive motor deficits or intolerable symptoms.
- Singleton J, Edlow J. “Acute Nontraumatic Back Pain Risk Stratification, Emergency Department Management, and Review of Serious Pathologies.” EM Clinics of North America. 2016