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
== BACK PAIN RED FLAGS == - HISTORICAL RED FLAGS - ***no fever, immunocompr, IVDA, bacteremia (suggesting epidural abscess) - ***no cancer or weight loss (suggesting epidural abscess) - ***no anticoagulant or spinal instrumentation (suggesting epidural hematoma) - ***no freq falls/ataxia, 3+w midline pain, night pain, BB dysfunction, bilateral leg symptoms - PHYSICAL RED FLAGS - ***no leg weakness - ***no sensory level or saddle anesth - ***no hyporeflexia or abnl Babinski - ***no sphincter dysfxn or urinary retention (PVR > 100cc) - FRACTURE RED FLAGS: - ***no older age - ***no prolonged steroids - ***no severe trauma / presence of abrasion or contusion on back == RISK STRATIFICATION == - ***LOW RISK: no red flags + normal neuro exam (x isolated root w/sciatica) - ***INTERMEDIATE RISK: 1+ Hx red flag and normal neuro exam - ***HIGH RISK: abnl neuro exam == WORKUP == - ***LOW RISK: supportive care at home (see DCI) - ***INTERMEDIATE RISK: - if cancer/infxn → consider ESR/CRP - MRI: in ED vs 48h outpatient - Consults: Neuro or NS - Dispo: home (talk to PCP) vs obs - ***HIGH RISK: - Emergent MRI - Empiric Abx - IV Dexamethasone - Consultation - Admit 1. Edlow JA. Managing Nontraumatic Acute Back Pain. Ann Emerg Med. 2015 Aug;66(2):148-53.
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 back pain. Our evaluation today suggests that there it is likely not from a serious cause, though it may hurt significantly. However, should anything change we would need to reassess your condition. 1. FOLLOW-UP: with your physician in the next 1-2 weeks for a reassessment. 2. COME BACK EARLIER FOR: If you develop any of the following symptoms, return immediately to the Emergency Room. We may need to reassess your condition. - Fever - Weight loss - Falls or loss of balance - Pain worse at night - Trouble controlling your bowel or bladder - Numbness in both legs, or between your legs (in "the crotch") - Weakness in your arms or legs 3. MEDICATIONS: Take Motrin 800 mg three times a day with food for the next three days, then as needed. Take Morphine IR 15 mg as needed for pain not relieved with the Motrin. - If you have a muscle spasm component, take the muscle relaxant as prescribed. 4. ACTIVITIES: rest in bed for at most the next 2-3 days, but as soon as you are able return to normal activities. Exercise isn't recommended until your symptoms resolve.
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