Back Pain
Elaine Rabin
Nelson Wong
Introduction
Acute lower back pain is most commonly defined as lower back pain of less than 6 weeks duration.
In the emergency department (ED), patients often present within hours to days of onset of pain.
Lower back pain has a broad differential diagnosis.
Eighty-five to 97% of acute low back pain is ultimately determined to be mechanical/musculoskeletal or nonspecific in nature.
Treatment goals in these cases include pain relief and restoration of function.
Epidemiology
Approximately one-fourth of US adults have had an episode of low back pain in the past 3 months.
It accounts for 3% ED visits/year.
Burden to society:
$84–625 billion annually in direct and indirect costs in the USA.
Second most common cause of lost time in the work place affecting 2% of US workforce.
Leading cause of work disability in adults less than 45 years.
Up to one-third of cases become chronic and last over 1 year, limiting activity in 20%.
Five percent of cases account for 75% costs.
Goals in the Emergency Department
Want to rule out life- and limb-threatening causes of back pain before presuming etiolgy to be musculoskeletal and treating for this.
Key questions to consider on history:
Periodicity and how this particular episode evolved.
History of trauma.
Associated features – anesthesia, paresthesia, paralysis, fecal incontinence, urinary retention.
Associated symptoms – fever, syncope, diaphoresis, nausea/vomiting.
A complete vascular and neurological examination should be carried out on all patients with back pain.
Red flags for patients presenting to the ED with back pain:
Fever with back pain.
Associated neurological symptoms.
History of intravenous drug use:
History of cancer.
Immunocompromised or recent steroid use.
Age older than 50 or younger than 17 years.
Pain lasting longer than 6 weeks.
Response to analgesia should not be an indicator of benign etiology.
Pearls
Routine imaging of uncomplicated lower back pain (i.e., no red flags) is not indicated.
Many asymptomatic patients will have disc bulges demonstrated on MRI, so disc bulges do not necessarily imply causality, especially without radiculopathy/sciatica.
Etiology
Musculoskeletal
Muscle spasm/strain
Disc herniation with or without sciatic symptoms
Spinal stenosis
Degenerative joint disease
Urologic
Renal colic (see Chapter 21)
Pyelonephritis
Vascular
Aortic dissection
Epidural hematoma
Abdominal aortic aneurysm
Infectious
Spinal epidural abscess
Osteomyelitis
Workup for suspected life- and limb-threatening etiologies of Back Pain in the Emergency Department
Cauda Equina Syndrome
Symptoms due to compression of lower spinal nerve roots.
Can result from compression for any reason (tumor, hematoma, etc.), but is often due to large intervertebral disc bulge into the spinal canal.
Signs/symptoms:
New, progressive or severe lower extremity motor or sensory deficits.
Saddle anesthesia.
Urinary retention or incontinence.
Decreased rectal tone, bowel incontinence.
Investigations:
If suspected, MRI without contrast is the preferred imaging technique.
CT without contrast may be useful if MRI is unavailable.
Abdominal Aortic Aneurysm Rupture
Risk factors:
Older age.
Male.
Hypertension.
Smoking.
Atherosclerotic disease.
Signs/symptoms:
Aneurysm without rupture is often asymptomatic.
Sudden-onset, colicky pain not related to movement.
Hematuria.
Classic triad of hypotension, abdominal or back pain, and pulsatile abdominal mass is found in less than half the cases.
Common clinical scenario is an older patient presenting with symptoms of renal colic without a previous history of nephrolithiasis.
Investigations:
Ultrasound is useful for detecting aneurysm and large amounts of fluid due to rupture.
CT scan with intravenous contrast can reveal both aneurysms and rupture.
Malignancy, Primary Tumor or Metastases
Primary tumors of the spine are most often lymphoma, leukemia, myeloma, ependymomas and other gliomas.
Metastases are often due to prostate, breast, and lung cancers.
Risk factors: Older age, cancer history.
Signs/symptoms:
New back pain in patients younger than 18 or older than 50.
Worse lying or sitting, and straining.
Gradual onset, unrelieved with medications.
Pain at night.
Radicular or cauda equina symptoms.
Systemic signs of malignancy (e.g., unexplained weight loss, fever).
Investigations:
If suspected, MRI with and without contrast is preferred.Related posts:
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