Back pain...its everywhere....and when people get it...they want YOU to fix them.
And while the path to back pain resolution can be frustrating and slow...it is essential that we consider and rule out more serious cause to our patients pain and angst.
There are 3 main groups of patients that we will see:
- Non-specific lumbosacral pain
- Radicular or sciatic pain
- Emergent pathologies including:
- Infection such as osteomyelitis or spinal epidural abscess,
- Fracture (trauma or pathologic),
- Disk herniation & cord compression,
- Cancer in spine causing cord compression,
- Vascular – leaking/ruptured AAA, retroperitoneal bleed, and spinal epidural hematoma.
The so-called 'Red Flags' of Back Pain help in identifying these sinister causes
- Features of Cauda Equina (Urinary Retention, Faecal Incontinance, Lower limb or saddle distribution neurology)
- Significant trauma
- Weight loss
- History of cancer
- Fever
- Intravenous drug use
- Steroid use
- Patient >50 years
- Severe night-time pain
- Pain that gets worse when lying down
- Recent/previous spinal surgery
Investigations should be guided by the presence or absence of red flags
ie No red flags=No investigations
In the above cases however, consider:
Physical exam for Low Back Pain Emergencies
Physical Exam Maneuvers:
- Percuss the spinous processes for tenderness, a red flag for infection and fracture,
- Test for saddle anesthesia (sensation changes may be subtle and subjective),
- DRE looking for tone/sensation
- Look for fever, or signs of infection,
- Check carefully for bilateral, or multi-level neurologic findings in lower extremities, and assess for gait disturbances.
Straight leg raise (SLR):
- Non-specific test, only positive pain is produced distal to the knee between 30–70°.
- Pain with contralateral SLR is more specific for siatica.
Slump test: Helps discriminate radicular pain from hamstring pain. With thoracic and cervical flexion, and knee in extension, dorsiflex the foot and flex the neck to determine if pain is produced, with release of cervical flexion to see if symptoms improve (image below).
Abdomen exam and ED ultrasound: look for AAA and bladder distention post-void.
Cognitive Forcing Strategy to Remember Serious Pathologies:
- Considering renal colic?
- Considering pyelonephritis?
- think about spinal infection!
SPINAL EPIDURAL ABSCESS
- Suspect epidural abscess in a patient with:
- back pain or neurologic deficits andfever,or
- back pain in an immune- compromised patient, or
- patient with a recent spinal procedure and either of the above.
- CRP and ESR may help, depending on the clinical suspicion for epidural abscess. If suspicion is low after the history and physical, low ESR and CRP levels support not doing an MRI, and discharging the patient home with close follow up. If there is a high index of suspicion, an MRI is indicated *regardless of CRP and ESR*.
- Remember the normal ESR cutoff is: (age+10)/2.
- In one study of epidural abscesses, 98% had ESR >20, and most were much higher (>60).
- Is there any role for CT scan? CT cannot rule out epidural abscess because it does not show the epidural space, spinal cord, or spinal nerves. CT can lead to the pitfall diagnosis of osteomyelitis, missing coexistent abscess (and the urgent indication for surgery).
- Remember if the suspicion is epidural abscess, the entire spine must be imaged by MRI. Spinal cord obstruction and paralysis can happen very quickly from epidural abscess, so there needs to be definitive imaging and surgical decompression as quickly as possible.
- Start antibiotics while awaiting definitive diagnosis: include appropriate coverage for MSSA and MRSA, and cover gram negatives.
Spinal Epidural Abscess Pearls and Pitfalls
- Spinal epidural abscess is rare (1–2/10,000 of hospitalized patients).
- The classic triad of fever, back pain, and neurologic deficit is present in only 15% of patients, depending on stage of disease. Spinal epidural abscess is often missed on first ED visit. Fever is present in only 50% of patients, and neuro deficits start very subtly.
- Risk Factors: Diabetes, IVDU, indwelling catheters, spinal interventions, infections elsewhere (especially skin), immune suppression (i.e. HIV), and “repeat ED visits.”
CAUDA EQUINA SYNDROME
Definition of Cauda Equina Syndrome:
- urinary retention or rectal dysfunction or sexual dysfunction (or all of the above)
- saddle or anal anesthesia and/or hypoesthesia (1).
- Urinary retention is non-specific for spinal cord compression, but sensitive. Post void residual <100cc has a very high NPV to rule out cauda equina syndrome.
- When are steroids indicated:
- Evidence supports dexamethasone for metastasis to spine causing cauda equina.
- There is no indication for IV steroids for patients with cord compression by other causes
SPINAL METASTASIS – A LOW BACK PAIN EMERGENCY
- Known cancer + new back pain = spinal metastases until proven otherwise!
- Time is Limbs: Spinal metastases are one of the most common causes of cord compression. Pre-treatment neuro status predicts outcome for this emergency.
- Workup:
- X-ray to look for compression #, soft tissue changes, blastic/lytic lesions, pedicle erosion (see image below)
- Consider testing ESR and CRP, and calcium profile if signs are consistent with hypercalcemia (e.g. polyurea)
- Give dexamethasone as soon as mets are suspected (at least 10mg IV) if the patient has neurologic symptoms. Consider bisphosphonate* and calcitonin if patient is hypercalcemic, or if you suspect compression # or bony metastasis.
- Get an urgent MRI if there are symptoms of cord compression. If there are hard neurologic findings, MRI is needed within 24 hours. If the x-ray findings are consistent with mets, but there are no neuro findings, an MRI should be done within 7 days.
*Bisphosphonates may decrease bone resorption in patients with metastatic disease to the bone, and relieve pain better than placebo.
VASCULAR EMERGENCIES ARE LOW BACK PAIN EMERGENCIES
Spinal Epidural Hematoma
- Spinal epidural hematoma may present after spinal procedures (epidural anesthesia), but can be spontaneous, especially in anti-coagulated patients.
- Neurologic findings depend on the extent of spinal cord compression— from isolated pain to flaccid paralysis.
- Suspect this emergency in patients with a history of trauma and neurologic findings who are coagulopathic.
Abdominal Aortic Aneurysm
- Typical manifestations of rupture of a AAA is abdominal or back pain, with a pulsatile mass in a patient with a history of HTN.
- However, symptoms may range from dizziness, syncope, groin pain, or flank mass to presentation with paralysis. Look for livedo reticularis (atheroemboli to feet) and signs of poor circulation in the lower extremities.
- Transient hypotension or syncope after onset of pain is an important clue for bleeding from a ruptured AAA. Patients may present in shock, and quickly decline.
- Do an ED ultrasound right away as an extension of the physical exam to rule out AAA in patients with low back pain and hypotension.
Retroperitoneal Bleed
- Patients with coagulopathies, as well as patients with retroperitoneal masses or tumors, or abdominal/pelvic trauma are at risk.
- Blood may dissect anteriorly, causing abdominal pain, or may cause pain to the hip, groin, or anterior thigh.
- On the physical exam, look for psoas sign caused by retroperitoneal irritation, femoral neuropathy and hip pain, as well as Cullen’s/Turner’s signs, or bruising or swelling in the groin caused by extension of bleeding into the skin.
LUMBOSACRAL SPRAIN & MECHANICAL LOW BACK PAIN
Lumbosacral sprain is a diagnosis of exlusion:
- Lumbosacral sprain or mechanical back pain is a diagnosis of exclusion, made only after carefully ruling out serious causes of low back pain.
Management of lumbosacral sprain:
- Education This is a mechanical problem requiring a mechanical solution – and pain medications alone will not fix the problem. Patients need to play an active role in their recovery, and prolonged bed rest will worsen the problem.
- Reassurance 90% get better with time (over weeks)
- Symptom Management Evidence from the Cochrane collaboration supports heat, NSAIDs, acetaminophen, massage and physical therapy. Muscle relaxants may be as effective as NSAIDs, but they have significant side effects, especially in combination with opioids.
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Management
- Analgesia should be provided. Initially this should be Paracetamol and a NSAID, if there are no contraindications. Opiate analgesia and benzodiazepines should be avoided in the management of an uncomplicated acute low back pain as there is evidence to suggest that the use of such can lead to harm in this setting.
- If the patient can safely mobilise after assessment and exclusion of Red Flags, then they can be discharged to be followed up by their General Practitioners.
- Discharged patients should be provided with the Acute Low Back Pain advice sheet. Patients should be encouraged to stay active. Referral to a Physiotherapist or Chiropractor may be of benefit in the first 6 weeks.
- Appropriate analgesia must be prescribed.
- ACC documentation must be completed including time off work.
- Features which would necessitate an urgent medical review (increasing pain, fevers, weakness of the legs, loss of bowel or bladder control, perineal sensory loss) must be discussed with the patient.
- Patients unable to be mobilised acutely, and who have no Red Flags, may be admitted to Adult Short Stay for a period of analgesia and mobilisation with a Physiotherapist.
- Patients with concerns regarding nerve root compression, cauda equina syndrome, spinal fractures, or spinal infections must be reviewed with the acute Orthopaedic service.
Finally...
Some Pearls and practice points from the excellent Academic Life in Emergency Medicine.
http://www.aliem.com/high-risk-back-pain-spinal-epidural-abscess/
http://www.aliem.com/high-risk-back-pain-cauda-equina-syndrome-erem/
http://www.aliem.com/trick-of-the-trade-percuss-the-spine-in-low-back-pain/
http://www.aliem.com/trick-of-the-trade-crossed-straight-leg-raise-test/
http://www.aliem.com/trick-of-the-trade-hip-flexion-strength-testing/
