Chapter 54 - Back pain Flashcards
What are the signs of idiopathic low back pain?
- No red flags on hx or physical exam
- Often no clear inciting cause
- Pain asymmetric in the lumbar paraspinal muscles
- Radiation to buttock and proximal thigh
- Exacerbated by movement
- Lasting less than 6 weeks
Describe the myotomes and dermatomes of L3-S1
L3:
1) Sensation/pain location: medial thigh
2) Strength: hip flexion
3) stress test: R-SLR
4) reflex: none
L4:
1) Sensation/pain location: medial foot
2) Strength: knee extension
3) stress test: R-SLR
4) reflex: patellar
L5:
1) Sensation/pain location: between 1st and 2nd toe
2) Strength: big toe/ankle dorsiflexion
3) stress test: SLR,C-SLR
4) reflex: none
S1:
1) Sensation/pain location: lateral foot
2) Strength: ankle plantar flexion
3) stress test: SLR, C-SLR
4) reflex: achilles
What’s the most common cause of sciatica?
Disc herniation posterior - laterally leading to sciatica wehre pain radiates down the posterior leg due to nerve root irritation
What are 4 red flag diagnosis for back pain?
1) cauda equina syndrome
2) fracture
3) spinal infection
4) malignancy
What are key pathophys, Hx and PEx and management for cauda equina syndrome?
1)Pathophysiology:
due to sudden compression of multiple lumbar or sacral nerve roots
2)Causes: epidural abscess, hematoma, trauma, malignancy
3) History:
back pain, may have atypical, equivocal neurological findings
4) PEx: multiple, bilateral nerve root pain in both legs
saddle anesthesia
decreased rectal tone/incontinence
urinary retention (if PVR is < 100-200ml rules out cauda equina)
5) management :
- need urgent operative decompression within 48 hours of symptoms onset
- overflow urinary incontinence may be an exception to the 48 hour rule
What are key pathophys, Hx and PEx for fracture?
Hx: trauma, or minimal trauma in an osteoporotic person
- chornic steroid users for any reason should be x-rayed even with no trauma history
- older than 50 years old
What are key pathophys, Hx and PEx and managment for spinal infection ?
1)Pathophysiology:
spinal epidural abscess or osteomyelitis of the vertebral bodies
2)Risk factors: immunocompromised, diabetes, alcoholism, renal failure, elderly, post trauma to the back, indwelling devices, instrumentation
(20% of pts with abscess have no risk factors)
3) History:
back pain at rest, fevers and chills, neurological deficits
4) PEx: tenderness over the affected spinous process
triad: fever, focal back pain, neurological deficit
5) investigations ESR, CBC, urine analysis ESR >20 has 98% sensitivity -If xray is normal and ESR high: do MRI 6) management: -Do not do lumbar puncture
- collections need drainage by a neurosurgeon
- antibiotics with MRSA and pseudomonas coverage
What are key pathophys, Hx and PEx and investigations and managment for malignancy?
1) Hx: cancer history, pain persists at rest, pain worse at night, B symptoms
- age >50
- typically spread/mets
2) PEx
ESR >50, low hematocrit
Spinal tenderness
3) Investigations:
CBC, ESR, ALP, PSA, SPEP
X-ray, CT, MRI
1)Back Pain without a history of cancer and without radiculopathy
(Suggestive history) -If -ve xray and -ve ESR/CRP workup can be done as an outpatient (10-20% false negative rate)
Symptom control
- either +ve x-ray or ESR/CRP = Ct or MRI as urgent outpatient test
2) Back pain without hx of cancer but radiculopathy presentIf blood work or x-ray abnormal = urgent MRI/CT to screen for impending spinal cord compression
3)Back pain with hx or cancer
Urgent CT and/or MRI regardless of x-ray/blood work
In anyone going for MRI = they should receive dexamethasone urgently to reduce the potential mass effect
Consider urgent radiation therapy as well
What are the symptoms and diagnostic tests for sciatica:
Sharp, shooting, lancing, burning pain from the low back to below the knee
- with associated numbness or weakness
- can be exacerbated by sitting, bending, coughing, straining
Test: SLR (sensitive for sciatica (91%) but poor sensitivity
sciatica has a high sensitivity for lumbar disk herniated
What’s a positive SLR?
-supine patient with legs extended
-symptomatic leg raised with knee extended
_+ for L5-S2 radiculopathy if presence of back pain AND radiating past the knee
What’s a positive crossed SLR ?
- passively raising the asymptomatic leg
- positive if pain present radiating from the back to the opposite affected leg
Whats the reverse SLR test and what does it mean if positive?
Used to detect L3-L4 radiculopathy
- Patient lies prone
- Each hip is passively extended
- Positive if pain along the L3-4 nerve root is experienced
List 5 indications for x-ray in low back pain:
1) Age <18 or >50
2) recent trauma other than simple lifting
3) Hx of malignancy or unexplained weight loss
4) History of fever, immunocompromised state or IVDU
5) prolonged duration of symptoms beyond 4-6 weeks
6) progressive neurological deficits or other findings consistent with cauda equina syndrome
What are the possible methods of imaging for back pain and what are they best utilized/diagnosis of?
X:ray: spondylolysis, vertebral osteomyelitis, metastatic disease (poor sensitivity 80%)
U/S: for PVR/bladder scan
to rule out cauda equina
CT: finds fractures best
MRI: BEST test for cauda equina, spinal infection, malignancy, epidural abscess,
What is the management for simple radiculopathy?
1) mobilization
2) analgesics
3) systemic vs. local injections
4) SSx >4-6 weeks may indicate need for MRI
