Case 69 - Low Back Pain

Question 1

Ddx of LBP

Answer 1

1) Red Flags?
* intraabdominal or lower thoraciac pathologies –> pancreatic cancer, pneumonia, cauda equina syn, aortic aneurysm
2) radiculopathy or no radiculopathy

• compression of nerve root
• herniated disk
• spinal osteophytes
• intradural or epidural tumor

3) others

• myofacial pain
• musculoskeletal pain
• facet joint arthropathy

Question 2

How do you evaluate a patient with LBP?

Answer 2

1) H&P

• location, severity, radiation of pain
• LE weakness, numbness, shooting pain, bladder or bowel dysfunction
• social history - job/work/activity
• focused neuro exam
• bending, side-bending, flexion, extension of back

2) imaging
* MRI or CT of lumbosacaral area –> r/o maligancy or epidural abscess

Question 3

what is classic presentation of a patent with a herniated nucleus pulposus?

Answer 3

• inciting event such as lifting heavy object
• herniation of disc –> mechanical compression of roots or chemical inflammation from substance released form degenerating intervertebral discs (histamine, bradkinin)
• pain worse with bending, coughing, sneezing.
• pain improves with rest/lying down

PE

• positive straight leg (radicular pain 2/2 foot dorsiflexion with leg extended)

Neuro

• sensory deficit dermatomal distribution
• reflex testing - L4 = patellar, S1 = achilles
• motor - L5 = weakness of dorsiflexion of foot

Question 4

what is the diference between spinal stenosis vs herniated disk?

Answer 4

1) spinal stenosis

• narrowing of central spinal canal
• 2/2 enlarging posterior facet joint, osteophytes, ligamentum flavum hypertrophy, bulging disk anulus
• Pain relieved with flexion
• pain and neuro deficits over several dermatomes
• chronic and mild discomfort progressing with time

2) herniated nucleus pulposus

• pain relieved by reclining (worse with flexion)
• pain and neuro deficit over a specific dermatome
• acute and severe onset

Question 5

what is the mechanism of action of epidural steroid injection?

Answer 5

• radicular pain is caused by nerve inflammation from chemical irritation or direct impingement of nerve
• steroid injection into epidural space –> antiinflammatory effect on nerve rot
• transforaminal vs caudal vs interlaminar
• always use Fluroscopic guidance

complication

• intravascular injection
• transforaminal –> radicular artery injection of particulate steroid = anterior spinal artery syndrome = paralysis (motor area)

Question 6

What oral meds are prescribed for LBP?

Answer 6

• oral analgesics and PT = best medical tx

Oral analgesics

1) NSAID

• antiinflammatory and analgesic
  
  • prostaglandin sensitize nociceptors to painfulstimuli
  • NSAID inhibit cyclooxygenase –> inhibit prostaglandin synthesis –> analgesia and antiinflam
• SE: bleeding, gastric ulcer, renal dysfuction, PLT dysfunction
• COX-2 = decrease risk of gastric ulceration and bleeding

2) anticonvulsant agents

• Neurontin
  
  • unknown mechanism of action
• SE: weight gain, sedation, dizziness

3) TCA

• amitrtryptline / nortriptyline
  
  • decrease reuptake of serotonin and NE –> neurotransmitters in decending inhibitory spinal cord pain nerve pathway

4) muscle relaxant
* cyclobenzaprine