Regional

Question 1

Wavelength vs frequency

Tissue penetration vs resolution

Answer 1

Bottom line:
increased wavelength = decreased frequency. Probes deliver better tissue penetration (depth) at the cost of resolution at increased wavelength (decreased frequency)
Higher frequency = better resolution = worse penetration (less depth)

Question 2

Which of the following conditions is LEAST appropriate for sympathetic nerve block?
Complex regional pain syndrome
lumbar spinal stenosis with radiculopathy
phantom limb pain
post herpetic neuralgia

Answer 2

Cannot treat spinal stenosis with nerve block.

Use PO meds (NSAIDs, APAP) and nerve channel modulators (AEDs) + PT

Question 3

Sympathetic nerve system pathway

Answer 3

thoracolumbar spinal cord via white rami –> synapse at sympathetic ganglia –> Postganglionic nerves then extend to target site.

Question 4

Sympathetic nerve blocks

Answer 4

cervicothoracic/stellate ganglion blocks done via landmarks or ultrasound.
Lumbar ganglion blocks under fluoroscopy

Sympatholysis can be achieved with use of LA +/- steroid injection or permanent ablation (radiofrequency)

General complications: bleeding, infection, damage to nerves, and rebound sympathetic pain flares
Cervical blocks carry extra risk of: vertebral artery injection, neuraxial injection, pneumothorax

Good marker of successful sympathetic nerve block: limb temp increase of 2-3 degrees as vessles dilate and skin flushes