Lumbar Sympathetic Block

 

Indications

Lumbar sympathetic blockade is indicated for diagnosis, prognosis, and therapy of circulatory and painful conditions such as:

 

Circulatory

Inoperable peripheral vascular disease and vasospastic disease of the lower extremities

 

Pain

Neuropathic pain

Reflexive sympathetic dystrophies

Urogenic/Pelvic pain

Cancer pain

Phantom pain

Herpes Zoster involving the lower extremities

 

Contraindications

Patients on anticoagulant therapy

Hemorrhagic disorder

Allergies to medications injected

Local infection

Local neoplasm

Local vascular anomalies

 

 

Drugs

Volume of at 15 – 25ml must be injected

Short-acting local anesthetic, such as 1% lidocaine, is commonly used for diagnostic sympathetic block

Longer-acting agents, such as 0.25%- 0.375% bupivacaine, is advantageous for both diagnostic or therapeutic block

Higher percentages of bupivacaine are typically not used related to chance of motor block

Epinephrine (adrenaline) or Clonidine may be added to prolong the effects of the injection.

For Neurolytic Blockade:

    Volume of 2 – 4ml at both L3 and L4, using 6 – 10% phenol or 50 – 100% alcohol

 

Anatomy

 

The lumbar sympathetic chain:

consists of three to five ganglia

lies anteriorly to the L2, L3, and L4 vertebral bodies

are anterior to the psoas muscle margin and fascia

are usually posterior to the vena cava on the right

is posterior to the aorta on the left

 

 

 

 

Positioning (either prone or lateral)

 

Prone Patient Positioning

The patient lies prone with a pillow under the lumbar spine

 

Benefits

Patient and anatomic landmarks more stable

Bilateral blocks performed more easily

 

Topographical Landmarks

Spinous process of L2 and L3 are identified and marked

A horizontal line is drawn through the midpoint of the L2 interspace and extended 5cm to the right and left of midline

An “X” marks these spots (which should overlie the space between the transverse process of the 2nd and 3rd vertebrae or the cauded edge of the 2nd transverse process)

 

 Technical Procedure

Skin and deeper tissues infiltrated with local anesthetic at the “X”.

A 10cm 20 g needle is inserted on each side through the “X” and angled 30-45 degrees cephalad.

Advance until the needle comes in contact with the transverse process. Mark the depth of the needle.

Withdrawl slightly, angle caudad, and walk inferiorly off the transverse process (usually in a direction perpendicular to the skin). A slight medial anqulation is used in hope of contacting the vertebral body.

 

 

Once contact is made with vertebral body, anterior repositioning of needle is made to walk off that body (the needle tip should remain close to vertebra).

“Pop” felt as needle passes through psoas fascia

Anteroposterior x-ray at this stage should show needle tip midway between lateral edge of vertebral body and spinous process

Injection of contrast solution should demonstrate linear spread in longitudinal axis without any lateral or posterior extension

 

Lateral Patient Positioning

 

Benefits

Reserved for patient who cannot lie prone

 

Topographical Landmarks

Spinous processes of lumbar vertebrae, twelfth rib, iliac crest

Point of entry 6-7 cm paravertebrally from midline in the middle between iliac crest and twelfth rib

 

 

Technical Procedure

Place pillow under flank

After placing a skin wheal, 12 cm long needle is advanced toward the body of L2 in medioventral direction

If bone contact is made at depth of 2-3 cm, needle is redirected cephalad or caudally

If sharp radiating leg pain encountered needle is redirected cephalad or caudally 

When needle contacts L2 body at depth of 6-8 cm, the needle is withdrawn 1-2 cm and readjusted upward to bypass L2 body

Aspiration in two planes

Local anesthetic injection should be achieved without resistance

 

 

Lumbar sympathetic blocks are commonly preformed under radiographic imaging, especially if a neurolytic drug is used.

Needle placement under x-ray control with contrast medium. (left)

Flouroscopic guidance with injection of radiocontrast solution increases the success rate and may reduce complications

 

 

 

Assessment of the Block

 

Test dose

A test dose is inserted after careful aspiration.

Inject 10cc of local anesthetic solution – this should produce sympathetic blockade.

1% lidocaine, 0.25% bupivacaine, or an equivalent concentration is adequate.

 

Within 5-10 minutes, one should note:

Vasodilation

Increased skin temperature

There should be a minimum change of 2 degrees C if there is a proper block

 

Psychogalvanic Reflex

Two electrodes (ECG) for each channel attached to each foot (dorsal and plantar)

Ground lead attached to any body surface

Measures changes in electrical resistance of the skin

After stimulation, the side with blockade of sympathetic fibers will demonstrate no ECG deviation

 

Sweat test

Ninhydrin test – relies on sweat protein to change color to yellow

Cobalt blue test – filter papers which are saturated with cobalt blue; sweat changes paper color to pink

Starch-iodine test – relies on color change

 

Pain assessment

Post-block pain relief provides indication of sympathetic blockade

Pain relief can be immediate or delayed for several hours

If narcotics or sedative drugs have been employed, pain assessment results may be immediately skewed

 

 

Complications

The most troublesome and frequent complication is simultaneous blockade of L2 somatic nerve root

 

Inadvertent injection into the subarachnoid space, epidural space, intravascular (vena cava, aorta, lumbar vessels

Damage by needle or neurolytic solution to the kidneys, renal pelvis, ureters, intervertebral discs

Infection

Mild backache

Neuropathic pain

Retroperitoneal hematoma

Sympathalgia

Destruction of sympathetic fibers - Produces cramping or burning pain in anterior thigh

Sympathectomy-mediated hypotension

Intravascular Steal - May occur in arteriosclerotic patients

Failure of ejaculation - Real risk after bilateral block.  The risk must be explained to male patients.

 

COMPLICATIONS WITH THIS TECHNIQUE ARE UNUSUAL!!

 

 

References

Questions