Lumbar Sympathectomy

Definition and Background

Anatomy

• Lies anterior to the psoas muscle and fascia
• Located in a more anteromedial position relative to the lumbar vertebral bodies than the thoracic ganglia
• On the right side: typically posterior to the inferior vena cava
• On the left side: just lateral to the aorta
• Supplies sympathetic fibers to the lower limbs and also to the pelvic plexus

Cross-section at L2 showing bilateral lumbar sympathetic block technique - needles inserted ~7 cm (left) and ~10 cm (right) from midline to reach the sympathetic ganglia (Morgan & Mikhail's Clinical Anesthesiology, 7e)

Indications

Methods of Lumbar Sympathectomy

• Patient positioned prone or lateral
• Single-needle technique at L3 is most commonly employed
• Needle inserted at the upper edge of the L3 spinous process, directed above or just lateral to the transverse process
• Fluoroscopic or ultrasound guidance is used
• Lignocaine is infiltrated along the needle track first (diagnostic and analgesic)
• Confirmation of correct placement: warming of the affected lower limb
• If placement is correct: 5-10 mL of 5% phenol is injected (neurolytic agent)
• Many clinicians prefer phenol for lumbar sympathetic block (vs. alcohol which is preferred for celiac plexus)
• "This technique is often best done by experts in pain relief as severe complications can arise if the phenol is injected in the wrong place" - Pye's

• Retroperitoneal approach to the lumbar chain
• Resection of L2-L4 ganglia and the intervening chain
• Now rarely performed

• Described as a minimally invasive surgical option, including in urological procedures

Physiological Effects

• Vasodilation of lower limb vessels - loss of sympathetic vasoconstrictor tone causes increased skin blood flow and warmth
• Orthostatic hypotension - pooling of blood in the splanchnic bed and lower extremities causes faintness and syncope on standing; patients tend to faint when standing but compensate over months by increased use of muscle pumps
• Loss of sweating (anhidrosis) over the denervated lower limb - this is the most consistent effect; exploited for plantar hyperhidrosis
• Ejaculatory dysfunction - retrograde ejaculation or emission failure may occur; semen is ejaculated into the posterior urethra and bladder due to paralysis of the periurethral muscle at the verumontanum (colliculus seminalis). Bilateral sympathectomy at L2 is particularly implicated.

Complications

Comparison with Thoracic Sympathectomy

Current Status

• Endoscopic transthoracic sympathectomy remains in active use for palmar/axillary hyperhidrosis
• Lumbar sympathectomy for ischaemia is largely obsolete given angioplasty and bypass surgery outcomes
• Chemical lumbar sympathetic block retains a role in palliative pain management (cancer, CRPS, inoperable ischaemia)
• The procedure should be preceded by a diagnostic block with local anaesthetic alone to confirm the pain pathway before committing to neurolysis

Lumbar Sympathectomy: Indications, Steps, and Complications

INDICATIONS

• Chronic lower limb ischaemia with rest pain (inoperable or failed reconstruction)
• Ischaemic skin ulcers of the lower limb not amenable to bypass or angioplasty
• Used when the patient is medically unstable for major vascular surgery

• Causalgia (complex regional pain syndrome type II) of the lower extremity
• Painful legs / intractable lower limb neuropathic pain
• Pelvic cancer pain unresponsive to epidural or caudal blocks
• Painful legs-moving toes syndrome (transient relief)

• Plantar hyperhidrosis (excessive foot sweating) - sympathectomy at the lumbar level
• Raynaud's phenomenon / lower limb digital vasculopathy and ulceration

• Hypertension treatment (widely used in the 1940s-50s, now completely replaced)
• General lower limb ischaemia management (replaced by endovascular techniques)

Key principle: Lumbar sympathectomy is used to relieve rest pain or aid healing of skin ulcers in patients who are either medically unstable OR who have not responded fully to vascular reconstruction. (Pye's Surgical Handicraft)

STEPS / TECHNIQUE

Pre-procedure

1. Diagnostic block first - always perform a diagnostic block with local anaesthetic alone before any neurolytic procedure to:
   • Confirm the correct pain pathway
   • Assess potential efficacy
   • Identify morbidity of planned neurolysis
   • Confirm lower limb warming as positive response

Patient Positioning and Setup

1. Patient placed prone or in the lateral decubitus position
2. Imaging guidance set up - fluoroscopy (image intensifier) or ultrasound is used throughout

Needle Placement (Chemical Sympathectomy - most common modern technique)

1. Single-needle technique at the L3 level is most commonly employed
2. Needle inserted at the upper edge of the L3 spinous process
3. Directed above or just lateral to the transverse process of L3 (direction varies with distance from midline)
4. The needle is advanced until it lies anteromedial to the L3 vertebral body, anterior to the psoas fascia

Cross-sectional anatomy: needle placement reaching sympathetic ganglia anteromedial to vertebral body, anterior to psoas, with IVC right and aorta left (Morgan & Mikhail, 7e)

Injection Sequence

1. Lignocaine infiltrated along the entire needle track (local anaesthesia + diagnostic)
2. Verify correct position by confirming warming of the affected lower limb
3. Local anaesthetic injected immediately prior to neurolytic agent under fluoroscopic guidance
4. If position confirmed: inject 5-10 mL of 5% phenol (neurolytic agent of choice for lumbar sympathetic block)
5. After injection, the needle is cleared with air or saline before withdrawal - prevents damage to superficial structures along the needle tract

Post-procedure

1. Monitor blood pressure (orthostatic hypotension risk)
2. Assess for limb warming and pain relief
3. If pain relief follows isolated sympathetic blockade signs (BP drop, no sensory/motor loss) → pain is sympathetically mediated and the block was appropriate

Note on neurolytic agents: Phenol is preferred for lumbar sympathetic block; alcohol is preferred for celiac plexus block. Phenol in glycerin is hyperbaric.

Open Surgical Sympathectomy (now rarely done)

• Retroperitoneal approach
• Resection of L2-L4 ganglia and interconnecting chain
• Largely replaced by the chemical technique

COMPLICATIONS

Immediate / Procedural

Early Post-procedure

Long-term / Permanent

Special Concern

• Bilateral sympathectomy carries a significantly higher risk of orthostatic hypotension and retrograde ejaculation than unilateral
• After lumbar sympathectomy, patients tend to faint on standing but usually compensate after some months by enhanced use of lower limb muscle pumps (Medical Physiology, Boron & Boulpaep)

Summary Table