SUPERIOR HYPOGASTRIC PLEXUS BLOCK - Dr Debjyoti Dutta MD. FIPP. FPM.

Superior hypogastric plexus, located bilaterally at the lower third of the fifth lumbar vertebral body and upper third of the first sacral vertebral body. This plexus plays a crucial role in innervating pelvic viscera and interrupting it, known as presacral neurectomy, has shown promise in relieving various painful pelvic conditions. The prevalence of pelvic pain associated with oncologic diseases has motivated our group to develop a reliable percutaneous approach to block the nerves in this region.

Anatomy: Superior Hypogastric Plexus

The superior hypogastric plexus (SHP) is a vital nerve plexus situated in the abdomen, positioned precisely at the bifurcation of the aorta, between the fifth lumbar (L5) vertebra and the first sacral vertebra. This significant structure resides bilaterally in the retroperitoneum, extending from the lower third of the L5 vertebra to the upper third of the S1 vertebra. Composed of the confluence of lumbar sympathetic chains and branches of the aortic plexus, the SHP is sometimes referred to as the presacral nerve. It's noteworthy that the SHP is loosely organized and lies close to the midline. Importantly, it receives fibers from the inferior hypogastric plexus, which in turn gathers all afferent fibers from pelvic organs. As it courses into the pelvis, the SHP divides into right and left inferior hypogastric nerves. The SHP is notable for its two well-defined ganglia, making it a feasible target for blocking procedures.

In clinical practice, understanding the anatomy of the SHP is crucial, especially in the context of pain management. Targeting the SHP for blockage involves positioning anterior to the L5-S1 disc, encompassing the lower part of the L5 vertebral body and upper part of the sacrum. Additionally, awareness of the anatomical relationships with major blood vessels is essential. The aorta and inferior vena cava bifurcate into the common iliac arteries and veins anteriorly to the L4 and L5 vertebral bodies. Anterior to the aorta bifurcation lies the inter-mesenteric plexus, which extends caudally as the superior hypogastric plexus. Notably, the SHP connects to the inferior hypogastric plexus via the left and right hypogastric nerves, positioned just anterior to the S1 vertebra.

Indications for Superior Hypogastric Plexus Block:

Indications for Superior Hypogastric Plexus Block:

1. Gynecologic Disorders:

• Chronic lower abdominal and pelvic pain associated with conditions such as endometriosis, pelvic inflammatory disease, and pelvic adhesions.

1. Nongynecologic Disorders:

• Persistent pelvic pain arising from disorders like interstitial cystitis and irritable bowel syndrome.

1. Sympathetically Maintained Pelvic Pain (Pelvic CRPS):

• Patients experiencing sympathetically mediated pain in the pelvic region may find relief through this block.

1. Pelvic Neoplasms:

• Effective for pain secondary to neoplasms in the pelvic area.

1. Sacral or Perineal Pain:

• Beneficial for alleviating pain originating from the sacral or perineal region.

1. Bladder Conditions:

• Useful in managing pain associated with bladder disorders.

1. Penile Pain:

• Can be employed for treating pain related to penile conditions.

1. Prostatitis:

• Provides relief for patients suffering from prostatitis-induced pain.

Contraindications for Superior Hypogastric Plexus (SHP) Block:

1.     Infection (local or systemic): If the patient presents with an active infection, it is prudent to defer the SHP block until the infection is resolved to prevent potential complications.

2.     Coagulopathy: Patients with bleeding disorders or those receiving anticoagulant therapy may not be appropriate candidates for the SHP block due to an increased risk of bleeding complications.

3.     Patient Refusal: Respect the patient's autonomy and decision-making process. If the patient declines the procedure, it should be respected and not performed against their wishes.

Procedure Steps for Superior Hypogastric Plexus Block:

1. Patient Positioning: Place the patient in the prone position on the fluoroscopy table.

2. Fluoroscopy Setup:

• Obtain an anteroposterior (AP) view of the L-S spine to visualize the targeted area.

• Tilt the C-arm obliquely so that the spinous process of L5 overlaps the contralateral facet line, known as the "scotty dog view".

• Cephalad tilt the C-arm to move the iliac crest out of view.

1. Needle Entry Point Localization:

• Utilizing the oblique-cephalad tilt, locate an unobstructed view of the anterolateral portion of the L5-S1 disc.

• The needle entry point is anterolateral to the lower part of the L5 vertebral body, just cephalad to the iliac crest.

1. Needle Insertion:

• Insert the needle laterally to the lower part of the L5 vertebral body, just cephalad to the iliac crest, under fluoroscopic guidance.

• Employ a coaxial approach to reach the lower portion of the L5 vertebral body or L5-S1 disc.

1. Confirmation of Needle Position:

• Check the lateral view to confirm the needle position.

• "Wiggle" the needle anteriorly in the lateral view until it is just slightly anterior to the L5-S1 disc.

1. Further Verification:

• Switch to the AP view to verify the needle position. The needle should be at the midpoint or at the junction of the lateral and mid-third of the vertebral body.

1. Contrast Injection:

• Inject contrast to visualize the spread anterior to the L5-S1 disc.

• If contrast demonstrates bilateral spread on the AP view, proceed to inject 15 ml Bupivacaine 0.25%- or 15-ml Phenol 6%, completing the procedure.

• If contrast only shows unilateral spread, repeat the procedure from the opposite side. Inject 10 ml on each side after verification.

1. Completion:

• Ensure proper documentation of the procedure and any adverse reactions.

• Provide post-procedural care and instructions to the patient.

Complications Associated with Superior Hypogastric Plexus (SHP) Block:

1. Nerve Injury:

• Needle entry at levels involving the exiting nerve roots of L4 and L5 poses a risk of nerve injury.

1. Disc-related Complications:

• Proximity to the L5-S1 disc can lead to complications such as discitis, disc degeneration, and persistent pain.

1. Vascular Injury:

• Care must be taken to avoid inadvertent puncture of the common iliac arteries and veins to prevent bleeding or intravascular injection.

1. Inadvertent Needle Advancement:

• Advancement of needles intrathecally or epidurally may result in unintended contact with structures like the ureter, potentially causing injury.

1. Post-procedural Complications:

• Complications such as infection, bleeding, or exacerbation of pain may occur following the SHP block.

1. Vasovagal and Allergic Reactions:

• Vasovagal and allergic reactions are possible and necessitate vigilant monitoring and prompt management.

Clinical Pearls:

1. Men typically possess a higher riding iliac crest, necessitating a greater degree of cephalad C-arm tilt during fluoroscopy.

2. In rare cases, individuals with a combination of a high riding iliac crest and severe arthritis in the L4–5 and L5-S1 facet joints may encounter difficulty in achieving the "unobstructed view". In such instances, trans-discal or anterior approaches may be easier to execute compared to the coaxial view.