Ultrasongraphy Versus Fluoroscopy in Lumber Sympathetic Block in Chronic Lower Limb Ischemia

The aim of this study is to compare total procedure time and success rate between FL-guided and US-assisted LSGBs in Lower Limb Ischemic patients.

Morbidity and death in acute lower limb arterial occlusion are well described. The patients often are in a debilitated state, with multiple concurrent medical comorbidities. An association with hypercoagulable phenomena (e.g., active malignancy) may explain the frequency of some of these conditions. Other conditions, however, may be directly responsible for the occlusive event itself (e.g., the association of myocardial disease and peripheral embolization) (1, 2).

The sympathetic nervous system controls many of the involuntary functions of the human body and plays a role in chronic pain conditions such as complex regional pain syndrome (CRPS) (3).

About 20% of patients who suffered lower limb ischemic pain are not suitable for surgical intervention for various reasons. In these patients, a lumbar sympathetic ganglion block (LSGB) can be used to reduce pain, improve the walking status and activities of daily living, and may delay or avoid amputation. LSGB technique has become increasingly popular in recent decades, and several diseases are treated with LSGB, including neuropathic pain (NP), vascular pain, and erythematous extremity pain (4).

An LSGB refers to injecting drugs (local anesthetic drugs: lidocaine, ropivacaine, etc.) into the lumbar sympathetic ganglia of the corresponding segment to destroy the nerve conduction function, thereby achieving the method of treating certain diseases. The use of LSGB can destroy the innervation of sympathetic nerves on the blood vessels of the lower extremities, and the innervated blood vessels continue to expand to improve local blood circulation and nutrient supply, thereby reducing pain (5).

This block is typically performed in the prone position at the L3 level under fluoroscopic guidance. Fluoroscopy (FL)-guided LSGB has been a popular technique, as it provided great accuracy in confirming the location of needle tip or intravascular (IV) injection. However, this technique exposes patients to radiation and its success rate ranges from 67% with FL guidance to 83% with computed tomography (CT) guidance (6).

Ultrasound (US)-guided or assisted techniques have been introduced to the field of pain medicine in the mid- 2000s. US guidance has been shown to be associated with many advantages, including minimal radiation exposure, as well as the ability to visualize soft tissue structures and observe needle insertion and spread pattern of injectate in real time (7).

As US guidance has undergone technical advancements, its applicability expanded from peripheral blocks to deep neuraxial blocks. A recent technical description of US guidance LSGB in a patient with CRPS type I showed that the anterior fascia of the psoas muscle and the anterolateral part of vertebral body are key landmarks during the procedure (8).

US-guided LSGB in conjunction with FL, may be expected to provide real-time visualization of the needle tip location with respect to the anterior fascia of the psoas major muscle in paravertebral space with an advantage of low radiation exposure.

Recently, numerous US-assisted procedures in pain medicine have been attempted, showing an advantage of low radiation exposure (8).However, only few publications relatively few sample size manipulate the comparison between FL-guided and US-assisted LSGBs in Lower Limb Ischemic patients.

Eligibility Criteria:
Inclusion Criteria:

* • Lower Limb Ischemic patients need LSGB procedures

Exclusion Criteria:

* • A body mass index (BMI) of \>30 kg/m2.

  * A history of post-lumbar laminectomy with internal fixation or any severe anatomic variation, such as scoliosis and tumor.
  * History of lumbar sympathetic chemical or thermal neurolysis.
  * Pregnancy.
  * Infection at the puncture site.
  * Coagulopathy.
  * Allergy to local anesthetics.