Image:  Ultrasound use for placement of needles used to treat patients with chronic pain is increasing in popularity. (Image source: Thinkstock)
Image: Ultrasound use for placement of needles used to treat patients with chronic pain is increasing in popularity. (Image source: Thinkstock)

Anesthesiologists use ultrasound in a variety of areas. Needle placement is probably the most common reason to use ultrasound and in this month’s issue of Anesthesia & Analgesia, Dr. Anuj Bhatia, Department of Anesthesia and Pain Management, Toronto Western Hospital (University Health Network), Toronto, Ontario, Canada, and co-authors review the use of ultrasound for needle placement in interventional chronic pain procedures in their article “Review Article: Is Ultrasound Guidance Advantageous for Interventional Pain Management? A Systematic Review of Chronic Pain Outcomes.”

Clinical Pearls

For which target structures is there evidence to show that ultrasound may improve performance outcome compared to traditional methods?

Cervical facet intraarticular, cervical facet joint nerve supply, cervical nerve root, lumbar facet intraarticular, lumbar facet joint nerves, lumbar nerve root, sacroiliac joint, caudal epidural, greater occipital nerve, cervical sympathetic trunk, suprascapular nerve, intercostal nerve, ilioinguinal and iliohypogastric nerves, lateral femoral cutaneous nerve, pudendal nerve, and piriformis muscle.

For which target structures is there evidence to show that ultrasound may improve efficacy as opposed to traditional methods?

Lumbar facet intraarticular, lumbar facet joint nerves, lumbar nerve root, greater occipital nerve, suprascapular nerve, intercostal nerve, and lateral femoral cutaneous nerve.

For which target structures is there evidence to demonstrate that ultrasound may improve safety compared to traditional methods?

Cervical nerve root, cervical sympathetic trunk, suprascapular nerve, intercostal nerve, and pudendal nerve.

From which patient population does the majority of studies come?

Most data that shows there’s an advantage to the use of ultrasound compared to traditional methods comes from cadaveric studies, small volunteer studies, or comparative studies that have statistical problems including blinding, randomization or insufficient power.

Why are cadaveric studies problematic?

The compliance of embalmed tissues is different from living tissue. Blood also does not flow in cadavers.

Why could patient studies be problematic?

Most studies do not include patients with anatomic variations or pathologies.

What are some problems seen with use of ultrasound?

The resolution of small portable machines can be problematic. Certain nerves can be relatively small, such as medial branches that supply lumbar facet joints. Image quality can also be reduced when patients are obese.

How is the view provided by ultrasound different from fluoroscopy?

Ultrasound images are a function of structures that are within the path of the beam. With fluoroscopy, surrounding tissues can be visualized. Ultrasound also does not illuminate contrast dye. Spinal anatomy may be more difficult to define with ultrasound because only one vertebra can be seen in a single view. Certain anatomical structures can also affect the imaging with either technology. For example, the ilium can cause acoustic shadowing when ultrasound is used, though with fluoroscopy, a large iliac crest and prominent transverse processes of the fifth lumbar vertebra can create visual challenges.

For a more comprehensive understanding of this subject, read the article in its entirety.  This article is also available for CME.