Ultrasound-guided blocks for the treatment of chronic pain

Neurological pain relief interventional radiology procedures

Neurological interventions have taken on a significant role in interventional radiology (IR) practice. Indications fall under three main categories: (1) intraprocedural pain management, (2) cancer pain palliation, and (3) chronic non-cancer pain control. Short-term regional anaesthesia can be achieved with local anaesthetics, while longer-term pain control can be attained with radiofrequency neuromodulation (pulsed or otherwise) or thermal/chemical neurolysis. This review article summarises the therapeutic options, applications, and techniques of commonly used peripheral nerve and plexus interventions in IR.

Ultrasound-guided truncal blocks: A new frontier in regional anaesthesia

The practice of regional anaesthesia is rapidly changing with the introduction of ultrasound into the working domain of the anaesthesiologist. New techniques are being pioneered. Among the recent techniques, notable are the truncal blocks, for example, the transversus abdominis plane block, rectus sheath block, hernia block and quadratus lumborum block in the abdomen and the pectoral nerves (Pecs) block 1 and 2, serratus anterior plane block and intercostal nerve block. This narrative review covers the brief anatomical discourse along with technical description of the ultrasound-guided truncal blocks.

[Ultrasound-guided puncture: applications in a chronic pain clinic]

Ultrasonography provides an excellent tool for the real-time visualization of peripheral nerve structures in regional anesthesia. Techniques are enhanced further when the progress of the needle and diffusion of the anesthetic can be observed. In a chronic pain clinic, ultrasound-guided puncture offers the advantages of accurate images of structures where pain arises: muscles, fascias, tendons, periostea, and joint structures. Visualization also helps the anesthetist to keep the needle away from structures (eg, the esophagus, pleura, vessels or peritoneum) that might lie near the target site. Unlike fluoroscopy, which produces radiation that is potentially dangerous for both patient and health care staff, ultrasound imaging is not harmful. Disadvantages are poor quality images of structures at a certain depth, acoustic shadows from bone structures that block the view of underlying tissues, and poor transport of ultrasound waves by air. Our aim is to describe a series of techniques for ultrasound-guided puncture and the results obtained on applying them weekly for 12 months in a chronic pain clinic.

Ultrasound demonstration of vascularity changes with changes in pain perception in a stump neuroma

BACKGROUND

Pain in the residual limb after an amputation has posed many challenges in treatment. Ultrasound (US) imaging has helped in the visualization of neuroma and its selective targeting for interventions.

OBJECTIVE

A 58-year-old man presented to the pain clinic with chronic stump pain after a below knee amputation during the Vietnam war. After multiple similar steroid injections around the area of pain in the following months, we decided to use the US to better target the stump neuroma. Color flow Doppler showed extensive vascularity around the posterior aspect of the neuroma where there was scar tissue. During a follow-up visit for intra-articular steroid injection to the L5-S1 left lumbar facet for coincidental lumbar facet arthropathy, an US scan of the stump neuroma with color flow Doppler was performed out of curiosity. Multiple US views of the neuroma with color flow Doppler was performed and all showed a significant decrease in vascularity. Similar absence of vascularity was noted after a spinal cord stimulator placement.

CONCLUSION

This is a case report of US demonstration of increased vascularity in a stump neuroma coinciding with the patient's pain. This serendipitous demonstration makes the need for US visualization useful in the evaluation of neuroma. It is also useful to use US guidance to avoid the vascular structures when testing the beneficial response to various medications. Larger randomized controlled studies are needed to further correlate the US demonstration of vascularity and neuroma pain.

Ultrasound-guided steroid injection for obturator neuralgia

Obturator neuralgia (ON) presents with pain in the groin, medial thigh, and sometimes the medial aspect of the knee. The causes include trauma, obturator hernia, pelvic cancer, pelvic surgery, hip surgery, following pelvic fractures, endometriosis, retroperitoneal hematoma, pregnancy, and delivery. Ultrasound (US) guidance facilitates real-time imaging, identification of vascular structures, and improves patient comfort in situations where nerve stimulation can be unpleasant. This is a case report of ON successfully treated with US-guided steroid injection. A 55-year-old man was referred to the pain clinic with groin pain and allodynia in the medial thigh and knee following a fall. He had tried multiple other therapies and none of them provided significant relief. Using a 10-5-MHz multi-frequency, 38-mm linear array transducer, the obturator nerve was scanned in both longitudinal and transverse directions. Under real-time imaging 10 mg of medroxy-progesterone in a volume of 1 mL was injected. Following the injection, a small area of the medial side of knee was still tender to light touch. A second injection was placed inferiorly and provided pain relief for more than 5 months. This successful demonstration of US guidance in ON may further encourage US guidance in pain clinic interventions.