Correspondence Address:
Dr. Amarjeet Kumar
AIIMS, Patna, Bihar
India

Full Text



Sir,

Lumbar transforaminal injections are routinely implemented in the interventional management of spinal radicular pain.[1] Ultrasound (US) guidance is not usually recommended for any interlaminar injections and should never be used solely for a transforaminal epidural injection due to the inability to visualize vasculature within the spinal canal during an injection or gauge the depth of the needle once advanced past the bone. With US guidance in an interlaminar or transforaminal epidural injection, there is no assurance that the injectate has not been placed intravascular or that a dural puncture has not occurred.[2],[3]

Here, we are going to report a new technique of lumbar transforaminal injection through interfacet approach. In operation theater, patients were placed in the prone position on procedure table. A pillow was placed under the abdomen to alleviate lumbar lordosis. A SonoSite TM M-Turbo machine and a linear 38 mm, 7–13 MHz US transducer were used for the procedure. After identification of the fifth lumbar spinous process, the desired spinal level for the injection was marked by cephalad counting of the spinous process starting from L5. A second scan was performed in the paramedian sagittal plane at the lower back with its orientation marker directed cranially. A slight tilt medially during the scan is assumed to insonate in a paramedian oblique sagittal plane. The probe is moved medially to laterally to visualize the horse head sign (lamina), camel hump (articular processes), and finally trident sign (transverse process). After infiltrating local anesthesia, a 90 mm needle was inserted approximately 45° into the skin and advanced through the out-plane approach, which enables real-time visualization of tip of the needle. The needle tip was advanced in between two articular facets until it hits the bony structure in between two articular facets. The needle was withdrawn by 2–3 mm and redirect anteriorly between two facet. If the patients complained of shooting pain or tingling in the leg during needle advancement, the needle was withdrawn slightly till the pain subsided. Once satisfactory position of the needle is achieved under US, fluoroscope (FL) image is taken to confirm the needle tip placement and contrast spread. Minor adjustments to position the needle tip were done if required at this stage. One milliliter of iohexol 300 mg/ml (contrast) was then injected under FL guidance. This is done to ensure that there is no intravascular or intrathecal spread [Figure 1].{Figure 1}

FL guidance method is the gold standard for performing lumbar transforaminal epidural steroid injections, but it is not devoid of adverse effects such as exposure to radiation and need to wear heavy lead aprons.[2] US-guided techniques are being evaluated recently, but methodological acceptability and reproducibility remain unknown. Hence, we have described this method after carefully reviewing the literature regarding the specific anatomy and performing this block successfully on many patients. This approach has the advantage of easy identification of lumbar structures when compared to transverse approach. Hence, it can be used as an adjunct to transverse scan. In short, US when used with fluoroscopy reduces radiation hazard tremendously and its use should be encouraged.

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Conflicts of interest

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