Ultrasound-Guided Injection to the Fifth Cervical Spinal Nerve Root Level
Walter R. Frontera, MD, PhD
Cervical radicular pain is manifested as pain shooting down the upper limb induced by the irritation of the spinal nerve as it exits the neural foramina. Treatments include cervical traction, exercises, and analgesics.1 Although surgery remains as the mainstream of treatment, its long-lasting efficacy is still unclear.2 Cervical transforaminal steroid injection can be used to treat radicular pain caused by disc disorders. This is performed under fluoroscopy or computed tomography guidance.3 However, these imaging tools are not able to visualize small vessels, and incidences such as brainstem or spinal cord infarction may occur.4 These complications are believed to be caused by inadvertent injection of therapeutic agents into the vertebral or radicular arteries.5 Therefore, accidental puncture of vessels must be prevented when performing neck injection procedures.
Recently, high-resolution musculoskeletal ultrasound (US) can be used to identify the target root and the nearby vessels. The advantage of using US as a guidance tool is that it does not expose patients or medical personnel to radiation such as fluoroscopy or computed tomography guidance. Ultrasound allows good visualization of the soft tissue such as abnormal blood vessels in the foramen and around the nerve root, which further enables accurate needle placement and avoids the risk of intravascular injections.5 As a result, US-guided cervical nerve root block (US-CRB) is a safe alternative treatment technique that can be used in the treatment of upper extremity radicular pain.6 It has been shown that US- and fluoroscopy-guided techniques for neck CRB showed no differences in efficacy.5
The objective of CRB is to place the needle in the intertubercular groove situated between the nerve root and the posterior tubercle.1 After the injection, the injectate can then spread close to the target nerve, reducing inflammation of the injured nerve roots and suppressing the transmission of nociceptive C-fibers.1,4 This article demonstrates how US-guided injection is performed to the cervical spinal fifth nerve root level because this is the frequent site that causes radicular pain.