Ultrasound-Guided 5-in-1 Injection: Trigger Point Injections and Nerve Hydrodissections for Nonspecific Upper Back Pain

Abstract

A 34-yr-old man had right neck and upper back pain, tightness, and numbness for 2 months, after backpacking a heavy pack. He denied trauma history. No limitation of range of motion of shoulder or motor weakness was found. Taut bands and trigger points were noted in the right upper trapezius, levator scapulae, and rhomboid muscles. Trigger point injection was performed to these muscles, with evident local twitching responses. His pain improved transiently (numerical rating scale, 7 to 2) for only 2 days without improvement of tightness and numbness. Based on the history, physical findings and the result of trigger point injections, myofascial pain syndrome with increased interfascial plane pressure, which causes entrapment neuropathy, was considered. We performed ultrasound-guided (linear probe, 5–14 MHz, Toshiba TUS-A500) trigger point injections of the trapezius, levator scapulae and rhomboid muscles, hydrodissection for the spinal accessory nerve (SAN) and dorsal scapular nerve (DSN), and release of interfascial compartment pressures in a single injection with 10 mL 5% dextrose (Video 1). Right after the procedure, he felt nearly complete relief of pain (numerical rating scale, 7 to 2) and tightness. His persistent numbness also improved to an episodic pattern, only attacked during extreme rotation or flexion/extension of upper torso. The therapeutic effect lasted for at least 2 months and no repetitive injection was required during this period. Neck and upper back pain is a common complaint in pain and rehabilitation clinics. This entity of pain is often multifactorial and the diagnosis is sometimes tedious. Myofascial pain syndrome of the trapezius, levator scapulae muscle or rhomboid muscles, entrapment of the SAN1 or DSN,2 and pain referral from the cervical facets are all possible causative factors. The SAN leaves the skull through the jugular foramen, heads posteriorly and caudally, exits from the posterior border of the sternocleidomastoid muscle to reach the levator scapulae and upper trapezius muscle. The DSN is a terminal branch of the C5 brachial plexus, pierces the middle scalene muscle, and continues deep to the levator scapulae and rhomboid muscles. The SAN and DSN are traditionally documented as “pure motor”; however, there are reports indicating that they may have sensory components and contribute to neck, shoulder, or upper back discomfort. When entrapment of these nerves is considered as a source of pain, hydrodissection technique is an intervention of choice. In nerve hydrodissection, fluid expansion around the nerve separates the adjacent structures from the target nerve, releasing the pressure on the nerve and relieving the symptoms.3 To find both nerves, trapezius, levator scapulae, and rhomboid muscles in a single view, we placed the ultrasound probe around superomedial border of scapula horizontally (Fig. 1). Identification of SAN and DSN could be assisted by the accompanying vessels, which are transverse cervical artery and dorsal scapular artery, respectively. The nerves were first localized in the horizontal view; then, the transducer was rotated 90 degrees to the sagittal view. A craniocaudal trajectory with in-plane approach was used to hydrodissect the interfascial planes where the SAN and DSN reside (Fig. 2). To avoid accidental nerve or vascular injury, the location of the neurovascular bundles is estimated in horizontal view before advancing needle. In the sagittal view, it is possible to inject trapezius, levator scapulae, and rhomboid muscles in a single injection. The ribs are clearly visualized, preventing pneumothorax during needling.FIGURE 1: Transverse view on superomedial border of scapulae. Trapezius muscle, superficial branch of transverse cervical artery and SAN (arrowhead), rhomboideus minor muscle, dorsal scapular artery (red circle) and nerve (yellow circle), levator scapula muscle, and serratus posterior muscle are identified.FIGURE 2: A, Needle trajectory, the superficial layer. B, Needle trajectory, the deep layer. Needling of levator scapulae and rhomboideus muscles was performed during needle advancement with fine adjustment of direction.In this procedure, we can do trigger point injections in the trapezius, levator scapulae and rhomboid muscles, and nerve hydrodissection of the SAN and DSN in a single injection. The treatment effect of nerve hydrodissection could be augmented by releasing the adjacent myofascial taut bands, which further decrease the pressure on the nerves. Nerve or vascular injuries, pneumothorax, hematoma, or bleeding could be avoided by meticulous ultrasound scanning. If local anesthetic is applied, low concentration is more feasible to prevent motor weakness and systemic toxicity. For patients with upper back pain with neuropathic characteristics, this 5-in-1 technique is a treatment of choice.