Ultrasound-Guided Needle Release Combined with Corticosteroid Injection for the Treatment of Supinator Syndrome

Summary

The deep branch of the radial nerve can easily be compressed at the arcade of Frohse due to its anatomical features. Ultrasound-guided needle release combined with corticosteroid injection is an effective and safe treatment for deep branch radial nerve adhesion.

Abstract

The two main branches of the radial nerve (RN) are the deep branch (DBRN) and the superficial branch (SBRN). The RN splits into two main branches at the elbow. The DBRN runs between the deep and shallow layers of the supinator. The DBRN can be easily compressed at the arcade of Frohse (AF) due to its anatomical features. This work focuses on a 42-year-old male patient who had injured his left forearm 1 month prior. Multiple muscles of the forearm (extensor digitorum, extensor digiti minimi, and extensor carpi ulnaris) were sutured in another hospital. After that, he had dorsiflexion limitations in his left ring and little fingers. The patient was reluctant to undergo another operation because he had undergone suture surgeries for multiple muscles 1 month prior. Ultrasound revealed that the deep branch of the radial nerve (DBRN) had edema and was thickened. The exit point of the DBRN had deeply adhered to the surrounding tissue. To relieve this, ultrasound-guided needle release plus a corticosteroid injection were performed on the DBRN. Nearly 3 months later, the dorsal extension in the patient's ring and little fingers was significantly improved (ring finger: −10°, little finger: −15°). Then, the same treatment was done for the second time. Nearly 1 month after that, the dorsal extension of the ring and the little finger was normal when the joints of the fingers were fully straightened. Ultrasound could evaluate the condition of the DBRN and its relationship with the surrounding tissues. Ultrasound-guided needle release combined with corticosteroid injection is an effective and safe treatment for DBRN adhesion.

Introduction

The radial nerve (RN) splits into two main branches at the elbow level: the deep branch (DBRN) and the superficial branch (SBRN). The DBRN originates from the main trunk of the RN at the level of the lateral epicondyle of the humerus¹. The DBRN curves around the neck of the radius and then goes through under the tendinous arch of the superficial edge of the supinator muscle, which is called the arcade of Frohse². This anatomical site is the most common entrapment site of the DBRN at the forearm^3,4. In some rare cases, the DBRN can be compressed from the entrance to the exit of supinator⁵. The entrapment of the DBRN can cause pain in the lateral-dorsal proximal forearm and weakness of the wrist extensor muscles^6,7,8.

When a nerve is injured, nerve conduction studies (NCS) and electromyography (EMG) sometimes show abnormal results indicating that the nerve is damaged. Although EMG is an established method and provides functional information about nerve disease, it lacks the ability to detect anatomical and morphological information related to the nerve⁹. Besides that, the sensitivity and specificity of EMG are not very high at early stages of nerve injury. Ultrasound can easily detect peripheral nerves and show them in sonographic imaging. Many studies have reported the value of high-frequency ultrasound in diagnosing the entrapment of peripheral nerves⁵. It has great potential as a diagnostic method for finding peripheral nerves. Babaei-Ghazani et al. reported ultrasonographic values for the DBRN at the arcade of Frohse, and they concluded that age was associated with the cross-sectional area (CSA) of DBRN, while other features such as height or gender were not¹. Some studies have reported that corticosteroid injections are effective in treating musculoskeletal diseases^10,11. However, until now, there have been no reports on ultrasound-guided needle release plus a corticosteroid injection in the DBRN for treating adhesion. Here, we report a method that can separate the adhesion without open surgery. A male patient who had a dorsiflexion limitation in his left ring and little fingers was treated using this method. This patient had injured his left forearm 1 month prior to the treatment. Multiple muscles of the forearm (the extensor digitorum, extensor digiti minimi, and extensor carpi ulnaris) were sutured in another hospital. His DBRN had edema and was thickened, and the exit point of DBRN was deeply adhered to the surrounding tissue. After treatment using US-guided needle release and corticosteroid injection of the DBRN, the patient's dorsal extension of the ring and the little finger was normal when the joints of the fingers were fully straightened.

Protocol

This study was approved by the ethical and scientific review board of our hospital. Written informed consent was obtained from the patient. All the treatment procedures were performed by personnel with 10 years of experience in musculoskeletal ultrasound intervention. The operator must have good knowledge of musculoskeletal anatomy. The ultrasound machine used here is mentioned in the Table of Materials and has a high-frequency probe.

1. Instrument setup and patient preparation

1. Enter the ID number and the patient's name to save the images.
2. Sanitize the ultrasound probe using equipment disinfectant wipes. Perform all the procedures with the probe covered with surgical gloves.
3. Set the image with the DBRN in the middle of the screen. To do this, perform cross-sectional scanning along the supinator muscle to find the DBRN. Then, rotate 90° to obtain a long-axis section. Under continuous ultrasound guidance, separate the adhesion between the surrounding tissue of the posterior spin muscles and the DBRN.
4. Ask the patient to sit and place their arm in a flexed 20° position on the examination bed. Perform ultrasound to check for DBRN adhesion to the surrounding tissue (Figure 1; Video 1).

2. Ultrasound examination and treatment

1. Use complex iodine to disinfect the patient's skin three times, and then place a sterile surgical towel on the patient's arm.
2. Provide local anesthesia using a 10 mL aliquot of a mixed solution (5 mL of 2% lidocaine and 5 mL of 0.9% sodium chloride) layer by layer until the DBRN surface is reached (Figure 2). The four layers that are anesthetized include the skin, the subcutaneous soft tissue, the brachioradialis, and the superficial supinator muscle. Confirm the anesthetization of each layer using ultrasound guidance, and check that the tip of the needle passes through each layer.
3. Identify the radial nerve by transversely using the probe at the level of the lateral epicondyle of the humerus. The radial nerve is located between the humerus muscle and the brachioradial muscle. Then, move the probe distally to find the deep branch of the radial nerve between the deep and superficial layers of the supinator.
4. Use a 5 mL syringe to separate the adhesion between the surrounding tissue of the posterior spin muscles and the DBRN under the continuous ultrasound guidance. Perform needle release from the DBRN distal area to the proximal area. Prick the adhesion tissue back and forth with the tip. Stop when there is resistance between the syringe and the tissues around the DBRN.
5. Ensure that the probe and the needle are accurately controlled, keep the tip of the needle visible during the entire operation, and avoid damage to the DBRN.
6. After the procedure, inject a mixture of 1 mL of corticosteroid (betamethasone) and 2 mL of 2% lidocaine into the superficial area of the DBRN.

Results

At 1 month after the treatment, the joints of the fingers were fully straightened, and the dorsal extension of the ring and little fingers was significantly improved upon fully straightening the fingers (ring finger: −15°, little finger: −25°). At 3 months after the treatment, the patient came back for re-examination of the DBRN. The range of DBRN adhesions, as assessed by ultrasound, was significantly reduced compared to before the treatment. The dorsal extension of the ring and little fingers was ...

Discussion

In recent years, ultrasound has become a valuable tool for assessing peripheral nerve entrapments. Ultrasound can be used to observe nerves in real-time and provide dynamic visualization¹². The obvious sonographic indicator of entrapment is the increased nerve CSA at the site of entrapment^13,14. Other findings such as a hypoechoic texture, nerve flattening, and increased vascularity are also reported in entrapment neuropathy

Materials

Name	Company	Catalog Number	Comments
Betamethasone	MSD Merck Sharp & Dohme AG	B7005-100MG
Injection syringe	Hangzhou Minsheng Pharmaceutical Co., LTD		5 mL and 10 mL
Lidocaine	Shanghai Zhaohui Pharmaceutical Co., LTD	H41022244	7 mL
Sodium chloride	Hangzhou Minsheng Pharmaceutical Co., LTD	http://www.mspharm.com/pro_list.asp?PageNumber=3&info_kind=004001 &d_add_date1=&d_add_date2=& skind=&p_keys=	5 mL
Ultrasonic diagnostic system	SIEMENS		Type:ACUSON Sequoia