Thoracic outlet syndrome (TOS) is a group of conditions in which the nerves or blood vessels in the upper chest and neck are compressed. TOS most commonly presents in the neurogenic form, and symptoms include pain and numbness whenever the arm is elevated.
Nonoperative management usually consists of physical therapy and injections. If patients fail conservative management, the indicated surgery includes removing a portion of the first rib to relieve compression within the thoracic outlet and debridement of the scalene muscles in the front of the neck. While the procedure often provides short-term relief, up to 50% of patients may experience symptom recurrence within two years of surgery.
These outcomes led Karan Dua, M.D., an orthopedic surgeon at NewYork-Presbyterian and Columbia who specializes in upper extremity surgery, to further explore alternative causes of TOS and provide a different treatment approach. Dr. Dua is one of the few surgeons in the country who can address TOS by performing an arthroscopic procedure releasing the pectoralis minor muscle with neurolysis of the brachial plexus.
Below, Dr. Dua shares details of a recent TOS case that he treated using this novel approach, why he sees this surgery as a better option for most patients experiencing dynamic brachial plexus entrapment, and why it’s important to raise awareness about this minimally invasive surgical option.
Anterior view of the pectoralis minor tendon, which inserts on the medial coracoid process. Deep to the tendon is the retropectoralis minor space, which consists of the brachial plexus.
Superior view of the retropectoralis minor space.
How the Patient Presented
The patient, a 31-year-old male, presented with numbness and tingling in the ring and small fingers of his left hand whenever he raised his arm. He also complained of a flushing sensation into his hand related to arm positioning. The symptoms had been ongoing for about 10 years and progressively getting worse. He had been treated by several specialists around the country over the years, who diagnosed him with TOS and scapular dyskinesia. He underwent physical therapy and had a steroid injection in his pectoralis minor muscle, with no improvement in his symptoms.
Earlier in the year, he received a diagnostic lidocaine interscalene block, which completely resolved his symptoms. This helped confirm his TOS diagnosis, thereby localizing the pathology to the scalene muscles or entrapment within the retropectoralis minor space. Based on the success of the injection, he was indicated for a rib resection and scalene debridement at an outside institution. He came to NewYork-Presbyterian and Columbia for a second opinion before undergoing the open procedure.
Diagnosing Pectoralis Minor Syndrome
The traditional surgical treatment for TOS is a partial first rib resection, scalene debridement, and an open neurolysis of the brachial plexus. When I saw the patient, I performed a thorough physician examination of his shoulder and periscapular area. There was hyperactivation of the pectoralis minor with significant tenderness to palpation at the medial coracoid. In addition, he had a positive Tinel’s sign medial to the coracoid indicating nerve irritability and compression in the shoulder. When his scapula was manually repositioned, his symptoms nearly completely resolved. Based on his symptoms and physical examination, I thought it was unlikely that his problem was originating in the scalene muscles. Rather, I suspected he had pectoralis minor hyperactivity causing dynamic entrapment of the brachial plexus.
I diagnosed him with pectoralis minor syndrome, which essentially indicates the muscle is hyperactive in the front of the chest. This creates an imbalance with the periscapular muscles, thereby tilting the scapula forward and narrowing the retropectoralis minor space. As a result, when you raise your arm, the scapula rubs against the nerves, causing numbness and tingling in the fingers.
The pectoralis minor can become hyperactive and pull on the coracoid process, causing the scapula to protract. Dynamic entrapment of the brachial plexus can lead to pain and numbness in the arm.
Taking an Arthroscopic Approach
After our consultation, the patient opted to forgo the rib resection in favor of an arthroscopic pectoralis minor release with brachial plexus neurolysis. During the procedure, I perform a shoulder arthroscopy using two small incisions. The subdeltoid and subacromial spaces are opened up in order to visualize the coracoid process. A bipolar radio frequency ablation probe is then used to release the pectoralis minor tendon from the medial coracoid.
View of the pectoralis minor tendon.
Once the tendon is released, it is manually separated from its underlying fascial adhesions so it can retract into the chest. In patients with chronic compression of the brachial plexus, there is often an enveloping thickened fascia that is then arthroscopically debrided to clean the neural elements. After completing the neurolysis, the skin is closed with absorbable sutures.
An arthroscopic pectoralis minor muscle release with brachial plexus neurolysis requires two small incisions in the shoulder. The pectoralis minor tendon is released from the medial coracoid using electrocautery.
WATCH: Arthroscopic release of the pectoralis minor tendon
The entire procedure takes about 30 to 45 minutes. The benefits are multifold: Postoperatively, patients are in a sling for comfort, which they can remove whenever they feel comfortable. Most patients take minimal pain medication. Physical therapy starts two weeks after the surgery, in which the primary focus is working on scapular retraction.
After the pectoralis minor muscle is released, the scapula will retract and the retropectoralis minor space will expand, relieving compression of the brachial plexus.
This patient had complete resolution of his pectoralis minor syndrome and neurogenic TOS after surgery and one year after his procedure, he remains symptom-free. He has resumed all his activities of daily living.
The Need for More TOS Treatment Options
Over the last year and a half, I’ve performed about 20 arthroscopic pectoralis minor releases for various conditions including pectoralis minor syndrome, thoracic outlet syndrome, snapping scapula, or scapulothoracic abnormal motion. In only two cases, it was not effective because the cause of the neurogenic compression was higher up in the scalene muscles.
I believe this arthroscopic approach is likely to be appropriate for most patients with dynamic brachial plexus entrapment. It allows patients to avoid the potential morbidity of an invasive, open surgery like a rib resection. I’m working with my former mentors and colleagues to continue research into diagnosing and treating scapula disorders, including neurogenic TOS and other nerve compressions in the periscapular area. We continue to study and refine how to perform these procedures in a minimally invasive manner.
There are only a few surgeons in the country who have adopted this approach because it’s a technically challenging procedure, and disorders of the scapula are not well understood or theorized. This is an evolving science, and as the recognition and popularity grows, I believe surgeons will become better trained in treating these conditions.
