Treating Thoracic Outlet Syndrome Through Minimally Invasive Surgery

Two newly published studies have found that minimally invasive surgery for neurogenic thoracic outlet syndrome (NTOS) can significantly improve patients’ symptoms. This relatively uncommon condition causes neck pain, paraesthesia in the arms, neck and hands, numbness and weakness in the upper body and is more frequent in young, active and generally healthy patients.

One of the studies found that a fairly recently developed type of surgery is particularly helpful at relieving thoracic outlet syndrome in adolescents when the pinched nerves are being caused by the pectoralis minor tendon.

New Surgical Option for Thoracic Outlet Syndrome

The research was published in February in the Journal of Vascular Surgery and was carried out by senior author Robert W. Thompson, MD, professor of surgery and director of the Washington University Center for Thoracic Outlet Syndrome at Barnes-Jewish Hospital in St. Louis, Missouri, and colleagues. The first study looked at 200 patients referred to the hospital for treatment of disabling NTOS over a three and a half year period (2008-2011) with some patients undergoing the relatively new type of surgery and others having this surgery combined with another procedure in order to compare the results.

What is Thoracic Outlet Syndrome?

Thoracic outlet syndrome (TOS) usually involves neck pain and occipital headaches (at the base of the skull), arm weakness and tingling (paraesthesia) in the upper extremities. It can also cause chest pain and this, as with the other symptoms, may make it particularly hard to diagnose. More than 80% of cases are thought to be a consequence of brachial plexus injury, often during contact sports or as a result of a car accident and whiplash where the ligaments, tendons and musculature in the neck and upper chest have been hyper-extended. Diagnosing thoracic outlet syndrome can be difficult as x-rays and nerve tests do not provide sufficient evidence for the diagnosis. Instead, physicians must rely on a full medical history and physical examination.

Nerve Compression and Neck Pain in NTOS

The new technique was developed based on the realization that some patients have nerve compression in the space underneath the pectoralis minor muscle tendon close to the shoulder (known as the subcoracoid space). Thoracic outlet syndrome is a result of compression of the brachial plexus nerves that branch through the neck above the collarbone and down into the chest and underneath the collarbone. Determining the site of compression is vital for performing precise surgery to relieve the pinched nerves causing neck pain and other symptoms of NTOS.

The brachial plexus is a complex region where nerves can easily become trapped and compressed, causing NTOS.

Causes of TOS and How New Surgery Helps

In some cases the patient may have a cervical rib that is causing the compression and removal of this may relieve symptoms. In other cases a muscle tear or injury can be the cause of pinched nerves due to scar tissue. The new minimally invasive surgery is referred to as pectoralis minor tenotomy (PMT) and involves the severing of the pectoralis minor tendon so as to free the nerves trapped beneath. This study aimed to provide some insight as to the effectiveness of this procedure which remains novel.

How the Study Measured Success

The majority of the patients (143) underwent open surgery combining PMT with supraclavicular decompression (SCD+PMT), while 57 patients had minimally invasive PMT for thoracic outlet syndrome. Patients were diagnosed using standard clinical guidelines including pain in the armpits, clavicle, and front of the chest that suggested involvement of the pectoralis minor tendon. To measure the success of the procedure, patients were scored on the Disabilities of Arm, Shoulder, and Hand survey, the Cervical-Brachial Symptom Questionnaire, and a 10-point visual analog scale for pain. An index for NTOS was compiled from these results, with low disability scores around 0 and severe disability scores approaching the top of the scale at 100.

Significant Improvement in Symptoms of TOS

Patients’ most common symptoms prior to surgery were neck pain and shoulder pain, as well as pain in the arms, weakness and tingling or altered sensation in the hands. The two groups of patients, those undergoing PMT and those undergoing SCD+PMT, had NTOS index scores of 54.5 ± 3.4 (n35) and 62.7 ± 2.3 (n113); the difference was insignificant. Patients were then assessed after surgery and at a three month follow-up with 82% of all patients reporting significant and progressive improvement in their symptoms.

Endoscopic Surgery A New Option for TOS

The combined procedure had a slightly higher success rate with some 84% of patients reporting improvement at three months compared to 75% of the patients undergoing the new procedure alone. The NTOS index scores fell in both groups but the differences between the two were insignificant (36.8 ± 3.8 from 26 PMT patients, 41.3 ± 2.5 from 84 SCD+PMT patients). The comparable benefits of the isolated procedure suggest that it is a viable alternative to traditional open surgery for thoracic outlet syndrome.

Benefits for Adolescents with NTOS

The focus of the second study was comparing the benefits of adding PMT to the traditional open SCD procedure by looking at 35 adolescents (average age 17.3 years) and a group of 154 adults (mean average age of 40 years). Aside from a reduced incidence of hand pain in the adolescents (56% compared to 79%), the symptoms were generally similar between the groups. All of the patients had the SCD procedure and some had additional PMT if the clinical signs indicated a potential benefit.

Vast Improvements for Younger Patients

NTOS index scores pre-surgery were 46.5 ± 3.6 for the adolescents and 58.5 ± 1.7 for the adults. These scores dropped remarkably for the adolescents by three month follow-up (18.4 ± 4.1), and even further by the six month follow-up (10.4 ± 3.1). In the adults the results were less convincing with scores of 41.0 ± 2.3, at three months and 39.3 ± 3.3 at six months. This greater improvement in the adolescent group is likely due to a number of factors including the lower incidence of depression in the adolescents, fewer patients having experienced car crashes, less use of opiate painkillers, shorter symptom duration, and a higher incidence of repetitive motion injuries and sports participation.

Long-Term Outcomes for New TOS Surgery

One word of caution from the researchers, however, is that the study period was insufficient to monitor for the potential recurrence of symptoms of thoracic outlet syndrome which may reappear around two years after surgery. As the adolescents’ bodies are still growing and developing it may be that further nerve compression arises and symptoms appear once again. Long-term studies are, therefore, needed to monitor the continued success of these procedures. The two studies do support the use of this new surgical procedure for neurogenic thoracic outlet syndrome, however, especially in adolescents and a minimally invasive surgery for the condition may also reduce surgical risks for patients.

References

Thompson, R.W., et al, J Vasc Surg. Published online February 4, 2013, and 2013;57:149-157. Abstract

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