Background Thoracic Outlet Syndrome (TOS) is a syndrome involving compression at the thoracic inlet, which is known clinically as the superior thoracic outlet resulting from excess pressure placed on a neurovascular bundle passing between the Anterior Scalene and Middle Scalene muscles. It can affect one or more of the nerves that innervate the upper limb, specifically in the Brachial Plexus.

Lymphedema is the most common complication and it is also the most disabling for women after breast cancer surgery. It is not a frequent cause of TOS, but the scar of breast surgery, the scar of lymphatic surgery and also the oedema can compress nerve structures of upper limb.

Methods Two women have been studied because they suffered from cervical and dorsal pain associated with paresthesias in left upper limb for months. Paresthesias get worse in summer and with tight clothing, but mainly with deep breathing and Valsalva manoeuvre. Both had a precedent of breast cancer surgery with big scars in breast and underarm.

The study started with a physical exam. We did not found Trigger Points in cervical or dorsal spine. The articular balance of spine was normal, but the right flex and rotation was difficult. Adson’s sign and the Costoclavicular manoeuvre were nonspecific, and Wright’s Test was positive. Tinnel and Fabere signs were also positive.

We used an ultrasound study of Serratus Anterior muscle and Diaphragm muscle with Rusi technique. We also study with ultrasound the function of the shoulder and cervical muscles (Trapezius, Longus Colli and deep posterior spinal muscles). We applied for complementary test (like X-ray and Electromyogram) and we started Manual Lymphatic Drainage.

Results Ultrasound study reveals an increase of skin and subcutaneous tissue thickness around the shoulder and arm, especially with isokinetic movements. The rest of the study was absolutely normal.

After 15 drainage sessions the symptoms entirely disappeared (oedema, pain, restricted mobility and paresthesias). Complementary test was normal and a new ultrasound study was now completely normal.

Conclusions Lymphedema after breast cancer surgery can cause a TOS with a compression of the brachial plexus. In these patients ultrasound can help with the differential diagnosis and it can be the unique test method.