Updated: Sep 10, 2020
Neurogenic Thoracic Outlet Syndrome (NTOS), which is estimated to account for more than 90% of all TOS presentations, remains elusive in both physical examination and diagnosis. Patients often complain of symptoms that are unrecognizable on X-Ray, MRI, and nerve conduction studies. This can be perplexing for patients seeking an origin to the pain and paresthesia they are experiencing in their upper extremity. Physical exam tests, although still useful clinically, lack the sensitivity and specificity needed to accurately diagnosis this condition.
The parameters of NTOS are not well defined. Entrapment of the brachial plexus can occur in several locations as it courses its way towards the upper extremity. This can make isolating the source of discomfort even more challenging for the clinician. However, there are some hallmarks of this condition that can be insightful and aid in the diagnosis and treatment of NTOS.
5 Simple Tips to Differentiate NTOS from Cervical Radiculopathy
Cervical distraction often alleviates paresthesia from cervical origin. With NTOS, distraction may aggravate symptoms due to tensioning of the brachial plexus.
The 4th and 5th fingers correspond to the C8 dermatomal distribution. C8 is not a common source of paresthesia compared to other lower cervical segments. With NTOS, the 4th and 5th finger commonly experience paresthesia due to the inferior trunk of the brachial plexus being compressed against the underlying first rib.
Bakody’s Sign, which involves the patient placing the ipsilateral forearm on top of their head, may provide relief of paresthesia from a cervical origin by taking tension off of the affected nerve roots. With NTOS, the paresthesia is often provoked with abduction of the upper extremity which may compress the brachial plexus underneath the pectoralis minor or in the costoclavicular space.
Cervical side bending toward the affected side is usually pain provoking and may reproduce paresthesia from a cervical origin. With NTOS, pain and/or paresthesia is often aggravated with contralateral side bending due to tensioning of the brachial plexus.
NTOS should be suspected when a patient complains of paresthesia in all 5 fingers. It is uncommon to encounter paresthesia from a cervical origin that involves all C6, C7, and C8 dermatomes.