This study by Hamoud et al (2024) aimed to assist clinicians with a screening test to determine the most probable cause of a patient's shoulder pain. The authors introduce the challenge of accurately diagnosing patients with shoulder pain due to the high number of patients with co-existing cervical spine pathology. They report that "35.0% of patients with shoulder impingement syndrome have ipsilateral cervical root compression". Therefore, in the presence of shoulder pain we need to thoroughly examine the cervical spine to arrive at an accurate diagnosis.

The authors studied the swimmer arm-to-shoulder (SAS) test (shown below). They defined a positive test as provoked pain that is ≥ 3/10. They report a positive SAS test is an effective tool to rule out the cervical spine as a cause of the patient's pain, and can confirm the shoulder as the cause. The good news, according to the authors, is the SAS test can reduce the burden of performing a comprehensive exam. I doubt it. 

The study includes 718 participants that were evaluated via the "gold standard" and distributed into 288 with shoulder pathology and 430 with cervical spine pathology. Despite their prior commitment that many patients have concurrent cervical and shoulder pathologies, there were no patients in the study diagnosed with both shoulder AND cervical spine pathology. I find this hard to believe. 

There were 17 patients who had a positive SAS test that were determined to not have shoulder pathology (17 false positives). 31 patients had a negative SAS test but were determined to have shoulder pathology (31 false negatives). That's 48 patients (6.7%) misdiagnosed, according to the test. As far as individual examination procedures go that is actually pretty good. However, the definition of a positive SAS test was pain of VAS = 3/10 or greater. Does that mean a patient with 2/10 shoulder pain during this test don't have shoulder pathology? Does it mean a patient with 4/10 shoulder pain can be excluded from having c-spine pathology?

I don't think it does.

• What happens if the patients reports 4/10 shoulder pain during the swimmer arm-to-shoulder (SAS) test but have the pain lessens to 1/10 after or during an opening maneuver of the ipsilateral c-spine foramen?
• What if they have 2/10 pain during the SAS test but the neck has been thoroughly investigated and ruled out?

In my opinion, this test is useless in isolation and the need for a thorough exam remains. This seems contrary to the authors concluding statement, but is nonetheless consistent with their final remarks of the discussion section:

"It’s important to emphasize that SAS and other provocative maneuvers can’t replace sophisticated and evidence-based approaches for established of definitive diagnosis on the basis of careful history taking, thorough clinical examination and standard laboratory and imaging studies. Instead, these tests provide clinicians with a readily available and easily performed screening tool that can accelerate or facilitate the demanding process of clinical diagnosis particularly in patients with confusing pathological entities."

Unfortunately, many people will only read the abstract. In my opinion a rewording of the concluding statements is necessary.

I would like to bring forward one additional point of contention. The authors describe a "gold standard" exam that omits neurodynamic testing. 

When a patient presents with local pain at the shoulder with the features of:

• provoked by overhead or reaching activities
• normal and non-provocative cervical spine exam
• an overtly abnormal shoulder exam (positive full / empty can, positive "impingement testing", etc)
• and the absence of neurological symptoms

The weight of the evidence shifts towards the shoulder being the primary pain generator. As a result, neurodynamic testing is omitted. 

Sadly, I can report several of my patients have suffered the consequence of this clinical reasoning. A few of them had imaging confirmed shoulder pathology, but, failed to respond to evidence based treatment and rehab for their shoulder pain. On re-exam abnormal neurodynamic testing was identified and upon engaging specific neurodynamic treatment, the patients symptoms quickly changed and within weeks (after several months to years of chronic symptoms), resolved. The mechanism is likely related to pathodynamics of the peripheral nerve leading to a nociception of the nerve, which will alter motor control (tone: inhibition/ excitability) of the tissues it innervates as well as the tissues that protect it, and neurogenic inflammation.

I have come to the conclusion that the location and nature of a patients pain is a terribly inaccurate and often misleading piece of information, and cannot be used in any way whatsoever to determine where the pain is coming from or what is causing a patients pain. 

This study adds value to the practitioner by providing data to support the swimmer arm-to-shoulder test and its use and its integration into the clinical exam. I just doesn't help us rule out the neck. Any statement to the effect "early differentiation" should be interpreted with caution since this immediately adds bias into the interpretation of future testing. My suggestion is to collect sufficient data points to differentiate, then add probability metrics to the tests after they are sufficiently performed. 

Lastly, I do want to give a shout out to the Functional Movement Screen ™ who, in contrast to what the authors report, have been using an eerily similar maneuver as a shoulder screening test since its inception. I think it is fair to say they now have reasonable data to support the use of this test in their system.