The most common condition affecting the shoulder is rotator-cuff disease. From acute tears to chronic tendinopathy, it’s common and needs a thorough workup. In fact, even asymptomatic shoulders can have full-thickness rotator-cuff rears in up to 40% of instances. Let’s look at additional conditions that can present to the office with weakness, loss of motion and pain in the shoulder beyond rotator-cuff tears.
Cervical Radiculopathy
Cervical radiculopathy is an obvious differential diagnosis for the patient with shoulder pain and weakness. Since the rotator-cuff muscles are innervated from the C5-7 nerve roots, correlation with muscle strength in the distal muscles of the arm for specific nerve root involvement would be needed (i.e., C5 – shoulder abduction, C6 – elbow flexion, wrist extension, C7 – elbow extension, C8 – thumb extension and wrist ulnar deviation, T1 – finger abduction).
In addition, there would be sensory and reflex changes in a true radiculopathy.
Referred Pain
Referred pain from the cervical and upper thoracic spine, as well as organs, can also present as shoulder pain. In addition, trigger points can be placed into this category of myogenic and sclerogenic pain referral patterns. There won’t be any reflex changes or sensory loss, while pain and loss of function can be significant.
Dust off your pain referral charts and give them another look if you need a refresher on these referral patterns. If the pain does follow a specific nerve root distribution, consider a radiculitis.
Clinical Tip: When loss of strength occurs rapidly in a nerve root compression syndrome, consider it a red flag to treatment until advanced imaging is done and nerve function is assessed. Any significant loss of strength (0-3/5) needs a thorough workup.
Shoulder Bursitis
Pain can cause loss of motion and weakness without nerve compression. Subacromial or subdeltoid bursitis can easily present with shoulder pain and weakness similar to a rotator-cuff tear. Bursitis will more likely present with global loss of motion, which is less common in rotator-cuff tears.
An acute or chronic shoulder bursitis can occur insidiously and affects older patients with pre-existing shoulder dysfunction. This would be a comparable demographic to the asymptomatic rotator-cuff-tear patient.
Clinical Tip: Septic bursitis will present with redness, swelling and heat. An elevation of skin temperature over 2.2 degrees centigrade, compared to the opposite side, indicates the possibility of septic bursitis.
Impingement Syndrome
Beyond rotator-cuff disease, anterior subacromial impingement syndrome (ASIS) is a leading cause of shoulder pain and dysfunction, accounting for up to 65% of all shoulder complaints. The supraspinatus becomes entrapped between the greater tuberosity of the humerus and acromion.
Similar to rotator-cuff disease, sleeping on the affected side and reaching overhead are painful. However, in ASIS the shoulder pain is more localized to the anterior and lateral deltoid regions. Scapular dyskinesis and rounded shoulders (Janda’s upper-crossed posture) are predisposing factors for ASIS.
Postural correction of rounded shoulders includes lengthening the upper trapezius, pectoralis group, teres major and levator scapulae muscles while strengthening the mid- and lower trapezius, deep cervical flexors and core. In fact, restoring sagittal-plane alignment and setting the humeral head in the glenoid fossa are beneficial for all shoulder syndromes.
Clinical Tip: The scapular assistance test is a functional indicator of ASIS. As the patient abducts the involved arm (with the elbow straight), the doctor actively rotates the scapula along the rib cage. If the patient can perform the motion with less pain and greater ROM while you assist them, then ASIS is suspected.
Case Study: Shoulder Pain & Weakness
John is a 45-year-old male who had a sudden onset of right biceps pain with no etiology. The pain prevented him from using his arm at all. His PCP recommended NSAIDs. John’s pain decreased within two weeks; however, he still had difficulty raising his arm fully in flexion and abduction, and he noticed his “shoulder blade was sticking out.” His condition persisted and he underwent CAT scans, MRIs and laboratory analysis for the upper arm, shoulder and cervical spine.
After eight months and negative testing, the pain was gone, but ROM remained limited, so he began PT, which made no significant change. Due to the shoulder weakness and scapular winging, EMG/NCV were ordered. The finding was a long thoracic nerve dysfunction, and his final diagnosis was Parsonage-Turner syndrome.
Clinical Tip: EMG/NCV testing is the gold standard for nerve function. To be accurate, at least three weeks must pass from the time of the injury/onset of symptoms before the test can be performed.
Parsonage-Turner syndrome is considered a brachial plexitis. It often affects the proximal muscles of the arm; however, it can affect the distal as well. The etiology is unknown, but a recent upper respiratory infection or vaccination is a suspected trigger.
The most common initial symptom is acute, intense pain in the shoulder, with or without radiation to the upper arm (39.7%) or neck with radiation down the arms (35.4%). Less frequently, it is in the scapular or posterior chest wall region, with or without radiation into the lower nerves of the brachial plexus. The pain may last from 2-3 hours to more than eight weeks.
The onset of the weakness is sudden in 80% of patients, with 70% developing weakness within two weeks of the onset of pain. Muscle weakness rarely affects a single peripheral nerve, and sensory changes are mostly found in the lateral arm and deltoid regions.
Diagnosis is one of exclusion, as there are no lab tests to suggest the diagnosis. MRI of the shoulder, electromyography, and nerve conduction studies provide important clues toward the diagnosis.
Clinical Tip: Sudden onset of pain with weakness needs to be addressed aggressively. Have the specialists in your referral base confirm the diagnosis of an MSK disorder when it presents to your office.
John presented to our office for low back pain of four weeks duration and 14 months after his brachial plexitis. His scapular winging and loss of shoulder flexion were evident upon postural and physical examination; and when asked he revealed his prior diagnosis. John does have rounded shoulders and anterior head carriage. Upon examination, only his serratus anterior was weak.
After 14 months, disuse atrophy and fatty degeneration of the serratus anterior have likely occurred and are difficult to reverse. His active care protocols include serratus anterior activation exercises, shoulder pulleys, and upper-crossed postural distortion principles as described by Janda, in conjunction with CMT.
In four weeks, he has increased his flexion by 10 degrees and we are hopeful his recovery will continue. The long-term goal is to repattern his movement pattern to allow the fully functional muscles to compensate for the weakened serratus anterior. Full ROM is expected, although the scapular winging may not completely resolve.
Resources
- Lawrence RL, Moutzouros V, Bey MJ. Asymptomatic rotator cuff tears. JBJS Rev, 2019 Jun;7(6):e9.
- Salomon M, Marruganti S, Cucinotta A, et al. Parsonage-Turner syndrome mimicking musculoskeletal shoulder pain: A case report during the SARS-CoV-2 pandemic era. J Telemed Telecare, 2023 Feb;29(2).
- Smith CC, Bevelaqua AC. Challenging pain syndromes: Parsonage-Turner syndrome. Phys Med Rehabil Clin N Am, 2014 May;25(2):265-77.
- Sigmund Ø. Gismervik S, Drogset JO, et al. Physical examination tests of the shoulder: a systematic review and meta-analysis of diagnostic test performance. BMC Musculoskel Dis, 2017;18:41.
- Myotomes. TeachMeAnatomy.com. Read Here
- Torres MO, Gudlavalleti A, Mesfin FB. Brachial Plexitis. StatPearls, 2023.
