Subacromial Impingement versus C5 Radiculopathy: Differential Diagnosis and Triage
In short
Learn how to differentiate shoulder impingement from C5 cervical nerve root compression: master the diagnostic tests that pinpoint the true pain generator.
In this guide (4 sections)
Differentiating between subacromial impingement syndrome (SAIS) of the shoulder and a C5 cervical radiculopathy represents one of the most common, challenging diagnostic dilemmas encountered in musculoskeletal physiotherapy. Both clinical conditions present with overlapping symptom patterns: dull, aching pain centered over the lateral deltoid prominence, weakness when attempting shoulder abduction, and difficulty sleeping on the affected side. Because the C5 dermatome covers the anterolateral deltoid and the suprascapular and axillary nerves arise from the C5 ventral ramus, pathology at the C4-C5 spinal segment closely mimics primary shoulder rotator cuff disease. Accurate clinical triage requires systematic application of provocative tests, neurological reflex testing, and directional cervical loading to identify the primary driver of upper quadrant pain.
Overhead Balcony Clothes Hanging, Sleeping on Shoulders, and Lifting Pots
In Indian households, the daily activities that provoke shoulder pain frequently overlap with cervical stressors. Hanging heavy wet clothes on elevated balcony clotheslines, reaching into high kitchen cupboards to lift heavy steel containers, or scrubbing walls during festival deep-cleaning requires prolonged shoulder elevation above ninety degrees. An individual experiencing lateral shoulder pain during these tasks may instinctively assume they have strained their shoulder joint. Similarly, sleeping on the affected side on a firm mattress compresses both the subacromial bursa and the lower cervical neural foramina. Without a thorough physical examination, many patients spend months receiving local shoulder ultrasound and rotator cuff friction massages with zero improvement, because the actual source of their deltoid pain is an uncovertebral osteophyte pinching the C5 nerve root in the neck.
Neuro-Anatomical Overlap: Dermatomal Referral versus Subacromial Compression
The diagnostic confusion between SAIS and C5 radiculopathy stems from shared embryonic and neurological pathways. The C5 nerve root provides primary motor innervation to the deltoid and supraspinatus muscles via the axillary and suprascapular nerves, and sensory innervation to the skin overlying the deltoid insertion. When the C5 root is compressed by a herniated disc or foraminal stenosis, it fires referred radicular pain directly into the lateral shoulder, accompanied by deltoid weakness. Conversely, true subacromial impingement is a local mechanical disorder where the supraspinatus tendon and subacromial bursa are compressed beneath the anterior acromion during humerothoracic elevation. The primary clinical distinction is that true SAIS is aggravated by isolated shoulder motion, whereas C5 radiculopathy is provoked by cervical motion and relieved by cervical distraction.
Systematic Differential Assessment: Physical Examination Cluster and Triage
A definitive clinical diagnosis is established through a structured physical examination battery. The physiotherapist begins by evaluating active cervical range of motion: if turning the neck to the symptomatic side or performing the Spurling test reproduces the lateral shoulder pain, cervical radiculopathy is strongly indicated. Next, the Bakody sign is assessed: if placing the hand on top of the head relieves the deltoid ache, C5 root decompression is confirmed. In contrast, local shoulder impingement tests (Neer, Hawkins-Kennedy, and the painful arc test between 60 and 120 degrees of abduction) will be exquisitely positive in true SAIS but completely painless in pure C5 radiculopathy. Deep tendon reflex testing (biceps reflex attenuation) and sensory pinprick testing over the deltoid further solidify cervical involvement.
Cervical Decompression and Pain-Free Scapular Float Drill
Objective: Safely differentiate and treat C5-driven shoulder pain through combined cervical retraction and supported shoulder mobility
- 1Sit upright in a supportive chair with your arms resting comfortably on your lap.
- 2Perform a gentle chin tuck, gliding your head horizontally straight backward into a retraction.
- 3While maintaining this retracted cervical posture, slowly float your symptomatic arm upward in the scapular plane (thirty degrees forward of your side).
- 4Elevate your arm only to shoulder height, keeping your thumb pointed upward toward the ceiling, then slowly lower it back down.
- 5If your shoulder pain resolves when you perform the chin tuck before lifting, your pain is originating from your neck.
- 6Execute the movement smoothly for eight to ten repetitions, breathing calmly and avoiding any painful pinching.
| Clinical Characteristic | C5 Cervical Radiculopathy | Subacromial Impingement Syndrome (SAIS) | Diagnostic Differentiating Value |
|---|---|---|---|
| Primary Pain Location | Lateral deltoid, medial scapular border, and lateral neck | Localized strictly to the anterolateral deltoid; does not involve scapula or neck | Scapular and neck pain strongly points toward cervical spine origin |
| Spurling / Distraction Tests | Spurling reproduces shoulder pain; Distraction immediately relieves it | Completely negative; neck compression or traction produces zero shoulder change | High specificity (>90%) for confirming cervical nerve root involvement |
| Shoulder Impingement Tests | Neer and Hawkins-Kennedy are negative (unless secondary dyskinesis exists) | Exquisitely positive; sharp pain reproduced at end-range elevation and internal rotation | High sensitivity for local subacromial bursal and rotator cuff pathology |
| Neurological Examination | Diminished biceps reflex; sensory blunting over deltoid; deltoid weakness | Completely normal reflexes and intact sensory pinprick sensation | Reflex and sensory deficits definitively establish neurological radiculopathy |
If a patient experiences sudden, profound inability to abduct the arm against gravity (true drop arm sign) following a trauma or fall, clinicians must urgently differentiate an acute massive rotator cuff tear from acute C5 motor root avulsion or axillary nerve injury. Perform urgent diagnostic musculoskeletal ultrasound or MRI of both the shoulder and cervical spine.
Frequently Asked Questions
Why did my doctor order an MRI of my neck when all of my pain is in my shoulder?
Your neck and shoulder are directly connected by the C5 spinal nerve, which exits your neck and travels down into your shoulder muscle (deltoid). When this nerve is pinched in your neck by a disc or bone spur, your brain perceives the pain as coming entirely from your shoulder. An MRI of your neck is the only way to confirm if a pinched nerve in your cervical spine is the true culprit behind your shoulder ache.
Do I need a doctor referral to treat cervical radiculopathy on BookPhysio.in?
BookPhysio.in does not require a doctor referral. Under the National Commission for Allied and Healthcare Professions (NCAHP) Act 2021, patients across India enjoy direct access to autonomous registered physiotherapists. Through BookPhysio.in, you connect directly with verified clinicians and pay per session with transparent fees, completely free from advance package commitments, commission markups, or platform subscription charges.
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