Pain Radiating Down the Right Shoulder with Left Neck Rotation: Cervical Radiculopathy vs Muscle Spasm
This presentation is most consistent with cervical radiculopathy from nerve root compression (likely disc herniation or osteophyte), not isolated muscle spasm. The specific pattern of pain radiating down the shoulder when rotating the head away from the painful side is a classic sign of nerve root irritation in the cervical spine 1.
Clinical Reasoning
Why This Indicates Cervical Radiculopathy
Cervical radiculopathy most commonly results from herniated discs or osteophytes causing nerve root compression, and this is the predominant cause of neuropathic pain radiating from the neck into the shoulder and arm 1.
The specific mechanism matters: When you rotate your head and neck to the left (away from the painful right side), this movement narrows the right-sided neural foramina and can compress an already irritated nerve root, reproducing radicular symptoms 2.
Pain radiating down the shoulder with neck movement is a hallmark of cervical spine pathology with nerve root compression, characterized by radiation patterns that follow dermatomal distributions 3.
Why Isolated Muscle Spasm Is Less Likely
Muscle spasm in cervical conditions is typically a secondary phenomenon, not the primary pain generator. While muscle spasm can occur with disc herniation, it accompanies the underlying structural problem rather than causing the radiating pain pattern 4, 5.
Research demonstrates that muscle spasm associated with spinal pathology does not produce the characteristic radiating pain patterns seen with nerve root compression. Studies show that even when muscle spasm is present on the concave side of sciatic scoliosis from disc herniation, the spasm itself doesn't lower pain thresholds or produce radicular symptoms 4.
Isolated muscle spasm would typically cause localized neck pain and stiffness, not pain that specifically radiates down the shoulder in a dermatomal pattern triggered by specific neck movements 6.
Diagnostic Approach
Clinical Examination Priorities
Document the exact radiation pattern of pain to determine if it follows a specific cervical nerve root distribution (C5, C6, C7, or C8) 1, 3.
Test for neurological deficits including sensory changes, motor weakness, and reflex abnormalities in the affected arm, as these confirm nerve root involvement 3.
Perform provocative maneuvers: Spurling's test (neck extension with rotation toward the painful side and axial compression) reproduces radicular pain in cervical radiculopathy 2.
Imaging Strategy
MRI of the cervical spine without contrast is the preferred initial advanced imaging when clinical examination supports radiculopathy, as it directly visualizes disc herniations, osteophytes, and nerve root compression 1.
Plain radiographs of the cervical spine may be obtained first to assess for gross structural abnormalities, degenerative changes, or alignment issues, though they cannot visualize disc herniations or nerve roots 1.
Electrodiagnostic testing (EMG/NCS) should be considered if imaging is negative or equivocal, with sensitivity over 80% and specificity of 95% for confirming nerve compression and localizing the affected level 3.
Critical Pitfalls to Avoid
Do not assume this is simply "muscle tension" or "muscle spasm" without ruling out structural cervical spine pathology. The specific pattern of pain with contralateral rotation is too characteristic of radiculopathy to dismiss 1, 2.
Do not confuse cervical radiculopathy with primary shoulder pathology. While rotator cuff disease can cause shoulder pain, it does not typically reproduce with neck rotation away from the affected side 7, 2.
Do not delay imaging if red flags are present, including progressive neurological deficits, severe or intractable pain, or symptoms suggesting myelopathy (gait disturbance, bowel/bladder dysfunction) 1.
Management Implications
If cervical radiculopathy is confirmed, most cases respond to conservative management including physical therapy, NSAIDs, and nerve-stabilizing medications (pregabalin, gabapentin) for neuropathic pain 3, 8.
Surgical intervention is reserved for patients with progressive neurological deficits or those who fail 6-8 weeks of conservative therapy with confirmed structural compression on imaging 8.
The presence of muscle spasm, if present, should be treated as a secondary phenomenon with muscle relaxants used only for short-term, time-limited relief while addressing the underlying nerve root compression 8, 6.