Benign Mechanical Causes of Numbness on the Left Side of the Neck
The most common benign mechanical causes of unilateral neck numbness are cervical radiculopathy from disc herniation or foraminal stenosis due to facet/uncovertebral joint hypertrophy, which represent the primary mechanical etiologies of cervical neuropathic symptoms. 1
Primary Mechanical Etiologies
Cervical radiculopathy is the leading mechanical cause, presenting as:
- Disc herniation or bulging compressing nerve roots, causing dermatomal numbness in a narrow band distribution 2, 3
- Foraminal stenosis from facet joint or uncovertebral joint hypertrophy narrowing the neural foramen 2
- Degenerative spondylosis with osteophyte formation impinging on nerve roots 2, 3
Additional Benign Mechanical Causes
- Facet joint arthropathy causing localized mechanical pain that may be unilateral 4
- Intervertebral disc degeneration (though often asymptomatic and correlates poorly with symptoms) 4
- Positional nerve compression that may only manifest with specific neck positions like extension or rotation 5
Critical Clinical Context
Most cervical radiculopathy cases (>50%) resolve spontaneously within 3-4 months with conservative treatment, making these truly "benign" in prognosis. 2
Important Diagnostic Pitfalls
- Imaging abnormalities are extremely common in asymptomatic individuals over age 30, with disc abnormalities and spondylotic changes correlating poorly with actual symptoms 2, 4
- Physical examination findings correlate poorly with MRI findings in cervical radiculopathy, resulting in high rates of both false-positive and false-negative imaging 2
- The presence of degenerative changes on imaging does not confirm they are the source of symptoms 4, 6
When to Suspect Non-Benign Causes
You must actively exclude serious pathology by screening for "red flags" that indicate non-mechanical etiologies: 1, 4
- Constitutional symptoms (fever, unexplained weight loss, night sweats)
- Elevated inflammatory markers (ESR, CRP, WBC)
- History of malignancy or immunosuppression
- Progressive neurological deficits (weakness, gait disturbance)
- Intractable pain despite appropriate conservative therapy
- Vertebral body tenderness on palpation
Imaging Recommendations for Benign Mechanical Causes
- For acute neck pain (<6 weeks) without red flags: No imaging is typically needed as symptoms usually resolve spontaneously 4
- For persistent symptoms beyond 6 weeks or with radicular features: MRI cervical spine without contrast is the preferred modality for evaluating nerve root compression 4, 3
- Plain radiographs may show spondylotic changes but have limited clinical correlation with symptoms 1, 4