Can a mild reversal of the normal cervical lordosis, likely secondary to positioning or muscle spasm, cause numbness in a patient's arm?

Can Mild Reversal of Cervical Lordosis Cause Arm Numbness?

A mild reversal of cervical lordosis due to positioning or muscle spasm alone is unlikely to directly cause arm numbness and should not be assumed as the primary cause without further evaluation for nerve root compression or spinal cord pathology. 1, 2

Understanding the Relationship Between Lordosis and Radiculopathy

The evidence strongly suggests that loss of cervical lordosis is often a coincidental finding rather than a causative factor for neurological symptoms:

• Loss of cervical lordosis does not correlate with muscle spasm or pain. A study of 160 patients found no significant difference in cervical spine alignment between patients with acute neck injury (19% straight spine), chronic neck problems (26% straight spine), and normal populations (42% straight spine), with confidence intervals overlapping substantially. 3

• Straightening of the cervical spine is a normal variant. Research demonstrates that 42% of asymptomatic individuals have a straight cervical spine on lateral radiographs, and women are nearly 3 times more likely than men to have this finding (odds ratio 2.81). 3

• Positioning changes do not indicate pathology. A comparative study of 60 neck injury patients versus 100 controls found no significant difference in sagittal alignment patterns between groups (p > 0.100), concluding that alterations in cervical lordosis "must be considered coincidental" and "should not be associated with muscle spasm caused by neck pain." 4

What Actually Causes Arm Numbness

Arm numbness requires nerve root compression or spinal cord involvement, not simply altered curvature:

• Cervical radiculopathy results from nerve root impingement due to soft disc herniation, hard disc (spondylarthrosis), or combination of both—not from lordosis reversal alone. 5

• MRI is the preferred imaging modality for evaluating suspected nerve root impingement due to superior soft-tissue contrast and spatial resolution, though false-positive and false-negative findings are common and must be correlated with clinical examination. 5, 1

• C6-C7 compression affects multiple peripheral nerves including the musculocutaneous, median, ulnar, and radial nerves through brachial plexus involvement, which can cause both myelopathic and radiculopathic symptoms. 1

Critical Diagnostic Pitfalls to Avoid

Do not attribute arm numbness to lordosis reversal without ruling out true nerve compression:

• Degenerative findings on MRI are extremely common in asymptomatic patients over 30 years of age, with 53.9% of individuals aged 18-97 showing disc degenerative changes. 5

• Physical examination findings correlate poorly with imaging in cervical radiculopathy, and MRI alone should never be used to diagnose symptomatic cervical radiculopathy without clinical correlation. 5

• Consider alternative causes of bilateral arm numbness including cervical spinal cord injury without fracture/dislocation (SCIwoFD), central cord syndrome (which presents with greater upper extremity than lower extremity weakness), diabetic peripheral neuropathy, and thoracic outlet syndrome. 2, 6

Recommended Diagnostic Approach

When a patient presents with arm numbness and incidental lordosis reversal:

1. Perform targeted neurological examination looking for dermatomal sensory loss, myotomal weakness, and reflex changes that localize to specific nerve roots. 5

2. Order MRI cervical spine without contrast if radiculopathy is suspected clinically, as this provides superior visualization of nerve root compression compared to radiographs or CT. 5, 1

3. Correlate imaging findings with clinical symptoms before attributing numbness to any radiographic finding, as 75-90% of cervical radiculopathy resolves with conservative treatment regardless of imaging findings. 5

4. Consider urgent neurosurgical consultation if bilateral hand numbness is present with any lower extremity symptoms, as this may indicate cervical cord pathology requiring immediate intervention. 2

Treatment Implications

The presence of lordosis reversal should not drive treatment decisions for arm numbness:

• Most acute cervical neck pain with radicular symptoms resolves spontaneously or with conservative treatment, with 75-90% achieving symptomatic relief without surgery. 5, 1

• Surgical decompression is indicated only for severe myelopathy (mJOA score ≤12), progressive neurological deficits, or persistent symptoms despite adequate conservative management. 1

• Attempts to restore lordosis through traction or manipulation may improve radiographic appearance but have not been proven to resolve radiculopathy symptoms, and manipulation carries risk of worsening disc herniation in patients with preexisting asymptomatic herniations. 7, 8, 9