What could be causing constant partial numbness on the left side of my neck for 8 days without pain or loss of motor function?

Evaluation of Unilateral Neck Numbness in a Young Adult

In a 24-year-old with isolated left-sided neck numbness for 8 days without pain or motor deficits, the most likely causes are benign nerve compression or irritation, but MRI of the cervical spine is warranted to exclude structural pathology, particularly if symptoms persist beyond 2-3 weeks or any red flags develop.

Initial Clinical Assessment

Key Features to Evaluate

Your presentation requires careful localization to determine whether this represents:

• Cervical radiculopathy: Numbness following a dermatomal distribution from nerve root compression 1
• Peripheral nerve entrapment: Isolated sensory nerve involvement
• Cervical plexopathy: Involvement of the cervical plexus (C2-C4 nerve roots) 1
• Central nervous system pathology: Less likely given the isolated sensory finding without motor deficits

Red Flags Requiring Immediate Imaging

The ACR guidelines specify red flags that mandate urgent evaluation 1:

• Trauma history
• Constitutional symptoms (fever, weight loss, night sweats)
• History of malignancy
• Progressive neurological deficits
• Bowel/bladder dysfunction
• Gait disturbance or balance problems
• Age >50 with new symptoms
• History of inflammatory arthritis 2

Your case lacks these red flags, which is reassuring.

Differential Diagnosis

Most Likely Causes in Your Age Group

Benign etiologies predominate in young adults without red flags:

• Cervical nerve root irritation: From minor positional stress, sleeping position, or repetitive neck movements 1
• Superficial cervical plexus involvement: The C2-C3 nerve roots provide sensation to the lateral neck 1
• Greater auricular nerve compression: Can cause isolated lateral neck numbness
• Thoracic outlet syndrome (neurogenic): Though typically involves arm symptoms, can present with neck discomfort 1

Less Common but Important Considerations

• Early cervical spine pathology: Disc herniation or foraminal stenosis, though unusual at age 24 1
• Inflammatory conditions: Early rheumatoid arthritis can rarely present with cervical involvement, though typically with pain 2
• Demyelinating disease: Multiple sclerosis can cause isolated sensory symptoms, though neck involvement alone is atypical 1

Imaging Recommendations

When to Image

Conservative observation is reasonable initially if:

• Symptoms are stable or improving
• No red flags present
• No motor weakness
• No progression after 2-3 weeks 1

MRI cervical spine should be obtained if:

• Symptoms persist beyond 3-4 weeks
• Any progression of numbness
• Development of motor symptoms
• New pain or radicular symptoms
• Patient anxiety warrants reassurance 1

Optimal Imaging Protocol

MRI cervical spine without contrast is the preferred initial study 1:

• Superior soft tissue contrast for evaluating nerve roots, spinal cord, and intervertebral discs
• Can identify early inflammatory changes not visible on CT
• No radiation exposure
• Detects foraminal stenosis, disc herniation, and intrinsic cord pathology

CT cervical spine has limited utility 1:

• Primarily evaluates bony structures
• Less sensitive for nerve root compression
• Not first-line for isolated sensory symptoms without trauma

Management Approach

Initial Conservative Management (First 2-3 Weeks)

• Observation: Most cases of isolated sensory symptoms resolve spontaneously 1
• Activity modification: Avoid prolonged neck flexion or extension
• Ergonomic assessment: Evaluate sleeping position and workstation setup
• NSAIDs: If any discomfort develops

Follow-up Timing

Re-evaluate at 2-3 weeks:

• If improving or resolved: No imaging needed
• If unchanged or worsening: Proceed to MRI cervical spine 1
• If new symptoms develop: Immediate re-evaluation

When to Refer

Neurology consultation indicated for:

• Abnormal MRI findings
• Progressive symptoms despite conservative care
• Development of motor deficits
• Bilateral symptoms
• Associated cranial nerve findings 1

Important Caveats

Do not assume this is benign if:

• Numbness spreads to involve the face, which could indicate trigeminal nerve involvement requiring different evaluation 1
• Bilateral symptoms develop, raising concern for central pathology
• Any motor weakness emerges, even subtle
• Symptoms persist beyond 6-8 weeks without improvement 1

The absence of pain is reassuring but not definitive - serious pathology can present without pain, particularly in young patients 1.