What is the diagnosis and treatment for a patient experiencing unilateral (one-sided) tingling in the left lower leg, as well as bilateral (both sides) tingling in the arms and upper back?

Evaluation of Unilateral Left Leg and Bilateral Arm/Upper Back Tingling

This symptom pattern demands urgent evaluation for cervical spinal cord pathology, as bilateral upper extremity involvement with unilateral lower extremity symptoms suggests a cervical cord lesion affecting both descending motor tracts and upper extremity nerve roots. 1, 2

Immediate Red Flag Assessment

Your symptom distribution is concerning for central nervous system pathology rather than simple peripheral nerve problems. The combination of bilateral arm tingling with lower extremity involvement—even if asymmetric—raises serious concern for:

• Cervical cord compression or myelopathy at the C5-C7 level, which can present with bilateral hand/arm numbness and descending tract involvement affecting the legs 1, 2
• Central cord syndrome, which classically shows greater upper extremity involvement than lower extremity, with bilateral hand numbness and burning dysesthesias 1, 2
• Guillain-Barré Syndrome (GBS), though this typically presents with ascending weakness starting in legs, asymmetric patterns can occur and approximately 20% develop respiratory failure 1

Critical Action Steps

You need urgent MRI of the entire cervical and thoracic spine without and with contrast to exclude cord compression, transverse myelitis, or nerve root pathology. 1, 2 This is not optional—bilateral upper extremity symptoms with any lower extremity involvement mandates immediate imaging.

Seek immediate neurosurgical consultation if you have any of the following:

• Progressive weakness in arms or legs 1
• Difficulty with fine motor tasks (buttoning, writing) 2
• Gait instability or leg weakness 1
• Bowel or bladder dysfunction 3
• Burning dysesthesias in the forearms 1, 2

Secondary Diagnostic Considerations (Only After Excluding Urgent Pathology)

If imaging rules out structural spinal cord disease, consider:

Peripheral Neuropathy

• Diabetic peripheral neuropathy typically presents in a "stocking-and-glove" distribution starting distally in feet first, not with the asymmetric pattern you describe 1, 2
• Assessment should include testing temperature/pinprick sensation and vibration with 128-Hz tuning fork 1, 2
• Check hemoglobin A1c, fasting glucose if not already done 1

Metabolic and Toxic Causes

• Vitamin B12 deficiency can cause combined upper and lower extremity paresthesias 1
• Uremic neuropathy—check creatinine and eGFR 1
• Medication-induced neuropathy from chemotherapy agents (taxanes, platinum-based), metformin, or statins 1, 4
• Hepatitis C-related neuropathy occurs in up to 50% of infected patients 1, 4

Vascular Considerations

• In patients over 50 with cardiovascular risk factors (hypertension, diabetes, smoking, atrial fibrillation), hemibody sensory symptoms may indicate stroke risk 4
• Check blood pressure in both arms—asymmetry suggests vascular pathology 4

Physical Examination Priorities

Upper motor neuron signs indicate cord pathology and demand urgent action:

• Hyperreflexia, clonus, or extensor plantar responses (Babinski sign) 1
• Weakness on examination, particularly if proximal or affecting both arms 1, 4
• Sensory level on the trunk 1

Peripheral nerve patterns suggest less urgent pathology:

• Stocking-glove distribution of sensory loss 1, 2
• Distal weakness more than proximal 1
• Absent or reduced ankle reflexes with preserved or brisk upper extremity reflexes 1

Diagnostic Testing Algorithm

1. Urgent MRI cervical and thoracic spine (with and without contrast) if any concern for cord pathology 1, 2
2. CSF analysis if GBS suspected (increased protein with normal cell count supports diagnosis) 1
3. Metabolic workup: Hemoglobin A1c, vitamin B12, TSH, creatinine, hepatitis C antibody 1, 4
4. Electromyography and nerve conduction studies may help differentiate peripheral from central pathology, but should not delay urgent imaging 2

Treatment Based on Diagnosis

If Neuropathic Pain from Peripheral Neuropathy

Duloxetine is first-line pharmacologic treatment for peripheral neuropathy with numbness and tingling. 1, 2, 4

Additional options include:

• Physical activity for symptom management 1, 2
• Acetaminophen or NSAIDs for associated pain 1, 2
• Pregabalin or gabapentin as alternatives 5, 1
• Tricyclic antidepressants 5, 1

If Diabetic Neuropathy Confirmed

• Improved glycemic control prevents progression but does not reverse neuronal loss 1, 2
• Annual screening with temperature/pinprick and vibration testing 1

Critical Pitfalls to Avoid

Do not assume this is simple peripheral neuropathy based on "tingling" alone. The bilateral upper extremity involvement with lower extremity symptoms is atypical for common peripheral neuropathies and suggests central pathology until proven otherwise. 1, 2

Do not delay imaging for electrodiagnostic studies. If central cord syndrome is suspected, imaging takes priority. 2

Do not attribute symptoms to "pinched nerves" or carpal tunnel syndrome when bilateral upper extremity symptoms are present—this pattern suggests a more proximal or central lesion. 1, 2

Do not miss GBS. If symptoms are rapidly progressive over days to weeks with associated weakness, this is a neurological emergency requiring ICU-level monitoring for respiratory failure. 1