What is the diagnosis and treatment for a patient with bilateral tingling in both legs, with sensation moving up the left leg into the knee, considering potential underlying conditions such as diabetes, peripheral artery disease, or multiple sclerosis?

Bilateral Leg Tingling with Ascending Symptoms: Diagnostic Approach

This presentation of bilateral tingling ascending into the knee requires immediate evaluation for Guillain-Barré syndrome (GBS), which is a neurological emergency that can progress to respiratory failure and death if not promptly diagnosed and treated. 1

Immediate Clinical Assessment

Perform a focused neurological examination immediately, specifically assessing:

• Deep tendon reflexes (areflexia or hyporeflexia is characteristic of GBS) 1
• Pattern and distribution of weakness (ascending, symmetric weakness starting in legs) 1
• Sensory deficits (paresthesias typically ascend from distal to proximal) 1
• Cranial nerve involvement (facial weakness, dysphagia, diplopia) 1
• Respiratory function (forced vital capacity, ability to cough) 1
• Autonomic dysfunction (blood pressure lability, cardiac arrhythmias, urinary retention) 1

Obtain a detailed history focusing on:

• Preceding events within 1-6 weeks: respiratory or gastrointestinal infections, vaccinations, recent travel 1
• Progression timeline: GBS typically progresses over days to 4 weeks, whereas chronic inflammatory demyelinating polyneuropathy (CIDP) progresses over >8 weeks 1
• Associated symptoms: difficulty initiating urination or constipation suggests spinal cord involvement 2

Critical Differential Diagnosis

The ascending bilateral nature of symptoms narrows the differential significantly:

Peripheral Nervous System Causes

• Guillain-Barré syndrome and variants (most urgent consideration) 1
• Chronic inflammatory demyelinating polyneuropathy (if progression >8 weeks) 1
• Toxic or metabolic neuropathies (diabetes, B12 deficiency, toxins) 1

Central Nervous System Causes

• Spinal cord compression or myelopathy (especially if urinary symptoms present) 1, 2
• Multiple sclerosis (can cause spontaneous tingling from demyelinating lesions) 3
• Spinal stenosis (particularly if symptoms worsen with walking) 1

Vascular Causes (Less Likely Given Bilateral Presentation)

• Peripheral artery disease is typically unilateral or asymmetric and associated with claudication, not ascending tingling 4

Immediate Diagnostic Testing

If GBS is suspected based on ascending weakness/paresthesias with areflexia:

1. Hospitalize immediately for monitoring (respiratory function can deteriorate rapidly) 1
2. Cerebrospinal fluid (CSF) analysis: Look for albuminocytologic dissociation (elevated protein with normal cell count), though this may be normal in the first week 1
3. Nerve conduction studies/electromyography (NCS/EMG): Demonstrates demyelinating features (prolonged distal latencies, conduction block, temporal dispersion) 1

If spinal cord pathology is suspected (urinary symptoms, sensory level, bilateral leg weakness):

1. MRI of the entire spine with contrast to evaluate for cord compression, myelopathy, or demyelinating lesions 5
2. Do not delay imaging if "red flag" symptoms present: progressive weakness, bowel/bladder dysfunction, saddle anesthesia 5

Management Algorithm

For suspected GBS:

• Initiate treatment within 2 weeks of symptom onset with either intravenous immunoglobulin (IVIG) 0.4 g/kg/day for 5 days OR plasma exchange 1
• Monitor respiratory function every 4-6 hours with forced vital capacity and negative inspiratory force 1
• Intubate if FVC <15-20 mL/kg or signs of respiratory distress 1

For spinal cord compression:

• Urgent neurosurgical consultation if mass lesion identified 5
• High-dose corticosteroids if demyelinating lesion (multiple sclerosis) suspected 3

Critical Pitfalls to Avoid

• Do not dismiss ascending bilateral tingling as benign peripheral neuropathy without excluding GBS, as delayed diagnosis increases mortality risk 1
• Do not wait for complete diagnostic workup before hospitalizing patients with progressive ascending symptoms—respiratory failure can occur within hours 1
• Do not attribute symptoms solely to diabetes or peripheral artery disease when the pattern is bilateral and ascending, as this suggests a central or acute peripheral nervous system process 1, 4
• Do not perform ankle-brachial index (ABI) as the initial test for bilateral ascending tingling, as this presentation is neurological, not vascular 4
• In diabetic patients, consider Charcot neuro-osteoarthropathy only if there is unilateral foot warmth, swelling, and redness—not for bilateral ascending leg tingling 6