What is the appropriate diagnosis and management for a 40-year-old female complaining of tingling and numbness in the bilateral upper limb, specifically the palms, with no systemic illnesses like Type 2 Diabetes Mellitus (T2DM) or hypothyroidism?

Bilateral Upper Limb Paresthesias in a 40-Year-Old Woman

This patient requires immediate evaluation for carpal tunnel syndrome and other peripheral nerve entrapment syndromes, with focused neurological examination including median nerve testing, followed by exclusion of systemic causes such as vitamin B12 deficiency, cervical radiculopathy, and chronic inflammatory demyelinating polyneuropathy (CIDP).

Initial Diagnostic Approach

Focused Neurological Examination

• Perform median nerve assessment with Tinel's sign (percussion at wrist) and Phalen's test (wrist hyperflexion for 60 seconds) to evaluate for carpal tunnel syndrome, the most common nerve entrapment causing bilateral palm numbness 1
• Test sensory distribution specifically in the thumb, index, and middle fingers for median nerve involvement versus the little finger and ulnar aspect of ring finger for ulnar nerve pathology 1
• Assess motor function by testing thumb opposition strength (median nerve), finger abduction (ulnar nerve), and wrist extension (radial nerve) 2
• Evaluate for cervical radiculopathy by checking neck range of motion, Spurling's test, and dermatomal sensory patterns that would distinguish nerve root compression from peripheral entrapment 1

Critical Exclusion of Systemic Causes

Diabetic neuropathy is a diagnosis of exclusion, and alternative causes must be ruled out before attributing symptoms to any single etiology 3, 4:

• Check vitamin B12 levels as deficiency causes peripheral neuropathy with bilateral upper extremity symptoms 4
• Order thyroid function tests despite patient denying hypothyroidism, as subclinical disease can cause nerve entrapment 1
• Consider CIDP if symptoms have been progressive over 8+ weeks with both motor and sensory involvement, requiring nerve conduction studies showing demyelination patterns 5
• Screen for rheumatoid arthritis with inflammatory markers, as it increases risk for bilateral nerve entrapment 1

Differential Diagnosis Priority

Most Likely: Bilateral Carpal Tunnel Syndrome

• Bilateral median nerve compression at the wrist produces numbness and tingling specifically in the palms, thumb, index, and middle fingers 1
• Risk factors include repetitive hand use, female gender, and age 30-60 years 1
• Initial management includes nocturnal wrist splinting in neutral position and consideration of corticosteroid injection if symptoms persist beyond 6 weeks 1

Alternative: Cervical Radiculopathy

• C6-C7 nerve root compression can produce bilateral upper extremity paresthesias, though typically asymmetric 1
• Requires cervical spine imaging (MRI preferred) if neck pain, dermatomal pattern, or reflex changes are present 1

Consider: Chronic Inflammatory Demyelinating Polyneuropathy

• CIDP presents with progressive bilateral weakness and sensory symptoms over at least 8 weeks, with areflexia and elevated CSF protein 5
• Nerve conduction studies showing partial conduction blocks, nonuniform slowing, and absent sensory responses confirm diagnosis 5
• This diagnosis is critical not to miss as it responds to immunotherapy (IVIG, corticosteroids, or plasmapheresis) 5

Diagnostic Testing Algorithm

1. Immediate bedside testing: Tinel's sign, Phalen's test, sensory mapping of all five digits, and motor strength testing 1, 2

2. Laboratory workup within 1 week:

   • Vitamin B12 level 4
   • TSH and free T4 1
   • Fasting glucose and HbA1c (despite no known diabetes, screen for undiagnosed disease) 3
   • Rheumatoid factor and inflammatory markers 1

3. Electrodiagnostic studies if:

   • Symptoms persist beyond 6 weeks despite conservative management 1
   • Clinical features are atypical for carpal tunnel syndrome 3
   • Progressive weakness develops 5
   • Bilateral symptoms with areflexia suggest polyneuropathy 5

4. Cervical spine MRI if:

   • Neck pain or radicular pattern present 1
   • Upper motor neuron signs detected (hyperreflexia, Hoffman's sign) 1

Management Strategy

Conservative Initial Treatment (While Awaiting Workup)

• Prescribe bilateral wrist splints for nighttime use in neutral position to reduce median nerve compression 1
• Advise activity modification avoiding repetitive wrist flexion/extension and prolonged gripping 1
• NSAIDs for symptom relief if no contraindications 1

Escalation Based on Findings

• If carpal tunnel confirmed: Consider corticosteroid injection or referral to hand surgery for carpal tunnel release if conservative measures fail after 3 months 1
• If CIDP diagnosed: Urgent neurology referral for immunotherapy initiation 5
• If vitamin B12 deficiency: Replacement therapy with monitoring 4
• If cervical radiculopathy: Physical therapy, epidural steroid injection, or neurosurgical evaluation depending on severity 1

Critical Pitfalls to Avoid

• Do not assume bilateral symptoms exclude focal nerve entrapment—carpal tunnel syndrome commonly presents bilaterally 1
• Do not delay vitamin B12 testing—deficiency is easily treatable and compounds neuropathy risk 4
• Do not miss CIDP—progressive bilateral symptoms with areflexia require nerve conduction studies, as delayed treatment leads to permanent disability 5
• Do not overlook thoracic outlet syndrome—compression of the brachial plexus can cause bilateral upper extremity symptoms, particularly with overhead activities 1
• Do not attribute symptoms to "stress" or "anxiety" without completing objective neurological assessment, as this delays diagnosis of treatable conditions 2