What causes hand numbness and how is it treated?

Hand Numbness: Causes and Treatment

Most Common Cause

Carpal tunnel syndrome is the most common cause of hand numbness, presenting with numbness and tingling in the thumb, index, middle, and radial half of the ring finger, with symptoms often worsening at night. 1

Diagnostic Algorithm by Distribution Pattern

Unilateral Thumb, Index, Middle, and Radial Ring Finger Numbness

• Carpal tunnel syndrome is the primary diagnosis when numbness affects this specific distribution 1, 2
• Perform the Durkan maneuver (firm digital pressure across the carpal tunnel to reproduce symptoms): 64% sensitive and 83% specific 1
• Test for Phalen's sign (wrist hyperflexion) and Tinel's sign (median nerve percussion at wrist) 2
• Electrodiagnostic testing is >80% sensitive and 95% specific when diagnosis is uncertain or proximal compression is suspected 1

Bilateral Hand Numbness (Both Hands Affected)

• Consider cervical spinal cord pathology first, especially if accompanied by burning dysesthesias in forearms or any lower extremity symptoms—this requires urgent MRI and neurosurgical consultation 3
• Diabetic peripheral neuropathy presents in a "stocking-and-glove" distribution starting distally; assess with 10-g monofilament, pinprick sensation, vibration with 128-Hz tuning fork, and ankle reflexes 3, 4
• Check vitamin B12 levels, particularly if patient takes metformin (≥2g daily increases deficiency risk) 4
• Screen for thyroid dysfunction, hepatitis C (causes neuropathy in up to 50% of infected patients), and review medications (metformin, chemotherapy, statins) 4

Little Finger and Ulnar Ring Finger Numbness

• Ulnar nerve compression at the elbow (cubital tunnel syndrome) or wrist (ulnar tunnel syndrome) causes this distribution 2
• Differentiate from cervical radiculopathy or thoracic outlet syndrome using electromyography 2

Single Digit Numbness

• Digital nerve compression from repetitive activities, tight jewelry, or local trauma is most likely 5
• Carpal tunnel syndrome and cervical radiculopathy typically do not present with isolated single-digit symptoms 5

Treatment Algorithm

For Carpal Tunnel Syndrome

1. First-line: Volar splinting (especially nighttime use) and/or corticosteroid injection temporarily relieve symptoms 1, 2
2. Definitive treatment: Open or endoscopic carpal tunnel release for patients unresponsive to conservative therapy or with progressive disease 1

For Peripheral Neuropathy (Bilateral Symptoms)

1. Optimize glycemic control in diabetic patients—the only proven strategy to prevent or delay progression 4
2. First-line pharmacologic treatment: Duloxetine 30mg daily for one week, then increase to 60mg daily for neuropathic pain and sensory symptoms (provides 30-50% pain reduction) 3, 4
3. Alternative agents: Pregabalin, gabapentin, tricyclic antidepressants, or venlafaxine 4
4. Non-pharmacologic: Physical activity has been shown to improve neuropathy symptoms 3, 4
5. Vitamin B12 supplementation 2500mcg daily for metformin-induced neuropathy 4

For Cervical Cord Pathology

• Immediate neurosurgical consultation is required for suspected cervical cord compression presenting with bilateral hand numbness 3

Critical Risk Factors to Assess

• Diabetes, obesity, hypothyroidism, rheumatoid arthritis increase risk for nerve entrapment 1, 2
• Occupational exposures: keyboard/mouse use, heavy machinery, vibrating tools, repetitive hand/arm labor 1, 6
• Medications: metformin (especially ≥2g daily), chemotherapy agents, statins 4
• Age and sex: carpal tunnel syndrome more common in women; thumb carpometacarpal arthritis affects 33% of postmenopausal women 1

Key Diagnostic Pitfalls to Avoid

• Do not miss cervical cord pathology: Any bilateral hand numbness with burning dysesthesias or lower extremity symptoms requires urgent cervical spine MRI 3
• Bilateral symptoms are rarely carpal tunnel syndrome alone: Consider systemic causes (diabetes, B12 deficiency, thyroid disease, medications) 4, 2
• Medication-induced neuropathy is symmetric and bilateral: Isolated unilateral or single-digit numbness does not fit this pattern 5
• "Working hand syndrome": Occupational sensory axonal polyneuropathy in laborers using hands/arms repetitively presents with pain, numbness, tingling, and burning that worsens at rest/nighttime, but with normal neurological exam and normal sural nerves on lower extremities 6