What are the common causes of right arm numbness and tingling?

Common Causes of Right Arm Numbness and Tingling

The most common causes of unilateral arm numbness and tingling are nerve compression syndromes—specifically carpal tunnel syndrome (median nerve at wrist), cervical radiculopathy (nerve root compression in neck), ulnar nerve entrapment (at elbow or wrist), and less commonly thoracic outlet syndrome or radial tunnel syndrome. 1, 2, 3

Peripheral Nerve Entrapment Syndromes

Carpal Tunnel Syndrome (Most Common)

• Carpal tunnel syndrome is the most common entrapment neuropathy, affecting 0.1-1% of the general population, causing numbness and tingling specifically in the thumb, index, middle, and radial half of the ring finger 2, 4
• Risk factors include female sex, obesity, diabetes, repetitive hand/keyboard use, vibrating tool use, rheumatoid arthritis, and hypothyroidism 2, 3
• The Durkan maneuver (firm digital pressure across the carpal tunnel) is 64% sensitive and 83% specific for diagnosis 2
• Symptoms characteristically worsen at night and may be reproduced by wrist hyperflexion (Phalen's test) or median nerve percussion (Tinel's sign) 3, 5
• Electrodiagnostic testing is >80% sensitive and 95% specific when diagnosis is uncertain or to exclude other neuropathies 2, 5

Ulnar Nerve Entrapment

• Causes numbness in the little finger and ulnar aspect of the ring finger, often with intrinsic hand muscle weakness 3
• Can occur at the elbow (cubital tunnel syndrome) or wrist (ulnar tunnel syndrome) 3
• Bilateral ulnar nerve distribution symptoms are less common and require nerve conduction studies to differentiate from polyneuropathy 6

Radial Tunnel Syndrome

• Less common, occasionally accompanies lateral epicondylitis ("tennis elbow") 3
• A radial nerve block can help differentiate this from isolated lateral epicondylitis 3

Cervical Spine Pathology

Cervical Radiculopathy

• New or progressive arm numbness with neck pain requires consideration of cervical radiculopathy, which results from nerve root compression due to disc herniation, foraminal stenosis, or degenerative spondylosis 1
• Most cases resolve spontaneously or with conservative treatment 1
• MRI is the most sensitive test for detecting soft tissue abnormalities but has high false-positive rates in asymptomatic individuals 1
• Physical examination findings correlate poorly with MRI evidence of nerve root compression 1

Cervical Myelopathy (Red Flag)

• Bilateral upper extremity paresthesias warrant urgent cervical spine MRI to exclude central cord syndrome or cervical myelopathy 7
• Central cord syndrome presents with bilateral hand numbness and burning dysesthesias, with greater upper extremity than lower extremity involvement 7
• Alarm symptoms include leg weakness, unsteady gait, numbness radiating from chest/groin downward, and pain worsening when lying down 7
• MRI within 12 hours is recommended if cord compression is suspected 7

Systemic and Metabolic Causes

Peripheral Neuropathy

• Diabetes, hypothyroidism, vitamin B12 deficiency, alcohol use, and certain medications can cause peripheral neuropathy, though these typically produce bilateral symmetric symptoms 6, 3
• Assessment should include testing small-fiber function (pinprick, temperature) and large-fiber function (vibration, 10-g monofilament) 6
• Screening labs should include glucose/HbA1c, thyroid function, vitamin B12, and renal function 6
• Electromyography with nerve conduction studies identifies the pattern (axonal vs. demyelinating, mononeuropathy vs. polyneuropathy) 6

Less Common Causes

Thoracic Outlet Syndrome

• Can cause ulnar-distribution symptoms and must be differentiated from ulnar nerve entrapment and cervical radiculopathy 3

Myofascial Trigger Points

• Trigger points in the infraspinatus and teres minor can reproduce upper extremity numbness and tingling, though this is uncommon 8
• Consider when more common neural compression cannot be identified 8

Critical Red Flags Requiring Urgent Evaluation

• Acute onset, rapidly progressive, or multifocal paresthesias require urgent evaluation to exclude Guillain-Barré syndrome or vasculitis 9
• Bilateral symptoms with motor weakness or severe dysautonomia are warning signs 9
• Symptoms with decreased leg strength, unsteady gait, or radiating numbness from chest/groin suggest cervical myelopathy 7

Diagnostic Algorithm

1. Determine distribution: Median nerve (thumb/index/middle fingers) suggests carpal tunnel; ulnar nerve (little/ring fingers) suggests ulnar entrapment; dermatomal pattern suggests radiculopathy 2, 3

2. Assess for bilateral involvement: Unilateral symptoms favor focal compression; bilateral symptoms raise concern for polyneuropathy or cervical myelopathy 6, 7

3. Identify red flags: Rapid progression, bilateral symptoms, leg involvement, or gait disturbance warrant urgent MRI cervical spine 7

4. Perform targeted physical examination: Durkan maneuver for carpal tunnel, Spurling's test for radiculopathy, assessment of intrinsic hand muscle strength 2, 3

5. Order electrodiagnostic studies when diagnosis is uncertain, to confirm nerve entrapment, assess severity, or differentiate peripheral from central causes 6, 2, 5

6. Screen for systemic causes with glucose, HbA1c, TSH, vitamin B12, and medication review if bilateral or no clear compressive etiology 6