What causes hand numbness and how is it treated?

Hand Numbness: Causes and Treatment

Primary Diagnostic Considerations

Hand numbness requires systematic evaluation starting with the most common causes: carpal tunnel syndrome (median nerve compression), peripheral neuropathy, cervical radiculopathy, and thoracic outlet syndrome. 1, 2

Most Common Causes

• Carpal tunnel syndrome is the most frequent nerve entrapment condition, causing decreased pain sensation and numbness in the thumb, index, and middle fingers 2, 3
• Peripheral neuropathy from diabetes, chemotherapy, vitamin B12 deficiency, or thyroid dysfunction presents with numbness and tingling, often in a "glove and stocking" distribution 4, 1
• Cervical radiculopathy can cause decreased sensation in specific finger distributions depending on the nerve root involved 2
• Thoracic outlet syndrome results from compression of the brachial plexus, causing chronic arm and hand paresthesia, numbness, or weakness 4, 5
• Ulnar nerve compression (cubital tunnel or ulnar tunnel syndrome) causes decreased sensation of the little finger and ulnar aspect of the ring finger 2

Initial Assessment Approach

History and Physical Examination

• Obtain a comprehensive history characterizing the numbness: onset, distribution (which fingers), progression, exacerbating factors, and associated symptoms like pain or weakness 1, 6
• Assess pain using a simple pain scale 4
• Identify risk factors: diabetes mellitus, smoking, alcohol consumption, rheumatoid arthritis, hypothyroidism, chemotherapy history, repetitive hand activities 1, 2

Specific Physical Tests

• For carpal tunnel syndrome: Test for decreased sensation in thumb, index, and middle fingers; perform wrist hyperflexion (Phalen's test) and median nerve percussion (Tinel's sign) to reproduce symptoms 2
• For peripheral neuropathy: Perform 10-g monofilament test, vibration testing with 128-Hz tuning fork, pinprick sensation testing, and ankle reflex assessment 6
• For thoracic outlet syndrome: Evaluate for symptoms with shoulder abduction and assess for neurological deficits in specific distributions 4
• For ulnar nerve compression: Test sensation of little finger and ulnar ring finger, assess intrinsic muscle weakness 2

Laboratory and Imaging Workup

Essential Laboratory Tests

• Fasting blood glucose and hemoglobin A1c to assess for diabetes mellitus 1, 6
• Vitamin B12 level to evaluate for deficiency 1, 6
• Thyroid function tests (TSH, free T4) to assess for thyroid dysfunction 1, 6
• Complete blood count to evaluate for anemia 6

Advanced Testing When Indicated

• Electromyography helps differentiate between cervical radiculopathy, thoracic outlet syndrome, and peripheral nerve compression 2
• Radiography may identify cervical rib, anomalous first rib, or post-traumatic changes in thoracic outlet syndrome 4
• MRI is indicated when central causes (cervical spine pathology, stroke) are suspected 4, 7
• CT or CT angiography in neutral and stressed positions for thoracic outlet syndrome evaluation 4

Treatment Strategies

For Carpal Tunnel Syndrome

• Volar splinting is first-line conservative treatment 2
• Steroid injection often ameliorates symptoms 2
• Surgical decompression when conservative measures fail 3

For Peripheral Neuropathy

• Optimize glucose control in diabetic neuropathy to prevent progression 1
• First-line medications: Duloxetine, pregabalin, or gabapentin for neuropathic pain, numbness, and tingling 4, 1
• Physical activity has been shown to improve neuropathy symptoms 4, 1
• Acupuncture demonstrates efficacy in decreasing pain intensity, though evidence for chemotherapy-induced peripheral neuropathy is limited 4
• Acetaminophen and nonsteroidal anti-inflammatory drugs for pain management 4

For Thoracic Outlet Syndrome

• Conservative management with physical therapy initially 4
• Surgical decompression (transaxillary first rib resection with transcervical scalenectomy) for refractory cases, with approximately 93% reporting symptom improvement 5
• The central objective is preserving digits and hand function without sacrificing vascular access in dialysis patients 4

For Ulnar Nerve Compression

• Conservative management with activity modification and elbow padding 2
• Surgical decompression or transposition for refractory cases 2

Critical Pitfalls to Avoid

• Do not overlook bilateral symptoms, which typically suggest systemic causes like diabetes, hypothyroidism, or vitamin deficiencies rather than isolated nerve compression 2
• Do not rely on single diagnostic tests for peripheral neuropathy; at least two tests should be performed 6
• Do not miss thoracic outlet syndrome, as approximately 40-50% of patients have associated peripheral nerve compression symptoms, yet only 10% show objective findings on examination 5
• Do not assume all hand numbness in cancer survivors is chemotherapy-induced; 30-40% of patients develop neuropathy after taxane or platinum-based chemotherapy, but other causes must be excluded 4
• Do not forget to assess for vascular steal syndrome in dialysis patients with hand numbness, as this represents a critical complication requiring prompt recognition 4

Referral Considerations

• Endocrinology for diabetes management in diabetic neuropathy 6
• Hand surgeon or orthopedics for carpal tunnel syndrome requiring surgical intervention 3
• Vascular surgery for thoracic outlet syndrome or vascular steal syndrome 4
• Neurology for complex peripheral neuropathy or when electrodiagnostic testing is needed 1