What are the possible causes and treatments for worsening right arm pain accompanied by numbness and tingling over a few months?

Worsening Right Arm Pain with Numbness and Tingling Over Several Months

You need to systematically evaluate for nerve compression syndromes, starting with cervical radiculopathy and peripheral nerve entrapments, while ruling out metabolic and systemic causes that predispose to neuropathy. 1

Initial Diagnostic Approach

The progressive nature of symptoms over months with both pain and sensory changes suggests either:

• Nerve compression (cervical spine, thoracic outlet, or peripheral entrapment sites)
• Polyneuropathy from systemic causes
• Mononeuropathy from focal nerve damage

Key History and Physical Examination Elements

Assess the specific distribution of symptoms: 2

• Thumb, index, and middle fingers → Median nerve (carpal tunnel syndrome most likely)
• Little finger and ulnar half of ring finger → Ulnar nerve compression (cubital tunnel at elbow or ulnar tunnel at wrist)
• Entire arm with proximal radiation → Cervical radiculopathy or thoracic outlet syndrome 3

Test for predisposing conditions: 4

• Diabetes screening (glucose, HbA1c)
• Thyroid function (hypothyroidism)
• Vitamin B12 levels
• Renal function (creatinine, eGFR) 1
• History of alcohol use, smoking, rheumatoid arthritis 2

Perform specific provocative tests: 2, 5

• Wrist hyperflexion test (Phalen's) and median nerve percussion (Tinel's at wrist) for carpal tunnel syndrome
• Elbow flexion test and Tinel's at elbow for cubital tunnel syndrome
• Assess for nocturnal paresthesias (highly suggestive of carpal tunnel syndrome) 5

Essential Diagnostic Testing

Electrodiagnostic studies are critical: 1

• Electromyography (EMG) with nerve conduction studies to differentiate:
  • Mononeuropathy vs. polyneuropathy
  • Axonal vs. demyelinating patterns
  • Specific site of nerve compression 1, 2

Consider imaging based on clinical suspicion: 2

• Cervical spine imaging if symptoms suggest radiculopathy
• Chest radiography if thoracic outlet syndrome suspected 3

Treatment Algorithm

For Confirmed Nerve Entrapment Syndromes

Carpal tunnel syndrome (most common): 2, 5

• Initial conservative management: Volar wrist splinting (especially at night)
• Steroid injection into carpal tunnel if splinting insufficient 2
• Surgical decompression (transverse carpal ligament release) if conservative measures fail or if irreversible motor/sensory changes developing 5

Cubital tunnel or ulnar tunnel syndrome: 2, 6

• Conservative management with activity modification and elbow padding
• Surgical decompression if symptoms progress
• Peripheral nerve stimulation may be considered for refractory neuropathic pain (75% pain relief reported in recent cases) 6

Thoracic outlet syndrome: 3

• Combined surgical approach with transaxillary first rib resection and transcervical scalenectomy shows 95% improvement rate in appropriate candidates 3

For Neuropathic Pain Management

Duloxetine is the only evidence-based pharmacologic treatment: 4

• Dosing: Start 30 mg daily for first week (to reduce nausea), then increase to 60 mg daily 4
• Provides 30-50% pain reduction for neuropathic pain 4
• Also improves numbness and tingling in addition to pain 4
• Must taper slowly when discontinuing to avoid withdrawal symptoms 4

Pregabalin showed superior results in one 2020 trial: 4

• 93% improvement in visual analog scores at 6 weeks vs. 38% with duloxetine (P < .001) 4
• However, this is a single study and not yet incorporated into formal guidelines

Avoid these interventions - insufficient evidence: 4

• Gabapentin (no consistent benefit demonstrated)
• Tricyclic antidepressants (no strong supporting trials)
• Topical amitriptyline/ketamine (462-patient RCT showed no benefit) 4
• Oral cannabinoids (increased toxicity without benefit) 4

Adjunctive Therapies with Preliminary Evidence

May consider but require larger confirmatory studies: 4

• Acupuncture: Some trials show improvement in physical function and sensory symptoms 4
• Exercise therapy: Small studies suggest benefit for neuropathy symptoms 4
• Scrambler therapy: One trial showed 50% improvement in pain, tingling, and numbness vs. TENS 4

Critical Pitfalls to Avoid

Do not delay surgical intervention for carpal tunnel syndrome if motor weakness or thenar atrophy present - irreversible changes may occur 5

Do not assume single-site compression - approximately 40-50% of thoracic outlet syndrome patients have associated peripheral nerve compression 3

Do not overlook systemic causes - diabetes, hypothyroidism, B12 deficiency, and renal insufficiency are common treatable causes that must be screened 4, 1

Recognize that polyneuropathy prevalence increases dramatically with age (7% in those over 65 years) and 20-25% remain idiopathic despite thorough workup 7