What are the potential causes and management options for tingling in hands and fingers in an adult patient with a history of coronary artery disease (CAD) who has recently undergone coronary artery bypass grafting (CABG) using bilateral internal mammary artery (BIMA) grafts?

Tingling in Hands and Fingers Post-CABG with BIMA

The tingling in your hands and fingers after BIMA grafting is most likely due to brachial plexus injury from surgical positioning or sternal retraction during the procedure, not a vascular complication of the grafts themselves.

Primary Etiology: Brachial Plexus Injury

Mechanism of Injury

• Bilateral internal mammary artery harvesting requires extensive sternal retraction and arm positioning that stretches the brachial plexus, particularly affecting the lower trunk (C8-T1) which supplies sensation to the ulnar aspect of the hand and fingers 1.
• The risk of sternal reconstruction is significantly increased with BIMA grafting (relative risk 3.24,95% CI: 1.54–6.83), which correlates with more aggressive retraction during the procedure 1.
• BIMA harvesting adds approximately 23 minutes to operative time (3-4 hours total), prolonging the duration of potentially injurious positioning 1.

Clinical Presentation Pattern

• Symptoms typically manifest in the immediate postoperative period as paresthesias, numbness, or tingling in the hands and fingers.
• The distribution often follows dermatomal patterns (C5-T1) depending on which nerve roots were affected during positioning.
• Bilateral symptoms are common given the bilateral nature of the surgical approach.

Critical Differential Diagnoses to Exclude

Cardiac-Related Causes (Must Rule Out First)

• Post-CABG patients have twice the incidence of adverse cardiac events compared to non-CABG patients, with graft failure occurring in 10-20% at 1 year 2.
• Obtain immediate 12-lead ECG to exclude new ischemic changes suggesting graft-related ischemia 2.
• Check troponin levels to exclude acute myocardial injury, as saphenous vein graft failure with atherosclerosis is common 2.
• If cardiac workup is negative, stress imaging (nuclear perfusion, stress echo, or cardiac MRI) should be performed to definitively exclude graft-related ischemia 2.

Vascular Causes

• Internal mammary artery grafts have superior patency (90-95% at 10-15 years), making graft-related vascular compromise to the upper extremities extremely rare 3.
• Subclavian steal syndrome is theoretically possible but exceedingly uncommon with proper surgical technique.
• Assess bilateral radial pulses and blood pressure in both arms to exclude asymmetric perfusion.

Neurological Causes Beyond Positioning

• Perioperative stroke occurs in approximately 0.9% of CABG patients and could present with upper extremity paresthesias 4.
• Cervical spine pathology (pre-existing or exacerbated by positioning) can mimic brachial plexopathy.
• Peripheral neuropathy from diabetes (present in 27.1% of BIMA patients) may be unmasked or worsened perioperatively 4.

Diagnostic Workup Algorithm

Immediate Assessment (Within 24-48 Hours)

1. Complete neurological examination focusing on:

   • Dermatomal sensory distribution (C5-T1)
   • Motor strength testing of intrinsic hand muscles
   • Reflexes (biceps, triceps, brachioradialis)
   • Presence of Horner's syndrome (suggests lower trunk/T1 injury)

2. Vascular assessment:

   • Bilateral radial and ulnar pulses
   • Blood pressure in both arms (>15 mmHg difference suggests subclavian pathology)
   • Capillary refill and temperature of digits

3. Cardiac evaluation (as outlined above) to exclude ischemia 2.

If Neurological Examination Confirms Peripheral Nerve Injury

• Nerve conduction studies and electromyography (EMG) at 3-4 weeks post-injury provide definitive diagnosis and prognosis.
• Earlier EMG is not helpful as denervation changes take 2-3 weeks to develop.
• MRI of brachial plexus if diagnosis remains unclear or symptoms are severe/progressive.

Management Strategy

Conservative Management (First-Line)

• Most brachial plexus injuries from surgical positioning are neurapraxias that resolve spontaneously within 3-6 months.
• Reassurance and patient education about expected recovery timeline.
• Physical therapy focusing on:
  • Range of motion exercises to prevent contractures
  • Strengthening exercises as motor function returns
  • Desensitization techniques for dysesthesias

Symptomatic Treatment

• Neuropathic pain management:
  • Gabapentin 300 mg at bedtime, titrate up to 900-1800 mg/day in divided doses
  • Pregabalin 75 mg twice daily, titrate to 150-300 mg twice daily
  • Duloxetine 30-60 mg daily for painful neuropathy
• Avoid NSAIDs, which are explicitly contraindicated in the setting of CABG surgery due to increased cardiovascular thrombotic events 2.

Monitoring and Follow-Up

• Reassess at 4-6 weeks with repeat neurological examination.
• If no improvement by 3 months, obtain EMG/nerve conduction studies.
• Refer to neurology or hand surgery if:
  • Progressive motor weakness develops
  • No improvement by 6 months
  • Severe functional impairment affecting activities of daily living

Prognosis and Expected Recovery

Timeline

• Neurapraxia (most common): Complete recovery in 6-12 weeks
• Axonotmesis (moderate injury): Recovery over 3-6 months as axons regenerate at 1 mm/day
• Neurotmesis (complete nerve disruption): Rare in positioning injuries; may require surgical intervention

Factors Affecting Recovery

• Severity and duration of intraoperative compression
• Patient age (younger patients recover better)
• Presence of diabetes (delays nerve regeneration) 4
• Preexisting cervical spine disease

Critical Pitfalls to Avoid

• Do not dismiss upper extremity symptoms in post-CABG patients without first excluding cardiac ischemia, as these patients have more extensive coronary disease and worse outcomes 3, 2.
• Do not order EMG/nerve conduction studies in the first 2-3 weeks post-surgery, as they will be falsely negative and waste resources.
• Do not prescribe NSAIDs for pain management in post-CABG patients due to FDA contraindication 2.
• Recognize that multiple mechanisms can coexist: a patient can have both positioning-related neuropathy and developing graft complications 3, 2.
• BIMA patients have increased risk of sternal complications (RR 3.24), so monitor for signs of mediastinitis (fever, sternal instability, drainage) which occurred in 2.2% of BIMA patients 1, 4.