What is the best course of action for a post-operative day #4 open heart surgery patient with a history of cardiovascular disease, complaining of left thigh tingling and numbness to the anterior and medial side?

Lateral Femoral Cutaneous Nerve Injury (Meralgia Paresthetica)

This patient has lateral femoral cutaneous nerve injury (meralgia paresthetica) from femoral artery cannulation during cardiopulmonary bypass, which is a recognized complication of open heart surgery and typically resolves spontaneously without intervention. 1

Clinical Recognition

The distribution of symptoms—anterior and medial thigh tingling and numbness—is pathognomonic for lateral femoral cutaneous nerve injury, which occurs when the nerve is compressed or injured during femoral artery access for cardiopulmonary bypass cannulation. 1 This nerve provides pure sensory innervation to the anterolateral and anteromedial thigh without motor function, explaining why patients have isolated sensory symptoms. 1

Immediate Assessment

• Rule out femoral nerve involvement by testing quadriceps strength (knee extension) and checking for saphenous nerve distribution symptoms (medial leg below knee), as femoral nerve injury would require more aggressive evaluation. 1
• Examine for signs of vascular compromise including distal pulses, capillary refill, and limb temperature, as femoral artery complications can present with neurological symptoms. 1
• Document the precise sensory distribution to differentiate lateral femoral cutaneous nerve injury from lumbar plexopathy or other nerve injuries. 1

Management Approach

Reassurance and observation are the primary interventions, as lateral femoral cutaneous nerve injuries following femoral artery surgery are typically transient with complete recovery or significant improvement by hospital discharge. 2 In a prospective study of 364 consecutive open heart surgery patients, 85.7% of neurological complications were central (not peripheral), and peripheral nerve injuries like this one showed complete recovery in the vast majority of cases. 2

Conservative Management

• Avoid compression of the inguinal region from tight dressings, positioning, or external pressure. 1
• Provide symptomatic relief with gabapentin or pregabalin if dysesthesias are bothersome, though most patients tolerate mild sensory symptoms without pharmacologic intervention. 1
• Reassure the patient that this is a recognized complication of femoral artery cannulation and that spontaneous resolution is expected over weeks to months. 1, 2

Prognosis and Follow-Up

The prognosis is excellent, with the majority of patients experiencing complete resolution or significant improvement. 2 In the cardiac surgery population studied, peripheral nerve pareses represented only 14.3% of neurological complications, and these were uniformly transient. 2

• Document baseline symptoms clearly in the medical record for medicolegal purposes and to track recovery. 2
• Schedule outpatient neurology follow-up only if symptoms persist beyond 3 months or worsen, as this would be atypical and warrant electrodiagnostic studies. 1
• No imaging or electrodiagnostic studies are indicated acutely unless there is concern for alternative diagnoses such as lumbar plexopathy, femoral nerve injury with motor involvement, or vascular complications. 1, 2

Critical Distinctions

This presentation differs from brachial plexus injury (which occurs in 1-4% of median sternotomy cases from sternal retraction) and affects the upper extremity. 3 It also differs from central neurological complications (stroke, encephalopathy) which occurred in 85.7% of neurological events in cardiac surgery patients and carry significantly worse prognosis. 2

The key clinical pitfall is mistaking this benign peripheral nerve injury for a more serious central neurological complication or vascular emergency. The isolated sensory distribution without motor deficits, hemodynamic instability, or altered mental status distinguishes this from conditions requiring urgent intervention. 1, 2