What are the differential diagnosis and management options for a patient with right hemidiaphragm eventration?

Right Hemidiaphragm Eventration: Differential Diagnosis and Management

For a patient with right hemidiaphragm eventration, the primary differential includes diaphragmatic paralysis (distinguished by paradoxical motion on fluoroscopy), traumatic or congenital diaphragmatic hernia (with visceral herniation into thorax), and true eventration (elevated but intact diaphragm without paradoxical movement), and symptomatic patients should undergo diaphragmatic plication via minimally invasive thoracoscopic approach. 1

Differential Diagnosis

Key Distinguishing Features

Diaphragmatic Eventration vs. Paralysis:

• Eventration presents with abnormal diaphragmatic elevation (>2.5 cm above the contralateral side) but demonstrates no paradoxical motion on fluoroscopy, as the diaphragm remains anatomically continuous though attenuated 2, 3
• Diaphragmatic paralysis shows paradoxical motion during respiration on fluoroscopic examination, moving cephalad during inspiration instead of caudally 4, 1
• Fluoroscopy is the reference standard for differentiating these conditions 4

Diaphragmatic Hernia:

• CT scan is the gold standard for diagnosing diaphragmatic hernia, showing discontinuity of the diaphragm, herniation of abdominal contents into thorax, "collar sign" (constriction at rupture level), or "dependent viscera sign" (abdominal organs abutting chest wall) 5
• Right-sided hernias are less common than left-sided (12-40% vs 50-80% in blunt trauma) due to protective effect of the liver 5
• Hernias present with both respiratory and gastrointestinal symptoms, including potential bowel obstruction, strangulation, or volvulus 5, 6

Etiology Considerations

Congenital eventration results from abnormal myoblast migration to the septum transversum, causing attenuated muscular fibers while maintaining normal diaphragmatic attachments 3

Acquired eventration occurs from phrenic nerve injury, which can be:

• Traumatic (most common acquired cause)
• Post-infectious (rare, following febrile illnesses causing nerve palsies) 7
• Iatrogenic (surgical injury)

Diagnostic Workup

Imaging Algorithm

Initial evaluation:

• Chest X-ray (anteroposterior and lateral) as first-line study showing hemidiaphragm elevation >2.5 cm 5, 8
• Right-sided eventration may be underdiagnosed, with recent data suggesting 23.5% prevalence in systematic reviews versus historically reported lower rates 8

Confirmatory testing:

• Fluoroscopy to assess for paradoxical motion (present in paralysis, absent in eventration) 4, 1
• Chest ultrasound is highly recommended, showing concordant results with fluoroscopy, can evaluate diaphragmatic excursion amplitude, thickness, and contraction with high sensitivity and specificity 4
• CT scan with contrast if diaphragmatic hernia suspected, to evaluate for visceral herniation, diaphragmatic discontinuity, and complications like bowel ischemia 5

Advanced imaging when needed:

• Cine dynamic MRI sequences allow direct visualization of diaphragm motion and comprehensive chest wall muscle analysis 4

Management

Conservative Management

Asymptomatic patients:

• Observation is appropriate for incidentally discovered eventration without symptoms 2, 3
• Most adults with eventration are asymptomatic and require no intervention 3

Surgical Indications

Surgery is indicated for symptomatic patients only, presenting with: 2, 3, 1

• Dyspnea (most common symptom, occurring in 86% of symptomatic cases) 6
• Orthopnea
• Recurrent pneumonia
• Tachypnea
• Failure to thrive (pediatric patients)
• Non-specific gastrointestinal symptoms

Surgical Technique

Diaphragmatic plication is the established treatment: 2, 3, 1

Approach selection:

• Minimally invasive thoracoscopic plication is preferred for stable patients, using 3-port video-assisted thoracoscopic surgery (VATS) 4, 3, 1
• Mini thoracotomy is an alternative minimally invasive option with less hospital stay and pain compared to open approaches 7
• Open laparotomy reserved for unstable patients or when hernia repair with mesh reinforcement needed 4

Technical considerations:

• Primary repair using non-absorbable sutures when possible 4
• For defects >3 cm, mesh reinforcement is recommended to prevent recurrence 4
• Biosynthetic, biologic, or composite meshes are preferred due to lower recurrence rates, higher infection resistance, and lower displacement risk 4

Expected Outcomes

Postoperative results:

• Immediate symptom remission in most patients, with gradual improvement over one year in others 2
• Normal diaphragmatic position restored in 93% of patients (14/15 in one series) 2
• The operated hemidiaphragm typically becomes immobile without paradoxical motion postoperatively 2
• No symptom relapse during follow-up in patients with immobile diaphragms 2
• Plication improves lung volumes and decreases paradoxical elevation 1
• Safe procedure with excellent outcomes and symptom improvement 1

Clinical Pitfalls

Common diagnostic errors:

• Unrecognized eventration can lead to unnecessary workups for other pathologies, as it may mimic pleural effusion, mass lesions, or pulmonary consolidation 8
• Initial chest X-ray findings can be misinterpreted in 25% of diaphragmatic pathology cases 5
• Right-sided diaphragmatic injuries have 50% delayed diagnosis rate, often presenting with complications 5

Critical distinction: If CT shows visceral herniation with signs of bowel ischemia (wall thickening, absent contrast enhancement, spontaneous hyperdensity), this represents a surgical emergency requiring immediate intervention for potential strangulation, not simple eventration 5